IB HL Biology 12 11.3 & 11.4

State the role of FSH in spermatogenesis.

FSH is located within the pituitary gland and stimulates meiosis I.

Outline the role of the seminal vesicle in the production of sperm.

The seminal vesicle produces mucus to protect sperm. The mucus is basic, not acidic.

Explain the reabsorption of glucose, water, and salts in the proximal convoluted tubule.

Selective reabsorption of glucose, water, and salts occurs in the proximal convoluted tubule of the nephron. Water, salts, amino acids, and glucose in the glomerular filtrate need to be reabsorbed. 1. Convolutions and microvilli increase the surface area for reabsorption. 2. Large numbers of mitochondria present in PTC cells generate ATP. 3. Active transport pumps Na+ ions from the PTC cells into capillaries, generating a concentration gradient between the PTC cells and filtrate in lumen. 4. Na+ ions move from the lumen to the PTC cells by facilitated diffusion. 5. Glucose and amino acids follow by cotransport. 6. The solute concentration increases in the PTC cells, leading to osmosis of water from the lumen into the PTC cells. 7. Facilitated diffusion carries glucose and amino acids into the blood. 8. The flow of blood maintains concentration gradient. 9. Some water, all of glucose and amino acids, and some urea are recovered into the blood.

Define sertoli cells.

Sertoli cells are located towards the center of the testis tissues, and they nourish developing spermatozoa.

State the function of the Loop of Henle.

Site of osmoregulation.

State the function of the renal capsule.

Site of ultrafiltration.

Outline spermatogenesis.

Spermatogenesis occurs within the testis of the male reproductive system. 1. Mitosis produces spermatogonia. 2. Spermatogonia grow to become primary spermatocytes. 3. Primary spermatocytes develop into secondary spermatocytes. 3. FSH stimulates meiosis. 4. Secondary spermatocytes divide into spermatids by meiosis I. 5. LH stimulates testosterone. 6. Testosterone stimulates meiosis II. 7. Spermatids divide into 4 haploid sperm cells through meiosis II. 8. Testosterone stimulates differentiation.

State the differences of spermatogenesis and oogenesis.

Spermatogenesis... occurs in the testis between puberty and death, and the result is 4 haploid gametes. Oogenesis... occurs in the oviduct from before birth, puberty to menopause, and the result is 1 haploid gamete.

State the role of testosterone in spermatogenesis.

Testosterone stimulates meiosis II.

Define the Bowman's capsule.

The Bowman's capsule surrounds the glomerulus and receives filtrate from the glomerulus.

Explain the role of the Loop of Henle in maintaining the water balance of the blood.

The Loop of Henle generates a high concentration of solutes in the cells and fluid of the medulla. The descending portion of the loop is relatively impermeable to salt ions but permeable to water so some water will leave the tubule here. The ascending portion of the loop is permeable to salt ions but impermeable to water so sodium ions will be pumped out into the intercellular fluid. The filtrate volume decreases, the output of urine is more dilute, and large amounts of salts are removed.

Explain the role of the medulla in maintaining the water balance of the blood.

The Loop of Henle is located in the medulla. As solute concentration increases in the medulla, an osmotic gradient is established, so some water leaves the filtrate by osmosis.

Define the Loop of Henle.

The Loop of Henle is the second extension of the Bowman's capsule; absorption of water and salt occurs here.

Define the afferent vessel.

The afferent vessel is a small branch of the renal artery that carries unfiltered blood to the glomerulus.

Explain the role of the collecting duct in maintaining the water balance of the blood.

The collecting duct balances the water concentration of the blood through hormonal control. The filtrate enters the collecting duct from the distal convoluted tubule. Water moves from the collecting duct to the capillaries by osmosis. The filtrate and the water flow in opposite directions, maintaining a concentration gradient, or a counter-current system.

Define the collecting duct.

The collecting duct extends into the medulla; where the reabsorption of salt, urea and water occurs.The absorption of water is regulated by ADH.

Distinguish between the descending and ascending parts of the Loop of Henle.

