Bio 449 - Exam 3 Key

Biology 449 - Animal Physiology

Spring 2002

Midterm 3 Key

Multiple choice: As always, choose the best answer for each multiple-choice question. Answer on your scantron form. Each question (except #1) is worth 3 points.

Fill in your scantron form as follows: (1 point)
- Write in your name in the upper left (last name first) and bubble it in.
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- Sign your form in the upper right.
1. Done and done.
2. – e. I swear I studied my name, but all I can remember right now is it starts with an “m” (I think) so I can’t fill in this part.
Glycogen is an example of a(n)
1. simple carbohydrate.
2. triglyceride.
3. amino acid.
4. polypeptide.
Which of the following releases the mucus that lines the stomach?
1. Chief cells
2. Gastric cells
3. Parietal cells
4. Mucoid cells
Gastrin is most properly considered
1. an autocrine agent.
2. a paracrine agent.
3. a neurotransmitter.
4. an afferent pathway.
Which of the following is (are) not released by the pancreas?
1. Bicarbonate ions.
2. Proteases.
3. Lipases.
4. Amylase.
The breakdown of fats in the small intestine requires which of the following?
1. Amylase alone.
2. Bile salts and amylase.
3. Lipases alone.
4. Bile salts alone.
The liver is involved in all of the following processes except
1. the digestion of fats.
2. the storage of carbohydrates.
3. the conversion of carbohydrates into fats.
4. the deactivation of toxic compounds.
In humans, most energy is stored for later use in the form of
1. glucose.
2. glycogen.
3. proteins.
4. ATP.
Which of the following is not typical of the absorptive state?
1. Increased levels of blood glucose.
2. Increased levels of blood insulin.
3. Increased use of glucose by most cells.
4. Decreased levels of blood glucagon.
Urine leaving the collecting tubule would pass through the following structures in what order?
1. ureter, renal pelvis, urinary bladder, urethra
2. renal pelvis, urethra, urinary bladder, ureter
3. urethra, renal pelvis, urinary bladder, ureter
4. urethra, urinary bladder, renal pelvis, ureter
The approximate rate of glomerular filtration in all nephrons combined is about
1. 1000 ml/min
2. 10 ml/min
3. 1 ml/min
4. 0.1 ml/min
The reabsorption of water in the proximal tubule of the nephron occurs because
1. high hydrostatic pressure in the tubule forces water out.
2. ADH makes the tubule permeable to water.
3. urea has a relatively high concentration in the tubule.
4. the tubule passes through the hyperosmotic renal medulla.
If a person had a developmental anomaly that caused his nephrons to lack loops of Henle, which of the following would be most likely?
1. The person’s glomerular filtration rate would be increased.
2. The person would be unable to reabsorb glucose from the urine.
3. Aldosterone would have no effect in this person.
4. There would be increased counter-current multiplication.
The direct effect of renin is to
1. convert angiotensin I into angiotensin II.
2. promote the release of aldosterone.
3. promote the reabsorption of sodium.
4. promote vasoconstriction.
Atrial natriuretic factor
1. is released when blood pressure is high.
2. inhibits the effects of ADH.
3. inhibits the effects of aldosterone.
4. Two of the above.
Someone suffering an asthma attack (in which alveolar ventilation is restricted) would likely exhibit
1. respiratory alkalosis.
2. metabolic acidosis.
3. metabolic alkalosis.
4. Two of the above.
In the male fetus, the SRY gene product is directly responsible for
1. the regression of the Müllerian ducts.
2. the development of the Wolffian ducts.
3. the activation of Sertoli cells.
4. the activation of Leydig cells.
Testosterone and other androgens
1. are found only in men.
2. are found in equal concentrations in men and women.
3. are found in higher concentrations in women than men.
4. are found only in women.
In order for Sertoli cells to stimulate spermatogenesis in adult males, these cells must themselves be stimulated by
1. follicle stimulating hormone.
2. luteinizing hormone.
3. testosterone.
4. All of the above.
Reproductive structures that contribute material to the formation of semen include all of the following except the
1. testes.
2. seminal vesicle.
3. prostate gland.
4. All of the above contribute to the semen.
The arterioles that supply the erectile tissue of the penis are unusual in that
1. they are incapable of dilation or constriction.
2. they become constricted then the erectile tissue begins to fill with blood.
3. they are part of a portal system.
4. There are no arterioles supplying the erectile tissue.
During the early to mid follicular phase of the female reproductive cycle, the direct effect of inhibin is to
1. inhibit the release of luteinizing hormone.
2. inhibit ovulation.
3. inhibit endometrial proliferation.
4. inhibit uterine contractions.
The primary source of progesterone during the reproductive cycle of a non-pregnant female is (are) the
1. granulosa cells.
2. theca cells.
3. pituitary.
4. hypothalamus.
During the first three months of pregnancy, the mother’s blood shows
1. low levels of estrogen and progesterone.
2. high levels of estrogen and progesterone due to increased gonadotropin releasing hormone in the mother.
3. high levels of estrogen and progesterone levels due to release from the endometrium.
4. high levels of estrogen and progesterone levels due to release from the placenta.
Parturition results from strong contractions by the
1. oviducts.
2. cervix.
3. vagina.
4. mother’s hand crushing the father’s so he can appreciate the pain she’s in.
The production of milk is promoted by
1. estrogen.
2. progesterone.
3. gonadotropin releasing hormone.
4. oxytocin.

