Human Development Combined

What is Muscular VSD caused by?

perforations in the muscular interventricular septum

Developing heart tube bulges more and more into what?

pericardial cavity

The SA node becomes incorporated into what?

the wall of R atrium WITH the sinus venosus

What does the interventricular foramen do?

permits communication between right and left ventricles

Development of Aortic Arch #1

#1: Maxillary artery By day 27 (end of 3rd week, beg of 4th week), most of first arch has disappeared although small portion persists as maxillary artery

____________ becomes the muscular wall of the heart.

(primordial) myocardium

Venous defect: double superior vena cava

persistence of left anterior cardinal vein and failure of left brachiocephalic vein to form

Partitioning of the atrioventricular canal: During week _____, the AV endocardial cushions approach each other and fuse.

week FIVE FUSE

Development of Aortic Arch #3

(*At 7 weeks) Forms 2 things: common carotid and first part of the internal carotid arteries

Development of Aortic Arch #6

(*At 7 weeks) Forms R and L side: LEFT SIDE: Left pulmonary artery and ductus arteriosus RIGHT SIDE: Right pulmonary artery

Development of Aortic Arch #4

(*At 7 weeks) Forms R and L side: LEFT SIDE: arch of the aorta from the left common carotid to the left subclavian artery RIGHT SIDE: Right subclavian artery (proximal portion)

Canicular stage of lung development

(16-26 weeks) C---C, #6-#6 Bronchioles divide continuously smaller canals and vascular supply increases by 24 weeks, each terminal bronchiole has given rise to 2 or more respiratory bronchioles each respiratory bronchiole then dives 3-6 passes (primordial ducts) respiration is possible by the end of this phase so fetus MAY SURVIVE if provided intensive care, but death still often occurs

Terminal sac stage of lung development

(26 weeks --> BIRTH) (26 insurance + terminate in birth) Primary alveolar ducts end in terminal sac epithelium (type 1 alveolar epithelial cells) becomes very thin and capillaries begin to bulge into the sacs (developing alveoli) BAB (blood air barrier) established by end of 6 months (intimate contact between the epithelial and endothelial cells establishes the BAB, which permits adequate gas exchange) type 2 alveolar epithelial cells develop and produce surfactant

Pseudoglandular stage of lung development

(5-16 weeks) Developing lungs resemble exocrine glands by week 16 all major elements of lung have formed ***except those involved with gas exchange fetus born during this period is NOT viable

Alveolar stage of lung development

(8 months-childhood) each respiratory bronchiole terminates in cluster alveolar sacs (represent future alveolar ducts) transitions from placenta for gas exchange for AUTONOMOUS gas exchange

What are the pair of lateral recesses bound by?

*LARYNGEAL VENTRICLES* bound by folds of tissue that differentiate into false and true vocal cords

All laryngeal muscles are innervated by branches of ______ nerve and which 2 arch #s?

*vagus nerve* arch 4 (superior laryngeal n) and arch 6 (recurrent laryngeal n)

Partitioning of what structures begins around the middle of week 4? (4-5 structures)

-Atrioventricular canal -Primordial atrium (A) -Primordial ventricle (V) -Bulbus cordis and truncus arteriosus

ASD: What is the common atrium defect?

-Interatrial septum is absent -Results from COMPLETE FAILURE of septum primum and septum secundum to develop

What are the 4 other clinically significant types of ASD?

-Ostium secundum defect -Endocardial cushion defect with ostium primum defect -Sinus venosus defect -Common atrium

Closure of the IV *foramen AND formation of the membranous part of the IV *septum results from fusion of tissues from what 3 sources?

-Right bulbar ridge (conotruncal ridge) -Left bulbar ridge (conotruncal ridge) -Endocardial cushion

What are the 5 heart dilations that develop/form? (from superior to inferior)

-Truncus arteriosus (trembling) -Bulbus cordis (beats) -Primitive ventricle (prefer very) -Primitive atrium (pulmonary administered) -Sinus venosus (shocks)

What are the four arterial system defects?

-patent ductus arteriosus -coarctation of the aorta -abnormal origin of right subclavian artery -double aortic arch

What are the 4 cardiovascular alterations that are produced by tetralogy of fallot?

1. NARROW R ventricular outflow region (pulmonary infundibular stenosis) 2. Large defect of interventricular septum 3. OVERRIDING aorta that arises directly above septal defect 4. HYPERTROPHY of R ventricular wall

At the end of week 3, what does the mesoderm differentiate into?

1. Paraxial mesoderm 2. Intermediate mesoderm 3. Lateral plate mesoderm

Diaphragm develops from what 4 embryonic structures?

