Organogenesis and Organ Structure (3)

Which is bigger, the afferent arteriole or the efferent arteriole? And why?

A detail that is important to remember for the physiological understanding of the nephron is that the afferent arteriole is larger than the efferent arteriole: this is relevant because it means that the resistances are higher at the level of the efferent arteriole with respect to the afferent one, and this results in an increment in the filtration pressure at the level of the glomerulus proper.

What is a renal lobule? How is it formed?

A group of nephrons emptying into one collecting duct; A renal lobe is formed by a pyramid whit on each side half of a renal column. On top of each pyramid there are extensions called medullary rays. A renal lobule is formed by a medullary ray and the convoluted region of the cortex on each side; the lobule is delimited by an intralobular vein on each side.

Clinical Drop: What are the symptoms of ARDS?

A person that suffers from this syndrome has shortness of breath (dyspnea), tachypnoea and cyanosis.

Clinical Drop: What are the various anomalies in this image?

A: unilateral renal agenesis (on one side the kidney does not develop); B: on the right side we have a pelvic kidney, while on the left side the kidney is divided with a bifid ureter; C: on the right side we have a malrotation of the kidney, while on the left side we have bifid ureter and supernumerary kidney; D: crossed renal ectopia, the left kidney crossed to the right side and fused with the right kidney; E: discoid kidney resulting from fusion of the kidneys while they were in the pelvis; supernumerary left kidney resulting from the development of 2 metanephric diverticula.

Clinical Drop: What is autosomal recessive polycystic kidney disease (ARPKD)?

ARPKD develops during childhood, which means that very early the baby starts to have problems. It is due to a mutated gene which codes for the protein fibrocystin. Image: Smaller cysts are visible in the kidney parenchymal.q

Clinical Drop: What is a common form of cancer in males related to the prostate gland?

Adenocarcinoma of the prostate gland 1. It is related to the glandular elements of the gland and it metastasizes to bones via blood vessels and 1/3 of men older than 75 years have it. 2. It is the second most common form of cancer in males.

Clinical Drop: What is the normal and abnormal development of the processus vaginalis?

After the testis have migrated in the scrotal bursa, the communication between the processus vaginalis and rest of the peritoneal cavity must be obliterated, otherwise the organs of the peritoneal cavity can slide through the processus vaginalis in the inguinal canal ending up in the scrotal bursa. In the event that peritoneal organs manage to slide through the processus vaginalis, the implications might be the following: 1. The herniating structures could be compressed 2. During the herniation the structures may twist, up to the point that they undergo necrosis In [image A] we have the physiological process of shutting down the communication between the processus vaginalis and the peritoneal cavity: the portion of processus vaginalis inside the scrotal bursa needs to remain since it will later become the tunica vaginalis (serosal part) of the testis. Conversely, the proximal part needs to be occluded, so that no communication can take place. What usually happens if the communication is not interrupted, is that the loops of the small bowels slide inside the inguinal canal and the scrotal bursa. This condition is called indirect inguinal hernia (this frequently happens since the small intestine is the most mobile part of the digestive tract) (image C). If there is only a partial obliteration, it results in the formation of fluid-filled cyst and hydrocele (image B).

What are all of the components of the penis crossed by?

All of them are crossed by the urethra.

What transition do cells undergo as you move along the collecting system?

Along the collecting system, cells undergo a transition form cuboidal to columnar (in the papilla).

Stages of lung parenchyma maturation: 1• Pseudoglandular stage (6 to 16 weeks or 5 to 17 weeks) 2• Canalicular stage (16 to 24-28 weeks or 16 to 25 weeks) 3• Terminal sac stage (24-28 weeks to late fetal period) 4• Alveolar stage (32-36 weeks to 8 years or more) What is the alveolar stage?

Alveolar stage (32-36 weeks to 8 years or more) 1. It begins in the weeks just before delivery. In this stage the terminal sacs become partitioned by septae (primary septation) to form sacs similar to alveoli bulging from respiratory bronchioles and alveolar ducts and sacs. In the meanwhile, type I pneumocytes become thinner and capillaries bulge in the lumen of alveoli. 2. By 38th week the alveolocapillary membrane is sufficiently thin. 3. 95% of mature alveoli will be formed only after birth. At birth, 20-70 million alveoli. 4. After birth we have an increment of the number of respiratory bronchioles and primordial alveoli. 4. A secondary septation leads to mature alveoli (200-400 million by 8 years).

Clinical Drop: What happens if the air-blood barrier is disrupted?

An intact air-blood barrier is extremely important: disruption of the barrier, which also prevents the leakage of fluid from the alveolar capillaries into the interalveolar space and in the lumen of the alveolus = If the barrier is damaged, then the endothelial lining is not efficient anymore and we can have an accumulation of fluid in the intra alveolar space. = may cause an ARDS = Acute Respiratory Distress Syndrome (ARDS causes dyspnea, mostly commonly referred to as shortness of breath).

Clinical Drop: What else can go wrong within the uterus?

Another situation can take place with aging: the muscles of the lower portion of the pelvic cavity gets less strong and the neck of the uterus can start to slide inside the vagina, more than the normal, even part of the body of the uterus, which can even arrive to protrude from the vagina.

How is the female inguinal canal different compared to the male?

As previously said, the inguinal canal is more rudimental compared with the one in males: the wall is made in the same way, nevertheless the content differs.

How many nephrons are there at birth?

At birth we have around 800,000 to 1,000,000 nephrons.

What happens to the vagina at menopause?

At menopause, vaginal tissue becomes thinner and less elastic, up to 47%, we also have a change in the vaginal microbiota (56%) and also there is a change in the pH and in the glycogen content.

What are the endocardial tubes and their role in the development of the heart?

At some point of development, we have the formation of 2 endocardial tubes in the region of the primary heart field and these tubes are in close relationship with the region of the intraembryonic mesoderm, which is going to develop in the pericardial cavity.

What happens at the beginning of the formation of the inguinal canal in terms of the abdominal cavity?

At the beginning, the mesonephric - gonadal complex is suspended in the abdominal cavity, it is kept in its position thanks to two ligamental devices: 1. One is located rostrally, it is called the cranial suspensory ligament (it attaches the gonads to the diaphragm) 2. The other one is located inferiorly, which is the caudal suspensory ligament (it can also be called genito-inguinal ligament or gubernaculum). The gubernaculum is attached on one side to the gonads whereas on the other it is fixed to the flood of the abdominal/ peritoneal cavity.

What can be found at the end of the trachea?

At the end of the trachea we find a region where it bifurcates, which is called carina trachea. There the trachea splits into the right and left bronchi, which will divide into lobar bronchi.

What do we find after the level of bronchioles?

At the level of the bronchioles, we find a lot of neuroendocrine cells that influence the state of contraction of the spiral muscle and the adjoining vessels present in the lung parenchyma.

What are Bartholin's glands?

Bartholin's glands are two bean shaped glands on either side of the vagina that secrete mucus during sexual stimulation; They are extramural glands that provide a mucous secretion used for protection and lubrication.

Clinical Drop: What causes more problems in the female urethra?

Because the female urethra is shorter it is more likely to contract infections and this infection can easily extend to the bladder.

Clinical Drop: What can go wrong with the urethra?

Benign prostatic hyperplasia (BPH) 1. We have an enlargement of mucosal glands and the urethra is partially strangulated, causing inability to begin and cease urination (dysuria), causing also nocturia (pee at night several times) and sensory urgency. 2. BPH is present in 50% of men older than 50 years and in 80% of men older than 80 years.

How is the right side of the 2 heart ventricles separated from the left side?

Between the 2 ventricles we find the interventricular septum.

What characteristics do bronchioles have?

Bronchioles: 1. There's no cartilage or submucosal glands. 2. The mucus cells and goblet cells are really very few and in terminal bronchioles are completely substituted by Clara cells = are secreting cells, but they do not produce mucus, but a substance very similar to surfactant. 3. The smooth muscle has a spiral arrangement and is important in determining the bore of the tubing system and resistance to airflow: the more I constrict, the less air enters. The neuroendocrine cells controls the muscle tone of bronchi and vessels. 💡 in people that suffer from asthma, you have a contraction (especially in bronchioles) of the spiral muscle layer that reduces the size of the tubing system. As a consequence, the air has to make a lot of effort to reach the alveoli and becomes very difficult to breathe.

Clinical Drop: What is congenital hydronephrosis?

CONGENITAL HYDRONEPHROSIS - Accumulation of fluid in the kidney: 1. We have a ureter obstruction, which causes a dilation of the pelvis and calyxes of the kidney and a consequent reduction in thickness of the cortex due to the stagnation of urine. 2. It can be caused by the bending of the junctions between the pelvis and a compression by an aberrant vessel, or due to an aberrant route of the ureter. 3. It can also be caused by anomalies in the development of the ureteric bud.

Stages of lung parenchyma maturation: 1• Pseudoglandular stage (6 to 16 weeks or 5 to 17 weeks) 2• Canalicular stage (16 to 24-28 weeks or 16 to 25 weeks) 3• Terminal sac stage (24-28 weeks to late fetal period) 4• Alveolar stage (32-36 weeks to 8 years or more) What is the canalicular stage?

Canalicular stage (16 to 24-28 weeks or 16 to 25 weeks) 1. This stage starts in the upper lobes. 2. The volume of the lumen of airways becomes larger and by the 24th week of development, each terminal bronchiole has formed 2 or more respiratory bronchioles and each of them is starting to give rise to primordial alveolar ducts (conduits in which the wall is mostly made by evaginations that start to have a thin wall). 3. We also start to see the formation of primordial alveoli or terminal sacs, dilation of the wall in which the epithelium lining them starts to become thin. 4. Also, we can notice the formation in the mesenchyme of blood vessels and association of capillaries, some of which are very attached to the region where the primordial alveoli are forming. 5. Some of the cells that line the terminal sac start to produce surfactants. 6. Surfactant production begins at 20th - 22nd week (reduces surface tension and prevents atelectasia, i.e. collapse of sacs during exhalation). 7. Survival is hardly possible, around the 24th week the baby may survive if there is a very good intensive care.

Why do we need cartilage in the tracheo-bronchial tree?

Cartilage is very important in the initial part because it protects the bronchial tree and keeps the lumen of the respiratory tree open; the cartilage is flexible and the more we move in the distal part, the less we need it, so in bronchioles we don't find any cartilage.

What is the epididymis?

Coiled tube inside the testes where sperm is stored; site of sperm maturation. The epididymis is one long tubular system that is coiled on itself and it is formed by pseudostratified columnar epithelium, which is surrounded by an evident layer of smooth muscle cells.

What is the urogenital system?

Combination of reproductive and urinary systems; The urinary organs and genital organs share many pathways and organs so we group them together to form one system (especially in the male, where the last part of the urinary tract is the same as the last part of the reproductive system).

Clinical Drop: What other set of problems can occur within the adrenal gland?

Congenital adrenal hyperplasia or adrenogenital syndrome: 1. Congenital adrenal hyperplasia is a group of autosomal recessive disorders encompassing enzyme deficiencies in the adrenal steroidogenesis pathway that lead to impaired cortisol biosynthesis. 2. Depending on the type and severity of steroid block, patients can have various alterations in glucocorticoid, mineralocorticoid, and sex steroid production that require hormone replacement therapy. 3. Presentations vary from neonatal salt wasting and atypical genitalia, to adult presentation of hirsutism and irregular menses.

Clinical Drop: What are congenital anomalies of the heart?

Congenital anomalies of the heart 1• Atrial septal defects, communication between the right and left atrium that causes blood to flow from left to right 2• Persistent atrioventricular canal, not a correct separation of the original atrioventricular canal 3• Ventricular septal defects, which is quite common and causes the communication between ventricles 4• Atrioventricular valve defects, which can be stenotic and not have the right size 5• Semilunar valvular stenosis 6• Septation defects of the outflow tract, the aorta and the pulmonary trunk can have an anomalous size (narrower or larger)

Clinical Drop: What is Congenital Bronchogenic Cyst?

Congenital bronchogenic cyst; 1. We may have the formation of a cyst from the trachea or from the bronchi (abnormal budding of the tracheobronchial anlage) that typical develop in the anterior mediastinum. 2. We can find in the mediastinum some cysts, usually one, which can even grow into the pericardium. 3. Some patients will discover it by chance, because it can cause no symptoms, but in some cases, it can cause recurrent infections or obstructions in the respiratory tree. 4. The bronchogenic cyst typically has cartilage plates and submucosal glands in the wall, similar to the normal microscopic anatomy of bronchi.

What is the distal convoluted tubule?

DCT - Functions more in secretion than reabsorption. Confined to the cortex. Last segment of the renal tubule.

Clinical Drop: What problems can arise in the external sphincter device?

Damages to the spinal cord can cause the malfunctiomng of the external sphincter and so incontinence. Both sphinteric devices (particularly the external) with aging can become weaker causing incontinence.

How do the bladder and urethra develop?

Development of the bladder and urethra (from the cloaca): 1. The last portion of the hindgut will form a dilation called cloaca, which is in continuation with the allantois. 2. Between 4th - 7th week, the urorectal septum (a mesenchymal septum, in orange below) grows towards the cloacal membrane (at the level of the proctodeum) and when it reaches the membrane, the cloaca will be subdivided into two compartments: the anterior one, called the urogenital sinus (still in continuity with the allantois) and a posterior portion (which is in continuity with the digestive tract), forming the rectum and anal canal.

Clinical Drop: What is direct inguinal hernia?

Direct inguinal hernia: In this case, the loops of the intestine herniate by pushing the posterior abdominal wall of the inguinal canal.

Development of the heart: What do the 2 endocardial tubes and pericardial cavity continue to form? And when does this occur?

During the 4th week, because of the folding of the embryo, the endocardial tubes and the pericardial cavities start to come close together on the mid line and finally they will fuse together, forming a single tubular heart.

What is the timeline of phenotypic sexual differentiation?

During the 7th week the phenotypic (externally representation of something that happens at the level of the genome) differentiation begins, by the 12th week female or male characteristics of external genitalia can be recognized; by the week 20, the phenotypic differentiation is complete.

How is the Bowman's capsule formed?

During the embryological development of the tubular system there is the formation of a sort of cap that surrounds the glomerulus.

What is the minor calyx?

Each minor calyx is at the apex of a unit of the kidney parenchyma called Renal Pyramid.

What is the histology of the ejaculatory ducts?

Ejaculatory ducts: simple columnar epithelium surrounded by connective tissue and smooth muscle tissue and by the parenchyma of the prostate gland.

Why are elastic fibers important in the interalveolar septa?

Elastic fibers are important for the elastic recoil of the lung parenchyma after stretching. We can find elastic fibers in all the respiratory system, up to the level where gas exchange takes place.

Development of the heart: What does the sinus venosus evolve into?

Evolution of the sinus venosus (4th to 8th week) 1. On the left side, the sinus venosus regresses and forms the left side of the coronary sinus (sinus that drains blood from the heart into the right atrium); while on the right side it enlarges and forms the site of venous blood entry in the heart: the venae cave and the coronary sinus. 2. From the vitelline veins, we have the formation of the hepatic sinusoids. 3. Due to all these major changes in the heart system, the left umbilical vein (which carries oxygenated blood) will end up draining in the inferior vena cava and not anymore directly into the heart.

Clinical Drop: What is a exstrophy of the bladder?

Exstrophy of the bladder: 1. Due to a problem in the formation of the abdominal wall in the pelvic region: the urinary bladder protrudes from the incomplete abdominal wall, and the mucosa of the bladder is exposed to the outside. 2. It is caused by defects in migration of the mesoderm in between the ectoderm and the endoderm. Consequently, we will have defects also in the anterior wall of the urinary bladder. The mucosal surface of the posterior wall of the bladder, the bladder trigone and the ureteric openings are exposed. 3. The exstrophy of the bladder doesn't only affect the bladder but it may also affect the urethra leading to a condition (in males) called epispadia or hypospadias - which means that the urethra does not open at the tip of the penis as it should, but it opens in the dorsal surface of the penis.

What is produced by the mesenchyme to encourage branching?

FGF10 (Fibroblast Growth factor) is produced by the distal mesenchyme (purple) and therefore it produces branching. If we take FGF10 from the distal mesenchyme (purple) and we put it in the mesenchyme surrounding the trachea (green), we can see that the trachea is induced to branch. [of course, we are in an experimental setting, so in a colture with the primordium of the respiratory tract of an animal]. On the other hand, if we take the green, so the tracheal epithelium, and we put it where there is the FGF10, the branching is inhibited. So we can demonstrate experimentally what determines branching by taking pieces of tissue and moving them from one place to the other.

Clinical Drop: What type of tumors can form in the uterus?

Fibroids or uterine myomas or uterine leiomyomas or fibromas: 1. In the wall of the uterus there can be the formation of leiomyomas, solid tumours made by the proliferation of smooth muscle cells and fibrous tissue. 2. It can cause heavy or prolonged menstrual periods, abnormal bleeding between menstrual periods, pelvic pain (also due to the compression of other organs), low back pain, pain during intercourse. 3. It is the most common pelvic tumour in women.

What is the tunica albuginea?

Fibrous capsule that surrounds the testicle and divides it into lobules; the outer component of the testis is the tunica albuginea.

What needs to happen for the kidney to form?

For the kidney to form, we need an interaction between the epithelium of the ureteric duct and the mesenchyme of the metanephrogenic blastema.

Clinical Drop: What is the coarctation of the aorta?

Formation of a bulge in the aorta that can burst (aortic aneurysm) and cause infection of the heart (endocarditis) especially at the level of the semilunar valve of the aorta, brain haemorrhage, stroke, heart failure and premature coronary artery disease.

What is there a sudden increase of in the development of the kidney?

From the 10th to the 18th week, we have a progressive increase of the number of glomeruli or corpuscles; after that we have a rapid increase up to week 32 and then there is a stabilization.

How does the tracheobronchial tree continue to subdivide into progressively smaller airways?

From: 1. Segmental Bronchus (bronchus dividing into segments) 2. Subsegmental bronchi 3. Bronchioles

How do the general histological features change from the proximal to the distal part of the tracheo-bronchial tree? Are glands present?

Glands are found, as well, in the initial part of the system; glands (in the submucosa of the lower respiratory tree): more or less disappear together with the goblet cells; glands contribute to the mucus-serous secretion that covers the mucosa of the respiratory tract (they are useless when we're too distal).

When does glomerular filtration occur?

Glomerular filtration starts around the 9th week.

How do the general histological features change from the proximal to the distal part of the tracheo-bronchial tree? Are there goblet cells?

Goblet cells are part of the epithelium up to the segmental bronchi = a lot of goblet cells moving from the larger tubing system to the smaller tubing system goblet cells become less and less and then disappear (e.g. in respiratory bronchioles NO goblet cells).

Annotate this image: SOL - What can you see in this image?

Here we are looking at an interalveolar septa. We can see there's a thick portion, but also a spot where the wall of a capillary is really attached to the wall of the alveolus, to the point that he basal lamina of the endothelium of the capillary and the basal lamina of the endothelium of the alveoli are fused together.

Clinical Drop: Histologically speaking, what is the neuroblastoma characterized by?

Histologically speaking, the neuroblastoma is characterized by a peculiar arrangement of cells (or neuroblasts) that is called Homer - Wright pseudorosettes. The rosettes can acquire different shapes in different kind of neuroblastomas.

Clinical Drop: What can affect endocardial swelling to go wrong?

Hyperglycaemia (increased blood sugar) and hypoxia (decreased blood sugar) can affect cushion formation; maternal diabetes can increase the possibility to have cardiac defects.

Clinical Drop: What happens if elastic fibers are damaged?

If elastic fibers are damaged, we have a situation called emphysema. In this condition, air is trapped in the lumen of the lungs because the elastic recoil is absent or reduced.

What is the advantage of having a spiral arrangement of smooth muscle?

If it is simply circularly organised when I contract I just reduce the size of the lumen; if it is a spiral arrangement when I contract I also shorten it. 1. submucosal glands are further decreased; 2. cartilage is reduced to very few irregular plates.

What happens if the ureteric bud doesn not interact with the metanephric blastema?

If the ureteric bud doesn't interact with the metanephric blastema, we don't have the formation of the kidney.

What do you see in this image?

Image - We can see the opening of the ureters in the base of the triangle and we see the opening of the urethra at the apex of this triangle.

What happens in the development of the female gonad?

In a female gonad, the primitive medullary cords degenerate, so the portion of the gonadal cords, which is situated in the medulla, degenerates and then the communication with the mesonephros is lost; while the portion of the cortex, which is more superficial, remains and it keeps on surrounding the germ cells. Later on, the cortical cords will break down into isolated cell clusters, which will become the primordial follicles.

What is the first stage in the transformation of renal mesenchymal cells into epithelial cells?

In a first stage of the transformation of the renal mesenchymal cells into epithelial cells, we have E-cadherin everywhere, then the cells start to differentiate and E-cadherin is limited to the lateral surfaces and then we have the formation of tight junctions, together with the differentiation of the apical surface (Brush border).

What is found in between the endocervix and the ectocervix?

In between them, there is a transition zone, called transformation zone. 99% of the tumours of the uterus are formed in this zone.

Clinical Drop: What other problems can occur in both ARPKD and ADPKD?

In both ARPKD and ADPKD, other problems can occur, for example cysts can also be found also in the biliary tree, and hypertension can occur (problems with the kidneys will usually affect the control of blood pressure).

What does the reproductive system consist of in females?

In females, we have the ovaries (gonads), fallopian tube, the uterus and the vagina.

What is the corpora amilacea?

In histological preparations, it is very common to find in the lumen of the tubular sections of the gland, the corpora amilacea, which are concretion of the secretion inside the lumen of the gland and they may be confused with follicles of the thyroid gland.

What does the last portion of the ductus deferens lead into?

In its last portion, the ductus deferens presents a dilated portion, which leads into the prostate gland and receives the short ducts of the seminal vesicles forming ejaculatory ducts.

Clinical Drop: What can go wrong in relation to clara cells?

In patients that suffer from certain pathologies of the respiratory tree (like Chronic Obstructive Pulmonary Disease and Asthma) that have damage to the wall of the bronchioles and this protein, rather than remaining inside the bronchioles tend to go inside the bloodstream = The amount of protein in airway fluid may decrease and serum may increase during Chronic Obstructive Pulmonary Disease and Asthma.

How does the external genitalia develop in females?

In the females, what happens is the elongation of the genital tubercule, that is going to form the clitoris. The urethral folds remain separated from one another, and they will give rise to the labia minora, whereas the labioscrotal swellings on the side will become the labia majora. The urogenital groove that remains in the middle is going to be the vestibule of the vagina, this happens because the urethral folds that are forming the labia minora do not fuse together so that a space remains in between them, forming the vestibule of the vagina. In this region there will be the opening of both the vagina and the female urethra.

Development of the heart: What do we have on the inflow region of the heart?

In the inflow region of the heart, we have oxygenated blood coming from the umbilical vein and venous blood from the cardinal and vitelline veins.

How is blood supplied in the lungs? What are the types of blood circulation in the lungs?

In the lungs we can recognize 2 types of circulation: a functional circulation, responsible for oxygenating blood and the trophic or nutritional circulation to nourish the lungs.

Development of the heart: What do we have on the outflow region of the heart?

In the outflow portion we will have mixed blood that reaches the dorsal aorta through the pharyngeal arch arteries.

Annotate this diagram: SOL

In the picture, in orange, we have the smooth muscle fibers and, in green, the elastic fibers. We can see that these two types of tissue (especially the elastic one) are there up to the last part of the respiratory tree (alveoli); that's because elastic tissue is fundamental to allow for the elastic recoil.

Development of the heart: What will there be the formation of in the 2 atrioventricular canals?

In the region of the 2 canals, there will be the formation of the atrioventricular valves: the tricuspid valve on the right and the bicuspid or mitral valve on the left.

What are the inguinal canals?

In the region of the pelvis, both males and females possess an inguinal canal. The inguinal canals, in males, is the passage way through which the testis migrate in the scrotal bursa. In female, the gonads remain in the abdominal cavity and the inguinal canal connects the abdominal cavity with the labia majora.

What is developing medial to the mesonephros?

In the same region, medial to the mesonephros, we have the gonads.

What are the angle of anteflexion and the angle of anteversion?

In the uterus, we can recognize the angle of anteflexion and the angle of anteversion. 1. The angle of anteflexion is the angle that is formed by the axis of the uterine body and by the axis of the cervix. 2. The angle of anteversion is formed by the axis of the cervix and the axis of the vagina.

What are the different layers of the Bowman's capsule?

In this capsule we recognize a parietal layer and a visceral layer.

What about the efferent innervation?

In this case too we both have sympathetic and parasympathetic fibers. When sympathetic efferent fibers are activated, we have vaso-constriction and bronco-dilation. On the other hand, when parasympathetic fibers are activated, we have, vaso- dilation (if vessels have smooth muscles), bronco-constriction (antagonist responses to the previous ones) and, also, the increase secretion from the glands (not from the goblet cells, but mostly up to where I have glands in the submucosa) of the trachea-bronchial tree.

What can we see in this electromicrograph?

In this electromicrograph we can see type 2 pneumocytes, which are more "fat" than type 1. Surfactant not only facilitates inflation of the alveoli, but it also has some involvement in inflammatory reactions of the immune response, like Clara cells; thus it doesn't only have a mechanical purpose with respect to reducing the surface tension.

What are the cells of the renal corpuscle?