Short answer:Write a concise answer to each of the following questions. Your answers should fit in the spaces provided. Each question is worth 4 points.

If the release of secretin by the small intestine was blocked, what would be the effects on the contents of the intestine, and why?

If secretin was not released, there would be no feedback to slow down the rate of stomach emptying and its secretion of acid, and there would be no signal for the release of bicarbonate from the liver and pancreas. The result would be that the chyme moving into the small intestine would be highly acidic and would stay acidic. In addition, chyme would move into the SI at a greater than normal rate.

[Note that this is a speculative question and other reasonable answers will be considered.]
Describe the workings of the loop of Henle. You can use a diagram to supplement your explanation, but be sure to include a written explanation of what is occurring. You do not need to show or describe other regions of the nephron.

The loop of Henle is a counter-current multiplier responsible for creating and maintaining the concentration gradient in the renal medulla (which is important for the creation of a hyperosmotic urine). Once established, this gradient runs from about 300 mOsm in the interstitial fluid at the top of the loop to about 1400 mOsm in at the bottom. The descending loop is permeable to water but not solutes, and as urine moves down the loop water is lost by osmosis, concentrating the urine to about the level of the interstitial fluid. The ascending loop of Henle is impermeable to water but permeable to salt. As the urine moves up the tubule, salt is first lost by passive diffusion (thin ascending) then removed by active transport (thick ascending), so that the concentration of the urine drops again to about 100-300 mOsm at the top of the loop. It is the active transport of salt in the thick ascending limb that maintains the concentration gradient in the medulla.
Discuss the regulatory system involving antidiuretic hormone. Describe the factors that control ADH release, where it comes from, and what its effects are.

Decreased water in the body leads to decreased blood volume and increased blood osmolarity. Baroreceptors sense decreased volume because of the resulting decrease in blood pressure, while osmoreceptors in the hypothalamus sense the increased osmolarity. These factors trigger the release of ADH from the posterior pituitary. When the hormone reaches the collecting ducts in the kidney, it increases the permeability of the ducts to water so that more water is recovered from the urine due to osmotic effects.
In the lectures on blood pressure regulation, what were the two equations that described how blood pressure could be controlled over the short-term and the long-term?

Short term: BP = CO ´ R_(Total)Long term: BP µ Blood volume
During ascent to high altitude, the respiratory response in humans can include hyperventilation. If this hyperventilation were chronic (i.e. long lasting), what might you expect the renal response to be? Why?

Hyperventilation leads to reduced levels of CO₂ in the blood, which means that respiratory alkalosis would result (As CO₂ leaves the blood, H⁺ and HCO₃^- will recombine to form CO₂ and H₂O, reducing the H⁺ levels in the blood). The renal response to an alkalosis is to secrete bicarbonate ions (or conserve H⁺ ions), creating an alkaline urine. This helps return blood pH to normal.
Describe the uterine aspect of the female reproductive cycle. What happens to the uterus, when does it happen, and what hormones are triggering these events?

The uterine cycle involves the cyclic changes to the endometrial lining of the uterus. During about days 6-14 of the menstrual cycle, increasing estrogen levels promote the proliferation or growth of the endometrium. This is the proliferative phase. During days 15-28, the increase in progesterone causes the development of the secretory ability of the endometrium – this is therefore called the secretory phase. During days 1-5 of the cycle, the drop in estrogen and progesterone causes the endometrial layer to die back and much of the lining is sloughed off. (Bleeding from the uterus also occurs as part of this process.)