1. Septum transversum ---> central tendon of diaphragm 2. Pleuroperitoneal membrane ---> represent small portions of newborn's diaphragm 3. Dorsal mesentery of esophagus ---> crura of diaphragm 4. Muscular ingrowth from lateral body walls from somites at cervical segments 3 to 5 ---> muscle of diaphragm

During the alveolar stage of lung development, transition from placenta to autonomous is by what 3 ways?

1. producing surfactant in alveolar sac 2. transformation of the lungs from secretory into gas exchanging organs 3. establishment of parallel pulmonary and systemic circulations

When diverticulum expends caudally, what things separate lung bud from foregut?

2 longitudinal ridges (tracheoesophageal ridges)

Angioblastic cords canalize to form

2 thin heart tubes

A probe patent oval foramen is present in about __% of people?

20% this condition is not clinically significant unless it is forced open into other cardiac defects (fxnl pathology)

This bending (of dextral looping) creates the cardiac loop and is complete by day?

28

Development of Aortic Arch #2

2nd arch soon disappears (after day 27) leaving only *HYOID and STAPEDIAL ARTERIES*

By the end of week ______, coordinated contractions of the heart result in unidirectional flow

4th week

Mesenchymal tissue becomes fibrous and form the?

AV valves these remain attached to ventricular wall by muscular cords

What would result in esophageal atresia with or without tracheoesophageal fistula?

Abnormalities in PARTITIONING of esophagus and trachea by the *tracheoesophageal septum* 90% are *blind pouch* atresia (absence of normal opening/tubular) in upper esophagus, with lower having fistula (btw 2 hollow structures)

Laryngotracheal groove appears where? What week does it first appear?

Appears in floor of the caudal end of the primordial pharynx Appears/groove forms by end of week 4

What are Congenital Lung Cysts due to? Describe.

Arise from abnormal development and dilation of terminal bronchi Air or fluid filled space on visceral surface/CYSTS OF LUNG that are caused by blockage of airway give lung honeycomb appearance found on periphery of lung Lung cysts drain poorly ----> cause infections ---> surgically removed

What affects the dextral looping (when regarding arterial and venous ends)?

Arterial and venous ends of the heart are FIXED by the PHARYNGEAL ARCHES and SEPTUM TRANSVERSUM

What are the two ends of the heart tube?

Arterial end Venous end

ASD is?

Atrial Septal Defects

What structure acts as the interim pacemaker of heart at first?

Atrium

Right supracardinal vein and portion of posterior cardinal vein become what?

Azygous vein

What does the extraembryonic coelom (cavity) do?

Basically is a cavity that surrounds the developing embryo Includes the yolk sac, amniotic cavity and the chorionic cavity

Why cardio develops so early?

Bc rapidly growing embryo can no longer satisfy its nutritional and oxygen requirements by diffusion alone

What does the somatic mesoderm layer become?

Becomes parietal serous membrane Parietal serosa lines cavity walls

What does the splanchnic mesoderm layer become?

Becomes visceral serous membrane Visceral serosa lines organs

What happens during week 3 and 4?

Beginning of gut tube formation The endoderm of embryo rolls down to form the gut tube

When does the heart begin to function?

Beginning of the 4th week

When does the heart begin to beat?

Begins to beat at 22-23 days

What are the two Lung and Bronchial Tree Abnormalities?

Bilateral agenesis --> not compatible with life Unilateral --> yes, it is compatible with life Abnormalities are due to the LACK of RESPIRATORY BUD formation

What has happened to the arches by day 29?

By day 29 1st and 2nd arches disappear 3rd, 4th, and 6th arches large Conotruncal region divided so 6th arches now continuous with pulmonary trunk

What affects courses of recurrent laryngeal nerves?

Caudal shifting and disappearance of aortic arch structures due to growth of forebrain, and elongation of the neck pushing the heart into the thoracic cavity ^ this also causes left subclavian a to shift its point of origin higher, close to origin of left common carotid

What is the coelom?

Coelom refers to a fluid filled cavity or space It is the space created between the 2 layers of lateral plate mesoderm Also called the primitive body cavity or the intraembryonic cavity

What are hematopoietic stem cells responsible for?

Colonize liver Stem cells from liver later colonize bone marrow

An infant is diagnosed with a common atrium. What is the embryological basis for this condition?

Complete failure of septum primum and septum secundum to develop.

What is Dextrocardia?

Condition where heart lies on right side of thorax instead of left heart loops to left instead of right May coincide with ***situs inversus**** (a complete reversal of asymmetry in all organs) or ***heterotaxy*** (random in which some organs are reversed and some are not)

What is the role of a mesentery?

Connects an organ(s) to the body wall Conveys vessels and nerves Ventral and dorsal mesenteries develop Visceral mesentery disappears, caudal foregut remains

The pleuropericardial membranes contain what?

Contain the common cardinal veins and phrenic nerves (cardinal veins drain the venous system into the sinus venosus of the heart)

Truncus arteriosus is continuous with what structure? What does this structure give rise to?