In this image above we can clearly notice that the parietal layer is characterized by very flat cells. They are not the cells in relation with the capillaries, their purpose is simply to line the structure. 1. On the other hand, the visceral layer is made by a special type of epithelial cells, the podocytes. 2. These cells, with their cytoplasmic processes, literally wrap themselves around the capillaries. The finest cytoplasmic processes of podocytes are called pedicels, which are going to come into contact with capillaries. 3. The brown structures represent the basal lamina, in between pedicels and the endothelium lining the capillaries. This basal lamina is actually very complex and will be further discussed in detail next year. 4. This structure is quite similar to type 1 pneumocytes with basal lamina and on the other side endothelial cells (check the sbobina on the respiratory system). 5. Contained within the basal lamina we find a special type of cells: mesangial cells, here colored in brown. 6. In this case we will call them intraglomerular mesangial cells, to distinguish them from the other mesangial cells, outside the glomerulus, which are called extraglomerular mesangial cells (you can see them in the image between the afferent and the efferent arteriole).

What can be seen in this image?

In this image we can see how many peritoneal layers contribute to the formation of the inguinal canal and of the scrotal bursa. 1. The abdominal wall is made by layers (skin, subcutaneous tissue, external oblique muscle, internal oblique muscle, fascia of the oblique muscle, transversus abdominis muscle, transversalis fascia and peritoneum). 2. During the formation of the inguinal canal, all these layers are pushed from the inside to the outside, so that finally we have some sort of extroflexions of the abdominal wall in communication with the scrotum and covering of testis, maintaining the same layers even around them.

Why does the lung in this example (image) not produce branching?

In this other experiment a lung bud epithelium, so a small sac from the epithelium of the lung is taken. If it is left alone in the Petri Dish, it won't branch, because there is just the epithelium (endoderm).

Clinical Drop: What is indirect inguinal hernia?

Indirect inguinal hernia: Through this hernia, the loops of the intestine access the inguinal canal via the internal inguinal ring, whereas they exit trough the external one.

Clinical Drop: What problems can occur in the urethra to do with its lumen size?

Inflammations of the urethra (possibly caused by sexual transmittable disease) causes its narrowing which can lead to disurya; if the inflammation is not treated it can lead to the formation of fibrot1c tissue which causes further narrowing of the urethra.

What is the internal urethral sphincter? Where is it located? What is it formed by?

Involuntary (smooth muscle) at bladder-urethra junction. Contracts to open. The internal urethral sphincter is located in the neck of the bladder formed by a thickening of smooth muscles fibers.

What is the nephron?

Is the functional unit of the kidney and is composed by different sections with different histological features which lead to different physiological functions.

What is the bladder?

It is a reservoir of urine, it can reserve from 250-350ml.

What is the broad ligament of the uterus divided into?

It is divided into the mesosalpinx; the mesovarium and the mesometrium.

How long is the uterus?

It is long 7-8 cm, which changes if there is the implantation of the egg.

How are bronchopulmonary segments separated?

It is separated from the other segments by septa (connective tissue).

Clinical Drop: What is a ventricular septal defects?

It is the most frequent congenital defect (12:10,000). Almost 70% of the ventricular septal defects occur in the membranous part of the septum. Initially we have a left-to-right acyanotic shunting of blood flow, but with time it can also cause right ventricular hypertrophy, which can lead to pulmonary hypertension and reverse of the shunt.

Why are the bronchioles important?

It's function is to lead air to where alveoli will be: of course it is important because if, for example, it gets occluded, air can't reach the alveoli. No gas exchange takes place in this section of the R.S.

About goblet cells, are they increasing in number going towards the bronchioles or are they becoming less and less?

Less and less.

Why are respiratory bronchioles called "respiratory"?

Let's imagine that, when entering the lumen of the respiratory bronchiole, on the right and on the left, I can enter small chambers here and there, so the wall is discontinuous (as it is in the terminal bronchiole) and, if I inter in those discontinuities, I find myself in alveolar chambers. Now let's imagine that traveling through the respiratory bronchiole, what comes next? I enter into the alveolar ducts.

What is the juxtaglomerular appartus?

Literally "close to the glomerulus". Associated to the vascular pole there is an apparatus, important for the control of blood pressure, but also for the regulation of the filtration from the kidney glomerulus. It will be further discussed in this lecture.

Male urethra:

Male urethra: it is approx 20cm long and it is divided into different segments: 1. Pre-prostatic urethra 2. Prostatic urethra 3. Membranous urethra 4. Penile urethra

Clinical Drop: Can many of these congenital anomalies of the heart occur together? If yes, what is this called?

Many defects of the heart occur together (e.g. tetralogy of Fallot).

Which mesenchyme induces branching and which inhibits it?

Mesenchyme from the tracheal region will inhibit branching when apposed to distal lung epithelium, while distal mesenchyme (from the region of lung bud formation) will induce ectopic branches when grafted adjacent to isolated tracheal epithelium.

Do you remember the story of the mesonephros?

Mesonephros forms in the urogenital crest/ridge.

What do we see in this image?

Microstructure of the trachea (section of the trachea in a region (depicted on the right) in between the rings.); When we look to a histological section of the trachea, we have to make sure in which portion it has been taken. For example, it can includes or not the cartilaginous ring, since the cartilage is not continuous. 1. In a histological preparation we can observe a mucosa, characterized by an epithelium and a lamina propria. 2. The epithelium is a pseudostratified ciliated epithelium and the lamina propria is pretty thick and it contains lots of elastic fibres, especially in the last portion of it, which can also be called elastic membrane. 3. After the lamina propria, we find the submucosa, which in the trachea is quite thick and it is characterized by the presence of many glands, which can be mucous secretory or serous mucus glands. After the submucosa we find the fibroelastic layer of the trachea, which is fibrous tissue with lots of elastic fibres. 4. If we were in a region where we can find cartilage, we would have found the mucosa, the submucosa and below it, some elastic tissue, the perichondrium, the cartilage, and some other elastic tissue. remember: In some places there are the rings and in between them there's no cartilage. If I make a cross-section where the rings are, I may expect to find cartilage; if I make a cross-section in between one ring and the other I may be looking at the section of the trachea where there's no cartilage. If there's a very large trachea (like in humans) I don't have the full section through the organ but just a small piece.

A person that has a tumor in the liver feels pain?

No, because our viscera, especially the solid viscera, do not have pain receptors. On the other hand, the hollow organs, (ex: the trachea-bronchial tree or the biliary tract), do have pain receptors, therefore can give rise to the sensation of pain.

Do we have cartilage in bronchioles?

No, but we have a relatively thick (compared to the size) smooth muscle layer organized in a spiral arrangement.

What about the epithelial cells? Do they have a lot of cilia? Are they still very tall? Is it a pseudostratified epithelium?

No, they are becoming shorter and shorter, and the amount of cilia is progressively reducing.

A person that has a tumor in the lungs does feel pain in general (unless it is extremely big)?

No, unless the tumor irritates one of the conduits inside the lungs, irritating the parietal pleura.

Clinical Drop: Where is pain information sent to from the uterus, cervix and uterine tube?

Nociceptive and pain information of the uterus, cervix and uterine tube reach the T10-L1, L2 segments of the spinal cord (same as lower ileum, sigmoid colon, and rectum).

How is it that we cough and why do we cough if an irritant enters our trachea?

Normally it is a reflex response: afferent sensory fibers, which for example innervate the trachea and the bronchi, send the signal of an irritation to the central nervous system and there, for example in the brain stem, there's a "cough center", that causes an outflow (efferent) of information towards the periphery that causes the cough reflex.

Are alveoli in communication with eachother? If so, how?

Oftentimes, alveoli are in communication with one another through very very tiny pores = "alveolar pores", which allow passage of air from one alveolus to another, so that they provide collateral respiration when one bronchiole may be occluded, for example. If one terminal or respiratory bronchiole were to be occluded, theoretically, it would mean that all the territory that is downstream (distal) does not receive air; that is not completely true though, because in-between groups of alveoli there are these very tiny opening called "pores".

What are cavernous bodies?

One of two columns of spongy tissue that runs through the shaft (body) of the penis.

What is hypospadias?

Opening of the urethra on the inferior surface of the penis; The two urethral folds need to come together as to delimit the penile urethra. If this coming together does not take place correctly, this would lead to the formation of some abnormal openings of the urethra along the inferior side of the penis. These abnormalities can be present in different regions of the ventral surface of the penis. To correct this defect, surgery may be performed even though it's not an easy procedure.

Clinical Drop: What is Potter Sequence?

POTTER SEQUENCE (Also called Potter syndrome/Oligohydramnios sequence): 1. Kidneys produce most of the amniotic fluid so if the kidneys don't develop correctly there will not be enough production of amniotic fluids which would lead to the problems mentioned in the previous lesson, but also especially Potter syndrome. 2. Potter syndrome can occur either if the kidneys don't develop (bilateral renal agenesis) or also be due to any reason which leads to there not being enough amniotic fluid output (oligohydramnios), or a leakage of amniotic fluid. 3. Potter sequence can also be caused by polycystic kidney disease.

Clinical Drop: How can the separating of the cloaca into the urogenital sinus and anorectal canal go wrong?

Partitioning of the cloaca into the urogenital sinus and anorectal canal is very complex and can be defective. Two examples of conditions that can result from this, both in males are, due to problems with the urethra: 1) Recto-bladder neck fistula: The rectum does not open as it should into the anal canal, but rather into the neck of the bladder, and therefore urine and feces would mix and empty out of the urethra. 2) Recto-urethral fistula:Also an abnormal connection between rectum and urethra, resulting also in faeces emptying through the urethra.

What is the inguinal canal?

Passage for the descent of the testis; The testis and the epididymis are enveloped by layers of tissue that derive from the formation of the inguinal canal.

Clinical Drop: What is a patent urachus/urachal fistula?

Patent urachus/urachal fistula: Full communication of the bladder with the umbilicus due to no process of obliteration of allantois taking place.

Clinical Drop: What is the 3rd phase of ARDS?

Phase 3, fibrotic process: if the situation is not solved, the inflammatory condition keeps worsening, fibroblasts keep on trying to solve the situation by producing a lot of extracellular matrix, collagen and elastic fibers and this may lead to fibrosis of the lungs and probably death = chronic fibrosis and occlusion of blood vessls.

Clinical Drop: What is polycystic kidney disease?

Polycystic kidney disease leads to many cysts developing in the kidney, and this causes them to become less and less functional. It can be caused by genetic or other facts. When genetic, there are two types: 1. Autosomal recessive polycystic kidney disease (ARPKD) 2. Autosomal dominant polycystic kidney disease (ADPKD)

Do you remember the story of the primordial germ cells?

Primarily, they form at the epiblast. Then we see them in the wall of the vitelline sac. They will then migrate to a region known as the intermediate mesoderm, which is located dorsally in the body of the embryo.

What is primary septa?

Primary septa: double layer of capillaries, thicker

Clinical Drop: What are is a patent oval foramen?

Probe patent foramen ovalis (it means that if you push the interatrium septum, you can cross the barrier) is an incomplete adhesion of the septum primum with the septum secundum. It affects 25% of people, but it is not haemodynamically and clinically significant, but it can become a problem if associated with other pathologies, like infection of the heart.

Stages of lung parenchyma maturation: 1• Pseudoglandular stage (6 to 16 weeks or 5 to 17 weeks) 2• Canalicular stage (16 to 24-28 weeks or 16 to 25 weeks) 3• Terminal sac stage (24-28 weeks to late fetal period) 4• Alveolar stage (32-36 weeks to 8 years or more) What is the pseudoglandular stage?

Pseudoglandular Stage (6-16 weeks) 1. During this stage we have the parenchyma similar to an exocrine gland. 2. The endodermal tubes is lined by simple columnar epithelium (also very similar to a typical exocrine gland), which is surrounded by mesoderm with modest capillary network. 3. Each tube gives rise to additional generation of branching up to terminal bronchioles. 4. The conductive portion ends here, at the level of the terminal bronchioles and, up to here, there is no respiratory function, which means that no survival is possible (A baby born at this stage would never be able to survive.)

Clinical Drop: What is pulmonary agenesis?

Pulmonary agenesis: failure of the bronchial buds to develop, incompatible with life if it is bilateral.

Clinical Drop: What is pulmonary aplasia?

Pulmonary aplasia: absence of lung tissue but presence of a rudimentary bronchus. If unilateral is incompatible with life.

Development of the heart: What needs to occur when the chambers of the heart have been formed?

Realignment of the cardiac chambers: During the formation of the chambers of the heart, there is the need of a realignment of the cardiac chambers: the future ventricles have to slide a bit to the left and the future atria have to slide a bit to the right. This creates the right communication between the right and left atria and ventricles.

Give a summary of the vascularization of the kidneys:

Renal -> segmental -> interlobar -> arcuate -> interlobular artery -> interlobular arterioles -> afferent arterioles -> glomerulus -> efferent arterioles.

What is the renal corpuscle?

Renal corpuscle: or Malpighi corpuscle, which is formed by the gromerolus and the bowman capsule. This part is mainly devoted to the filtration of water and low molecular weight plasma components in order to produce primary urine. This portion of the nephrons is found in the cortex.

Clinical Drop: What is the most common site of cancer in kidneys?

Renal pelvis are the most common site of cancer of kidneys.

Where do the terminal bronchioles lead to to?

Respiratory bronchioles (first part of respiratory zone)

Clinical Drop: What are sexually transmitted diseases?

STD (sexually transmitted diseases): 1. We have an abnormal vaginal discharge, related to STD, with change in colour and consistency. 2. It can also take place in penis. We have painful urination (dysuria), especially in men; painful sexual intercourse in women; bleeding between menstrual periods (AVB); painful testicles; pain in lower abdomen and pelvis; pain during bowel movements; vaginal or penis itching and irritation; odour. 3. Moreover, it can cause fever, headache, sorethroat, rash, fatigue, and swollen lymph nodes.

What is secondary septation?

Secondary Septation = The secondary septa (single layer of capillaries) are produced from the primary septa (double layer of capillaries), which means that the secondary are much thinner than the primary. Due to their thin structure, the capillaries near the alveoli are much closer to the lumen of the alveoli. In primary septa that divide the primordial alveoli, there is a clear double layer of capillaries. In secondary separation, the wall of the primary septa begins to invaginate inside the lumen of the original primordial alveoli, and in doing so it becomes thinner- just one layer of capillaries- and splits the original primordial alveoli into smaller compartments which are now called the mature alveoli.

What is secondary septa?

Secondary septa: single layer of capillaries

Development of the heart: What are the septa of the heart that are being formed? And what is the process?

Septum intermedium or atrioventricular septum 1. At the moment, we have the communication between atria and ventricles, so we have only 1 atrioventricular canal, but in order to have a right and left side of the heart, we want to have in it 2 atrioventricular canals (each of them with its valve). 2. In the region of the atrioventricular canal, we have the formation of 2 endocardial cuschion, formed by the enlargement of the endocardium, which forms the superior (or dorsal) endocardial cuschion and the inferior (or ventral) endocardial cuschion. These 2 cuschions will grow as to meet in the centre of the lumen and they finally come in contact, as to form the septum intermedium or atrioventricular septum. When they touch each other, the atrioventricular canal will be divided into 2 sides. In the meanwhile the 2 septa of the heart are forming.

Clinical Drop: What are signs and symptoms of congenital anomalies of the heart divided into?

Signs and symptoms of heart congenital defects depend on number, type, and severity. Some heart defects cause few or no symptoms. 1. Some of the signs can be rapid breathing, cyanosis, fatigue, or poor blood circulation; usually there is no chest pain. 2. The children may not gain weight, may tire easily, or have shortness of breath. 3, Many congenital defects can cause heart failure. 4. Moreover, they can cause shortness of breath; fatigue with physical activity; build-up of fluid in the lungs; swelling in the ankles, feet, legs, abdomen, and veins in the neck.

Clinical Drop: What are signs and symptoms for Wilms tumour or nephroblastoma?

Signs and symptoms*: 1. 80% of cases: a child may be asymptomatic but have an abdominal mass. 2. 25% of cases: abdominal pain or haematuria (blood in the urine) will be present. 3. Hypertension (kidney problems affect overall blood pressure) 4. Fever (due to infections resulting from this condition) 5. Infection of urinary tract (due to an anomalous flow of urine) 6. If not treated early, the tumour can metastasize to the lungs and cause respiratory symptoms.

Is smooth muscle present in the tracheo-bronchial tree?

Smooth muscle can be found from the beginning but not up to the end ( Smooth muscle tissue can be found everywhere except in the alveolar wall).; it is still found in the respiratory portion, in respiratory bronchioles, alveolar ducts and sacs (even though it is organised in a special way).

What happens at the vascular pole?

So, in the renal corpuscle, we identify the vascular pole, where afferent and efferent arterioles respectively enter and exit the corpuscle and, in between them, the capillary network of the actual glomerulus.

Clinical Drop: What are some uterine malformations?

Sometimes the process of the fusion of the two mesonephric ducts and the disappearance of the septum in between the two sides does not take place correctly, resulting in various kinds of uterine malformation. For instance; 1. Uterus Didelphys (Uterus Duplex Separatus) - There was no fusion between the two paramesonephric ducts, resulting in two strange bodies of the uterus, each communicating with one uterine tube. Two necks to the cervixes of the uterus. 2. Uterus Duplex Bicornis (Septus) - The two paramesonephric ducts do come together, but the septum (medial wall of the two sides) does not disappear. 3. Uterus Bicornis Unicollis - The disappearance of the system did not fully occur, and it remains in the upper part of the future uterus. From a clinical perspective, these can result in difficulties in conception and pregnancy.

Clinical Drop: What can go wrong with the Bartholin glands?

Sometimes, these glands can get inflamed and, since there is not a lot of tissue surrounding them, they can start to compress the surrounding tissues and cause lots of pain; moreover, they are very superficial, so they can cause a swelling and even cysts; in this case, they can produce purulent secretion, which can be released in the area of external genitalia.

Symptoms vs. Signs

Symptom: Non-observable feature, only what patient tells you. E.g. abdominal pain. Sign: Observable feature. E.g. abnormal mass is visible.

Stages of lung parenchyma maturation: 1• Pseudoglandular stage (6 to 16 weeks or 5 to 17 weeks) 2• Canalicular stage (16 to 24-28 weeks or 16 to 25 weeks) 3• Terminal sac stage (24-28 weeks to late fetal period) 4• Alveolar stage (32-36 weeks to 8 years or more) What is the terminal sac stage?

Terminal sac stage (24-28 weeks to late fetal period) 1. In this stage there are many more structures with a thin wall: alveolar ducts, terminal sacs with thin epithelium separated by narrow regions deriving from the mesenchyme known as primary septa (in which we find elastic and collagen fibers). 2. Capillaries bulge into the sacs, forming the blood-air barrier. 3. Moreover, there is the development of elastic fibers from the mesenchyme surrounding the endoderm that is very important; elastic recoil is one of the most necessary characeristics of the lungs and these fibers are found in the most distal part of the organ. Most of the expiratory events (breathing out) are due to the elastic recoil of the lung. 4. The epithelium is quite flat and we can start to talk about type I pneumocytes or alveolar cells and type II pneumocytes. 5. By 24-28 weeks after fertilization the fetus is around 1 kg and the surfactant is enough and there is a good chance for it to survive if there is the intensive care unit available.

How is the broad ligament of the uterus formed?

The 2 paramesonephric ducts had to come together caudally on the mid line, so there is a swinging of the 2 urogenital crests so that the 2 distal portion of the paramesonephric ducts may come together and during this swinging, the parietal peritoneum is lifted, causing a peritoneal fold that becomes the broad ligament of the uterus, a fold of the peritoneum that covers the uterus and the fallopian tubes.

How do the 2 ventricles communicate?

The 2 ventricles communicate with their great vessels through the semilunar valves.

What is the ductus deferens (vas deferens)?

The Ductus Deferens carries the sperm from the Epididymis to the ejaculatory duct.

What are the macroscopic aspects, functional architecture and structure of the kidney, ureters and lower urinary tract?

The Urinary System: Rostrally to Caudally. We have the 2 kidneys → the 2 ureters (which connect kidneys to the bladder) → the bladder (storage of urine) → and the urethra (which connects the bladder to the outside). Of course here the star of this system- because of its complexity, is the kidneys; because the rest are conduits for urine or storage for urine. Not that they are not important of course- try having an infection of the lower urinary tract! But from the organisational/functional/structural point of view it is the kidneys that are the star of this story.

Where does the adrenal gland form from?

The adrenal gland forms by the intermediate mesoderm in the urogenital crest.

What is the adrenal gland made of?

The adrenal gland is constituted by a cortex and a medulla, these two components have a different embryological origin.

Clinical Drop: What can go wrong during the formation of the urachus (fibrous remnants of the allantois)?

The allantois, which is at the upper part of the bladder, soon starts to regress forming the urachus (a fibrous cord), that will become the median umbilical ligament. During the formation of the urachus things can go wrong and we can have: 1. Formation of cysts: Allantois does not regress completely, but it remains in some regions, forming some urachal cysts, which contain some fluid. 2. Urachal sinus: Part of the allantois regresses, but the part in communication with the umbilicus (part that is in continuity with the umbilical ring) does not regress which leads to a spilling of urine from the umbilicus onto the abdominal region. 3. Patent urachus/urachal fistula 4. Exstrophy of the bladder

Development of the heart: Why do we need the atrioventricular valves? How are they formed?

The atrioventricular valves valves are formed from the endocardial cushions of the atrioventricular septum and by the processing of remodelling of the myocardium.

What is the body of the uterus?

The body is the major portion of uterus; which is formed by a flattened anterior surface, the surface with through the uterus is in contact with the urinary bladder; and a posterior convex surface, which is in relationship with the loops of the small intestine.

What type of capillaries are in the glomerulus?

The capillaries of the glomerulus are fenestrated capillaries: there are large openings within the endothelial cells.

What is the cervix divided into?

The cervix is divided into an endocervix, the upper portion that does not protrude in the vagina and an ectocervix, the portion that protrudes in the vagina.

By what is the cervix formed?

The cervix is formed by a part that protrudes in the vagina, which is surrounded by the vagina fornix.

What are the components of the female genital tract?

The components of the female genital tract are the fallopian tubes, the ovaries, the uterus, the vagina, and the external genitalia.

How is cortical zone separated?

The cortical zone above each pyramid bulges on the renal surface and is separated from the others by grooves called interlobal grooves. Although, it may happen that some pyramids fuse together, especially at the level of the apex, so it may happen that one minor calyx may receive urine from more than one renal pyramid. The fetal kidney presents some grooves, which represent the passage zone between one pyramid and the other, but then the lobulation will disappear.

What are the 3 narrowest points of the ureters?

The diameter of the ureters varies, there are three narrower points (where stones are more likely to be stuck): 1. Junction with renal pelvis 2. Where it crosses the iliac artery 3. At the entrance of the bladder

Clinical Drop: What may the broad ligament contain that is problematic?

The different parts of the broad ligament may contain cysts from the remnants of the mesonephros and the mesonephric duct.

What is the broad ligament of the uterus?

The double fold of peritoneum that hangs over the uterine tubes.

What does the ductus deferens link?

The ductus deferens link the testis with the urethra in the posterior part of the urinary bladder.

The ectocervix epithelium is lined by...

The ectocervix is lined by a squamous stratified epithelium.

What do the ejaculatory ducts open into?

The ejaculatory ducts enter into the parenchyma of the prostate gland to reach the posterior wall of the prostatic urethra, to open at the level of the seminal colliculus or verumontanum.

What is the embryological origin of the adrenal cortex?

The embryological origin of the cortex is the mesenchyme of the intermediate mesoderm of the urogenital crest.

The endocervix epithelium is lined by...

The endocervix is lined by a columnar epithelium, which has mucus secreting properties;

What is the endometrium divided into?

The endometrium is divided into a basal layer and the functional layer.

What is the histology of the ductus deferens?

The epithelium is a pseudostratified columnar epithelium and it is surrounded by a very thick muscle layer, which is formed by an inner longitudinal layer, a middle circular layer, and an outer longitudinal layer.

What is the female genital tract largely covered by?

The female genital tract is largely covered by a fold of peritoneum: the broad ligament of the uterus (a peritoneal ligament).

Development of the heart: What can the formation of the endocardial cushions also be called?

The formation of the endocardial cuschions can also be called endocardial swelling and it has very complicated embryological origins: the cuschions originate from an extracellular matrix secreted by the myocardium that is colonized by endocardial cells, which undergo epithelio-mesenchymal transition.

What is the functional layer of the endometrium divided into?

The functional layer has 2 other layers: 1. the spongy layer 2. the compact layer During the cycle, the functional layer that gets lost and it is reconstructed by the basal layer (which does not get shed).

What is the nephron?

The functional unit of the kidney is the nephron, whose main function is filtering blood.

Where do the afferent arterioles originate from?

The glomerulus is a network of capillaries coming from the afferent arteriole, which originates from the interlobular artery.

What is the glomerulus surrounded by?

The glomerulus is surrounded by an epithelial capsule, Bowman's capsule

Development of the reproductive system: Where do the gonads develop?

The gonads develop in the intermediate mesoderm, in the region where the mesonephros is developed, that is why that region becomes so big, since besides the developing of the mesonephros, we also have the formation of the gonads.

How is the content of the inguinal canal in females different from males?

The gubernaculum is present also in the future female gonads even though is shorts just a little, it attaches to the paramesonephric duct while the latter is forming the uterus and the uterine tubes, giving rise to the formation of the round ligament of the uterus and the round ligament of the ovary.