The descending side is permeable to water, and impermeable to sodium ions. It is the filtrate. The ascending side is impermeable to water but permeable to sodium ions. It is the collecting duct.

Define the distal convoluted tubule.

The distal convoluted tubule is the last portion of the Bowman's capsule's extension where the reabsorption of salt occurs.

Define the efferent vessel.

The efferent vessel carries filtered blood away from the glomerulus.

Outline the role of the epididymis in the production of sperm.

The epididymis is where the maturation of sperm occurs.

What is the fetus supported and protected by?

The fetus is supported and protected by the amniotic fluid and the amniotic sac.

Describe the role of the germinal epithelium in the ovaries.

The germinal epithelium is the outer layer of the ovary. It produces primary follicles, and undergoes constant cell division.

Define the glomerulus.

The glomerulus is a capillary bed in the nephron that filters various substances from the blood through ultrafiltration.

How is osmosis significant to selective reabsorption?

The increase in solute concentration due to the inflow of sodium ions leads to osmosis of water into the cells of the proximal convoluted tubule.

Describe the role of mature follicles in the ovaries.

The mature follicles contain oocytes, which are ready for ovulation.

Describe the role of the medulla in the ovaries.

The medulla is the central main body of the ovary, containing blood vessels, lymph, and nerves.

Explain how the structure and functions of the placenta maintain pregnancy.

The placenta releases progesterone and estrogen. The fetus receives oxygen, water, lipids, glucose, amino acids, and antibodies from the mother through the placenta. The mother receives water, carbon dioxide, HCG, and urea from the fetus.

Describe the role of primary follicles in the ovaries.

The primary follicles are the location for the development of oocytes, which are surrounded by support cells.

Outline the role of the prostate gland in the production of sperm.

The prostate gland produces fluid that is basic to produce sperm.

Define the proximal convoluted tubule.

The proximal convoluted tubule is the first extension of Bowman's capsule; most reabsorption of glucose, salt and water occurs here.

Define the renal artery.

The renal artery carries blood to the kidney.

Define the renal vein.

The renal vein carries blood away from the kidney.

Describe the role of the secondary oocyte in the ovaries.

The secondary oocyte is a haploid gamete. The final stage of meiosis occurs after fertilization.

How are protein pumps and channels significant to selective reabsorption?

They are present during filtration.

State the similarities of spermatogenesis and oogenesis.

They both... begin with mitosis, use LH and FSH, and have 2 mitotic divisions.

How are convolutions of the tubule significant to selective reabsorption?

They increase surface area for reabsorption.

How are microvilli significant to selective reabsorption?

They increase surface area for reabsorption.

How are mitochondria significant to selective reabsorption?

They produce ATP for active transport.

Explain the process of ultrafiltration.

Ultrafiltration takes place in the renal capsule in the cortex of the kidney. 1. Blood enters through the afferent arteriole and leaves through the efferent arteriole. The afferent arteriole is larger than the efferent arteriole, causing high pressure in the renal capsule. 2. Water, glucose, amino acids, and solutes are forced out of the blood, including metabolic wastes through the fenestrated capillaries and basement membrane. 3. Podocyte cells act as a filter. 4. The plasma proteins, platelets, and cells are so large that they remain in the blood. 5. Glomerular filtrate is carried through the nephron, where selective reabsorption takes place in the proximal convoluted tubule.

List three molecules that are recovered back into the blood by selective reabsorption.

Urea, glucose, and amino acids.

What percentage of glucose and amino acids are recovered during selective reabsorption?

100%

What percentage of water is recovered during selective reabsorption?

65-80%

Distinguish between afferent and efferent arterioles.

Afferent arterioles take in blood. Efferent arterioles put blood out.

Outline the process of birth.

After fertilization and fetal development, the baby is ready to be born. 1. Progesterone levels are decreased. 2. The fetal head engages the cortex. 3. Stretch receptors stimulate oxytocin secretion. 4. Oxytocin causes contractions of the uterus to occur. 5. Contractions further stimulate the release of oxytocin (called positive feedback). 6. The cervix is continually dilating the whole time, and eventually the baby is born.