Continuous with aortic sac Aortic sac gives rise to pharyngeal arch arteries

What does the secondary heart field do?

Contributes cells to formation of the atria at the CAUDAL end of the heart Forms REMAINDER of **right** ventricle and outflow tract (conus cordis and truncus arteriosus) as well as dorsal mesocardium

The mesenchyme of arches 4 and 6 transform into what 3 types of cartilage?

Cricoid, Arytenoid, and Thyroid cartilages (CAT cartilages) the characteristics adult shape of laryngeal orifice can be recognized now

Dextral looping often abbreviated to?

D-looping

What happens at day 26 and day 28?

Day 26: still communication btw intra and extraembryonic coelom/cavities Day 28: less communication btw those two cavities AND lateral folds fully fused, ventral mesentery disappears

What happens in week 6 of lung development?

Descent of the heart and lungs into thoraX (siX); pleuroperitoneal foramen closes

What does the aorticopulmonary septum do?

Divides truncus arteriosus into 2 arterial channels: ascending aorta and pulmonary trunk Other info but not on slide/don't need to know?: Contributes to formation of interventricular septum. When aorticopulmonary septum doesn't form, truncus arteriosus persists rather than being divided and membranous interventricular septum is incomplete.

What is Respiratory Distress Syndrome due to?

Due to a lack of surfactant --> alveolar collapse --> baby can't breathe Previously known as hyaline membrane disease Common cause of death in premature infants

CDH has an unusually flat stomach when newborn is lying down. This is due to what?

Due to abdominal viscera having herniated into thorax

What does the intraembryonic coelom (cavity) do?

During 4th week, it forms pleural, pericardial and peritoneal body cavities Appears as a HORSESHOE cavity

Proliferation of cells in the walls of the bulbus cordis results in formation of bulbar ridges in what week?

During week 5 Similar ridges form in TRUNCUS ARTERIOSUS (truncal ridges or swellings)

What happens in week 7 of lung development?

Enlargement of liVer (seVen) stops descent of heart and lungs

What happens in week 5 of lung development?

L and R lung buds push into the pericardioperitoneal canals (primordia of pleural cavity)

A newborn infant cannot breath and soon dies. An autopsy reveals a large diaphragmatic defect on the left side, with the stomach and intestines occupying the left side of the thorax. Both lungs are severely hypoplastic. What is the embryological basis for this defect?

Failure of pleuroperitoneal membranes to fuse properly

What does the laryngotrachael groove form with those grooves?

Forms pouch respiratory diverticulum (lung bud) Lung bud/pouch is an out growth of the ventral wall of the foregut

What does the parietal layer (of the lateral plate mesoderm) form?

Forms the embryonic body wall (or somatopleure). Forms dermis in body wall and limbs, bones and connective tissue of limbs, and sternum. Form mesothelial, or serous, membranes which will line peritoneal, pleural, and pericardial cavities.

What does the visceral layer (of the lateral plate mesoderm) form?

Forms wall of gut tube (splanchnopleure). Forms connective tissue and muscle of viscera, primordial heart, suprarenal cortex, blood and lymphatic cells. Form a thin serous membrane around organs.

Bronchial buds grow into what? And they produce what?

Grow into pericardioperitoneal canals Produce pair of membranous ridges in the lateral wall of each canal

How do you reduce herniation in CDH and ease the pressure in the lungs?

Improve the breathing by placing infant in an upright or sitting position

2 main channels of thoracic ducts?

L and R thoracic ducts joining jugular sacs with cisterna chyli and anastomosis (for between ducts)

What happens in week 4 of lung development?

Laryngotracheal groove forms on floor foregut (caudally)

Which structure develops into the hemiazygous vein?

Left supracardinal vein

What adult structures are formed by parts of the sinus venosus?

Left supracardinal vein ---> Hemiazygous vein

During the 4th week, the septum transversum does what?

Lies opposite the 3rd-5th cervical somites

What happens in months 3-6 of lung development?

Lungs appear glandular End of month 6: alveolar cells type 2 and begin to secrete SURFACTANT (*this is when the fetus starts to become viable out of womb)

Eventration of the diaphragm results from what?

Mainly from failure of muscular tissue from the body wall to extend into pleuroperitoneal membranes on affected side

What holds the two tubes (neural tube and gut tube) together?

Mesoderm

During the 5th week, myoblasts (from the cervical somites of septum transversum) do what?

Migrate into developing diaphragm --> bring their nerve fibers Results in phrenic nerves also arising

Regarding the formation of the primitive pleural cavities, in what orientation does it fill with expanding lung buds?

Narrow and lie on each side of the foregut

Both bulbar ridges and truncal ridges are derived largely from?