What is the heart divided into? And what chambers do they have?

The heart is divided into the left and right side and each of them has 2 chambers: an atrium and a ventricle.

What is the inflow portion of the heart?

The inflow portion is made by the inferior and superior vena cava.

What is the function of the inguinal canal in males?

The inguinal canal allows a passageway of the male gonads and their positioning in the scrotal bursa. It contains the ductus deferens (which must communicate with the prostatic urethra), veins (Pampiniform plexus), arteries and nerves.

Where does the inguinal canal form from?

The inguinal canal and the scrotal bursa form from the abdominal musculature and fasciae when they are pushed outward by the formation of an evagination of the peritoneum named procesus vaginalis.

What is the function of the inguinal canal in females?

The inguinal ligament simply allows the round ligament of the uterus to pass from the uterus to labia majora. This is the female inguinal canal. We can see that the uterus is located inside the abdominal cavity (we can see it in transparency). The round ligament of the uterus crosses inside the inguinal canal to eventually attach in the region of the labia majora. In men instead, in the region corresponding to labia majora, there is the formation of the scrotal bursa.

How are the left atria and left ventricle separated?

The left atria and ventricle communicates through the mitral or bicuspid valve.

Which is smaller, the left or right lung?

The left lung is slightly smaller due to the fact that the heart is mostly to the left, taking up space. In fact, there's the so-called "cardiac notch", which is an incisura caused by the apex of the heart.

How long is the fallopian tube aka. uterine tube aka. oviduct aka. salpinges?

The length of the fallopian tube is from 10 to 18 cm.

How does the lumen change shape between the body of the uterus and the cervix?

The lumen of the body of the uterus has a triangular shape and it is smooth; while the lumen of the cervix has palmate folds that interdigitate, which are used to protect the access to the uterine cavity.

What is the nerve supply of the pleura?

The lung parenchyma is innervated by the autonomic nervous system, but, when we consider the pleura, the situation is a bit different. The visceral pleura (the one attached to the lung) is innervated by the autonomic nervous system and it's very insensitive to pain and touch, while the parietal pleura is innervated by the somatic nervous system and is very sensitive to pain.

Are the lungs developed by birth?

The lungs, like many other organs in our body, are not completely developed at birth, because they are developing up for survival and growth; they are ripe for the first years of our life. After birth there is an addition of 7 other ramifications, so the branching process in the finer branching system proceeds and this maturation of the lung parenchyma and of the finest ramification of the lungs is stabilized around 8 years. It takes some time for the lungs to be fully mature.

What is the mediastinum of the testis?

The mediastinum of the testis is made by a tubular system, constituted by the straight tubules (continuation between the seminiferous tubules and the rete testis), the rete testis and the ductuli efferentes, which put in communication the rete testis with the epididymis.

What is the embryological origin of the adrenal medulla?

The medulla come from the neural crest cells (it makes sense, since the purpose of the medulla is the secretion of adrenaline and noradrenaline, two neurotransmitters).

How is the mucous changing characteristics at different periods of the menstrual cycle?

The mucous has changing characteristics: at ovulation it is less viscous, hydrated, with an alkaline pH, thus to favour cell migration. High content of ions is responsible for crystallization in a fern-like pattern (useful feature to assess optimal time of fertilization).

What type of arrangement does the muscle layer of the uterine tube have?

The muscle layer has a spiral arrangement: there are 2 spirals: 1. The inner one that has a circular arrangement and the outer one. 2. They perform a propulsor activity of the egg or zygote through a gentle peristaltic action. 3. The muscle layer is very thick in the isthmus.

What layers is the myometrium of the uterus made of?

The myometrium is made by 3 layers of smooth muscle fibers, which are not well defined. 1. The middle layer or stratum vasculare has circular muscle fibers and lots of blood vessels. 2. The other 2 layers are longitudinally or obliquely oriented.

What is the outflow portion of the heart?

The outflow portion of the heart is made by the aorta and by the pulmonary trunk

How many erectile columns is the penis composed of? What are they?

The penis is composed of 3 erectile columns (the 2 corpora cavernosa and the corpus spongiosum), which can give rise to erection because they are formed by a system of cavities, which can get filled in blood.

What is the penis formed by?

The penis is formed by a root, a body, and a glans.

What can be seen in this image?

The peritoneum is depicted in orange. The peritoneum in the abdominal cavity, at a certain point starts to form an out-pocketing, the processus vaginalis. What happens is that the processus vaginalis, from the inside of the abdominal cavity, starts to push through the outside, against the different layers of the abdominal wall. It keeps on propelling, until it manages to form a canal and a pocket, in the region where the gonads will finally end up.

What is the location & shape of the bladder?

The position and the shape of the bladder varies whether it is empty or not if it is empty is covered only superiorly by peritoneum, while if is filled is greatly covered by peritoneum; Traumas to the bladder are more severe if is filled, in addition when is filled it can spread urine in the peritoneal cavity causing peritonitis.

Development of the heart: How is the primary heart field formed from the migration of cells of the primitive streak?

The primary heart field or cardiac crescent is formed rostral to the oropharyngeal membrane and it originates from the migration of cells of the splanchnic layer of the lateral plate mesoderm.

Development of the heart: By what is the primitive circulation formed?

The primitive circulation is formed by 3 network of vessels: 1. the umbilical vessels (to placenta) 2. the vitelline arteries and veins (yolk sac) 3. the embryonic body circulation. At the beginning the network of vessels is the same on the right and on the left, but then it will undergo some major changes and it will become asymmetrical.

Development of the heart: How do the 4 heart chambers form?

The primitive heart tube quickly forms 5 distinct regions. From head to tail, strong include the sinus venosus, primitive atrium, primitive ventricle, bulbus cordis, and the truncus arteriosus. 1. The inflow tract of the primitive heart is called the sinus venosus, which communicates with the right and left venous horns (where the 3 systems of veins enter into the heart). 2. If we proceed further from the sinus venosus, the heart starts to dilate in some regions, forming the primitive atrium, which together with part of the sinus venosus will form both the definitive atria. 3. If we proceed rostrally, the next dilation that we find is called primitive ventricle, which will form the left ventricle of the heart. 4. More rostrally, we find the bulbus cordis, which will form the right ventricle. The bulbus cordis is the region of the heart that communicates with the outflow tract, which is divided into conus cordis and truncus arteriosus. 5. The truncus arteriosus is going to be divided into the ascending aorta and the pulmonary trunk.

Development of the urinary system: How does it begin developing?

The process of the formation of the kidney is quite complicated: we have 3 types of kidney that develops one after the other (when one is regressing, the other one is starting to form). Just one of these 3 will be our definitive kidney, the others will regress. 1. The first kidney starts to develop very rostrally, and it is called pronephros, which is not functional and it is there from the 3rd to the 4th week. 2. When the pronephros degenerates, we have the formation of the mesonephros, which forms more caudally than the pronephros. It is also called ad interim kidney since it is functional for the weeks it is there. It degenerates during the 8th week. 3. In the 5th week we have the formation of the metanephros, which will be the definitive kidney. The metanephros is formed much more caudal and it becomes fully functional around the 10th week of gestation. We need the kidney to work because it is necessary for the production of primitive urine, which is released in the amniotic cavity and it will be one of the main components of the amniotic fluid.

Where does the prostate gland develop from?

The prostate gland develops from the primitive urethra and surrounds the prostatic urethra.

What is the region of the female external genitalia called?

The region of the female external genitalia is also called vulva region and it is formed by the labia majora, the labia minora, which form the fourchette (when the 2 labia minora connects), the clitoris (sort of primitive penis), a proper vestibule of the vaginas with the opening of the urethra meatus anteriorly and the vagina posteriorly. Until the first sexual intercourse, the opening of the vagina is closed by a membrane called hymen.

The renal corpuscle is made by two structures:

The renal corpuscle is made by two structures: the glomerulus and the Bowman's capsule.

What is the first site of urine filtration? What is the urine called at this level? And why?

The renal corpuscle is the first site of filtration of urine: the urine produced at this level is called pre-urine. It is not the definitive one, since a lot of modifications will happen to this primary urine while flowing into the tubular system.

How are the right atrium and the right ventricle separated?

The right atrium and the right ventricle are separated by the tricuspid valve.

How is the right side of the 2 heart atria separated from the left side?

The right side is separated from the left side: in between the right and left atria we can find the interatrial septum.

Development of the heart: How is the secondary heart field formed from the migration of cells of the primitive streak?

The secondary heart field derives part from the splanchnic mesoderm in the posterior region of the pharynx and part from the migration of neural crest cells.

Where are the seminiferous tubules contained?

The seminiferous tubule are contained into compartment of the testis, which are called testicular lobules.

How does the size of the lumen of the male urethra change from segment to segment?

The size of the lumen (as for the ureters) is not homogeneous: 1. In the pre-prostatic portion there is a narrowing which correspond to the internal sphincter; 2. Then it becomes larger in the prostate and than in narrows again at the level of the external sphincter; 3. It enlarges again along the penis (penile urethra), then it narrows again before the navicular fossa (which is surrounded by the glans of the penis) and it narrows again forming the external urethral orifice.

Which are the other organs in our bodies through which we can eliminate waste?

The skin, for example. We usually only think of the skin as a "container" right? But it is an enormous surface- it is the largest organ we have and is also important for excretory purposes. If I paint your skin completely with paint that doesn't allow passages of substances, you die. It is a very important excretory organ.

What is the surfactant made of?

The surfactant is a mixture of things: phospholipids ("dipalmitoyl-phosphatidylcholine"), cholesterol and then proteins.

What territory of the lung parenchyma do the terminal bronchioles serve vs. the respiratory bronchioles?

The terminal bronchioles lead to the respiratory bronchioles. 1. The terminal bronchiole subserve a territory of lung parenchyma called pulmonary lobule. 2. While the respiratory bronchiole subserves a smaller territory called pulmonary acinus.

What is the scrotal bursa?

The testis and the epididymis are contained in the scrotal bursa.

What are the testis? How big are they?

The testis are 2 ovoidal structures with a height of 4-5 cm and with a width of 3 cm.

What is the trachea?

The trachea is a flexible tube and a large membranous tube reinforced by rings of cartilage, extending from the larynx to the bronchial tubes and conveying air to and from the lungs; the windpipe; it is like a bloodvessel but for air.

What is the size of the trachea?

The trachea is a flexible tube that can have a 2.5 cm diameter and a length of 10 cm.

How does the trachea remain open, although it is flexible?

The trachea is flexible and due to the presence of the cartilage the lumen does not get constricted and it remains open; it allows expansion in diameter and extension in length during inspiration and passive recoil during expiration.

How is the tracheobronchial tree and lung parenchyma innervated?

The trachea-bronchial tree and the lungs are both innervated by the parasympathetic and sympathetic nervous system; usually, they have an antagonist action in an organ in respect to one another but they can also act synergistically.

What are ureters?

The tubes that carry urine from the kidneys to the bladder.

What are the straight tubules?

The tubuli seminiferi recti (also known as the tubuli recti, tubulus rectus, or straight seminiferous tubules) are structures in the testicle connecting the convoluted region of the seminiferous tubules to the rete testis, although the tubuli recti have a different appearance distinguishing them from these two ..

What is the tunica vaginalis?

The tunica vaginalis is a small serosal sac and we recognize a parietal and a visceral layer.

What does the urethra in the inferior part of the urogenital sinus connect?

The urethra forms the vestibule of the vagina in females and the penile portion of the urethra (which elongates respect to the female) in males. Around the male urethra, we have the formation of the prostate gland.

Development of the urinary system: Where does it begin to develop?

The urinary system develops at the level of the intermediate mesoderm (the same area where we have the formation of the gonads).

How is the urinary system divided?

The urinary system is divided into the upper urinary tract, made by the kidney and the ureter, and the lower urinary tract, made by the urinary bladder and the urethra.

What is the urinary system made of?

The urinary system is made by the kidneys (solid organs), right and left, and by tubing systems that serve the purpose of a conduit of urine, so after the kidneys, we have the pelvicalyceal system, then the ureters (which are 2 long tubes, the right and the left), which bring urine into the urinary bladder, a hollow organ, which communicates with the outside through a canal called the urethra.

What is the uterine tube?

The uterine tube or fallopian tube or oviduct or salpinges are the site of fertilization; are the site of early cleavage of the zygote and allow the propulsion of the egg toward the uterus.

Where is the uterus located?

The uterus is located in the middle of the lesser pelvis; between urinary bladder and rectum

What is the uterus?

The uterus is the hollow organ, muscular organ, pear-shaped organ that nourishes and protects a fertilized ovum until birth.

What is the wall of the renal pelvis like?

The wall of the pelvis is thinner than the one of the ureter but they are very similar in composition. The one of the renal pelvis is composed by: 1. Mucosa: composed of a transitional epithelium called urothelium which is an epithelium that allows a distention of the wall of the organ with specific junctions which prevents the absorption of urine. There is a lamina propria but no submucosa. 2. Muscle layer: longitudinally oriented because it has a milking effect on the renal papilla. 3. Adventitia

What is the thin portion of the alveoli vs. the thick portion?

There are thick and thin layers of connective tissue in the alveoli. 1. The thin portion is in which gas exchange occurs. In many places the basal lamina of the alveolar epithelium is fused with the basal lamina of capillaries (no fibres, no fibroblasts, no macrophages, no collagen in between) so that the total barrier air and blood can be as small as 0.2 micrometre. 2. The thick portion is the site which tissue fluid accumulates and crosses into the alveolus.

Clinical Drop: What is another problem that can occur in the process of formation and ascending of the kidney?

There can be a ureteral duplication that can even lead to the formation of an additional kidney: if the duplication takes place very early, then the interaction with the mesenchyme is still going on and therefore we may have the possibility that 2 kidneys are formed; if the duplication takes place later, then we have the duplication of the ureter with just one kidney.

What descends, while the kidneys ascend?

There is a change in the blood supply while the kidneys ascend and while they ascend, the gonads descend.

In what terms do the nephrons grow after birth?

There is a postnatal growth, but it is not related to the increase of nephrons, but is the lengthening of Henle's loop and growth of the interstitial tissue between the nephrons.

Clinical Drop: What can go wrong in relation to the neuroendocrine cells?

These neuroendocrine cells, from the clinical point of view, can give rise to very aggressive tumours of the lungs that unfortunately affect young people. They are due to problems in proliferation and control of the proliferation of neuroendocrine cells.

How long are the ureters?

They are 25-30cm long.

The testis are oriented in what way?

They are slightly oblique one another: they converge anteriorly and diverge posteriorly. We

Clinical Drop: What are congenital anomalies of the heart caused by?

They can be caused by genetic mutations, chromosomal aberrations, teratogens (lithium, alcohol, diabetes, infections) or they can be multifactorial.

What is the proximal convoluted tubule?

This is the first and major site of reabsorption.

Where is the proximal convoluted tubule located?

This portion of the nephron is found in the cortex of the kidney.

Development of the heart: How will the process of septation of the heart occur?

This process of septation takes place by 2 mechanisms: 1. from remodelling of the myocardium (muscular portion of the interatrial and interventricular septa) 2. from cushion tissue coming from the endocardium and from the neural crest cells (membranous portion of the septa, cardiac skeleton, and valves).

How is the system of cavities allowing erection kept together?

This system of cavities allowing erection kept together is kept together by a fascial system that envelops the columns, the nerves, lymphatics, and blood vessels, and all is covered by skin. It is suspended by 2 suspensory ligaments, composed of primarily elastic fibers, support the penis at its base.

Our trachea-bronchial tree and lungs receive fibers from the parasympathetic nervous system, but how?

Through the vagus nerve, among other things, innervates the lungs and is classified as a parasympathetic nerve. Still, sympathetic fibers reach the lungs and trachea-bronchial tree and these two components collect information and bring it to the central nervous system.

What are subsegmental bronchi?

Tracheobronchial tree continues to subdivide into progressively smaller airways

What do type II pneumocytes do?

Type II pneumocytes produce surfactant, which reduces the surface tension of alveolar surface facilitating inflation, participates to local inflammatory response and modulates immune response. It can also be a progenitor for type I and II pneumocytes.

How is urine collected by the renal pelvis?

Urine is collected by the renal pelvis form the major calixes; the renal pelvis then leads urine to the ureter.

Clinical Drop: What are congenital anomalies of the heart divided into?

Usually, the congenital defects of the heart are divided into acyanotic and cyanotic (mixing of arterial and venous blood before the aorta).

What is the external urethral sphincter? Where is it located? What is it formed by?

Voluntary (skeletal) muscle surrounding the urethra as it passes through the pelvic floor; The external sphinteric device is formed by skeletal fibers and is under voluntary control; in males this sphincter is found below the prostate.

Clinical Drop: What are the different kinds of malformation of the kidney?

We have a spectrum of malformation of the kidney: we can go to a dysplasia of the kidney to a renal agenesis. A dysplasia is a poor formation of the kidney, while the agenesis is the not formation of kidney. In this case we will require either a transplant or continues dialysis.

Why does cartilage in the tracheo-bronchial tree decrease?

We have cartilage in the initial part to prevent compression of the large tubing system. Deep in the parenchyma of the lungs cartilage is no longer needed to protect the tubing system. Therefore, it starts to decrease and its shape changes.

What are the layers of tissue that derive from the formation of the inguinal canal?

We have the internal spermatic fascia, the cremasteric fascia, the external spermatic fascia, and the tunica or processus vaginalis (serosa).

Why is the fact that the right and left bronchi do not have the same size clinically important?

When something is inhaled, for mechanical reason (larger and lower angle) there are higher chance for it to end up in the right lung, because the right bronchi (20°), is more in continuity with the trachea = if something goes into the trachea, it is more likely going into the right, because it is more in line with the trachea, and it is larger.

Clinical Drop: What things can go wrong during the process of formation and ascending of the kidney?

When things go wrong, several issues can arise: 1. One thing that can happen is malrotation: the kidney does not rotate at all or it rotates in the wrong direction; we can have duplication of the ureter; or diverticula along the urinary tract; or pelvic kidney; horseshoe kidney: the kidneys remain in the pelvic region and they fuse together... 2. It may happen that one of the 2 kidney or maybe both of them, do not migrate, so they remain in the pelvic region. It can be caused because the primitive renal artery that supply the kidneys in their original position, do not regress, so they remain anchored in their original position. 3. Usually this does not create problems and can be discovered incidentally. It can be relevant if the ureter elongates, the kidney does not migrate and therefore the ureter bends, causing stagnation of urine in the kidney. 4. Another condition that may happen is called horseshoe kidney. If the kidneys are fused, when they try to migrate, they get blocked by the presence of the inferior mesenteric artery. This can be both relevant or irrelevant from the clinical point of view.

What happens to pre-urine?

While it moves along tubules and ducts discussed below two main things happen: 1. Reabsorption: partial of some substances (water, Na, bicarbonate ecc) and complete of others (glucose). Reabsorption can take place actively or passively. 2. Secretion: of other substances in the urine such as creatinine, acids and bases.

How does the lung parenchyma mature?

While the tracheobronchial tree is forming, the lungs will be forming as well. Maturation of lung parenchyma takes place through stages and proceeds from proximal to distal (from apex to base), from the largest bronchi outward. There are 4 main stages, plus the initial one (embryonic stage), which can't be really considered a stage: Embryonic stage (26 days to 6 weeks): after this stage, we reach the level of the segmental bronchi and nothing else. 1• Pseudoglandular stage (6 to 16 weeks or 5 to 17 weeks) 2• Canalicular stage (16 to 24-28 weeks or 16 to 25 weeks) 3• Terminal sac stage (24-28 weeks to late fetal period) 4• Alveolar stage (32-36 weeks to 8 years or more) According to books and author the periods can vary. Moreover, stages are overlapping.

What is the prostate gland?

a gland surrounding the neck of the bladder in male mammals and releasing prostatic fluid (secrete nutrients and fluids for sperm).

Several nephrons drain into ______.

a straight collecting tubule. ***Lobule: all the nephrons that drain in a collecting tubule.

If there are only alveoli, we are either in... or ..., where?

alveolar duct or in an alveolar sac.

From the respiratory bronchiole we enter in the _____.

alveolar ducts, where all the wall is substituted by alveoli and finally, proceeding further we arrive in the alveolar sacs, a large chamber with the openings of lots of alveoli. Proceeding further the number of alveoli increases.

The histological features of the prostatic urethra are characterized by:

an urothelium immediately surrounded by the glandular and stroma tissue of the periurethral zone of the prostate.

What is the glomerulus?

ball of capillaries from the afferent artioles in the nephron with many pores;

What are the 2 main roles of the respiratory system?

brief summary - functional anatomy of respiratory system divided in: 1. conducting portion and 2. respiratory portion, starting at the level of respiratory bronchioles (even though there are still some of the characteristics of the conducting portion)

What does the collecting duct do?

carries filtrate through the medulla to the renal pelvis; variable reabsorption of water and reabsorption or secretion of sodium, potassium, hydrogen, and bicarbonate ions. 1. Here urine becomes more concentrated because of the passive reabsorption (no energy required) of water, thanks to the osmotic gradient created at the level of the pyramidal (or medullary) interstitium by vasa recta which flows fluid (blood) countercurrently to loops of henle; diffusion takes place again tanks to aquaporins. 2. Water is then drained by vasa recta. 3. ADH regulates the permeability of sodium channels which are related to water concentration.

How do the general histological features change from the proximal to the distal part of the tracheo-bronchial tree? Are ciliated cells present?

ciliated cells are present only up to where there are mucus cells; Cilia are quite abundant and present up to the segmental bronchi: cilia are used to move mucus towards the oropharynx, so that it then goes into the digestive system, so if the mucus presence is lower, we need always less cilia.

Clinical Drop: What is a problem that can occur to do with the mucus?

clinical drop - cystic fibrosis; 1. Cystic Fibrosis is a condition in which mucus is not as fluid as it should be. 2. It has to do with defective chloride ion channels that finally lead to increased thickness and viscosity of the mucus and altered mucus ciliary escalator (making it very difficult to get rid of) leading to obstruction of airways, which can cause infections, proliferation of bacteria. 3. Cystic fibrosis does not affect only the respiratory tree, since it isn't the only place where we can find chlorine ions (e.g. we find them at the level of the ducts of the liver and pancreas, at the level of sweat glands). 4. As a result, the sweat secretion of individuals affected by cystic fibrosis is denser than those of normal individuals. ***Symptoms: cough, dyspnea (shortness of breath), fever.

What is the loop of Henle responsible for?

conserving water and minimizing the volume of the filtrate.

The characteristics of the tracheobronchial tree and the tissue composition vary from the trachea to the distal part of the tracheobronchial tree: it's a ______.

continuum.

From the vascular pole we also have the exit of the _______.

efferent arteriole. Regarding this arteriole, remember the different characteristics of it in juxtaglomerular and cortical nephrons, that we analyzed in the previous lectures.

⚠In hollow organs you can remove a tumor by ________.

endoscopic surgery without anesthesia.⚠

What are the functions of endothelial cells in the lung?

endothelial cells = cells lining the blood vessels; 1• Respiratory or gas exchange barrier 2• Convert angiotensin I in angiotensin II (important in the control of blood pressure), they act on angiotensin converting enzyme (ACE). This system is very important in the control of blood pressure in our body and, for it to work properly, we need the endothelial cells in the lung's parenchyma to be able to produce the ACE enzyme. People who suffer from hypertension are usually given an ACE-inhibitor that reduces the conversion of angiotensin I into II. 3• Process hormones and prohormones; These endothelial cells are also able to produce hormones, to synthesize prostaglandins (which is important in the inflammatory conditions), to modulate hemostasis: for example, they produce anti-coagulating proteins, but if injured promote coagulation. COVID: one of the problems with it is that it damages endothelial cells, causing a lack of ability to produce anti-coagulation proteins and thus causing coagulation inside the capillaries of the lungs. The balance between anti and prothrombotic activities determines whether thrombus formation, propagation, or dissolution occurs. Sometimes damage to the endothelial cells may cause the formation of thrombus. 4• Synthesize prostaglandins 5• Modulate haemostasis: anticoagulating properties, but if injured promote coagulation. The balance between anti and prothrombotic activities determines whether we have thrombus formation, propagation, or dissolution.

The cortex of the adrenal gland present during the fetal life is called ______.

fetal cortex, it is there during the fetal life and a few months after birth, then it degenerates and it's substituted by the adult one.

What happens at the urinary pole?

filtrate exits into renal tubule; It is where urine, that is collected in the space between the visceral and parietal layer, will flow into the tubular system of the nephron, so where the corpuscle of Malpighi communicates with the proximal convoluted tubule.

What are the tertiary or segmental bronchi?

further branching of bronchi supplying air to specific regions of each lung

Renal-> segmental-> interlobar -> arcuate From arcuate arteries another level of branches form:

interlobular arteries (which delimitate each lobule).

Where does the afferent arteriole go?

into glomerulus; The afferent arteriole reaches the vascular pole, a region of the corpuscle that we will further discuss in this lecture, and gives off this very extensive branching of capillaries, actually several loops coming together, forming the glomerulus.

According to the position of the renal corpuscle, there are two types of nephrons:

juxtamedullary (renal corpuscle next to renal pyramids, only 20%) or cortical nephrons (renal corpuscle not so much close to the renal pyramids)

A bronchopulmonary segments is the ____________.

largest subdivision of a lobe. In the image, we see two segments close to each other. A segment is pyramidally-shaped, with the apex towards the lung root (so towards the hilum) and the base towards the periphery (the pleura covering the lungs).