Explain the differences in the concentration of proteins, glucose, and urea between blood plasma, glomerular filtrate, and urine.***

Blood plasma has a high concentration of oxygen and urea when it enters the kidney. When blood plasma leaves the kidney, it contains carbon dioxide, more water and salt, and the same amount of proteins and glucose as it had when it entered the blood. It leaves with very little urea. The glomerular filtrate has a similar concentration of glucose and urea to the blood plasma. It does not contain the large proteins because these have been filtered by the basement membrane and prevented to enter the filtrate. The urine contains less water, no proteins, no glucose, and less salt than both blood plasma and the glomerular filtrate. It does contain a lot more urea than the glomerular filtrate.

State the function of the glomerulus.

Delivers blood to and from the kidney.

State the function of the collecting duct.

Delivers urine into pelvis.

Define excretion.

Excretion is the removal from the body of waste products of metabolic pathways.

Describe the process of fertilization.

Fertilization occurs either in the fallopian tubes or the oviduct of the female reproductive system. 1. When the sperm reaches the zona pellucida, an acrosome reaction occurs, where enzymes eat through the zona membrane. 2. The plasma membranes of the sperm and the egg fuse, and Ca+2 is released to stimulate meiosis II in the egg cells. 3. A cortical reaction occurs, and cortical granules fuse with the egg plasma membrane to form a barrier where the zona pellucida can no longer bind with the sperm. Polyspermy cannot occur. 4. The nucleus of the sperm is posted into the cytoplasm of the egg.

Define germinal epithelium cells.

Germinal epithelium cells are located towards the outer membrane of individual testis tissues, and produce spermatogonia.

Outline the role of HCG in early pregnancy.

HCG is a hormone. After implantation the blastocyst secretes HCG, causing the corpus luteum to secrete progesterone and estrogen.

Explain the role of the hormone ADH in maintaining the water balance of the blood.

If a person is dehydrated, ADH acts on the walls of the collecting duct, producing aquaporins, making it more permeable to water. More water is transferred into the blood. The urine output is hypertonic, or has a high solute concentration.

Distinguish between Type I and Type II diabetes.

In both types, the liver does not take up glucose from the blood. In Type I, insulin is not produced. In Type II, insulin receptors are inactive.

Explain the presence of glucose in the urine of untreated diabetic patients.

Insulin is either not produced or the insulin receptors inactive, therefore the liver does not take up glucose from the blood. The blood sugar concentration remains high. In the kidney, all glucose is passed into renal filtrate through ultrafiltration. There is too much glucose to be processed by selective reabsorption in the proximal convoluted tubule, so some glucose continues through the nephron and is excreted in urine.

Define interstitial cells.

Interstitial cells are located outside the individual testis tissue, producing testosterone.

Outline early embryo development.

It goes... zygote-->2-->4-->8-->16-->32 cell blastocyst.

What does the posterior pituitary gland do, relating to the processes within the kidney?

It releases ADH.

State the role of LH in spermatogenesis.

LH stimulates testosterone production.

Outline the process of oogenesis.

Oogenesis occurs in the oviduct of the female reproductive system. It begins before birth, and ends in menopause. 1. Before birth, oogenia divide by mitosis to become primary oocytes, then nothing happens until puberty. 2. After puberty, one primary oocyte will mature during each cycle due to the stimulation of FSH. 3. The secondary oocyte, which is a gamete, is supported by the mature follicle until ovulation, which is triggered by LH on day 14 of a cycle. 4. Meiosis II does not complete until fertilization. 5. The empty follicle becomes the corpus luteum. 6. If fertilization does not occur, the corpus luteum becomes the corpus albicans. 7. If fertilization does occur, the corpus luteum begins to excrete progesterone.

Define osmoregulation.

Osmoregulation is the control of water balance of the blood, tissue, or cytoplasm of a living organism.

List three components of the blood which are not pushed into the glomerular filtrate and state the reason why.

Plasma proteins, platelets, and cells remain in the blood and are not pushed through the glomerular filtrate because they are too large.

State the function of the distal convoluted tubule.

Secretes toxins into urine.

State the function of the proximal convoluted tubule.

Site of selective reabsorption.