Neural crest cells* *Because neural crest cells also contribute to craniofacial abnormalities, it is not uncommon to see FACIAL and CARDIAC abnormalities in the same individual

At gut tube formation, the embryo has what 2 things?

Neural tube (dorsally) Gut tube (ventrally)

What do we have at weeks 7 & 8?

Now have the pleural cavities and pericardial cavities FORMED By 7th week, the pleuroperitoneal membranes SEPARATE pleural cavities from peritoneal cavities They do this separation by fusing with the mesentery of the esophagus and septum transversum

What is Persistent Truncus Arteriosus (PTA)?

Only part of the aorticopulmonary septum develops Caused by: abnormal neural crest cell migration Result: one large vessel leaves the heart and receives blood from both right and left ventricles Accompanied by: ventricular septal defect Clinical sign: cyanosis

What is responsible for forming the heart?

PHF (splanchnic layer of lateral plate mesoderm) [where progenitor cardiac cells are reside) and neural crest cells

What do pericardioperitoneal canals develop into?

Paired pleural cavities

ASD: What is the ostium secundum defect?

Patent foramen ovale due to faulty septaum primum or septum secundum What is patent forament ovale - open foramen ovale (Still open) correct using surgery Symptoms usually appear as pulmonary hypertension in 30s or later

What does the primordial mediastinum consist of?

Primordial mediastinum consists of a mass of mesenchyme that extends from the sternum to the vertebral column, separating the developing lungs

What is the septum transversum?

Primordium of the central tendon of the diaphragm (and connective tissue of the liver) Between the thoracic cavity and the stalk of the yolk sac Openings exist on either side of the foregut called pericardioperitoneal canals

Regarding bronchi and lung development, what are the different stages of lung maturation and timeline (which weeks/months)?

Pseudoglandular (5-16 weeks) Canicular (16-26 weeks) Terminal sac (26 weeks --> BIRTH) Alveolar (8 months-childhood)

What happens in month 7 of lung development?

Respiratory bronchioles proliferate End in alveolar ducts and sacs

ASD: what is the sinus venosus defect?

Results from INCOMPLETE ABSORPTION of the sinus venosus into the RIGHT atrium and/or abnormal development of the septum secundum

TBX4 is associated with what acid and where is it expressed?

Retinoic acid Expressed in endoderm of gut tube at site of lung bud

How is the bulbus cordis is incorporated into the walls of the definitive ventricles?

Right ventricle- bulbus cordis (represented by conus arteriosus) gives origin to the PULMONARY TRUNK Left ventricle- bulbus cordis forms the WALLS OF AORTIC VESTIBULE (the part of the ventricular cavity just inferior to the aortic valve)

Progenitor cardiac cells come to reside in the what layer?

SPLANCHNIC layer of the LATERAL plate mesoderm, forming the PHF

Beginning at the end of the 4th week, the primordial atrium is divided into right and left atria by the formation and subsequent modification and fusion of 2 septa. What are these septa?

Septum primum (thin crescent, fuses endocardial cushions) Septum secundum (thick, grows during 5th-6th week, grows from ventrocranial wall of R atrium)

What forms the foramen ovale?

Septum secundum forms an incomplete partition between the atria forming foramen ovale Cranial part of the septum primum DEGENERATES Remaining portion of septum primum forms the VALVE OF FORAMEN OVALE

What happens to the dorsal mesentery?

Serves as a pathway for the arteries supplying the developing gut (goes from foregut to hindgut)

ASD: What is endocardial cushion defect WITH ostium primum defect?

Several cardiac defects grouped together under this heading but ALL result from a deficiency of the **endocardial cushions and the AV septum**

Lateral plate mesoderm splits into what 2 layers?

Splanchnic (visceral) mesoderm layer Somatic (parietal) mesoderm layer

What is the most common cause of death among healthy infants?

Sudden infant death syndrome (SIDS) It is a conducting tissue abnormality

What heart defect is the most frequently occurring abnormality of the conotruncal region?

Tetralogy of Fallot

What is the first indication of lower respiratory system development?

The development of the laryngotracheal groove

What do the pleuropericardial membranes form?

The fibrous pericardium

What give the embryo its shape?

The lateral folds

What separates the pleural and pericardial cavities (around week 7)?

The pleuropericardial membranes that fuse with the mesenchyme ventral to the esophagus

Dilation of Primitive atrium, affects what adult structures?

Trabeculated parts of R + L atria

Dilation of Primitive ventricle, affects what adult structures?

Trabeculated parts of R + L ventricles

What is tricuspid atresia?

Tricuspid atresia is complete failure of the tricuspid valve to develop. There is no communication from the R atrium to the R ventricle. Complete mixing of unoxygenated and oxygenated blood = cyanosis, tachycardia and dyspnea. AV SEPTUM MALFORMATION

Treatment of preterm babies with Respiratory Distress Syndrome?