The kidney is made of:

o Cortex o Medulla The cortical zone contains the convoluted part of the nephrons, whereas the medulla contains the straight portions of ducts and loops of Henle.

The male genital tract ends at the level of the ______.

penis, which is the organ of copulation.

What is the filtration membrane?

porous membrane between blood and interior of glomerular capsule; This "membrane" has a certain degree of plasticity: it is not an a passive mechanism but an active mechanism. If one component of the membrane is affected can affect also the other two. The whole process is regulated by a protein called nephrin.

What is the nephron composed of?

renal corpuscle and renal tubule

Development of the heart: What is the septation process (continued, specifically the septation of the atria)? Why is it important?

septation of the atria 1. An important step in the formation of the heart is the separation of the systemic and pulmonary circulation. 2. During gestation, the separation is partial: it allows a right to left atrium shunt of blood. In this way, most of the oxygen-rich blood coming from the inferior vena cava (which is the only vein in the fetal carrying oxygenated blood) bypasses the lungs and reaches the systemic circulation. At the moment of birth, this communication must disappear. 3. The formation of the interatrial septum takes place by the formation of 2 septa and 2 openings. In the primordial atrial chamber, on the roof of it, we have the elongation of a portion of tissue that is going to form the septum primum. This septum is never completely formed: while elongating, it leaves, inferiorly, an opening called the ostium primum that allows the communication between the atria. While the septum primum is growing, the ostium primum starts to disappear, but since we want to maintain a communication between the atria, while it is disappearing, in the upper part, we have the formation of the ostium secundum, which is formed through a process of vacuolization. 4. While the ostium secundum is forming, we have the formation of another septum, called septum secundum, which grows on the side of the right atrium. Similar to the septum primum, the septum secundum, while formed, leaves an opening in its middle portion. This opening will be called foramen ovalis. Thanks to this 2 openings, most of the blood coming from the inferior vena cava is shunted into the left atrium through the foramen ovalis first and then through the foramen secundum.

Development of the heart: What is the septation process (continued, specifically the septation of the ventricles)? Why is it important?

septation of the ventricles 1. The interventricular septum is made by a muscular portion and a membranous portion. The origin of the membranous portion is quite complicated: it is divided into an atrioventricular and an interventricular part due to their different embryological origin. 2. At 44 days of development there is a rearrangement of the inner myocardium, with the formation of the septum (which forms the muscular portion of the interventricular septum) and of the trabeculae or ridges of the myocardium. If we look at the heart at 46 days, the muscular ventricular septum is elongating. 3. The membranous portion, to be formed, requires the contribution of the atrioventricular endocardial cushions and of the conotruncal endocardial cushions. 4. While the atrioventricular endocardial septa are forming, at the level of the outflow tract of the heart, we have the formation of 2 endocardial cuschions, which will be called conotruncal endocardial cuschions. For the formation of these 2 cushions, we need the migration of neural crest cells. The conotruncal cuschions will come together on the midline and towards the muscular portion of the interventricular septum, while rotating along the longitudinal axis of the outflow tract. While they grow, they separate the outflow tract of the heart in the pulmonary trunk and in the aorta. 5. The interventricular septum is going to separate the 2 ventricles, the conotruncal septum instead, will make sure that each ventricle is connected with the right atrium. 6. At the end of the formation of the septum, it will be made of the muscular portion, the membranous portion coming from the conotruncal septum and the portion originating from the atrioventricular septum. 7. The heart does not originate only from the primary heart field: it also originates from the mesenchyme situated around the primordial pharynx, the ones that migrate to form the pharyngeal arches. Some of the neural crest cells situated in this area, rather than continuing to stay in the pharyngeal apparatus, they migrate to form the secondary heart field, which is important for the formation of the outflow tract and for the right ventricle.

What is the urinary space?

space between the inner layer lining of the glomerulus and the outer layer of the capsule = space between the parietal and visceral layers of Bowman's capsule - We can also recognize the urinary space, the one between the visceral and parietal layer. The pre-urine that is filtered enters into this space.

The definitive renal architecture is very outlined by, when?

the 10th week of gestation, in the same period when the definitive kidneys take charge of the production of urine; Several renal pyramids (8-12) drain into a minor calyx, contained in the medulla and on the top of the base and between the pyramids, we find the cortex of the kidney, or convoluted portion of the parenchymal of the kidney, in the sense that the cortex contains all the other components of the nephron: the corpuscles of Malpighi, the proximal convoluted tubules and the distal convoluted tubules; while the pyramids contain the collecting ducts and also part of the straight system of the nephron. The cortex in between the pyramid is called renal columns, also called columns of Bertin.

The true gas exchange barrier is made by:

the alveolar cells (type 1 pneumocytes) and the basal lamina of the alveolar cells fused with the basal lamina of the endothelial cells (of the capillaries). We understand that this structure is very delicate, mostly because the barrier to allow for the passageway of air must be really thin.

The terminal bronchiole is the last component of ...

the conductive portion of the respiratory system. In the R.S. there is a conducting portion and then a respiratory portion.

From the metanephrogenic mesenchyme we have the formation of ______.

the excretory unit: the nephron.

The male reproductive system is formed by:

the male gonad, whose purpose is to produce the gametes (spermatozoa) and hormones (testosterone).

What is the air-blood barrier?

the respiratory membrane; alveolar epithelium, endothelium, and fused basement membrane site of gas exchange. includes: 1. Type I alveolar cells 2. basal lamina 3. capillary endothelium

What are interalveolar septa?

the shared walls inbetween alveoli; Interalveolar septa have both thin and thick portions, and the "thin portion" is the most important one for gas exchange. The portion surrounding the alveoli, containing collagen, elastic fibers, fibroblasts and maybe macrophages, is called the "thick portion" of the interalveolar septa, and it's certainly not the most important one for gas exchange.

At the level of the penis we have the communication of _____.

the urethra with the bulbourethral gland, which also contribute to lubrication.

Where does the urogenital system develop from?

the urogenital system (both the reproductive and urinary system) intermediate mesoderm; and during the course of development part of the primitive urinary system will be incorporated in portions of the urogenital tract.

What are alveoli?

tiny air sacs in the lungs where gas exchange occurs; 1. The alveoli are sorts of small chambers, which can open either in a sac or in a duct. 2. They are characterized by squamous simple epithelium, which lines on a basal lamina, where we can find elastic fibres and a fine network of capillaries. 3. The alveoli are separated by interalveolar septa, which are formed by collagen, elastin, and capillaries. 4. However, frequently, alveoli abut on to one another, without the interposition of elastic and collagen fibers and they communicate through pores, called pores of Kohn.

What is the urethra?

tube that carries urine from the bladder to the outside of the body

Type 2 pneumocytes are precursors of ...

type 1 pneumocytes, meaning that if some were to be damaged, for example in respiratory distress syndrome, then type 2 pneumocytes can lead to the production of some type 1.

What 2 sections does the cloaca divide into?

urogenital sinus and anorectal canal

What's the difference between alveolar ducts and respiratory bronchioles?

⚠ In the alveolar ducts all the wall is substituted by alveoli! ⚠ These alveolar ducts open into large chambers which are called "alveolar sacs". Here, as in the alveolar duct, all the walls are made by alveoli (the difference is in the large structure, which is not a duct anymore). While moving from the terminal bronchiole to the alveolar sacs, the wall becomes substituted by alveoli.

Clinical Drop: What is asthma?

🚑 clinical drop - asthma (mentioned for the importance of the size of the tubes) 1. Asthma is a chronic inflammatory disorder of the airways, characterised by hypersensitivity to allergens, which causes reversible (up to a certain point) outflow obstruction and bronchospasm. 2. Meaning that there's a constriction of the airways that is reversible especially if you take drugs 3. Asthma doesn't only cause a contraction of the smooth muscle layer. In the beginning, the constriction is a functional contraction, but then with time, it may become a more structured constitutional contraction. 4. Asthma also causes inflammation of the mucosa, which further reduces the size of the lumen. 5. During an asthma attack, smooth muscle located in the bronchioles (but even more proximally) in the lung constricts and decreases the flow of air in the airways. 6. The amount of airflow can both be decreased by inflammation but also by excess mucus secretion if I'm still in the bronchioles that have mucus. It is characterized by recurrent episodes of wheezing, shortness of breath, chest tightness, and coughing

What are the bronchopulmonary segments?

"Lung units" - the anatomic, functional, and surgical units of the lungs -each lobar (secondary) bronchus, which passes to a lobe of the lung, gives off branches called segmental (tertiary) bronchi -each segmental bronchus enters a bronchopulmonary segment

⚠Our solid organs have a very poor ______.

"nociceptive innervation", that's why tumors can grow inside a solid organ very much without being noticed. ⚠

How do the general histological features change from the proximal to the distal part of the tracheo-bronchial tree? Is cartilage present?

(hyaline) cartilage: in the last part it becomes elastic cartilage; at a certain point, it disappears. Can still be found at the level of segmental bronchi, but is very much decreasing from the main bronchi.

What are the different types of cells lining the epithelium of the trachea?

(same type of cells we will find in bronchi ...) 1. goblet cells (yellow in the drawing); 2. ciliated cells, pseudostratified in the trachea and columnar towards the lobar bronchi; 3. club cells, special type of cells (named "club" because of their appearance) producing substances with protective and immunomodulatory roles, meaning that modulate response of epithelium to different types of agents + detoxifying functions; 4. basal cells (greenish in the drawing), stem cells or progenitor cells for continuous renewal of epithelium; 5. pulmonary neuroendocrine cells, both isolated or clustered together in neuroendocrine bodies (not surprisingly, since respiratory diverticulum is an endodermal diverticulum originating from intestinal tube, where we find as well neuroendocrine cells) to prove the environment, so to sense what's going on in the environment and in response release their own their hormones in the surrounding influencing the state of contraction of smooth muscle tone; 6. brush or tuft cells (rare epithelial cell type), contributing to type 2 immune response (special type of immunitary response); 7. ionocytes, special types of cells specifically involved in transport of ions (like Cl-) and therefore are an actor in cystic fibrosis. ***Rare epithelial cell types, including brush (tuft) cells, which may serve an important role in regulating allergen driven type 2 immune response, and the recently identified ionocytes, which appear to be a main source of cystic fibrosis transmembrane conductance regulator (CFTR) activity, thereby regulating mucus production (with a potential role in cystic fibrosis).

What can be seen in this image?

*description of the image on the right*, preparation of the mucosa of the trachea prepared to be examined on the scanning electron microscope. Cilia (CC) are visible together with the top of goblet cells (GC).

What can be seen in this image?

*description picture on the right* there's the epithelium (RE), under which we find the lamina propria (LP) and then there's the submucosa (SM) where there are still some glands. I start to see some bundles of smooth muscle cells between the lamina propria and the submucosa.

What can be seen in this image?

*section through central portion of the neck* where we see the trachea; in particular, we can see a cartilaginous ring and posteriorly the fibroelastic membrane and (if there is) the smooth muscle. Behind the trachea, we find the oesophagus. ** It wouldn't be so efficient to have cartilage also posteriorly: the oesophagus has movements of contraction and relaxation when food needs to move towards the stomach; the fact that there's a flexible surface in front of the oesophagus permits those peristaltic movements. ***In some histological preparations of the trachea, especially from older individuals, rather than cartilage in some regions of the cartilaginous rings you find bones (not a disease) since cartilage with ageing tends to ossify in certain places (like in the picture above).

What are the rete testis?

- A meshwork of interconnected channels that receive sperm from the seminiferous tubules - located within the mediastinum testis - Lined with simple cuboidal epithelium with short microvilli is - merge to form the efferent ductules 1. The straight tubules communicate with the rete testis. 2. They are surrounded by a highly vascularized stroma; moreover, the spermatozoa at this level are not yet motile, so we have myoid cells (contractile cells), which help to mix spermatozoa and to move them forward. 3. The rete testis is made of cuboidal cells with microvilli and cilium, which are used for reabsorption of fluids.

What is the size of a bronchiole? When can we say that we are in the domain of the bronchioles (size-wise)?

1 mm of size.

Site of fertilization and early cleavage of the zygote. They are about 10-18 cm and are the site where the propulsion of the egg in the uterus occurs. Here we recognise 4 anatomical regions:

1) Infundibulum with fimbria, 2) Ampulla, 3) Isthmus, 4) Uterine part (where the uterine tube communicates with the uterus).

Clinical Drop: What is autosomal dominant polycystic kidney disease (ADPKD)?

1. ADPKD is not present at birth, and only presents in adults because it progresses much slower. The protein affected here is instead polycystin I & II. 2. In this disease, problems in the formation of blood vessels can also occur, with a consequent formation of aneurysms. (This is a weakening of an arterial wall, which causes an enlargement/dilation of the vessels and could lead to a rupture if not detected early). Image: large cysts are visible in the kidney parenchymal.

What is the order of sites in the nephron?

1. Afferent arteriole 2. Bowman's capsule 3. Proximal convoluted tubule 4. Loop of Henley 5. Distal tubule 6. Collecting duct

How can we distinguish a bronchiole from a terminal bronchiole?

1. Again, macroscopically speaking is a question of size. A terminal bronchiole is a bronchiole with a diameter of 0.5mm or less than that: the tube is really narrow. 2. That's the reason why we don't want goblet cells, otherwise everything becomes clogged. 3. A terminal bronchiole supplies a territory of the lung parenchyma called pulmonary lobule (whatever is downstream to the terminal bronchiole). 4. Terminal bronchioles, in turn, give rise to respiratory bronchioles. 5. Each respiratory bronchiole, that is inside the pulmonary lobule, supplies a territory of the lung parenchyma which is called pulmonary acinus (smaller because is contained within the lobule).

What is airway mucus and what does it do?

1. Airway mucus covers the cilia of the epithelial cells and is divided into 2 subdivisions with different densities: the subdivision that surrounds the cilia is the periciliary layer, more fluid, while the one on the top is more jelly-like and is called the mucus gel layer. 2. Mucus contains water and glycoproteins. 3. Low viscosity and elasticity determine effective mucus clearance by cilia beating and cough.

What are alveoli surrounded by?

1. Alveoli are surrounded by a basal lamina (since they are lined by an epithelium, which needs a basal lamina), elastic fibers and a fine network of capillaries. 2. In-between one alveolus and another we find the "interalveolar septa" where we see elastic fibers, collagen fibers, fibroblasts and the capillaries.

The pelvis has usually a funnel shape but there are also two possible (extreme) configurations of the pelvis (these are not anomalies, just variations):

1. Ampullary pelvis: where the minor calixes seems to collect urine directly to the pelvis (and not into the major calix). 2. Ramified pelvis: where the pelvis is almost not visible because of the dimension of the major calixes

Clinical Drop: What is congenital lobar emphysema?

1. An emphysema is when air gets trapped in the distal portion of the respiratory tree, this is caused by collapsed bronchi due to failure in cartilage development. 2. Air gets trapped, causing a progressive distension of the lobe, which at a certain point, can even rupture it.

How is the external genitalia developed?

1. Around the 4th week of development there is the migration of the mesenchymal cells around the cloacal membrane. This migration led to the formation of two thickening/folds called the urogenital folds. 2. We can see that the cloacal membrane is surrounded by the urogenital folds (they can also be called cloacal folds or urethral folds). The two folds (on the right and on the left) will fuse together in the anterior region of the cloacal membrane forming the genital tubercule. In the meanwhile, in the inside, the urorectal septum is reaching the cloacal membrane, dividing it into a posterior and anterior domain. 3. The urogenital folds are divided into an anterior part and a posterior part too: the first one remains to surround a part of the cloacal membrane, that is now part of the urinary system, whereas the posterior part surrounds what is becoming the anal membrane. 4. On the side of the urethral folds the formation of the labioscrotal swellings is taking place, thanks to the migration of the mesenchyme. 5. In males the labioscrotal swelling will become the scrotal swellings, they will contribute to the formation of the skin of the scrotal bursa. 6. In females they will become the labia majora.

During the migration of the kidney is there also a change in blood supply? If so, how?

1. At the beginning the kidneys are in the pelvic region of the embryo and at that point they are supplied by vessels that originate from the common iliac arteries, but when the kidneys ascend, the old vessels degenerate and new vessels are formed from a higher level of the abdominal aorta; in the final state, they will be supplied by the final renal arteries.

How does the bronchial tree develop?

1. At the end of the 4th week, the respiratory diverticulum starts to form 2 evaginations, called primary bronchial buds, which grow surrounded by the mesenchyme from the splanchnic mesoderm. This connection with the mesenchyme is important, not only because the mesenchyme is going to give rise to some tissue and cells and the endoderm to others, but also because this interaction between the mesenchyme and the endoderm is important to determine the branching pattern, where branching is going to take place and when it is going to stop. There is much molecular crosstalk between the endoderm and the mesenchyme. 2. The 2 buds will undergo a process of further branching, which leads to the formation of the tracheo- bronchial tree. 3. The 2 initial bronchial buds will form the right and left primary bronchi, called main or primary bronchi. 4. At the beginning of the 5th week of development we can see that the direction of the right bronchus is not the same as the one of the left bronchus, so the angle that each of them forms with the trachea is slightly different from the other. Also, the right one is slightly larger and shorter than the left one. There are already some differences. 4. The primary bronchi will branch again (42 days) as to form the secondary bronchi or lobar bronchi. We have 3 lobar bronchi on the right and 2 on the left. 5. Around the 8th week, the lobar bronchi will branch again to form the segmental bronchi or tertiary bronchi. 6. We have 20 segmental bronchi, 10 to the right and 10 to the left. 7. On the left we have only 2 lobes because on the left side there is less space due to the presence of the heart. 8. The segments are important especially from the surgical point of view: if it is necessary to resect the lung, it is necessary to try to leave some functional tissue to let the patient breath and it is possible since every segment is independent from the others.

How does circulation change at birth?

1. At the moment of birth, we have several changes in the blood circulation. These changes are driven by the cutting of the umbilical cord (umbilical arteries and veins are not connected any longer with the placenta) and by the changes happening in the lungs after the first breath. 2. Because the umbilical vein has been cut, blood flow in the ductus venosus of Arantius decreases, which means that the amount of blood in the inferior vena cava and in the right atrium decreases. In the meanwhile, the resistance to blood flow of the lungs decreases due to the reabsorptions of fluid and this causes an increase in blood flow towards the lungs and therefore, less blood flows into the ductus arteriosus of Botallus. Since the lungs are receiving more blood, we will also have more blood coming back in the left atrium through the pulmonary veins. All this events cause the pressure in the left atrium to be higher than the pressure in the right atrium. This cause the septum primum to be squeezed against the septum secundum and therefore we have a functional closure of the communication between the 2 atria. At the beginning they are only closed by the difference in pressure, but with time, they will be fused together. 3. Since less blood is entering in the ductus venosus of Arantius and since the umbilical veins are not longer carrying blood from the placenta, it is no longer necessary and so it starts to contract and to degenerate, becoming a ligament, called ligamentum venosus. What remains of the umbilical vein becomes the round ligament, or ligamentum teres. 4. The ductus arteriosus of Botallus also needs to be closed and, at the beginning, the closure is only functional, but then the muscle layers start to contract and, in few days, it becomes a fibrous cord, the ligamentum arteriosum.

How are the kidneys vascularized?

1. Branches of the aorta enter the hilum of the kidney. 2. The renal artery (the branch of the aorta) inside the kidney branches in order to supply each segment (segmental arteries). 3. Segmental arteries divide into interlobar arteries (arteries which runs at the center of the renal columns of bertin). 4. This arteries bend (not branch) forming arcuate arteries which line the upper surface of pyramids (ad delimitate the medulla form the cortex). Renal-> segmental-> interlobar -> arcuate

What does this image show?

1. Branches of the pulmonary artery (vessels coloured in blue) carry venous blood reaching the alveolar bed. 2. Blood that comes out from the other side of the alveolar bed is red because it's oxygenated. 3. On the left (*) we see a system that goes from the lungs to the heart, the venous system.

Clinical Drop: What is Bronchiectasis?

1. Bronchiectasis is an abnormal and permanent dilation of the bronchi. 2. This can be due to a congenital condition, like Kartagener syndrome (whatever affects the ciliary movement, like the ciliopathy in this syndrome, is going to damage the mucus ciliary, causing inflammation and problems in the bronchial wall), cystic fibrosis, immunodeficiency disorders. 3. It can also be caused by chronic necrotizing infection or bronchial obstruction. 4. Signs of bronchiectasis are cough, fever, foul smelling purulent mucus, dyspnea. 5. The bronchiectasis is part of the COPD (Chronic obstructive pulmonary diseases).

How do the lungs continue development after the formation of the bronchopulmonary segments? What do they form?

1. By the 24th week of gestation, there are 17 orders of ramifications (development) and we have reached the level of respiratory bronchioles, but 7 additional ramifications will be formed after birth. 2. Only around 8 years there will be a complete maturation and stabilization of the respiratory system. 3. Because of that, looking at radiological images of babies, they look denser because the branching pattern still needs to be fully established.

Clinical Drop: What is Congenital pulmonary airways malformation (CPAM, or congenital cystic adenomatoid malformation)?

1. CPAM is a multi-cystic lung mass, resulting from a proliferation of terminal bronchiolar structures, with an associated suppression of alveolar growth. 2. It will cause abnormalities in bronchial branching, cysts filled with fluids and damage the bronchial tree. 3. Moreover, it can undergo a progressive growth, causing mediastinal shift, compression of the heart, compression of the venae cave, compression of the oesophagus, lung hypoplasia, polyhydramnios, fetal hydrops (lots of edema in the peripheral tissue of the fetus).

What are cavernous bodies formed? How do they allow an erection to occur?

1. Cavernous bodies are formed by connective tissue, which delimits lots of small cavities called vascular lacunae, which are lined by endothelium. 2. The scaffold is made by elastic, collagen, and muscle fibers and everything is kept together by the tunica albuginea. 3. During erection, blood flows in the vascular lacunae from the helicine arteries (there is a limit of expansion, which is determined by the tunica albuginea). 4. Veins are compressed and erection is maintained. When erection is absent, blood flow is impaired by the presence of myoepitheliod cushions. 5. The spongy body of the urethra is also made by erectile tissue. However, the tunica albuginea is thinner and more elastic and the caves are smaller and their wall thicker. It never reaches the rigidity of the cavernous body and the urethra is never compressed allowing ejaculation.

What are clara cells?

1. Clara cells (aka. club cells) are found in terminal bronchioles. They are protein secreting cells and produce a surface-active agent, which prevents luminal adhesion (particularly during expiration). 2. Clara secretory protein can also be called club secretory protein CC16.

What are dark cells?

1. Dark cells: (or intercalated cells, present in smaller number) they can secrete H+ or bicarbonate ions; because of this function they present microvilli and cytoplasmic folds. 2. Their number decreases towards the renal papilla until they disappear.

Simplified version of cardiac circulation:

1. Deoxygenated blood starts to run from the body 2. It flows into Superior/ Inferior Vena Cava 3. The flow of deoxygenated blood reaches the right atrium 4. The atrium will push the flow through the Tricuspid valve 5. The gore stays in the right ventricle 6. The line will continue to pass the systemic veins and flow into pulmonary valve 7. The oxygenated blood is pumped into the lungs through the systemic arteries. The marginal arteries will provide the heart muscle with blood. 8. The hemoglobin comes into the pulmonary veins 9. It reaches the left atrium 10. The flow of blood goes through the bicuspid valve 11. The valve pull it into the left ventricle 12. The bloodline moves to the aortic valve 13. After that, it flows through the aorta and coronary arteries 14. Finally, the oxygen-rich blood moves back to papillary muscle and the body.

Clinical Drop: What may cause alveolar damage?

1. Direct injury: toxic inhalation (smoke), a chemical irritant, a blunt trauma, water when drowning, pneumonia when it is too overwhelming, aspiration of gastric content (because of a fistula which establishes a communication between the lower part of the esophagus to the trachea-bronchial tree). 2. Indirect injury: not due to something that happens directly to the lungs, but systematically in the body. Sepsis (diffuse inflammation in the body), pancreatitis, it releases a lot of enzymes into the bloodstream (also causes pulmonary damage), anything that can cause a cytokine storm, meaning a huge number of cytokines produced by the immune-system.

What are the parts of the pleurae?

1. Double-layered sac surrounding each lung: A) Parietal pleura B) Visceral pleura 2. Pleural cavity: - potential space between the visceral and parietal pleurae. 3. Pleurae help divide the thoracic cavity A) Central mediastinum B) Two lateral pleural compartments

What happens to the prostate gland during puberty and over time?

1. During puberty, the prostate enters a period of accelerated growth and typically achieves its mature size. 2. The prostate continues to change over time and in the fifth decade of life a significant enlargement of the gland is common. The prostate gland epithelium is androgen dependent, or better in the parenchyma of the prostate gland we find the cells of the stroma, which are influenced by the testosterone, which gets transformed in dihydrotestosterone (DHT) which acts on epithelium cells.

Do kidneys undergo migration? If so, how?

1. During the early phases of development, the kidneys are quite caudal, so they have to migrate and relocate in the lumbar region. 2. The kidney "ascends" and rotates medially: the body of the embryo grows, elongating and in the meanwhile the kidney is brought in the rostral part, while it is moving, it rotates, so that the hilum of the kidneys face medially. 3. The adult kidneys are at the level of the duodenum, or of the last floating rib. 4. The kidneys are in the retroperitoneal space, they are not secondarily retroperitoneal. They are surrounded by an adipose tissue layer and then by a fascia of connective tissue, not by the peritoneum.