Tx baby with artificial surfactant and Tx mother with premature labor w/ glucocorticoids -----> to stimulate surfactant production + have reduced mortality

most common type of congenital heart defect?

VSDs more common in MALE (think "V": Ventricular, Vas deferens) most common in membranous part of IV septum

What is the difference btw Vasculogenesis and Angiogenesis?

Vasculogenesis- vessels arise from blood islands, major vessels including dorsal aorta and cardinal veins from this way Angiogenesis- vessels sprout from existing vessels, remainder of vascular system formed this way

At week 5, what happens?

Ventral mesentery has disappeared except for esophagus, stomach, duodenum R + L parts of intraembryonic coelem separate more cranially (become more continuous caudally) Peritoneal cavity connects to extraembryonic coelom Caudal part of 3 guts are suspended in peritoneal cavity by DORSAL MESENTERY Pericardioperitoneal canals are still present

VSD is?

Ventricular Septal Defects

What is responsible for formation of coronary arteries?

Visceral pericardium, or epicardium

What is the aorta-gonad-mesonephros region?

Where the definitive hematopoietic stem cells (derived from mesoderm) surrounding the aorta near developing mesonephric kidney come from

Division of the primordial ventricle is first indicated by what? In what week?

a median ridge, the muscular interventricular (IV) septum, in the floor of the ventricle near its apex appears in week 5

What are the vitelline arteries?

a number of paired arteries that supply the yolk sac

What is the hypopharyngeal eminence?

a prominence produced by mesenchyme proliferation from pharyngeal arches 3 and 4

Ectopic Lung Lobes arising from trachea or esophagus are believed to be formed from?

additional respiratory buds of foregut that develop independently of main respiratory system

What does the foramen ovale do before birth?

allows most of the oxygenated blood to pass from right atrium directly into left atrium prevents the passage of blood in the opposite direction

Retinoic acid's appearance and location of the lung bud is dependent upon what?

an increase in RA production by adjacent mesoderm

What is tetralogy of fallot caused by?

an unequal division of the conus results from anterior displacement of the aorticopulmonary septum produced 4 cardiovascular alterations (know these)

Vitelline and umbilical

anastomtic network around duodenum develops into signal portal vein superior mesenteric vein drains the interstinal loop and is derived from right vitelline vein distal part of left vitelline vein also disappears remainder of right umbilical vein disappears leaving only left umbilical vein to carry blood from placenta to liver increase in placental circulation a direction communication forms between the left umbilical vein and right hepatocardiac channel (ductus venosus, bypasses the sinusoidal plexus of liver) ****after birth left umbilical vein and ductus venous are obliterated forming (ligamentum teres hepatis or round ligament of liver, ligamentum venosum)

Initially the central portion of cardiogenic area is ________ to oropharyngeal membrane and neural plate

anterior

Dilation of Truncus arteriosus, affects what adult structures?

aorta and pulmonary trunk

Ventral body defects: urogenital organs outside of body wall called?

bladder or cloacal exstrophy

When ventricles contract, blood is pumped through what 2 structures into the aortic sac?

bulbus cordis and truncus arteriosus

First major system to function in the embryo?

cardiovascular system

What is eventration of the diaphragm?

caused by a defective musculature in one half of the diaphragm. Half of diaphragm goes up with contraction of diaphragm during respiration. (Paradoxical bc diaphragm generally moves down during inspiration)

What adult structures do the vitelline arteries form?

celiac arteries superior mesenteric arteries & inferior mesenteric arteries

The cardiac progenitor cells migrate through what? In what orientation do they position themselves?

cells migrate through the PRIMITIVE STREAK position themselves ROSTRAL to the oropharyngeal membrane and neural folds (NF) (OROPH & NEURO-al)

Regarding development of the larynx, the mesenchyme rapidly proliferates, and the laryngeal orifice (primordial glottis) changes in appearance from _______ to ________ shape?

changes in appearance from a sagittal split to a T-shape

What does the foramen ovale do after birth?

closes due to higher pressure in the LEFT atrium than in the right atrium immediately after birth

Posterolateral defect of diaphragm is lethal because?

compression of lung leads to hypoplastic lungs (incompletely developed)

The processes of partitioning occur separately or concurrently?

concurrently

Posterolateral defect of diaphragm is associated with what disorder?

congenital diaphragmatic hernia (CDH) (herniation of abdominal contents into thoracic cavity) occurs in 1 out of 2000 newborns

What does the transverse pericardial sinus do?

connects both sides of the pericardial cavity

Regarding the conducting system of the heart, (initially) the muscle in the primordial atrium and ventricle is separated or continuous?

continuous

Pharyngeal arches and their vessels appear in a ______________ sequence starting in week #?

cranial-to-caudal sequence week 4 *The fifth arch either never forms or forms incompletely and then regresses

Tricuspid Atresia is associated with what clinical defects?

cyanosis always accompanied by the following: -Patent foramen ovale -Interventricular septum defect -Overdeveloped left ventricle -Underdeveloped right ventricle

When it is day 28, the the endo/myo/epi-cardiums form, but also the dorsal mesocardium is ______

degenerating this creates the transverse pericardial sinus

When muscular tissue in cords degenerate, they are replaced by?

dense connective tissue connected to thick muscular trabeculae in the wall of the ventricle (known as papillary muscles by means of chordae tendinae)

How do the semilunar valves develop?

develop from 3 swellings of subendocardial tissues around the orifices of the aorta and pulmonary trunk

The 5 heart dilations (in development) undergo what kind of looping? This looping in heart dilations leads to what happening?

dextral (right-handed) looping dilations (loops) develop into adult structures of the heart

Thoracic duct develops from ?

distal portion of right thoracic duct the anastomosis and the cranial portion of left thoracic duct

In secondary HF, the dorsal mesocardium attaches the developing heart tube to what?

dorsal side of pericardial cavity

Most blood that bypasses the lungs by passing through the ?

ductus arteriosis

On the LEFT side, recurrent laryngeal n does not move up because of ____?

ductus arteriosus

During which week does the sinuatrial (SA) node develop?

during the 5th week (originally located in wall of sinus venosus)

When do the 1st blood islands appear in mesoderm?

during week 3 in mesoderm surrounding yolk sac ***slightly later in lateral plate mesoderm and other regions

Ventral body defects: heart outside of the body wall called what?

ectopia cordis

Partitioning of the atrioventricular canal: During week ________, outgrowth of the _______ and ______ walls of the atrioventricular canal form swellings which are called the ________ cushions.

end of week 4 dorsal and ventral walls endocardial cushions

IV foramen closes by what week?

end of week 7

Regarding the development of the larynx, where does the epithelial lining come from?

endoderm

The ostium secundum does what?

ensures continued shunting of blood when ostium primum disappears

Cardiac progenitor cells lie in the _______.

epiblast IMMEDIATELY LATERAL to the primitive streak

What does Membranous VSD results from?

faulty fusion of the R and L bulbar ridges and AV endocardial cushion

Lung bud is open communication with _______?

foregut

cardinal veins

form a symmetric system consisting of anterior and posterior cardinal v they join and form: common cardinal before entering sinus horn during 5th-7th week additional veins are formed: subcardinal (to drain kidneys), sacrocardinal (lower extremities) and supracardinal (drain the body wall by way of intercostal v)

Where do angioblastic cords form? Which week?

form in the cardiogenic mesoderm (PHF) during the third week

What does TBX4 induce?

formation of the lung bud and the continued growth and differentiation of the lungs

How is the myocardium formed?

formed from splanchnic mesoderm surrounding the pericardial cavity

Highly oxygenated and nutrient-enriched blood returns to the fetus from _____?

from placenta via left umbilical vein

How would an infant with esophageal atresia (w/ or w/o TE fistula) present with this condition? (Aka name the symptoms)

frothy, white bubbles in the mouth drooling couching or choking when feeding vomiting cyanosis (especially when baby is feeding) difficulty breathing very round, full abdomen

At approximately 3 months of age, what happens with the valve of the foramen ovale?

fuses with the septum secundum, forming the FOSSA OVALIS

Ventral body defects: if abdominal viscera defect, called what?

gastroschisis

What do the vitelline arteries form into?

gradually fuse and form the arteries in the dorsal mesentery of gut

Blood percolates through ________ but most blood bypasses them by passing through _____?

hepatic sinusoids most bypass through ductus venosus and entering IVC

SA node is located high in ______ atrium near the entrance of ____________?

high in the R atrium near the entrance of the superior vena cava

When heart descends, the recurrent laryngeal n moves up and _____?

hooks around RIGHT subclavian artery

What are the 6 lymph sacs?

i. 2 jugular sacs at the junction of subclavian and anterior cardinal veins ii. 2 iliac sacs at junction of iliac and posterior cardinal veins iii. 1 retroperitoneal sac near root of mesentery iv. 1 cisterna chyli sac dorsal to retroperitoneal

Where do the secondary (heart) field of cells reside?

in splanchnic mesoderm BUT VENTRAL **to pharynx** (not lateral like primary HF, or oropharyn + neural folds like primary HF)

Respiratory primordium maintains its communication with pharynx via what?

laryngeal orfice

At what stage is the heart composed of a thin endothelial tube (separated from a thick myocardium by gelatinous connective tissue known as cardiac jelly)?

lateral embryo folding aka heart tube fusion

From left atrium, blood enters ______ and is delivered to _____?