Clinical Drop: What pain can occur during the menstrual period?

1. During the menstrual period, we can have dysmenorrhea, when the pain is quite strong. 2. Dysmenorrhea can be divided into primary and secondary.

What does each collecting duct give rise to? What will these enter and form? And what does this mean/form?

1. Each collecting duct gives rise to several arch collecting tubules and each of them will enter into contact with the mesenchyme, forming many nephrons. 2. This means that several nephrons drain into the same straight collecting tubule, forming a kidney lobule, which is formed by all the nephrons that drain in a collecting duct.

How are the septa supplied with blood?

1. Each segment is supplied independently by its own segmental bronchus and by a bronchial artery (segmental branch) and a pulmonary artery (tertiary branch of the pulmonary artery) (blood poor of oxygen). 2. They are named according to the segmental bronchi supplying them. They are drained by intersegmental pulmonary veins (contains oxygenated blood).

Why do we need elastic fibers in the tracheo-bronchial tree? And where are they found?

1. Elastic fibers can be found up to the last portion of the respiratory tree; they are very important for the elastic recoil. 2. Elastic fibers, very important in the respiratory system, are there from the beginning up to interalveolar septa (up to the end). 3. That's why when there are pathologies of the lungs that destroy the elastic fibres (e.g. some types of emphysemas) when elastase is produced and digests the elastic fibers, the lungs lose their ability to provide elastic recoil during expiration, meaning that air tends to get trapped in the lungs because it's not so easy to get it out.

Clinical Drop: What is emphysema?

1. Emphysema is a Chronic Obstructive Pulmonary Disease, it causes persistent airflow limitation (it is persistent because the elastic fibers have been digested and there is nothing to solve this problem), progressive, enhanced chronic inflammatory response, which increases the problem. 2. A person that suffers from emphysema is going to complain about shortness of breath. 3. Emphysema affects the structures distal to the terminal bronchiole, consisting of the respiratory bronchiole, alveolar ducts, alveolar sacs, and alveoli, known collectively as acinus. 4. These structures in combination with their associated capillaries and interstitium form the lung parenchyma. 5. The part of the acinus that is affected by permanent dilation or destruction determines the subtype of emphysema.

Clinical Drop: What are problems that can occur with the endometrial tissue?

1. Endometriosis is a condition that is caused by endometrial tissue that grows in other places: areas of endometriosis bleed each month, causing inflammation and scarring of the binding organs. 2. It causes pelvic pain, dysmenorrhea, infertility, lower back pain, dysuria (urgency, frequency, and painful voiding). 3. Women that suffer from endometriosis can be infertile because fallopian tubes may not work properly due to the presence of this inflamed tissue.

How do the general histological features change from the proximal to the distal part of the tracheo-bronchial tree? Start with the epithelium:

1. Epithelium: its characteristics change from the trachea to alveoli; in the initial part cells are tall and the epithelium is pseudostratified. 2. The more we move from proximal to distal, the epithelium becomes first columnar → cuboidal (cells will become shorter and shorter) → at the level of the alveoli will become a squamous epithelium.

How do the 3 cells that compose the juxtaglomerular apparatus affect blood pressure?

1. Extraglomerular mesangial cells, juxtaglomerular cells and macula densa cells compose the juxtaglomerular apparatus. 2. These 3 cells affect blood pressure activating the renin angiotensin aldosterone system in which the secretion of renin (stored in juxtaglomerular cells) catalyzes in blood the formation of angiotensin one which in the endothelium is transformed in angiotensin two which stimulates the secretion of aldosterone (in the zone glomerulosa of the adrenal gland) which acts on collecting duct increasing Na+ (and so also water) absorption. Note: afferent arterioles which enters the gromerolus are larger than efferent arterioles which exit the glomerulus

Clinical Drop: What are the phases of ARDS?

1. Exudative 2. Proliferative 3. Fibrotic

Female urethra:

1. Female urethra: it opens anteriorly to the vagina, in the most caudal portion the anterior wall of the vagina and the posterior wall of the urethra are fused (walls, not lumens). 2. It presents longitudinal folds called urethral folds (which distends with the passage of urine). One of this folds is not transient and is present posteriorly where the walls of the urethra and he vagina ere fused. 3. On the surface of these folds there are urethral glands which opens at the bottom of small pits which produce a mucus secretion. 4. There are also paraurethral glands (skene's glan'ds) which are found in the most distal portion, in fact they open directly at the side of the opening of the urethra.

In renal corpuscles happens the filtration which leads to pre-urine, 3 structures contribute to this process:

1. Fenestrated capillaries: of which the porous endothelium contains numerous aquaporins 2. Glomerular basement membrane: between capillaries and podocytes, this membrane is thicker and present special features: it acs as a physical barrier (does not allow the passage of large molecules) and as an ion- selective filter. Hematuria or albuminuria (presence of blood or albumin in urine) indicate a physical or physiological malfunctioning of the basemen membrane. 3. Podocytes: which envelop capillaries projecting on it primary processes which extend into secondary processes which form a network around them. Fenestres of this network are called interdlgitate spaces through which molecules can pass.

Clinical Drop: What are the 2 different proteins affected in ADPKD and ARPKD? How are they affected?

1. Fibrocystin in ARPKD and polycystin in ADPKD - the two proteins affected by these diseases - are associated with the primary cilium, especially in the region where the kidneys are developing. 2. Most of the cells of our body, especially during development, possess the primary cilium, which is a sort of antenna on which most of the transmembrane proteins are localised. 3. The primary cilium is used to sense the environment for regulating the proliferation, differentiation, cell-cell interactions, cell-extracellular matrix interaction and sensing flow. 4. Therefore, if there are problems with these proteins, then the cells cannot properly sense the messages of the environment and then the kidney parenchymal does not develop correctly. 5. These primary cilia with these specific proteins are also present where the bile duct is developing and therefore there will also be problems in this region.

What are fimbriae?

1. Fimbriae are finger-like projections on the ends of your fallopian tubes closest to your ovaries. 2. Each month, your fimbriae catch the egg that one of your ovaries releases during ovulation. 3. Your fimbriae then sweep the egg (ovum) into the fallopian tube where the egg can be fertilized. 4. Close to ovulation the fimbriae are swollen with blood, enlarged and they get very close to the ovary.

How do we get the air to move so quickly in airways?

1. First, you do a deep intake of air, close the glottis to trap the air in and contract the trachealis muscles, creating a lot of pressure in the airway; at this point, you open the glottis and air comes out very quickly and rushes over the mucosa trying to move very fast mucus outside. 2. To have an efficient cough we need to be able to raise the intrathoracic pressure, a mechanism used also to contract the trachea a bit.

Several molecular events control kidney development: What control the ureteric bud to develop?

1. For the definitive kidney to develop we need it to be able to express the correct molecules. 2. The ureteric bud develops from the mesonephric duct. 3. We have the formation of the ureteric bud just before the metanephrogenic mesenchyme attaches to it, that can be explained by the fact that the metanephrogenic mesenchyme, which is close to the mesonephric duct, starts to release some factors, like the GDNF (Glial Derived Neurotrophic Factor), while on the side of the duct, there are lots of receptors for this factor. 4. In the area where the GDNFs will attach to their receptors, we will have the formation of the ureteric bud. 5. The mesenchyme produces WT1, which gives to the mesenchyme the ability to respond to substances released by the ureteric bud; and GDNF and HGF (hepatocytes growth factor), which stimulate the growth of the ureteric bud. 6. The epithelium produces Ret (used to link GDNF) and Met (HGF receptors); the epithelium expresses also FGF2 (fibroblasts growth factor 2) and BMP7 (bone morphogenetic protein 7), which induce the mesenchymal proliferation; PAX2 and WNT4, which induce epithelial transformation: fibronectin and collagen I and III (present in the region of the extracellular matrix where the vessels are forming) are substituted with laminin and collagen IV, typical of epithelial basal lamina, moreover, we have the synthesis of adhesion molecules typical of epithelia.

Development of the heart: Why do we need the semilunar valves? How are they formed?

1. For the heart to work properly, we need valves between the ventricles and the great vessels, at the origin of the aorta and of the pulmonary trunk. These valves are called semilunar valves. 2. The semilunar valves form while the conotruncal septum and the 2 great vessels are forming. They are formed due to a hollowing out and reshaping of the conotruncal cushions, moreover, the formation of other cuschions, called intercalated cushions contribute to the formation of 3 thin-walled cusps. 3. A valve will be formed by 3 leaflets, 2 of them originates from the conotruncal cushions, while 1 originates from the intercalated cushions.

What arises from interlobular arteries?

1. From interlobular arterioles (which derive from interlobular arteries) afferent arterioles extend to form the glomerulus (the same interlobular arteriole can give rise to more than one efferent arteriole and so can form more than one gromerolus), efferent arterioles instead leave the gromerolus and are narrower then the afferent ones. 2. In cortical nephrons (which have a shorter narrow portion of the loop of henle) efferent arterioles form a capillary network around the convoluted tubes called peritubular capillary network. 3. In juxtamedullary nephrons afferent arterioles in addition to form the peritubular network as in the cortical ones, they form also vasa recta which are vessels supporting the loop of henle, which create the countercurrent circulation in the medullary region.

What are the ductuli efferentes?

1. From the rete testis, the fluid is moved into the ductuli efferentes. 2. They are formed by cells with microvilli (reabsorption) and ciliated cells that are used for propulsion of spermatozoa towards the epididymis. 3. Moreover, a thin band of circular smooth muscle cells help the propulsion of the spermatozoa. 4. There is a progressive increase in smooth muscle tissue from the straight tubules to the epididymis.

Clinical Drop: What is Germinal Matrix Hemorrhage (Periventricular or Intreventricular Hemorrhages)?

1. Germinal matrix haemorrhage (GMS); One problem associated to the RDS, especially in premature babies, is the germinal matrix haemorrhage: in a premature baby, the lungs are not mature, but also the vascular system is not yet maturated. 2. For example, the capillaries of the brain are very fragile and in babies the mechanisms that allow to keep a constant and correct pression of blood in the brain are not yet functional. 3. Moreover, there are regions of the brain where the neurons are still forming and in case of bleeding (due to fragile capillaries) in that area, that germinative zone can be damaged. 4. In RDS patients, this problem is even more accentuated by all the stress, both physical and respiratory, to which the baby is subjected. 5. GMS can cause, then, serious neurological sequelae, causing stroke, cerebral palsy, mental retardation, and seizure.

How do the general histological features change from the proximal to the distal part of the tracheo-bronchial tree? Why do the goblet cells disappear?

1. Goblet cells produce mucus that traps pathogens. This process has to happen early (we don't want to wait for the alveoli or the respiratory bronchioles to act as entrapping substances). 2. In addition, mucus cannot stay there, it needs to be pushed by the cilia to go into the digestive system (advantage of having communication at the level of the oropharynx between the respiratory tract and the digestive tract), and since alveoli don't have ciliated cells it would be difficult for them to move mucus away. 3. But there's also the question of the size of the tubes: they become very narrow and small (at the level of alveoli we have squamous epithelium) and can't be clogged by mucus.

What are the histological features of the male urethra?

1. Histological features: the mucosa is very similar to the one of females but here the transition is more complex: until the prosaic portion there is still urothelium which then transforms into pseudostratified epithelium which then becomes stratified in the most distal portion. 2. In the lamina propria there are glands of littre and as in females there are elastic fibers. 3. The muscle layer are only two (internal longitudinal and external circular) and are continuous with the one of the bladder. 4. The two muscle layer disappear in the penile urethra where are substituted by the spongious body. 5. Above the spongious body there are two fused cavernous bodies (or corpora cavernosa) which are connected to the glans penis. 6. Both the spongious body and the cavernous bodies present "caves" on their inside which at the moment of erection are filled with blood. The cavernous tissue (of both the spongious body and the cavernous bodies ) is lined by endothelium (because they are going to be filled with blood); the trabecule are formed of collagen, elastic and smooth muscle fibers. Around the spongious body there is a tunica albuginea.

What are the histological features of the female urethra?

1. Histological features: the mucosa, as the one of the anal canal, represent a transition. 2. In this case from the one of the bladder to the one of the external surface: the upper portion has a transitional epithelium, the lower portion has a stratified squamous epithelium. 3. Below the mucosa there is a lamina propria made of dense connective tissue rich in elastic fibers (as in ureters). In the distal portion the lamina propria is supplied by a rich plexus which forms the spongious body of the female urethra. 4. The muscle layers are continuous with the one of the bladder and present the same features (recall that there is a contribution of striated muscle fibers which form the external sphincter).

Clinical Drop: What can go wrong in the formation of the vagina?

1. If something goes wrong in the process of formation of the vagina, we can have some anomalous communications between the vagina and the urethra or between the vagina and the rectum. 2. If there is meconium (original content of the intestinal canal) that comes out from the vagine, it means that the vagine is somehow in communication with the rectal canal.

Clinical Drop: What happens if ARDS is cardiogenic?

1. If the syndrome (ARDS) is cardiogenic, the problem is more concentrated at the base of the lungs, while in a non-cardiogenic situation, the problem is more diffuse all over the lungs. 2. Endothelial cells have anti-coagulative properties so they try to prevent thrombosis, but if they are damaged, they tend to promote it.

What happens if there is too much mucus produced in the airways?

1. If too much mucus is produced, the cilia system is not enough to get rid of it and therefore there is a reflex activity called cough. 2. With cough we increase the pressure of the abdominal and thoracic cavity and we do that inspiring and then releasing abruptly the air. 3. Cough average velocity is in males around 15.3 m/s and 10.6 m/s for females. 4. Cough is a reflex driven by the irritation and clogging (lots of mucus) of the airways.

Male vs. Female Development

1. If we are in a genetically male fetus, the somatic support cells present, in the gonads, start to express the SRY factor (sex determining region of the Y chromosomes) and transform in Sertoli cells and trigger the transformation of the mesenchymal cells into hormone producing Leydig cells. 2. Leydig cells start to produce testosterone, which acts on the mesonephric duct of Wolff, causing its transformation in the epididymis, in the ductus deferens and into seminal vesicle. Moreover, testosterone starts to travel in the fetus and in the periphery it gets transformed in dihydrotestosterone. This will cause the formation of the external characteristics of a male individual: the prostate gland, the scrotum and the penis. 3. Sertoli cells also produce a factor called Mullerian inhibiting substance, which inhibits the paramesonephric duct of Muller, which degenerates (in women, there is not the production of Mullerian inhibiting factors, so it will not degenerate). So, by default, the gonads develop into a female gonads, but if we are in a male, the presence of the SRY gene will trigger the formation of Sertoli cells, causing the differentiation of the gonads. Sertoli cells will produce also androgen binding factor, which binds androgen keeping the right concentration of androgen in the seminiferous tubules. 4. So, it is important that it is produced because when at puberty there will be a surge of testosterone, then it will be able to bind to the androgen binding protein and because it is in a very high concentration, the gonadal cords will be able to transform into seminiferous tubules, allowing further differentiation of spermatozoa (since we don't have seminiferous tubules, until puberty, there is no formation of spermatozoa). 5. In a genetically female individual, we have no SRY factor and therefore, the primordial germ cells will undergo the first meiotic division and they will be committed to become oocyte. Moreover, the mesonephric duct of Wolff will degenerate because there is no testosterone, while the paramesonephric duct will remain because there aren't any Sertoli cells, leading to the formation of the uterus and of the fallopian tubes. 6. The mesonephric tubules, those that were connected originally with the gonadal cords, remain and transform into the ductuli efferentes or efferent ducts that, through the rete testis, will connect to the seminiferous tubules. 7. Remnants of the ducts and tubules can give rise to cysts. In female, we can have some remnants of the mesonephric duct and they are called epophoron and paraophoron.

Clinical Drop: How ARDS affect the rest of the body? What is the pathophysiology (the study of how disease processes affect the function of the body) of ARDS?

1. If we have an increase in hydrostatic pressure in the alveolar capillaries, there is an opening in the epithelium cells and therefore fluids start to move from the lumen of the capillaries into the alveola, causing a cardiogenic or hydrostatic pulmonary edema. 2. Moreover, it can also be caused by a damage to the endothelial cells or alveolar epithelial lining, caused by inhalation of agents such as smoke, water (near drowning), bacterial endotoxins (sepsis), trauma.

What do we see in this image?

1. In [A] we see the paramesonephric duct depicted in blue. The paramesonephric duct, on the right and on the left, will come together caudally behind the urethra, to form the uterus. In green we can appreciate the gubernaculum, which is attached on one side to the ovary, and on the other to the floor of the abdominal-pelvic cavity (as in males), it will later become the labia majora (in females only). 2. What happens is that the gubernaculum shortens, and in the meanwhile, it attaches to the paramesonephric duct (in the region where the uterus is forming). In this way the first one is stacked, and it cannot shorten any longer, that's why the ovaries are not further pulled down. The gubernaculum attached in the region of the paramesonephric duct that is going to form the uterus, evolves as to form the round ligament of the uterus. The latter is the part of the gubernaculum that remains between the uterus and the labia majora, crossing through the inguinal canal. On the other hand, the portion of the gubernaculum that remains between the uterus and the ovary becomes the ovarian ligament.

How is the urethra different in males and females?

1. In a female the urethra is quite short and it opens into the vestibule of the vagina; while in males the urethra is much longer. 2. The fact that in females the urethra is that short, causes a higher probability to get infections at the urinary bladder. 3. In females, behind the urethra we can find the vagina and behind that there are the rectum and the anal canal. 4. While in males, the urethra is surrounded in the initial portion by the prostate gland (prostatic portion, in this region we have a communication between the urinary and genital system) and then it continues with the penile urethra. 5. The last portion of the digestive tract, in males, can be found right behind the urinary bladder.

How is the urethra different in males and females?

1. In females the urethra is not fused with the genital tract while in males yes, at the level of the prostate. 2. The male urethra is a more complex and long structure, the only anatomical thing that it has in common with the female one is that it crosses the urogenital diaphragm.

What is the fetal circulation? How is it developed?

1. In the fetal circulation we have the umbilical vein (just one, the other has regressed), which is connected with the placenta, that through the umbilical cord reaches the inside of the fetus, runs within the parenchyma of the liver (it gives some blood to the liver, but most of it goes on in the circulation) and then the blood is shunted within the vena cava through the ductus venosus of Arantius. 2. The inferior vena cava, distal to the communication with the ductus venosus, contains blood coming from the limbs and from the abdomen, which is poorly oxygenated; instead, after the connection with the ductus venosus of Arantius, the blood is enriched with the very oxygenated blood coming from the umbilical vein (this is the most oxygenated blood that the fetus can have). 3. Once the blood enters the heart, most of it is shunted though the foramen ovalis in the left atrium and then in the left ventricle. 4. From there, blood goes into the ascending aorta, which continues with the arch of the aorta and then with the descending aorta. 5. When the blood leaves the left ventricle, it is still very oxygenated and that is why because the arch of aorta is linked with the vessels that carry blood in the superior part of the body, where the brain is developing; after the arch the blood becomes mixed oxygenated. 6. The blood that remains in the right atrium, the one not shunted in the left atrium, goes in the right ventricle, together with the blood arriving from the superior vena cava (forming mixed oxygenated blood). 7. From the right ventricle, blood is shunted in the pulmonary trunk, then to the pulmonary arteries and then to the lungs. 8. The lungs, though, do not oxygenate blood, but they use it to continue to grow. 9. The lungs, which are filled with fluid up to the moment of birth, cannot expand and there is lots of resistance towards the flow of blood. The pulmonary trunk, besides the right and left pulmonary arteries, forms a connection, an anastomosis, with the arch of the aorta, right after the arteries directed to the upper half of the body. 10. This shunt is called ductus arteriosus of Botallus and due to it, the highly oxygenated blood of the aorta becomes mixed oxygenated blood. From the aorta, the blood goes to the rest of our body. 11. The only region of our body thar receives highly oxygenated blood is the region of the head. From the lower branches of the aorta we have a communication through the umbilical arteries with the placenta.

What do we find in the thick portion of the interalveolar septa?

1. In the interalveolar septa we find collagen fibers, elastic fibers, fibroblasts and macrophages. 2. In the septa there are no lymphatics, only capillaries, and fluid is drained in the lymphatics of the sacs (when the alveolar sacs become large, then there we find the lymphatics) = so the fluid accumulated in the interalveolar septa is drained by lymphatics present around the alveolar sac. 3. Fibroblast produce collagen and elastin and appear to have contractile properties and thus they are able to regulate the blood flow. 4. Macrophages shuttle between the alveolar space and the interstitium.

What happens in the last phase of the uterine cycle?

1. In the last phase of the uterine cycle, the spiral arteries start to contract and relax, causing a deprivation of oxygen to the functional layer. 2. The functional layer starts to become first ischemic and then necrotic; moreover the spiral arteries, after a while have a breakdown, causing a detach and shed of the functional layer into the uterine cavity (menses). 3. The basal layer is not affected. 4. The muscle layer of the uterus undergoes to contractive waves, especially during the menstrual period (increase in amplitude) to get rid of the menses. Increase in waves is also present during ovulation.

What happens in the development of the male gonad?

1. In the male gonad, the portion of the medullary cords remain, while the cortical cords degenerate forming the tunica albuginea (fibrous tissue). 2. The medullary cord surrounds the primordial germ cells and at the same time the connection with the tubule of the mesonephros remains, forming the rete testis and efferent ductules. 3. The mesonephric duct will form the epididymis. 4. The cords that contain the spermatogonia, at puberty, will undergo a process of canalization and they will become the seminiferous tubules.

How is the inguinal canal formed (in males) -- their descent from the gonads?

1. In the male the gonads are located outside the abdominal wall, they are accommodated in a sac (bursa) below the pelvis. 2. At this point of development, the gonads are still positioned inside the abdominal cavity, so at a certain point they must migrate on the outside. 3. To do so, a passageway is needed and a bursa that will contain the gonads must form as well. 4. The passageway will be open also during adulthood since the gonads need to be located outside the abdominal wall: this has to do with the fact that the spermatozoa to mature need a lower temperature than the body one. 2. On the other hand, it is important to have a communication between the external gonads (testis and penis) and the rest of the genital tract located inside the abdomen.

Where is the smooth muscle located in the trachea?

1. In the trachea, the smooth muscle is located only posteriorly and forms the trachealis muscle. 2. The muscle bundles run transversally from one side of the tip of the ring to the other side (→). 3. The presence of the trachealis muscle and its contraction reduces the diameter of the trachea and assists in raising intrathoracic pressure during coughing.

What are the different parts of the uterine tube?

1. In the uterine tube we have the infundibulum, which ends with the fimbriae, which gets closer to the ovary during ovulation. 2. We have one fimbriae, called ovaric fimbria, which is attached to the ovary. 3. After the infundibulum, we have the ampulla portion, the isthmus and the uterine part or intrauterine part, which is the zone where the fallopian tube becomes the uterus.

What can be found in the wall of the respiratory bronchioles?

1. In the wall of the respiratory bronchioles, in the alveolar duct and also in the opening of the alveolar sacs, there is still smooth muscle tissue. 2. There is an arrangement of "knobs"/"rings" made by smooth muscle cells, elastic fibers and collagens. 3. These knobs are important because they permit the control of the flow of air in the distal portion of the respiratory tree. ⚠ Up to where you have smooth muscle, you can constrict, meaning you can control the flow of air. ⚠ 4. These smooth muscle knobs are under the control of the autonomic nervous system, for example the parasympathetic nervous system. 5. In this case the vagus nerve is able to regulate the state of contraction of these muscle knobs, as well as local events, for example local cells producing histamine. 6. Upon release of histamine they can regulate the state of contraction of the lungs.

Clinical Drop: What could be the cause of an ARDS in an adult?

1. Increase in hydrostatic pressure in the alveolar capillaries: if the pressure inside the capillaries of the lungs increases, fluids from the capillaries can enter into the interalveolar septa and also in the alveoli. In some cardiac conditions in which the heart doesn't work well, this causes an increase in pressure in the capillaries of the lungs, which can cause an edema of the interalveolar septa and a condition which is called "Pulmonary edema". 2. Damage in the alveolar epithelial lining, for example, caused by the inhalation of agents such as smoke. Also water entering the alveoli when drowning can damage them. 3. Bacterial endotoxins, such as sepsis, are another menace. 4. Trauma can lead to damage, of course a mechanical one.

What are the 3 phases of coughing?

1. Inspiratory phase: breath in; 2. Compressive phase: glottis closes, intrathoracic pressure increases 3. Expiratory phase: contraction of the muscles of the thorax and abdomen, the air comes out.

Why do we need smooth msucle in the tracheo-bronchial tree?

1. It has to do with the boring of the tube: the tubing system needs to be able to change its boring, so how much air goes through it. The only way to change its size is by having something that can constrict or release or change the tone, all obtained through smooth muscle. 2. The reason why we have to change the size of the tube is, for example, due to high levels of exercise that increase the amount of air that we introduce in our lower respiratory system or need to change the distribution of air from one section of the lungs to the other.

Clinical Drop: What is a ostium secundum defect?