left ventricle fetal tissues via aorta

After atrioventricular endocardial cushions fuse, each atrioventricular orifice is surrounded by?

local proliferations of mesenchymal tissue derived from the endocardial cushions

Both (thoracic and lymphatic) ducts maintain their original connection with ________ and empty into ______?

maintain connection with venous systems empty into 1) junction of internal jugular veins and 2) subclavian veins

Regarding the development of the larynx, cartilage and muscles originate from what arches?

mesenchyme from 4th and 6th pharyngeal arches

Blood cells and blood vessels arise from ?

mesoderm

Regarding the formation of the primitive pleural cavities, _________ covering the outside of lung develops into visceral pleura while ______________ covering body wall becomes parietal pleura?

mesoderm covering the outside of lung --> visceral pleura somatic mesoderm covering body wall --> parietal pleura

Cardiovascular system is of __________ origin (and neural crest cells)

mesodermal

Laryngeal cartilage development from the mesenchyme is derived from what kind of cells?

neural crest cells

What happens with small, isolated patent oval foramen?

no hemodynamic significance unless: (other defects) blood shunted through the oval foramen into the left atrium and produces CYANOSIS

What forms the ostium secundum?

perforations (that are produced via apoptosis) coalesce to form this foramen

How does cephalocaudal embryo folding affect the oropharyngeal membrane and pericardial cavity?

oropharyngeal membrane is pulled forward the heart and pericardial cavity move first to cervical region ----> and finally to thorax

This foramen serves as a shunt, enabling oxygenated blood to pass from RIGHT to LEFT atrium (like how you write in farsi)

ostium

As septum primum grows, what two things appear? (they are between its free edge and the endocardial cushions)

ostium (foramen) and primum (large opening)

Earliest sign of the heart is the appearance of

paired endothelial strands called angioblastic cords

What are the umbilical arteries?

paired ventral branches of dorsal aorta in course to placenta in close association with allantois during 4th week, each artery acquires a connection to common iliac artery and loses earliest origin

Phrenic nerves initially pass into ________ through the _________?

pass into septum transversum through pleuropericardial membranes

Most common form of Atrial Septal Defects is?

patent foramen ovale common, congenital more common in females

A hospitalized patient required the placement of a central venous catheter. Imaging was conducted to determine whether there were any vascular abnormalities. The patient was noted to have a left superior vena cava. What is the embryological basis of this venous system defect?

persistence of left anterior cardinal vein and obliteration of common cardinal + proximal part of anterior cardinal veins on the right

Venous defect: left superior vena cava

persistence of left anterior cardinal vein and obliteration of common cardinal and proximal part of anterior cardinals on the right

Surfactant is a complex mixture of what?

phospholipids and proteins capable of REDUCING surface TENSION at the air-alveolar interface

Poorly oxygenated and nutrient poor fetal blood is sent back to _____ via _____?

placenta via R and L umbilical arteries

Posterolateral defect of diaphragm results from defective formation and/or fusion of?

pleuroperitoneal membranes with the other 3 components

When the septum primum fuses with the fused AV endocardial cushions, it forms the?

primordial AV septum ostium (foramen) becomes smaller and smaller

Another name for the laryngeal orifice?

primordial glottis

Visceral pericardium, or epicardium, is derived from?

proepicardial organ this organ is located in the dorsal caudal border of dorsal mesocardium

This dextral/cardiac looping is responsible for what?

proper alignment of the atrioventricular canal and the conoventricular canal

After birth- proximal portions of umbilical arteries persist as _______, while distal parts are obliterated to form _______?

proximal persist as: -internal iliac arteries -superior vesical arteries distal obliterated to form: -medial umbilical ligament

Congenital diaphragmatic herniation often results in what?

pulmonary hypoplasia --> complete loss of breath at times cyanosis (blue) auscultations (no breath) sound on affected side (usually L side)

Blood that does not enter right ventricle then enters _____?

pulmonary trunk to go to the lungs

Repositioning of the diaphragm is caused by?

rapid growth of the dorsal part of the embryo (vertebral column)

patent ductus arteriosus (PDA)

refers to failure of ductus arteriosus to close generates a L to R shunt causing pulmonary HYPERTENSION and possibly congestive heart FAILURE and cardiac ARRYTHMIAS may be isolated abnormally or occur with other defects

What do the 3 swellings of the subendocardial tissues (that develop the semilunar valves) form?

reshape to form THREE THIN-WALLED CUSPS CUSPS!!