1. It is caused by an excessive reabsorption of the ostium secundum, which does not cover the foramen secundum and then it remains open. 2. At birth, pressure becomes higher in the left ventricle, blood is shunted from the left to the right atrium. 3. At the beginning it is asymptomatic, but later it can cause enlargement of the right side of the heart (hypertrophy), pulmonary hypertension (excessive blood flow in the lungs) and debilitating atrial arythmias. It is compatible with many years of normal life, with time, if the pressure in the right atrium raises above that in the left atrium, we have a reversal of the shunt and cyanosis. It has a rate of 6:10,000.

Clinical Drop: What is the tetralogy of fallot?

1. It is the most common cyanotic congenital malformation due to a defect in the septation of the truncus arteriosus that favours the aorta and causes also a defect in the superior portion of the interventricular septum. 2. It is caused by defect in migration of neural crest cells. 3. It is called tetralogy of Fallot because it is usually characterized by 4 defects: stenosis of the pulmonary trunk (1); ventricular septal defect (2); overriding aorta (3), rightward displacement of the aorta, so that the vessel receives blood from both ventricles); enlarged right ventricle (4). 4. A patent ductus arteriosus is also present.

What are juxtaglomerular cells?

1. Juxtaglomerular cells: are modified smooth muscle cells. 2. They present baroreceptors (a type of mechanoreceptors specific for pressure) so that they can detect blood pressure and eventually in response release renin which is stored in cytoplasmic granules (renin coverts ADH in tis active form which increases blood pressure). 3. These cells are in relation with intreglomerular mesangial cells.

What are the differences between cortical nephrons and juxtamedullary nephrons?

1. Juxtamedullary nephrons have a longer thin portion of the loop of henle, because of this, this nephrons perform a greater reabsorption. 2. These two types of nephrons are differently supplied by arterioles (discussed below).

What are the terminal bronchioles?

1. Last component of the conductive portion of the respiratory tree. 2. In the terminal bronchioles we have no cartilage. 3. The epithelium is cuboidal and we have very few ciliated cells, but the Clara cells are very abundant. 4. Below the mucosa we can find smooth muscle and the submucosa is absent.

What are the different regions of the ovary?

1. Looking at the ovary, we can distinguish the cortex, the more peripheral region, and a more central region, where blood vessels are branched, which is called medullary region. Then we have a hilum, where veins and artery enters. 2. On the outside, we find the tunica albuginea, which forms during transformation of the gonads and outside it, we find the germinal epithelium of the ovary, which is called germinal because at the origin it was thought that that was the origin of the germinal cells, instead it is very similar to a mesothelium, that is why the ovary is only apparently covered by the peritoneum. 3. The germinative epithelium, every time we have an ovulation, it gets disrupted and then it has to regenerate. It is believed that one of the origin of the ovarian cancer is due to this process of continuous inflammation and regeneration of the germinative epithelium. 4. The stroma of the ovary contains fibroblasts cells with lipid droplets, collagen fibers and bundles of smooth muscle fiber. The cortex contains follicles at different stages of development. On the surface there is the ovarian germinative epithelium which is a continuation of the peritoneum. The medulla is highly vascular, we have 10 coiled arteries, called helicine arteries (very coiled on themselves). From the helicine arteries, straight arteries form a capillary plexus around the follicle.

What are macular densa cells?

1. Macula densa cells: as mentioned they are found at the level of the interaction (in the vascular pole) with the distal convoluted tube. 2. These tightly packed cells are strictly associated with both cells discussed above, they present chemoreceptors specific for Na+ and Cl- (if too much sodium as been filtered they stimulate a reduction of the filtration pressure at the level of the afferent arteriole trough the mediation of extragromerular mesangial cells).

What is the physiology of the urinary system?

1. Maintenance of water, electrolytes ad acid base homeostasis 2. Excretion of waste products (which may be harmful for the body) 3. Hormonal and metabolic function as vitamin D conversion (vitamin dis absorbed by the body from the diet or from the skin. Particularly is absorbed in the small intestine together with chylomicrons and is delivered to the liver where it is firstly transformed, this transformed version is delivered to the kidneys where is finally transformed in its active form. Active vitamin Dis involved in calcium balance, particularly it decreases the blood calcium levels), erythropoietin (increases erythrocytes) and renin (blood pressure) Most of this functions are performed at the level of the nephron.

What are the cells that compose the juxtaglomerular apparatus?

1. Mesangial cells 2. Juxtaglomerular cells 3. Macula densa cells

What are mesangial cells?

1. Mesangial cells: found in the basal lamina. Are associated with capillaries and have a communicating function between the intreglomerular and the extraglomerular spaces (so they can be found also in the extragromerular space). 2. They have receptors for angiotensin and so increase blood pressure (but recent studies have shown that they do not control directly blood pressure but instead act in response to an increase in blood pressure increasing glomerular distention). 3. They have contractile filaments so that they can regulate the calibre of capillaries. 4. They have also phagocytic and endocytic properties and produce vasoactive substances such as interleukins and platelet growth factor; for this reason they play an important role in injuries. 5. Even tough mesangial cells have phagocytic properties they do not derive from monocytes but from smooth muscle cells (as juxtaglomerular cells).

How does the mesonephros form?

1. Mesonephros (4-8 weeks): it's also called the "ad interim kidney" because it is functional (produces some urine while it is in function). 2. Vesicles continue to form caudally, while the pronephros is regressing, and they connect with the mesonephric duct, forming temporary and primitive nephrons that filter blood. 3. The mesonephros occupies a lot of space in the abdominal cavity and is so big that it takes the name of wolffian body. 4. The mesonephros forms in the same region of the urogenital ridges/crest, where the gonads and the adrenal glands are forming. (The gonads will be formed medially to the mesonephros where there is a region called genital ridge). 5. Mesonephros starts to filter blood and starts to form nephrons.

How do we classify the bronchioles?

1. More than anything is a question of size: when the conduit has ≃1 mm of diameter, it is called bronchiole. 2. There is no cartilage and there are a lot of elastic fibres. 3. The smallest bronchioles of the conducting portion are called terminal bronchioles.

Why is it important to have a communication between the external gonads and the rest of the genital tract?

1. Most of the genital tract is inside the abdomen, especially it is important to have a communication with the penile urethra. 2. Testicles need to be supplied by blood vessels which originate from the aorta (arteries). They also need a draining system (veins), lymphatics and nerves innervating them.

What are histological features of the bladder?

1. Mucosa: with transitional epithelium, the lamina propria underlining the epithelium is thick (in some books it is referred as a submucosa) and provides a sliding plane for the epithelium and muscles (when the folds must to distend). In the region of the trigone this sliding plane is absent. 2. Muscle layers: all muscles layers are called detrusor muscles of the bladder. Is made of an inner longitudinal layer, middle circular layer and an outer longitudinal layer (as in the more distal part of the ureters). Also elastic fibers are present among these layers. 3. Adventitia/serosa: according to the surface of the bladder and to the physiological situation of it.

The process of reabsorption in the proximal convoluted tubule is driven mainly by:

1. Na/K-ATPase pumps: which reabsorb Na in exchange of K. This transport is followed by the diffusion of Cl in order to maintain the electrochemical balance 2. Aquaporins: which are diffusive channels for water

Can you control your lungs? Can you control the state of contraction of your bronchi or of your trachea?

1. No, so the lungs are under the control of the autonomic nervous system because they contain smooth muscle cells. 2. The lungs are viscera and our central nervous system needs to know something about them. It needs to know what's going on, therefore there's an afferent innervation of the lungs and trachea-bronchial tree, as well as an efferent one. !! Afferent is information that from the periphery reaches the center, while efferent is information that from the center reaches the periphery. !!

Clinical Drop: What are other conditions that can lead to ogliohydramnios?

1. Other conditions resulting in oligohydramnios can be obstructive uropathy (the ureters are bend or they do not canalize properly), cystic kidney diseases (the kidney develop fully, but they start to form lots of cysts inside the parenchyma and therefore they become less and less functional), renal hypoplasia, and premature rupture of the chorion amniotic membrane lead to the same clinical findings. 2. Regardless of the root cause for oligohydramnios, the terms Potter syndrome, Potter sequence and oligohydramnios sequence are used interchangeably in the published literature.

The epithelium of the collecting tubules and the collecting ducts, the ones that run straight into the medulla, have 2 types of cells (one more numerous than the other):

1. Pale cells 2. Dark cells

What are pale cells?

1. Pale cells: (majority) the name is due to their staining. 2. These cells present a monocilium (or primary cilium) on their surface which act as a mechanoreceptor which detects the amount of urine that is flowing through the duct. 3. There are not microvilli because reabsorption of sodium here is very low, there are sodium channels anyway which regulate water absorption (regulated by ADH). 4. Here there are also aquaporins.

Where and how are the kidneys located in the adult body?

1. Part of the kidneys is covered by the ribs; they are at the level of the last ribs. 2. The kidneys are in the retroperitoneal space, behind the duodenum, even though they have nothing to do with the duodenum. 3. They are not secondarily retroperitoneal since they do not have anything to do with the peritoneum and they do not develop in the peritoneal cavity. 4. The kidneys are surrounded by adipose tissue and then they are surrounded by a fascia, made by connective tissue. Anteriorly to the kidney, we find the peritoneal cavity.

Clinical Drop: What are the various anomalies that can occur in the process of formation and ascending of the kidney?

1. Pelvic kidney: the kidney doesn't ascend and remains instead in the pelvic region. This isn't usually clinically relevant, unless the ureter elongates and bends and causes stagnation of urine. 2. Horseshoe kidney: the two inferior poles of the right and left kidney fuse together. When they try to migrate to the future position, they're blocked by the inferior mesenteric artery. Some of the cases are asymptomatic, but it can cause different problems, such as cysts, kidney failure. If diagnosed in time, it can be treated with surgery. 3. Divided kidney with a bifid ureter: the ureter splits in two in the distal portion and it triggers the formation of two smaller kidneys. 4. Discoid (pancake) kidney: the kidneys fuse together completely. 5. Supernumerary kidney resulting from the development of two metanephric diverticula 6. Renal agenesis: one or both kidneys do not develop. It's usually caused by lack of interaction between the ureteric bud and the mesenchyme, and in many cases by a mutation in the gene that codes for GDNF. Bilateral renal agenesis leads to oligohydramnios; the baby is stillborn or dies a few days after birth. Oligohydramnios results in 7. Potter syndrome/sequence: anuria, hypoplastic lungs, abnormal facies, wrinkly and dry skin, limb deformities. Other conditions resulting in oligohydramnios, such as obstructive uropathy, cystic kidney diseases, renal hypoplasia, and premature rupture of membranes lead to the same clinical findings. Regardless of the root cause for oligohydramnios, the terms Potter syndrome, Potter sequence, and oligohydramnios sequence are used interchangeably in the published literature.

Clinical Drop: What is the 1st phase of ARDS?

1. Phase 1, acute exudative process: a person is caught in a fire and inhales a lot of smoke. 2. Firstly there's interstitial and alveolar edema, some of these capillaries are damaged, therefore there may be a hemorrhage; then to try to prevent it, our organism causes the deposition of fibrin (coagulation). 3. At this point the debris of the damaged pneumocytes start to line the wall of the alveoli creating a hyaline membrane. 4. Endothelial cells may be damaged as well, causing microthrombi (since endothelial cells help to regulate coagulation as we said before).

Clinical Drop: What is the 2nd phase of ARDS?

1. Phase 2, proliferative process: the body tries to solve the situation. 2. If pneumocytes are damaged, the remaining type 1 pneumocytes try to proliferate to restore the normal alveolar lining and proliferation of fibroblast (provisional extracellular matrix). 3. Fibroblasts help to restore the normal condition of the inside of the interstation. In this phase (center of the picture in the bottom), most patients recover. 4. The patient is under medical care; if the damage is not too extensive and the reparatory processes are working as they should, the patient may recover.

Clinical Drop: What is a problem related to the cells of the epithelium of the collecting tubules and collecting ducts?

1. Polycystic kidneys is inked to problems to the primary cilium of pale cells: two proteins called polycistin 1 and 2 which are impo11ant for the function of the cilium. 2. If these proteins are not functioning properly there might be a retention of urine within the ducts: these leads to the formation of cysts.

What is the pre-prostatic urethra segment of the male urethra?

1. Pre-prostatic urethra: associated with the internal urethral sphincter

Development of the reproductive system: How do the gonads develop?

1. Primordial germ cells are formed at the level of the epiblast, then they migrate in the wall of the yolk sac and after some weeks, they migrate back to reach the intermediate mesoderm, where the tubules of the mesonephros are being formed. 2. Once they reach that region, which is medial to the forming mesonephros, several changes start to take place: there is a condensation of the mesenchyme of this region and also the epithelium of the serosa that lines the coelomatic cavity start to proliferate, starting to form the gonadal cords, that will proliferate inside the intermediate mesoderm, becoming the source of supporting cells of the gonads (Sertoli cells and follicular cells). 3. We have the formation of the primitive gonad or gonadal ridge and medial to it, we have the formation of the adrenal glands. This whole region takes the name of urogenital ridge. 4. Laterally to the mesonephric duct, we have the formation of the paramesonephric duct of Muller or Mullerian duct. The paramesonephric duct, on the right and on the left, extends from the region where the gonads are forming, to the region where urogenital sinus is forming. 5. The gonads become organized into a more peripheral region, called the cortex and a more internal region, called the medulla. Observing the gonads, we can notice some clusters of cells, those that come from the proliferation of the coelomatic epithelium, that form the gonadal cords, which can also be called primitive sex cords. Germinal cells and primitive sex cords (gonadal cords) surround the primitive gonad. 6. Up to the 6th week of development the gonads are exactly the same in male and female. Up to that point is only possible to establish whether the baby is male or female doing a karyotype of the fetus. 7. During the formation of the primitive gonads, the gonadal cords anastomise with part of the tube of the mesonephros, forming a communication between the urinary and the genital system.

How does the pronephros form?

1. Pronephros (3-4 weeks): it develops as a rostral rudiment and it is non-functional in humans. 2. The intermediate mesoderm starts to form a rod of mesenchymal cells (that will then canalize), the mesonephric duct of Wolff. 3. It elongates caudally and opens in the cloaca. This process of differentiation requires a mesenchymal-to-epithelial transition. 4. Close to this mesonephric duct, the rest of the intermediate mesoderm starts to undergo a process of fragmentation, splitting into domains called nephrotomes, which are going to become vesicles. 5. The pronephros is formed by the first part of the mesonephric duct and by the vesicles that connect with it and collapse soon after. 6. In the meanwhile, other vesicles are formed more caudally and then they will connect with the mesonephric duct, forming some very primitive nephrons (nephrotomes), which will allow the mesonephros to function as an interim kidney for a couple of weeks. After that, more caudally, we will have the formation of the definitive kidney.

To sum up:

1. Proximal convoluted tubule: major reabsorption with sodium potassium pumps and aquaporins 2. Loop of henle: descending limb permeable to water, ascending limb permeable to solutes 3. Distal convoluted tubule: regulation of osmolarity and secretion of ions which acidify urine.

Clinical Drop: What is pulmonary hypoplasia?

1. Pulmonary hypoplasia: poorly developed tracheobronchial tree. 2. Usually on the right lung, associated with obstructive right-sided congenital heart defects. 3. Also found in association with congenital diaphragmatic hernia. 4. It is more common on the left and postero-laterally (Bochdaleck hernial), while if it is in other positions is called Morgagni hernias. 5. Can also be caused by oligohydramnios, due to renal agenesis (Potter's syndrome).

Clinical Drop: What is the pulmonary valve stenosis?

1. Pulmonary valve stenosis is caused by a defective development of the semilunar valve that connects the right ventricle with the pulmonary trunk: the valve is stenotic (narrower) and therefore there is an enlargement of the wall of the right ventricle. 2. This condition, if untreated, can cause chest pain due to difficulties in breathing, low energy, poor feeding, rapid breathing, tiring easily with exercises and cyanosis.

Hormones:

1. Renin: secreted by juxtamedullary cells, it activates ADH 2. ADH or vasopressin or angiotensin: secreted by adenohypophysis, increases Na and so water absorption which leads to an increase in blood pressure. Receptors on mesangial cells. 3. Aldosterone: produced in the zone glomerulosa of the adrenal glands, has particularly effect on the distal convoluted tubule and in the collecting duct system; it increases sodium absorption, so water retention and potassium secretion; the whole process leads to an increase ion blood pressure.

How are respiratory bronchioles characterized?

1. Respiratory Bronchioles are characterized by alveoli, which allow gas exchange. 2. They are called "respiratory" bronchioles because part of their wall is substituted with alveoli.

Clinical Drop: What are developmental problems in the respiratory system?

1. Respiratory Distress Syndrome (RDS) or Hyaline Membrane Disease 2. Germinal Matrix Hemorrhage (Periventricular or Intreventricular Hemorrhages) 3. Congenital Bronchogenic Cyst 4. Congenital Pulmonary Airways Malformation (Congenital Cystic Adenomatoid Malformation) 5. Congenital Lobar Emphysema 6. Bronchiectasis 7. Pulmonary Agenesis 8. Pulmonary Aplasia 9. Pulmonary Hypoplasia

Clinical Drop: What is Respiratory Distress Syndrome (RDS) or Hyaline Membrane Disease?

1. Respiratory distress syndrome (RDS) or hyaline membrane disease: deficiency or absence of surfactant. 2. It affects 2% new-borns, premature infants are more susceptible (accounts for 50-75% of death); more common in infants of diabetic mother, or in case of fetal asphyxia or maternofoetal haemorrhage. 3. The baby suffers of pulmonary insufficiency with cyanosis and gasping, tachypnoea, dyspnea (shortness of breath), retraction of the chest wall and nasal flaring. 4. The fact that there is not enough surfactant and that the baby is subjected to mechanical respiration, can cause a damage to the alveolar wall, to the pneumocytes, which once disrupted will contribute to the formation of a Hyaline membrane, which further reduces the possibility of gases exchange. 5. This syndrome is treated with corticosteroids and exogenous surfactants.

The main features of kidneys are:

1. Retroperitoneal 2. Parenchymatous (solid) 3. 12 cm long, 6,5 wide, 150-1709 4. Enveloped by a capsule and a perlnephric fat which enters also in the hilum 5. Hilum with vessels (renal artery and vein), nerves, pelvis and beginning of the ureter

Clinical Drop: What is secondary dysmenorrhea?

1. Secondary dysmenorrhea is the recurrent lower abdominal pain shortly before or during menstruation that is due to an underlying condition. 2. Possible causes can be endometriosis, pelvic inflammatory disease (PID), intrauterine device (IUD), uterine leiomyoma, adenomyosis, psychological factors.

What is the histology of the seminal vesicles?

1. Seminal vesicles: they are formed by lots of folds that almost completely fill the lumen. 2. The folds are formed by the lamina propria and by the overlying epithelium and at the level of these cuboidal and cylindrical cells that cover the folds, there is the production and secretion of substances that contribute to the formation of the seminal fluid (fructose, prostaglandins, Vitamin C, seminal vesicle-specific proteins). 3. The seminal vesicle-specific proteins are coagulating proteins, while the prostate glands produce some anti-coagulating proteins. 4. They are useful because, in the vagina, part of the semen coagulates, so that there is no risk for it to slide outside the vagina (evolutionary device used to keep as much semen as possible inside the vagina) and the coagulation happens because of coagulating proteins; when the spermatozoa have to proceed in the uterus, then there is a de-coagulation which happens thanks to the de-coagulating proteins produced by the prostate gland.

Clinical Drop: What can go wrong in the transition area with proliferation and age?

1. Since the transition area is very close to the urethra, as soon as there is a proliferation of cells, the lumen of the tube starts to narrow, causing dysuria (painful urination). 2. In this area, with aging, almost every man has a hyperplasia of the prostate gland. If something happens in the peripheral zone, before signs and symptoms are evident it is going to take some time and at that point the tumour will have been growing and invading adjacent areas and metastasize.

Clinical Drop: What problems can occur in relation to the angles in the uterus?

1. Sometimes these angles are not in the correct position, so we can have an angle of retroversion and an angle of retroflexion. 2. These can cause problems during fertilization or implantation.

Clinical Drop: What can wrong in the looping of the heart?

1. Sometimes, the looping can go wrong, so rather than looping to the right, there is a looping to the left, which makes it so that the bulbus cordis, rather than sliding to the right, slides to the left (slides to the opposite side). This situation is called dextrocardia: the heart is mirrored, so the chambers are inverted. 2. You are left with a situation similar to Kartagener's syndrome, where everything is mirror-like. The image below shows the same thing, but with the image of the heart from behind. The portion of the heart with the venus horn and the sinus venosus is now behind.

What are the 4 surfaces of the bladder?

1. Superior surface 2. Inferior surface: here the neck of the bladder is found which is the region where there is the internal urethral opening 3. Apex: opposite to the base (antero-superiorly). This surface is continuous with the median-umbilical ligament (remnants of the allantois) 4. Base: it faces postero-inferiorly, here the trigone is located. In males there is a relationship with the prostate gland, in females with the vagina. The lumen of the bladder present transient folds apart in the trigone.

What do we find at the center of the thoracic cavity?

1. That space that is not the serosal space and contains the esophagus and the heart. The mediastinum (the medial aspect of the lung) represents the hilum of the lungs (the "entrance" to the lungs). 2. Here we see a lot of stuff exiting and entering in the hilum of the lung: the bronchi, blood vessels entering and exiting (from the pulmonary trunk there are the pulmonary veins, 2 on the right and 2 on the left, going from the lungs to the left atrium of the heart), the lymphatics and the nerves that enter into the lungs parenchyma. 3. In the drawing in the bottom, on the left, we can notice that the medial surface of the lungs is not smooth: there are a lot of imprints due to the fact that medially, in the mediastinum, there are structures like the apex of the neck, with whom the apex of the lungs come into contact. 4. The imprints are different in the 2 lungs because they are caused by the relation each one has with the neighboring content of the mediastinal structure.

What is the histology of the loop of Henle?

1. The Loop of Henle is characterized by a thinning of the tubule. 2. It is composed by a thin descending limb which is highly permeable to water but scarcely permeable to solutes and a thin ascending limb which present the opposite features; these portions are characterized by a simple squamous epithelium. 3. Reasoning on these function is possible to state that the urine is mostly concentrated (high osmolarity) after passing along the thin descending limb but then it becomes less concentrated while it passes along the thin ascending limb (because solutes are reabsorbed). 4. Recall that the loop of henle of juxtamedullary nephrons is supported with vasa recta. 5. According to some authors also a thick descending and ascending portion compose the loop of henle; these potions present features similar, but not identical, respectively to the distal and proximal convoluted tubules.

Clinical Drop: What kind of problem can occur within the adrenal gland?

1. The adrenal gland can be the site of the formation of neuroblastoma, a tumour that originates from the neural crest and that, in many cases, forms in the medulla of the adrenal glands. 2. They contain neuroblasts (small cells arranged in Homer-Wright pseudo rosettes) of neural crest origins. 3. They are found mainly in children and in 40% of the cases, they develop in the adrenal medulla, while in the 60% of the cases, they develop in sympathetic ganglia. 4. They can cause metastasis to bones and lymph nodes.

Clinical Drop: Where do a lot of different herniations occur? And why?

1. The anterior abdominal- pelvical wall is a place where a lot of different types of herniation can take place. 2. Some of them are generate d by the herniation of the abdominal wall, whereas some others are due to the fact that the wall is made wicker in response to a surgical approach.

What is the process of urine being supplied to the bladder and leaving the bladder?

1. The bladder is supplied with urine by the ureters which open in two ureteral meati found at the two superior edges of the trigone. 2. Urine leaves the bladder by the urethral meatus. 3. The mucosa of the bladder present folds apart for the zone in which there is the trigone.

There are many branchings in our body (eg: biliary tree, some glands, and typically wherever there is a conduit). Branching is very complex, and it needs to be tightly controlled: how many branches? Where? How large? How is the branching regulated?

1. The brancing process is regulated by the interaction between the mesoderm/mesenchyme (we are still in the developmental phases) and the endoderm. 2. Around the tracheal bud, for example, the mesoderm is inhibitory as it doesn't allow the formation of bronchi along the tube (so where they shouldn't be). 3. On the other hand, the mesoderm at the tip of the trachea, the region where the right and left bronchi will form favors branching. It does it through several factors, which represent the crosstalk between the epithelium and the mesenchyme.

What are the ligaments of the uterus?

1. The broad ligament (legamento largo in the image) of the uterus that forms from the peritoneum. 2. The round ligament (legamento rotondo in the image) of the uterus is made by connective tissue.

How are the cells of the proximal convoluted tubule different from the distal convoluted tubule?

1. The cells are different from the one of the proximal convoluted tubule because here there are are less microvilli, no glycocalix and less organelles. 2. Recall that the loop of henle becomes in contact with the corpuscle of malpighi on the vascular pole, in this section the distal convoluted tubule properly begins, in addition at this level there are modified epithelial cells called macula densa cells which are chemoreceptors.

What is the histology of the proximal convoluted tubule?

1. The cells lining the proximal convoluted tubule tubule are columnar-cuboidal and present microvilli with a glycocalix, these structure are important to increase the surface area and so to improve metabolic functions of the cells. 2. In addition their cytoplasm stains darkly because of the presence of lysosomes and mitochondria (important for active transport}, particularly the mitochondria are arranged vertically along the cells. 3. Their cytoplasm present folds at the point of attachment with adjacent cells; these portions are called interdigitations of basal processes and are sites of Na+ reabsorption (sodium-potassium pumps). 4. Also the pH of the pre-urine is varied: here bicarbonate is reabsorbed and eventually some organic acids are secreted.

What do the cells present on the epithelium of the epididymis do?

1. The cells of the epithelium present non motile branching stereocilia. 2. They perform reabsorption of testicular fluid (90% of testicular fluid is reabsorbed inductuli efferentes and epididymis). 3. They secrete carnitine, sialic acid, glycoproteins, glycerophosphocholine (inhibits capacitation). 4. The epithelium of the epididymis is androgen-depending. 5. Androgens and androgen-binding protein are present in the rete testis up to the epididymis (in the seminal fluid), after that, the ductus deferens is only a passage way. The androgen and androgen-binding protein promote the progressive maturation of spermatozoa

What are the cells of the mucosa of the fallopian tube like?

1. The cells of the mucosa need to be able to nourish the egg and to move it toward the uterus. 2. In the fallopian tube, we can see that there are some ciliated cells (they undergo a continuous process of ciliogenesis in the estrogenic phase, and deciliation in the luteal phase, they beat towards the uterus), some non-ciliated cells (peg cells, which commits secretory activity and nourishment for the egg), and cells of the muscular layer.

Where is the collecting duct system? And what is it made of?

1. The collecting duct system extents form the distal convoluted tubule (not comprehended) to the pelvis (comprehended). 2. The nephron is continuity with a series of collecting tubules. 3. Specifically the distal convoluted tubule connects to arched collecting (or connecting) tubules which enters the medullary rays in the cortex which enters the medulla in a system of straight collecting ducts of increasing size that delivers urine to bellinl's duct at the level of the papilla (more then one bellini's duct for each papilla) of the renal pyramid (which is connected to a minor calix ecc.)

What is the embryology of the collecting tubing system?

1. The collecting tubing system (or excretory system or urine collecting system; this is not the tubing system which belongs to the nephron!) is formed by the renal pelvis, major calix, minor calix, straight ducts and arched tubules). 2. Derives from endoderm (ureteric bud) while nephrons derive from the metanephrogenic blastema (intermediate mesoderm).

What are components of the seminiferous tubules?

1. The components of the seminiferous tubules are Sertoli cells and spermatogonia. 2. In particular, there is a transition zone (tubulus rectus), from seminiferous tubules and straight tubules, which is made only of Sertoli cells, while if we proceed in the lumen of the straight tubules, we still find Sertoli cells, but in the distal portion, they become cuboidal and have microvilli and a cilium (mechanical detector of the movement of fluids from the seminiferous tubules in the direction of the epididymis). 3. They acquire the microvilli to perform absorption functions, thus to reabsorb the fluid secreted in the seminiferous tubules and that creates the hydrostatic pressure that moves the spermatozoa.

Clinical Drop: What is the inter-ureteric ridge? How can it be used to spot abnormalities in the bladder and ureters?

1. The corners of the trigone are formed by three orifices: the paired ureteral orifices and the internal urethral orifice. The superior boundary of the trigone is a slightly raised area between the two ureteric orifices, called the interureteric ridge. 2. Careful attention to the dimensions and symmetry of the interureteric ridge, when it is visible, aids in interpretation of abnormalities in the bladder and ureters. It is important in evaluating renal agenesis, low ureteral calculi, trauma, and neo- plasm. 3. On top of the trigone there is a sort of depression called inter-ureterlc ridge, when in males the prostate with aging becomes ipertrophic, bulges on the trigone accentuating this depression and so enhancing the stagnation of urine in this ridge; in this cause the expulsion of urine is more difficult. Stagnation of urine leads to bacterial proliferation which can lead to inflammation which in turn causes disurya.

How is the adrenal gland developed?

1. The cortex of the adrenal glands originates from proliferation of coelomatic epithelium inside the mesenchyme, while the medulla originates from neural crest cells. 2. The coelomatic epithelium (the epithelium that covers the abdominal peritoneal cavity) proliferate inside the mesenchyme and this epithelium starts to migrate in a first wave of migration, giving rise to the fetal cortex (which will be there up to few months after birth). 3. Then, we have a second wave of migration, which is going to form the future adult cortex.

How does the metanephros (aka. the definitive kidney) form?

1. The definitive kidney originates from the metanephros and for the definitive kidney to be formed we need the interaction of the ureteric bud (which is an evagination of the mesonephric duct situated before it connects to the cloaca) and the metanephric blastema or metanephrogenic mesenchyme (blastema = mass of cells capable to differentiate into an organ). 2. Starting from the 5th week of development, the ureteric bud will give rise to the urine collecting system (ureter, pelvis of the kidney, major and minor calyxes, collecting ducts of the kidney), while the metanephric mesenchyme will give rise to the excretory units and therefore the nephrons. 3. Because of the interaction between the ureteric bud and metanephric mesenchyme, we have the formation of the renal pelvis (sort of small cup that receive urine and communicates with the ureter), of the major calyxes (usually 2, superior and inferior, that drain in the renal pelvis), the minor calyxes, the straight collecting duct and arch collecting duct (which drains in the straight collecting duct). 4. The ureteric bud undergoes a complex branching mechanism when it comes into communication with the mesenchyme, so that all the structures are formed. It happens that we have several generations of branching and then the newest branches start to be intussuscepted into the old branches, which mean like if the new generation slides inside the old generations, forming the major and minor calyces. 5. From the minor calyxes we have the formation of some other orders of bifurcation, that will not undergo intussusception, but they will form the system of collecting tubules or ducts. The collecting tubules that drain in a minor calyx form the region of the kidney called Renal Pyramid of Malpighi. The mechanism of reabsorption of water takes place at the level of the connecting ducts. 6. The epithelium of the arch connective tubules starts to interact with the mesenchyme of the metanephric blastema and because of this interaction, some of the mesenchyme start to condense around of the tip of the arch collecting tubule, forming a blastema cap, but very soon, these cells will undergo a mesenchymal to epithelium transition and there will be the formation of a nephric vesicle. 7. This vesicle starts to elongate and on one side, it comes in touch with the arch collecting tubule. While the vesicle continues to elongate, it starts to communicate with the tubule, while in the distal part, it comes into contact with the capillaries network that in the meanwhile is being formed from the renal arteries (this will be called the glomerulus of the kidney, and it is characterized by an efferent and afferent arteriole, forming an arteriole portal system). 8. The vesicle starts to enlarge even more and it envelops the glomerulus, forming the Bowman's capsule. The network of capillary, together with the capsule, form the corpuscle of Malpighi.

Why is the distal convoluted tubule important?

1. The distal convoluted tubule is important for the regulation of "post" urine osmolarity: here there is the reabsorption of Na+ and Cl- ions in exchange with H+ ions and K+ ions, so here urine is again acidified. 2. Aldosterone (produced by the adrenal gland stimulated by angiotensin II) increases the absorption of sodium ions: more reabsorption of sodium lads to more absorption of water which increases blood pressure.

Development of the heart: What occurs after the tubular heart is formed?

1. The endocardial tube is surrounded by a matrix, called cardiac jelly, and on the outside of the cardiac jelly, we have the formation of the myocardium. 2. At this stage of development, the primitive heart is suspended into the pericardial cavity by a dorsal mesocardium, from which we will have the formation of the lung bud. 3. The structures that originates from the secondary heart field are mainly the right ventricle and the outflow tract of it. 4. At some point, the dorsal mesocardium is going to disappear and the region where the dorsal mesocardium is reabsorbed takes the name of the transverse pericardial sinus. At this point, we have a communication of the pericardial cavity both dorsally and ventrally. 5. At the beginning the region of the heart is very rostrally localized; then, because of the folding of the embryo, the heart is positioned ventral to the embryonic disk and to the foregut. 6. The first tubular heart is not linear, it has a S-shape. It has an inflow and an outflow region, which are connected with the vessels belonging to the primitive circulation.

What is the endometrial cycle?

1. The endometrial cycle is composed by the menstrual phase (last phase, when the mucosa is shed), the proliferative or estrogenic phase (when the functional layer is reconstructed), the ovulation and the secretory or progestinic phase. 2. In the onset of menstruation, stroma disaggregates and glands collapse. We find apoptotic bodies and blood in the stroma. 3. In the proliferative phase: from the early to the late, glands are reconstituted and the lamina propria (stroma) starts to be more and more swollen, oedematous, while it gets reconstituted. 4. After ovulation, we have the secretory phase, which is characterized by the presence of even more tortuous glands.

What is the histology of the endometrium?

1. The endometrium is formed by simple columnar epithelial lining and a lamina propria (endometrial stroma). 2. It is a mucosa and it contains also some glands. 3. It varies in thickness (1-6 mm) during the menstrual cycle (guided by the hormones produced by the ovaries). 4. The epithelium is composed of ciliated and secretory cells that invaginates to form glands.

What is the difference between the microstructure of the trachea and that of the main and lobar bronchi?

1. The epithelium cells of the main and lobar bronchi are less tall and fewer goblet cells. 2. In the lamina propria, there are still lots of elastic fibers in the main and lobar bronchi, but rather than being dense only in the distal part, they can also be found in the upper layer of the lamina propria in the main and lobar bronchi compared to the trachea. 3. Smooth muscle in main and lobar bronchi can be found between the lamina propria (mucosa) and the submucosa and progressively it becomes a continuing layer with a spiral arrangement. 4. There are less glands in the submucosa of main and lobar bronchi 5. The cartilage is not ring-shaped but it forms plates in the main and lobar bronchi.

Why is the fetal cortex important?

1. The fetal cortex is important to sustain pregnancy and for lung, liver and digestive tract maturation. It regresses during the second post-natal month. 2. During the 2nd trimester it produces dehydroepiandrosterone, which is converted by the placenta into estradiol, which is crucial for the maintenance of pregnancy. Indeed, if the placenta does not receive the precursor hormone from the fetal adrenal gland, it cannot perform its function as an endocrine organ (essential in supporting pregnancy) -- major contribution to the sustaining and development of the organs.

What is the function of the kidney, while the baby is still in the uterus?

1. The function of the kidney, while the baby is still in the uterus, is not clearing waste products, since this is the job of the placenta. 2. Their function is to produce urine, a watery fluid that do not contain waste products and it is used to contribute to the amniotic fluid. 3. If the baby grows without kidney, he can survive, while in the uterus because he can survive with the help of the placenta, but at birth, he will not be able to survive without kidneys.

How does the functional circulation in the lungs work?

1. The functional circulation starts in the right ventricle of the heart, from which we have the origin of the pulmonary artery or pulmonary trunk. 2. The pulmonary trunk contains deoxygenated blood, it divides into the right and left pulmonary artery, which then branches inside the parenchyma of the lungs and finally they reach the most distal portion of the tracheobronchial tree where alveoli are localized and then the pulmonary arteries divide into capillaries which surround the alveoli and allow gas exchange. 3. Gas exchange consist in CO2 being released and reaching the alveoli lumen, with the consequent release of oxygen from the alveoli, which is attached to haemoglobin. 4. From the other side of the capillaries circulation we have the origin of the part of the capillary network that is going to carry oxygen and the consequent formation of pulmonary veins (that carry blood towards the heart). 5. The network of pulmonary veins bring oxygenated blood to the left atrium, then it goes into the left ventricle and from there it will go into the aorta (from which blood goes everywhere in the body).

How does the external genitalia develop in males?

1. The genital tubercle elongates much more than in the females and will give rise to the phallus. While the phallus is growing, it pulls the ureteral folds, determining in between them a narrow groove, named urethral groove. 2. At the end of the 4th month, the two urethral folds that delimit the urethral groove come together delimiting the penile urethra. (In the females the urethral folds do not come together, instead they leave a space that is the vestibule of the vagina). At the tip of the penile urethra, a thickening of the ectoderm is forming, eventually it will canalize and form the external urethral meatus. It is important to point out this latter concept, since the mucosa that lines the distal part of the male urethra (the one communicates with the outside) is composed of a squamous stratified epithelium because of its embryological origin (from the ectoderm). In this case, the genital swellings won't become the labia majora, instead they will give rise to the scrotal bursa.

Development of the heart: What is the conduction system of the heart? How is it developed?

1. The heart starts to beat when it is still a simple tube, around the 21st day. 2. It starts to beat because some primitive myocardial cells differentiate in cells able to rhythmically depolarize and hyperpolarize the plasma membrane autonomously (not under the control of the nervous system). 3. The excitation due to the electrical activity of these cells starts at the level of the inflow region, to spread up to the outflow region. 4. With heart development, these specialized cells will finally form the conductive system of the heart: the sinu-atrial node, the atrioventricular node, the bundle of His and the Purkinje fibers.

What is the organization of the kidney?

1. The hilum of the kidney is continuous with the renal sinuses within the kidney (those portion not occupied by the renal pelvis). 2. In continuity with the pelvis there are major calyxes (usually two) form which minor calyxes (usually 8-10) extend. Each minor calyx is in relation with one renal pyramid (in normal cases) by way of several bellini's duct. 3. Pyramids are striated because of the presence of collecting ducts and straight of portions of the loop of henle. Pyramids correspond to the medullary region of the kidney, the apex of a pyramid is called renal papilla (towards minor calyxes). 4. The cortex (which extends also between pyramids forming bertin's columns) contains distal and proximal convoluted tubules, the Malplghl corpuscles (gromerolus and bowman capsule), some times the beginning of the loop of henle and the arched collecting ducts and the beginning of the straight collecting ducts (which are part of the collecting system, not of the nephron). 5. The convoluted portion of the cortex (renal corpuscle and convoluted tubules) is called cortical labyrinth, while the straight portion, which extends from pyramids, is called medullary ray. 6. In the medulla are present the straight portion of the collecting ducts, portions of the loops of henle and special capillaries called vasa recta.

What is the histology of the lung parechnyma like?

1. The histology of the lung parenchyma is not so simple, because there is a lot of air and the wall of alveoli is very thin, meaning it is very difficult to preserve when preparing histological samples. 2. Around the wall of the terminal bronchiole there are no alveoli, then, entering the respiratory bronchioles, they start to substitute the wall more and more. Also, the epithelia becomes thinner and thinner, making it difficult to clearly distinguish what is what. 3. In the wall of respiratory bronchioles and alveolar ducts and at the opening of alveolar sacs and alveoli there is the presence of knobs of muscle cells, elastin and collagen that form rings that regulate alveolar air movement. 4. They are there because are used by the nervous system to control and direct more air to an alveolar duct rather than to another. 5. Since there is smooth muscle, the tone of the muscle can increase or decrease and this control is under the parasympathetic nerve fibers, but we also have some cells that can release histamine (mast cells) which helps in the contraction of the muscle.

How is the inguinal canal formed (in females) -- their descent from the gonads?

1. The inguinal canal forms as well, even though it is more rudimental. 2. Indeed, this passageway in the female gonads has the purpose of making them migrate downward even though they don't have to migrate outside the abdominal cavity. 3. In this case, the canal will form a ligament that attaches the ovary to the region of the labia majora, it also contains a nerve (which derives from the branchias of the genitofemoral nerve).

What is the kidney?

1. The kidney is the solid organ associated with the urinary system. 2. At the level of the kidney, the blood is filtrated and therefore we have the production of urine, in which there will be all the substances that have to be eliminated, like products of metabolisms, excess of salts and sugars. 3. In the kidney, the functional unit is called nephron, which is a very complex structure, which is responsible for the filtration of blood.

What is the pleurae of lungs?

1. The lungs are surrounded by a visceral space, which is called the pleural space: a serosal space characterized by a visceral layer and parietal layer. 2. The visceral pleura is attached to the surface of the lungs, between them there is a virtual space, called pleural cavity, filled with the pleural fluid.

Morpho-functional considerations on lung development:

1. The lungs must be ready to take charge of respiration at birth. 2. To perform normal post-natal breathing, the lung must grow to an appropriate size, respiratory movements must occur continuously and the air sacs must configure for gas exchange. 3. The fetus starts to practice breathing movement around the 10th week, which is very important for the maturation of the rib cage and of the skeletal system, but it is also very important because when the fetus expands the rib cage, it helps the amniotic fluid to enter through the mouth which favours the lung development. The breathing movements are periodic, few times per day, especially they are associated to the REM (rapid eye movement) phase of the sleep cycle of the fetus; they are also associated to the state of the mother and they are impaired by maternal smoking (causing accumulation of lots of fibrous tissue and a consequent reduced lung development). 5. At birth, lungs are filled with fluids important for their maturation (amniotic fluid, secretion by fetal lung epithelium). Since the lungs are full of liquids, the baby can't breathe, so fluids are eliminated by mouth, nose, capillaries, and lymphatics. 6. If a baby is found abandoned and it is dead, we can establish whether it was born already dead or alive: if we take the lungs and put them in water, if they float it means that the baby was alive.ga

What is the mesonephric duct and what role does it play in the development of the urogenital system?

1. The mesonephric duct opens into the uro-portion of the cloaca that is becoming the urogenital sinus. 2. During development of the urogenital sinus, the distal portions of the mesonephric duct and the ureteric bud are incorporated in the posterior wall of the urogenital sinus. 3. In the region of the urogenital sinus where the urinary bladder is going to be formed, we have the incorporation of the mesonephric duct, then the ureteric bud will open independently in the urogenital sinus, specifically in the region that is becoming the bladder. 4. Then the mesonephric duct is incorporated more caudally, it elongates and while doing that, it forms the bladder trigone, a triangular region. 5. In males the mesonephric duct will become the ductus deferens and the epididymis (with the formation also of the seminal vesicles), while in female it will disappear. 6. The trigone has a different embryological origin compared to the rest of the bladder and at the vertexes of it we can find the opening of the ureters. 7. The most upper part of the bladder communicates with the allantois, which soon starts to regress forming the urachus (a fibrous cord), that will become the median umbilical ligament.

What happens the further/deeper we move into the parenchyma of the lung?

1. The more we progress deeper in the parenchyma of the lung the cartilage changes (before disappearing is completely substituted) from hyaline to elastic: everything becomes more flexible. 2. While cartilage reduces, the amount of smooth muscle organised in a spiral fashion increases up to where we reach the level of the bronchioles.

What is the labirintineous appearance?

1. The mucosa of the uterine tube protrudes in the lumen, giving to the surface a labirintineous appearance. 2. Their function is to slow the eggs to allow the spermatozoa to reach it. 3. The mucosa is supported by a lamina propria and below the mucosa we find a smooth muscle layer and on the outside of it, we find the serosa since they are covered by the peritoneum.

What is the nephron composed of?

1. The nephron is formed by a corpuscle, called renal corpuscle or corpuscle of Malpighi, it is made by capillary network surrounded by an epithelial capsule, which is called Bowman's capsule. 2. At the level of the renal corpuscles, there is the filtration of the primary urine, then the corpuscle of Malpighi continues with a very convoluted tubule, called proximal convoluted tubule, then it continues with a straight portion of this tubule, which will continue with a thin conduit, called loop of Henle, which is made of a descending portion and an ascending portion. 3. The ascending portion continues with the distal convoluted tubule, which is made by an initial straight part and a more distal part which is quite convoluted; this part will then communicate through the arch collecting tubule with the collecting duct that we find in the corpuscle of the kidney. 4. In the different parts of this structure there will be lots of reabsorption going on, but also some secretion, so the urine that is filtered at the level of the corpuscle is not the definitive urine, is the primary urine. After the urine enters in the collecting duct system, other changings will take place (reabsorption of water).

What are the paramesonephric (Muller) ducts?

1. The paramesonephric duct of Muller originates on both side, forming a conduit that extends from the urogenital crest up to the region where the cloaca is transforming into the urogenital sinus. 2. The 2 paramesonephric ducts, while they reach caudally the cloaca, they come together behind the region where the bladder is forming. 3. The initial part (which is close to the ovary) of the paramesonephric ducts is going to transform in the fallopian tubes, while the distal portions will be the uterus and it will also contribute to the development of the vagina. 4. The distal portions of the paramesonephric ducts become in contact with the endoderm of the urogenital sinus, and specifically in the region where the urethra is forming from the urogenital sinus. 5. The contact with the Mullerian duct will trigger the proliferation of the endoderm of the urethra and it will lead to the formation of the utero-vaginal plate. 6. Then this plate will elongate, remaining in contact with the distal portion of the uterus and finally it will canalize as to form the vagina. 7. Moreover, after that it will detach from the uterus and it will open independently in the vestibule of the vagina. 8. The upper portion of the vagina, where the fornix is forming, originates from the paramesonephric duct, while the lower portion originates from the endoderm of the urethra. The formation of the vagina takes place in the region of the urorectal septum.

Clinical Drop: What is the patent ductus arteriosus?

1. The patent ductus arteriosus is caused by the non-closure of the ductus arteriosus of Botallus, which persists and causes higher pressure in the pulmonary trunk; increase in the intrapulmonary pressure; and dyspnea. 2. These problems are caused because some of the blood that should flow through the body, goes instead to the lungs. 3. The patent ductus arteriosus is common in premature children for the first 24 h, especially if they have a weight < 1750 g.

What is the renal pelvis?

1. The pelvis is just a container of urine, which is 2-3 cm high and can contain 4-8 ml of urine. 2. This is not a major structure, but is still very important because it drains the calyces.

How do the testes migrate?

1. The peritoneum on the side of the gubernaculum, starts to form pockets, pushing the layer of the abdominal wall [image B]. As a result, the wall of the abdomen is progressively pushed downward. This protrusion of the peritoneum is called the processus vaginalis (a serosal/peritoneal pocket). First, there is the formation of the processus vaginalis that triggers instead the genesis of the inguinal canal so that the testis eventually has a place to descend. The gubernaculum is attached to the floor of the abdominal cavity, since this region is pushed outwards, the gubernaculum is now attached to the floor of the future scrotal bursa. As a result of the shortening of the gubernaculum, the testes are progressively pulled caudally, sliding below the processus vaginalis inside the inguinal canal, so that in the end, they will reach the scrotal bursa.

Clinical Drop: What is primary dysmenorrhea?

1. The primary dysmenorrhea is the recurrent abdominal pain shortly before or during menstruation (in absence of pathologic findings that could account for those symptoms). 2. It is perceived by up to 90% of women. The etiology is unknown, it may be associated with some risk factors, like smoking, obesity, positive family history. 3. The mechanism is the release of some substances that cause sustained uterine contractions (increased endometrial prostaglandin PGF2 alpha production that causes vasoconstriction and ischemia and stronger, sustained uterine contractions). 4. The clinical features are spasmodic and crampy pain in the lower and or pelvic midline. Usually occurs during the first 1-3 days of menstruations. 5. It can cause headaches, diarrhea, fatigue, nausea and flushing.

Development of the heart: How does the primitive atrium continue to develop?

1. The primordial atrium is formed by just 1 chamber, in which we can recognize the right and left side. On both side, we can distinguish a posterior region, which is smooth; while in the anterior portion is characterized by trabeculated tissue. 2. The posterior smooth portion on the right side is formed due to the incorporation of the sinus venosus, which also causes the superior and inferior vena cava and the coronary sinus to open at the level of the right side of the primitive atrium (30th day). The incorporation of the sinus venosus will form the portion of primitive atrium called sinus venarum. On the left posterior portion, we have the incorporation of the initial part of the vein pulmonary system, which develops in the mesenchyme (which is dorsal to the heart) and at the beginning we have only one veins opening into the heart, a common vein that branches in its posterior part. Proceeding in its developing, the heart will then incorporates the branching of the common pulmonary vein, arriving to have 4 openings to 4 different arteries. 3. If we look at the primitive heart during the 31st day of development, we can notice that on the left side we will find 2 openings of the pulmonary veins; moreover, the sinus venarum (on the right side) is more enlarged, and at the openings of the coronary sinus and of the vene cavae (especially the one of the inferior vena cava) we will have the formation of valves. In the adult heart this valves will disappear. In the region of passage between the smooth and trabeculated portion, we have the formation of the crista terminalis. The trabeculated portions become more elongated and form the right and left auricle. 4. At 32 days of development, we have a further incorporation of the pulmonary vein, which will create the definitive 4 openings of the pulmonary veins.

Development of the heart: What is the process of septation of the heart?

1. The process of septation of the heart leads to the formation of 4 chambers (2 atria and 2 ventricles). 2. The septa will be formed at the level of the primitive atrium, of the primitive ventricle and of the outflow tract.

What does the prostate gland produce? Why is it important?

1. The prostate gland produces an alkaline fluid, which is important to neutralize the pH of the vagina, moreover, it is rich in citric acid and proteolytic enzymes: liquefy coagulated semen that has been deposited in the vagina. 2. Proteins include prostate specific acid phosphate and prostate specific antigen (marker for early detection of prostatic cancer).

What is the purpose of lung maturation?

1. The purpose of lungs maturation is to reach the formation of the gas exchange barrier, which will happen when there is the formation of a very thin-walled air-containing sacs that has to be formed in close contact with capillaries. This needs to occur so that gas from the inside of alveoli can move to blood, to peripheral tissues and carbon dioxide carried by the peripheral tissue to be released into the alveoli so it can be expelled. An incredibly thin barrier is needed for this exchange that is in close contact with the very thin walled vessels- capillaries. 2. On one side of this barrier, with in the sac, needs to be lined by epithelium cells (mesodermal in origin) and in the mesenchyme surrounding the sacs there needs to be an extensive network of capillaries in very close association so that gaseous exchange is able to occur effectively. 3. A lot of effort is necessary in the expansion of the lung, air needs to reach up to the alveoli and the alveoli need to be able expand when inhaling. In order to reduce this effort a substance called surfactant/pulmonary is needed to reduce the surface tension of the alveoli and prevent alveolar collapse. 4. If a baby is born immature, there needs to be enough surfactant to make the expansion of the primordial alveoli possible.