From IVC, blood enters _____ atrium where most blood bypasses _____ by passing through ______ to enter ______?

right atrium right ventricle foramen ovale left atrium

Venous defect: double inferior vena cava

sacrocardinal and subcardinal vein failing to lose its connection

coarctation of the aorta (CoA)

significant narrowing of the aortic lumen below the origin of the left subclavian artery preductal version- ductus arteriosus persists postductal- more common type, ductus arteriosus is usually obliterated collateral circulation between proximal and distal parts established by way of large intercostal and internal thoracic arteries, classic clinical signs include HYPERTENSION in right arm concomitant with LOWERED BP blood pressure in LEGS and numbness and tingling in both feet

Blood from sinus venosus enters primordial atrium and is controlled by

sinuatrial valves THEN goes through AV canal, then primordial ventricle

Contractions occur in peristalsis-like waves that begin in?

sinus venosus

What structure takes over the atrium in being the pacemaker of the heart?

sinus venosus

Dilation of Sinus venosus, affects what adult structures?

smooth part of R ATRIUM (sinus venarum) coronary sinus oblique vein of L ATRIUM

Dilation of Bulbus cordis, affects what adult structures?

smooth part of R ventricle *(conus arteriosus)* smooth part of L ventricle *(aortic vestibule)*

What things form the AV node and bundle?

some cells from sinus venosus ALONG WITH cells from AV region

Venous defect: absence of inferior vena cava

subcardinal vein fails to make is connection with liver

Essentially the partitioning is completed by the end of what week?

the 8th week

Cells in PHF form what parts of the heart?

the atria the left ventricle a part of the right ventricle

Cephalocaudal embryo folding involves

the closure of the neural tube and formation of brain vesicles/CNS extends over the central cardiogenic area (which is anterior to the oropharyn memb + neural plate) and future pericardial cavity

Right lymphatic duct is derived from ?

the cranial portion of right thoracic duct

During lateral embryo folding, initially the heart tube remains attached to the pericardial cavity by what?

the dorsal mesocardium NO VENTRAL mesocardium is ever formed

The ventral layer is AKA

the endoderm

What is the myocardium?

the external layer of the embryonic heart tube

Expansion of lungs & descent of septum --> shift phrenic nerves into?

the fibrous pericardium

Primary heart field (PHF) refers to?

the first wave of mesodermal cells (progenitor heart cells) that differentiate to FORM THE INITIAL HEART TUBE

What happens as lateral folding occurs?

the heart tubes fuse fusion begins at cranial end and extends caudally

Epiglottis develops from what?

the hypopharyngeal eminence

What does the endothelial tube become?

the internal endothelial lining of the heart known aka the ENDOCARDIUM

Vacuolization and recanalization produces what?

the laryngeal ventricles (which are a pair of lateral recesses)

By 8th week, the dorsal part of the diaphragm lies at?

the level of the first lumbar vertebra

By 6th week, the developing diaphragm is at?

the level of the thoracic somites

Primordial heart and vascular system appear in what week?

the middle of the third week

Arterial and venous ends of the heart are fixed by what two structures?

the pharyngeal arches and the septum transversum (respectively)

The spaces between parietal and visceral pleura is?

the pleural cavity

Regarding the formation of the primitive pleural cavities, what ultimately separate the pericardioperitoneal canals from the peritoneal and pericardial cavities?

the pleuroperitONEAL and pleuroperiCARDIAL folds the *remaining spaces* form the primitive pleural cavities

When partitioning of truncus arteriosus is nearly completed, what structure begins to develop?

the semilunar valves

The tracheoesophageal ridges fuse to form what?

the tracheoesophageal septum this septum divides the fOregut into esOphagus dOrsally and trachEa and lung buds vEntrally

After the laryngeal epithelium proliferates rapidly, what happens?

there is temporary occlusion of lumen

large patent oval foramen in adult

this is a large atrial septal defect resulted from an abnormally large oval foramen and excessive resorption of septum primum

What type of cells produce surfactant?

type 2 alveolar epithelial cells

Sinus venosus receives what three structures?

umbilical (chorion) vitelline (yolk sac) common cardinal (embryo) veins ***Sinus ven ---> VUC!! (like yuck)***

As cells migrate, what happens with the bulbar and truncal ridges?

undergo a 180° spiral the two ridges fuse to form the aorticopulmonary septum

Retinoic acid increase causes what?

up-regulation of transcription factor TBX4

AV endocardial cushions contribute to the formation of the what parts of the heart?

valves and membranous septa of the heart

DOUBLE aortic arch

vascular ring surrounds trachea and esophagus compressing these two to the point that the individual has difficulties swallowing and breathing (double --> double the trouble --> can't breathe well)

Phrenic nerves that supply the diaphragm arise from what?

ventral rami of C3-C5 spinal nerves

Another name for epicardium?

visceral pericardium

abnormal origin of RIGHT subclavian artery

when artery is formed by distal part of right dorsal aorta and 7th intersegmental artery may compress esophagus ***generally no problems with breathing or swallowing because neither is severely compressed (right- "right to still breathe")