Why are the testis outside the abdominal cavity?

1. The reason why the testis are outside the abdominal cavity is because for the maturation of spermatozoa we need a temperature lower than the one which is inside the abdominal cavity. 2. The vein surrounds the artery because it brings in the testis blood at high temperature, so the pampiniform plexus, being near the artery allows an exchange of heat, which is able to lower the temperature of the blood coming from the artery. 3. The dissipation of heat of the arterial blood lower the temperature from 36.66 to 33.88 °C.

What does the reproductive system consist of in males?

1. The reproductive system, in males, begins with the gonads (the testis), which are outside the abdominal cavity, then we have the rete testis, the epididymis, the ductus deferens, which communicates with the male urethra. 2. During its formation, the ductus deferens will give also rise of the seminal vesicles.

What is the order of cardiac circulation?

1. The right atrium receives venous blood from the superior and inferior vena cava and from the coronary sinus. 2. Then the blood goes into the right ventricle, passing the tricuspid valve and then the right ventricle sends blood in the pulmonary trunk, which divides in the right and left pulmonary artery. 3. The pulmonary arteries branch into the parenchyma of the lungs, until they reach the level of the alveola, forming a capillary plexus surrounding them, where blood is oxygenated. 4. From here, blood is moved in the pulmonary veins, which reach the left atrium. 5. We have 4 pulmonary veins that enter in the left atrium; then blood is moved in the left ventricle, through the bicuspid valve, which communicates with the ascending aorta.

How is the terminal bronchiole characterized?

1. The terminal bronchiole is characterized by the presence of an epithelial lining, which is not any longer made by cylindrical cells (they are becoming less cylindrical and more and more cuboidal), and very few ciliated cells. 2. Anyway, there is a new population of secretory cells called "Clara Cells". 3. They secrete a substance very similar to the surfactant produced by Type 2 ("fat") pneumocytes in the alveoli. The purpose of the secretion is to prevent sticking of the bronchial wall during the expiratory phase. 4. If the sides come in contact with one another they may really stick together, which makes it so that when you have to breath-in you'd need a lot more effort (because you have to detach the terminal bronchioles stuck together).

What is the trachea made of?

1. The trachea is made of a series of cartilaginous rings, which are C-shaped (not completed posteriorly), because posteriorly they are completed by fibres and elastic tissue, plus bundles of smooth muscle. The smooth muscle located only posterior and in the area that connects one ring with the other is called the trachealis muscle. 2. The trachea is also made by a skeleton (skeleton of the trachea), a fibroelastic-muscular-cartilaginous structure that has the function to sustain the mucosa. The trachea has a skeleton (skeleton of the trachea), a fibroelastic-muscular-cartilaginous structure that sustains a mucosa. 3. The skeleton is made by cartilage (cartilaginous rings), fibroelastic tissue (the tissue between one ring and the other) and also elastic fibers. 4. The fibroelastic tissue (yellowish stuff on the right) is connecting one ring with the other, forming a sort of membrane. Posteriorly this membrane is enriched by the presence of smooth muscle fibers that form the trachealis muscle.

Why is the trachea flexible?

1. The trachea needs to be flexible, allowing expansion in diameter and extension in length during inspiration and passive recoil during expiration. 2. When I breathe in during inspiration, the trachea elongates and enlarges a bit, while during expiration there's the elastic recoil that allows the trachea to come back to its normal shape.

What is the uterine cervix?

1. The uterine cervix is the narrowest part of the uterus and it comes into relationship with the vagina. 2. Part of it is in the last part of the vagina. 3. The function of the uterine are to admit spermatozoa when fertilization is possible; to protect the uterus and the upper tract from bacterial invasion. 4. During delivery, it must dilate.

What is the uterus supplied by?

1. The uterus is supplied by the uterine artery, which has branches that enter into the muscle layer of the uterus and start to divide. 2. Inside the middle layer of the myometrium, they form the arcuate arteries; they, then, give rise to radial arteries, which reach the endometrium. 3. At the level of the endometrium, radial arteries form straight and spiral arteries. 4. The straight arteries vascularize the basal layer, while the spiral arteries vascularize the functional layer.

What is the histology of the vagina?

1. The vagina is formed by a mucosa, with folds, characterized by a squamous stratified epithelium non-keratinized. 2. Below the epithelium there is a very thick smooth muscle layer, characterized by elastic fibers. 3. The mucosa is sustained by a lamina propria, where we can also find lots of elastic fibers and a rich plexus of small veins. There are no glands. 4. Inside the epithelial cells, there is lots of glycogen, which is metabolized to lactic acid by resident microbiota, lowering the pH of the vagina. Fluctuation of pH affect change susceptibility to infections.

What is the vagina?

1. The vagina is the last portion of the female genital system and it is a fibromuscular canal. 2. The posterior wall is longer than the anterior wall and the upper portion surrounds the lower cervix, forming the vaginal fornix. 3. The lower portion opens into the vestibule of the vagina. The mucosa of the vagina is characterized by rugae vaginalis (transverse) and 2 longitudinal crest folds: the anterior one is due to the relation with the urethra, while the posterior is due to the presence of a venous plexus which is prominent in that region.

How long does the process of migration of the testes take? And how does it occur? How is it important?

1. The whole process of testes migrating begins during the 7th week of development and ends in the 3rd month of the postnatal life. 2. Consequently, in a newborn the testis must complete the process of migration in the scrotal bursa. 3. If the testis remains in the abdominal cavity, the spermatozoa production cannot take place. 4. The process of migration is important for the functional maturation of the spermatozoa, and that's way it needs to be monitored. 5. The condition determined by the bilateral non-descending of testis is called cryptorchidism, it could lead to sterility since the spermatozoa need to be placed outside the abdominal cavity to fully mature.

Development of the heart: How do the 4 heart chambers form? (2)

1. These primitive positions of the components of the heart are not the ones that the organ will have in its definitive conformation, thus, to change them, it is necessary a looping of the heart, which will cause the bulbus cordis to be positioned caudal and to the right; and the primitive atrium to be positioned dorso-cranially and to the left. 2. This looping is very important, as it brings the different chambers of the primitive tubular heart, to their correct positions, even though there is a long way to go.

What are the 3 major functions in the adult lung for clara cells?

1. They represent the major secretory cell of the bronchiolar epithelium where they contribute nonmucinous secretory proteins to the extracellular lining fluid. 2. Clara cells represent the principal site of xenobiotic metabolism within the lung. 3. Clara cells represent an abundant progenitor cell pool for maintenance of the epithelium in the steady-state and for regeneration of the injured bronchiolar epithelium. ***Altered Clara cell function is likely to be a significant factor contributing to declining lung function in airway disease.

Where are the ureters located?

1. They run into the retroperitoneal space until they enter the pelvic cavity in order to reach the bladder. 2. When ureters enters the bladder they run along its posterior wall in an intramural portion, particularly between the mucosa and the muscle layer of the bladder. 3. This is important because when the bladder is filled with urine it compress the ureters so that the bladder is not successively filled with urine until is not eliminated; they open in the bladder posteroinferiorly at the level of the bladder trigone, the sites of opening are called ureteral meatus.

As mentioned above the composition of the ureters is similar to the one of the pelvis but their wall is thicker. In addition the pelvis there have:

1. Thick lamina propria: which is rich in elastic fibers 2. Folds: in the lumen 3. Two muscle layers: which look like if one is longitudinal and the other is circular but in truth here are organized in a spiral fashion in which the longitudinal layer is composed by a loose spiral and the circular is composed by a tight spiral. The "longitudinal layer" is inner. In the distal part of the ureters (in which they are about to connect to the bladder) there is an additional outer longitudinal layer (this organization is very similar to the one of the bladder discussed below). For these three features is possible to confuse a cross section of the ureter with a cross section of the esophagus, but recall that the esophagus is larger, has a squamous stratified epithelium (not transitional), the circular muscle layer is the innermost (not the longitudinal) and has also skeletal muscle fibers in the upper region (not only smooth).

Clinical Drop: What can go wrong in the development of the ureteric bud?

1. Things can go wrong in the formation of the ureteric bud: there might be conditions in which the ureteric bud is not formed, which will cause a defective formation of the nephrons, which means that the kidneys will not form. 2. We can also have a situation in which we have more than one formed ureteric bud, which can cause the formation on one side of more than one kidney parenchyma.

Clinical Drop: What is polycystic ovarian syndrome?

1. This syndrome is caused by an excessive production of androgens from the ovary, which is due to a disruption of the communication between the oocyte and the granulosa cells. This can lead to the formation of an insulin-resistance by the woman. 2. Symptoms and signs may include irregular or no menstrual periods (oligomenorrhea or amenorrhea), heavy periods, excess body and facial hair (hirsutism), acne, pelvic pain, and infertility. 3. Complications of this syndrome include: infertility; gestational diabetes, including high blood pressure; miscarriage or premature birth; non-alcoholic steatohepatitis, a severe liver inflammation caused by fat accumulation in the liver; metabolic syndrome, a cluster of conditions including high blood pressure. 4. Along the genital tract, there is more or less the same structure: a wall of smooth muscle, an inner mucosal lining, and an outer layer of loose supporting tissue. The mucosal and the muscle layer vary according to their location and function. We can have cyclical changes due to the ovarian cycle. 5. All these changes are due to facilitate the entry of the oocyte into the fallopian tube; the entry and progression of the spermatozoa into the cervix and in the fallopian tubes; the passage of the fertilized ovum into the uterus; implantation and development of the ovum in the mucosal lining of the uterus.

Are the right and left bronchi the same size and length?

1. Those 2 are not exactly equal: the right is shorter and larger, moreover the angle that is formed between the bronchi and the middle line, the left one is more accentuated. 2. If I draw an imaginary line along the axis of the trachea (dashed line in picture on the left) and then I consider the angle that right and left bronchus form with the dashed line, I can see that I have 20° on one side and 50° on the other. WHY DO WE CARE? Clinically speaking stuff ends up in the right bronchi (20°). 3. Already during embryonic development, the size of the right and left bronchus, the length, the diameter and the angle they were forming with the trachea were not exactly the same.

Why is the mucus surrounding the cilia?

1. To facilitate the movement of the cilia, so that they can bend, even though there's mucus surrounding them. 2. Doesn't matter if the mucus layer on the top is more jelly-like because cilia are moved by the layer below it. 3. Mucus contains water and glycoproteins. 4. Low viscosity and elasticity determine effective mucus clearance by cilia beating and cough: there's the mechanism of cilia beating under normal conditions, and when this clearance mechanism is not enough mechanism of cough intervenes.

What is the tubing system?

1. Tubing system: which is composed of a proximal convoluted tubule (next to the renal corpuscle), the loop of henle and the distal convoluted tubule. 2. The loop of henle is divided into a thick portion (cuboidal epithelium) and into a thin portion, (among authors it is debated that the loop of henle correspond only to the thin portion or to the whole loop, we do not care!). 3. A portion of the distal convolute tube (even if does not begin from the renal corpuscle but from the loop of henle) becomes in contact with the renal corpuscle and in correspondence to that point there is a thickening of the epithelium, in the tubule, which is called macula densa. 4. The tubing system of the nephron is mainly involved in selective reabsorption of water and some molecules. 5. Different parts of the tubing system perform different functions such as secretion of other products or secretion of H+ ions. 6. The convoluted tubules are found in the cortex and together with the renal corpuscle form the cortical labyrinth, the loop of henle, instead, extend into the medulla.

What is the urinary tract divided into?

1. Upper: composed by calixes, pelvis ad ureter 2. Lower: composed by bladder and urethra

What are the 2 poles of the renal corpuscle?

1. Vascular pole 2. Urinary pole At the opposite end of the renal corpuscle with respect to the vascular pole we find the urinary pole.

How does the trophic or nutritional circulation in the lungs work?

1. We also have a nutritional circulation that has the function to nourish the lungs, this circulation origins from the bronchial artery, which brings oxygenated blood from the aorta to the bronchial tree. 2. This circulation proceeds up to the level of the terminal bronchioles and from there we have a venous circulation that goes back to the heart, the system of the bronchial veins. N.B. when studying vessels inside lungs, need to consider there are those belonging to functional and those belonging to trophic circulation.

Clinical Drop: What other abnormality can occur during the menstrual period?

1. We can call a loss of blood from the uterine abnormal if it happens in between the menstrual period, if the menstrual flow is lighter or heavier than normal or if it is at a time in life when it is not expected, such as before age 9, during pregnancy or after menopause. 2. Causes not related to pregnancy: we can distinguish between structural (something that alters the state of the uterus) and non-structural causes (not related to the uterus). Structural causes can be polyps, adenomyosis, leiomyomas, malignancy/hyperplasia (PALM); non-structural causes can be coagulopathy, ovulatory disfunction, endometrial, iatrogenic, not yet classified (COEIN).

What is the histology of the prostate gland?

1. We can recognize a glandular and a stromal (made by connective tissue, collagen fibers, elastic fibers, bundles of smooth muscle cells important to promote the squeezing of the glandular elements inside the urethra) components, which are surrounded by a capsule (fibroelastic, smooth muscle fibers). 2. Inside the parenchyma we can fine fibromuscular septae. 3. If we look at the cross section, we can see that anteriorly to the urethra, most of the components of the gland are made by fibromuscular stroma. 4. The glandular elements are classified in relation to the urethra as mucosal, submucosal, and main prostatic glands (which are branched tubuloacinar).

What margins do the testis have?

1. We can recognize a superior pole, an inferior pole, a lateral and medial surface, an anterior and a posterior margin. 2. The superior pole and posterior margin are in relation with the epididymis.

What happens when we cough?

1. We first inhale, then close the glottis, then contract muscles and pop open the glottis causing the air to come out forcefully and rapidly; but in order to do that we must have both an efferent and an afferent component. 2. For example, in the vagus nerve run visceral-sensory fibers that come from the trachea-bronchial tree that are important for reflex activity (such as the cough one). Examples: the mucosa of the trachea-bronchial tree, and the muscle tissue as well, are innervated. Also, there are so called "touch and stretch" receptors, meaning that, if an irritant irritates the mucosa, an impulse is sensed by the sensory fibers and, if the wall is stretched, this is sensed by the sensory fibers as well. The information is then brought to the central nervous system. There also are receptors in the arteries and in the veins of the lungs and trachea-bronchial tree, for example: the information that originates from the trachea-bronchial tree is important for the regulation of the "bronchial tone", meaning the size of the tubing system. Sensory fibers run also in sympathetic nerves (SEE SLIDE, second part) and, in this case, the type of information is different: it doesn't have to do with reflex, but rather with pain. The information that comes from the trachea-bronchial tree and that is related to pain is processed in the upper thoracic segments of the spinal cord.

When we progress from subsegmental bronchi to bronchioles what happens to the cartilage?

1. We move from hyaline cartilage to elastic cartilage. 2. As cartilage decreases, smooth muscle increases (spiral). 3. Bronchioles (1mm diam): elastic fibers predominate, no cartilage 4. Terminal brochioles ≤ than 0.5 mm diam): pulmonary acinus 5. Respiratory bronchioles: pulmonary lobule

How and why do we cough?

1. When the normal movement of the mucus cilia escalator is not enough to get rid of the mucus, we try to get rid of it by coughing; also if there's an irritation of the mucosa of the tracheobronchial tree, coughing is an attempt to get rid of the irritant. 2. When we cough, we try to propel air at a very high velocity along the upper airways so that this very rapid movement of air running on the surface of the mucosa displaces the mucus layer. 3. Otherwise, the cilia act very slowly, and if there's too much mucus (like in bronchitis), the cilia are not enough, so we start coughing.

Clinical Drop: What is Wilms tumour or nephroblastoma?

1. Wilms tumour or nephroblastoma is the most common childhood abdominal malignancy. 2. The median age at diagnosis of Wilms tumour is approximately 3-4 years of age. With current multimodality therapy approximately 80-90% of children with a diagnosis of Wilms tumour survive. 3. In 10-15% of cases, we have a mutation in the tumour suppressor gene WT1; in the other cases, it can derives from remnants in the kidney of the mesonephros, which may develop into a tumour. 4. This tumour has the characteristic to resemble, histologically, different stages of development of the kidney. 5. When WT1 is mutated, we can have a loss of E-cadherin and the consequent cell adhesion, causing the mesenchymal transition and migration of the cells. If we lose cell-cell adhesion, then they are free to move around and undergo to an epithelio-mesenchymal transition.

The parenchyma of the prostate can be divided into zones that are relevant from the clinical point of view:

1. a transition zone, which surrounds the proximal part of the urethra (mantellar zone) and it is characterized mostly by benign hyperplasia; 2. a central zone, formed by ejaculatory ducts and proximal part of the urethra (irrelevant from the clinical point of view); 3. a peripheral zone located postero-laterally to the central zone, surrounds the distal prostatic urethra, it is the zone with most cases of carcinoma.

What are the basic functions of the respiratory system?

1. breathing = the movement of air in and out of the lungs; it's different from respiration (= possibility to move in and out air without having gas exchanges). Breathing pattern is divided into inhalation and expiration: 2. gas conditioning = the air that we introduce in the respiratory system needs to be: a) warmed to body temperature (in the initial part of respiratory system); b) humidified; c) cleaned up; especially in initial part of the respiratory tree thanks to some mechanisms, among which the major one is mucus, in addition to immunitary mechanism; 3. gas exchange; Also called respiration, it supplies the body with oxygen and disposes of carbon dioxide; it's the reason why we need a respiratory system. 4. production of sounds 5. site of olfactory sensations

What are the characteristics of the tertiary bronchi (aka. segmental bronchi)?

1. columnar epithelium with very little pseudostratification; 2. goblet cells are greatly diminished; 3. lamina propria is thinner than in the larger bronchi and there is lots of elastic tissue. 4. The lamina propria is completely surrounded by smooth muscle (while initially, we had the appearance of bundles of smooth muscle cells) = arranged in a spiral fashion as to allow contraction of bronchi both in length and diameter during expiration (the more distal I go = the more spiral fashion organization of smooth muscle) When making a cross-section, it seems like a circular layer but in reality, it's a spiral, whose spires are really close to one another.

What are the layers that make up the trachea?

1. mucosa (since the trachea is a hollow organ) characterised by a) the respiratory epithelium, that high in the respiratory tree is pseudostratified; b) lamina propria (supporting the epithelium) characterised by a lot of elastic fibres, very concentrated deeper in the lamina propria to the point that this region of the lamina propria takes the name of the elastic membrane. 2. submucosa, characterised by the presence of a lot of glands (sero-mucus exocrine glands, that release their secretion on the surface of the mucosa). In particular, looking at the cytoplasm of the cells that make up those glands, somewhere cytoplasm is white (= mucus secretion = goblet cells unless there's special staining) but there are also some acini (some demilunes of the glands), which have a serous secretion. 3. fibroelastic layer (only visible if we don't look posteriorly, otherwise smooth muscle): a lot of collagen and elastic fibres. ***If my section was not in between one cartilaginous ring and the other, but was at the level of the cartilaginous ring, the submucosa would blend with the perichondrium (unless is a section that includes only the posterior part, no perichondrium and no cartilage, but smooth muscle cells)

What are the layers of the uterus?

1. perimetrium 2. myometrium 3. endometrium The uterus is a very muscular organ, so most of the thickness of the organ is made by smooth muscle (myometrium), then we have the endometrium, which is the innermost layer and then the adventitia or serosa, depending on where we are, which correspond to the perimetrium.

Clara cells are also important because:

1. prevent sticking of the sides of the wall of the bronchioles, but they also intervene in the metabolism of agents that are extraneous to the living organism: there are some substances, that may even come from bacteria or viruses or of chemical origin, that are completely extraneous to the organism and Clara cells contribute to their metabolism; These tubing systems are really narrow (around less than 0.5 mm in diameter). What we don't want is that when the wall of the two sides of the tube come together (especially during expiration), stick to one another. The substance produced by Clara cells, among other purposes, is there to prevent the sticking of these narrow tubes to one another. Otherwise, the next inspiration would be made really difficult. 2. provide for progenitor cells.

Then we have a system of ducts in the male reproductive system:

1. straight tubules 2. rete testis 3. ductuli efferentes 4. epididymis 5. vas deferens 6. ejaculatory ducts (that converge in the urethra).

What 3 parts is the fornix divided into?

1. the anterior 2. the posterior 3. the lateral part

What are the different parts of the uterus?

1. the fundus of the uterus, the portion above the entrance of the uterine tubes; The lowest part of your uterus. Your cervix opens to your vagina. 2. the uterine horns, where the fallopian tubes communicate with the uterus; 3. In the uterus we recognize a body; The main body of your uterus. This is where a fertilized egg implants during pregnancy. 4. The region of passage between the body of the uterus and the cervical canal is called isthmus of the uterus; during pregnancy it elongates and it is called inferior uterine segment. 5. the cervix or neck of the uterus (partially surrounded by the upper portion of the vagina); The lowest part of your uterus. Your cervix opens to your vagina. 6. inside the cervix we can recognize the cervical canal, which is delimited by an internal os (opening) through which the cervical canal communicates with the uterine cavity and an external os, where the cervical canal communicates with the vagina. 7. The region of the vagina that surrounds the last part of the neck of the uterus is called fornix and it is divided into 3 parts.

We have 2 exocrine glands in the male reproductive system:

1. the seminal vesicles 2. the prostate gland

In the scrotal bursa there are also some arterious and venous structures:

1. the testis when they develop are supplied by a branch of the abdominal aorta, called genital artery (in male testicular artery and in female ovarian artery), and when the testis descent in the abdominal bursa, the testicular artery follows the testis in the scrotal bursa. 2. The testicular artery is surrounded by the pampiniform plexus of veins, which is situated in the spermatic cord and also surrounds the ductus deferens. 3. While the testicular artery brings blood from the inside of the abdominal cavity to the testis, the pampiniform plexus drains blood from the testis and the epididymis and brings it inside the abdominal cavity (inferior vena cava).

The urogenital sinus can be divided into 2 portions:

1. the upper portion is going to enlarge and form the urinary bladder; 2. the inferior part becomes narrower and it will form the urethra.

Which are the cell types that we find in the alveoli?

1. type 1 pneumocytes and type 2 pneumocytes. 2. Then we have macrophages, which are found both inside in the alveoli and in the interalveolar septa.

What are factors that slow mucociliary transport (can be damaged by...)?

1• Cigarette smoke because together with smoke there's the inhalation of toxic substances that damage the movement of cilia. People that are heavy smokers with time start to develop bronchitis, both because there's an irritation of the respiratory tree but also because since cilia are damaged the mucus ciliary escalator doesn't work well and mucus tends to remain there resulting in clogging and presence of infective agents; 2• Dehydration, mucus needs to remain quite fluid otherwise is very difficult for cilia to move forward; 3• Positive pressure ventilation, meaning that if I keep pumping air with positive pressure into the respiratory tree finally I damage the cilia because there's too much mechanical stress; 4• Endotracheal suctioning, endotracheal means from the inside of the trachea; suctioning means aspirating something from the trachea and if I'm too violent or I do it too frequently cilia are damaged; 5• High inspired oxygen concentrations, too much oxygen can damage cilia; 6• Hypoxia, too little oxygen can damage cilia; 7• Atmospheric pollutants, what pollutes the air that we breathe can damage cilia, despite being a smoker or not; 8• General anaesthesia, due to mechanical factor or question of medications used for anaesthesia that affect the movement of the cilia; 9• Parasympatholytic drugs, drugs that affect the function of the parasympathetic nervous system.

What are the different cell types of the alveoli?

1• Type I pneumocytes, sites of gas exchange. 2• Type II pneumocytes, secrete surfactant and are also the stem cells of alveoli. 3• Macrophages, can be found both in the lumen and in interalveolar septa. The more particles reach the alveoli, the more macrophages filled with those particles we will find.

How many lobes does the left lung have?

2 lobes (superior and inferior)

What is the prostatic urethra segment of the male urethra?

2. Prostatic urethra: (which crosses the prostate) where the secretion of the prostate gland is delivered. Here, in the posterior wall of the lumen, there is an elevation called seminal colliculus (or veromontatum) in which the ejaculatory ducts open (this ducts come from the union of ducts deference and the ducts of the seminal vesicle). Below these two openings (still in the veromontatum) there is the prostatic utricle which is the vestibule of the paramesonephric duct. On the side of the veromontatum there are other openings which deliver the secretion of the prostate gland.

How many lobes does the right lung have?

3 lobes (superior, middle, inferior)

What is the membranous urethra segment of the male urethra?

3. Membranous urethra: (which crosses the urogenital diaphragm, so it exits the abdominal cavity). Here, on the sides of the lumen, are found the bulbourethral glands of cowper (even if the glads are found here, their secretion is delivered through some ducts in the penile urethra). Their secretion is classified as a pre-seminal fluid and is stimulated by sexual activity so its function is to lubricate the urethra and to remove eventual urine remnants before of ejaculation. These glands are under the control of testosterone.

What is the penile urethra segment of the male urethra?

4. Penile urethra: (or spongy), here in addition to the secretion of bulbourethral glads (which are found at the level of the membranous urethra) there are some lacunae (similar to the one of the female urethra) in which at the bottom there are the openings of urethral glands of littré which produce mucus secretion. This mucus is both filamentous and alkaline (alkaline in order to buffer the acidity of the urine).