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.

1.      Fill in your scantron form as follows:  (1 point)

a.      This time I really did everything exactly as indicated.

2.      Which of the following is a different type of compound than the others?

e.      Peptides

3.      Enzymes are involved in which of the following processes?

b.      Digestion

4.      The movement of nutrients out of the gut and into the blood is

d.      absorption.

5.      Saliva is involved in

b.   the digestion of foods.

and

c.   the lubrication of food particles.

so the correct answer is

d.      Two of the above.

6.      The parietal cells of the stomach release

a.      hydrochloric acid

7.      Which of the following is not a response to secretin release?

e.      Increased release of bile salts from the liver.

8.      Which of the following is not true concerning the pancreas?

c.   It responds to gastrin release.

9.      The absorption of glucose in the small intestine involves

a.      cotransport of glucose with sodium ions.

10.  The primary reason fats in consumed foods must be converted into fatty acids is to allow them

c.   to diffuse through the apical membrane of the gut epithelium.

11.  The main function of the large intestine is

d.      water recovery.

12.  The urge to defecate results from

c.   the mass movement of material in the large intestine.

13.  Which class of absorbed foods does not pass directly through the hepatic portal system?

c.      Fats

14.  Which of the following types of tissue cannot utilize fats as an energy source?

a.      Neural tissue

15.  A person who secreted excess insulin but was otherwise normal would most likely exhibit

d.      lower than normal blood glucose levels.

16.  Most nitrogenous waste in mammals exists in the form of

d.      urea.

17.  The movement of fluid out of the glomerulus and into the Bowman’s capsule of the nephron is driven by

c.      hydrostatic pressure.

18.  About what fraction of the water than enters the nephron is eventually reabsorbed?

e.      99%

19.  Which region of the nephron is always impermeable to water?

c.      Ascending thick limb of the loop of Henle

20.  The most important function of the loop of Henle is

a.      creation of a strong osmotic gradient in the medulla.

21.  Angiotensin II helps maintain correct blood pressure by directly affecting

d.      vasoconstriction.

22.  Which type of receptors are most directly involved with the regulation of blood pressure?

c.      Baroreceptors

23.  A decrease in blood pH due to the production of large amounts of lactic acid would be considered an example of

c.      metabolic acidosis.

24.  The basal metabolic rate for a typical adult woman would be roughly

d.      1500 kcal/day

25.  Which of the following statements is true?  Relative to a cat, a mouse will have

b.   a lower metabolic rate but a higher mass-specific metabolic rate.

26.  A disadvantage to anaerobic metabolism is that

d.   it produces an acidic end product.

27.  If a person increases her activity level until she reaches her maximal oxygen consumption

e.      None of the above.

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

28.  List two stimuli and one effect of gastrin release.

Stimuli:  Distention, peptides

Effect:  Acid release; pepsinogen/pepsin release

29.  For each tissue type below, list one response to high insulin levels.

[Those mentioned in lecture are given here, others are possible]

Liver:  Converts glucose to glycogen; converts glucose to fat

Adipose tissue (fat cells):  Glucose converted to fats

Muscle:  Burns glucose as fuel

30.  A substance called “fifaceen” binds to the same receptors as the hormone known as ADH, preventing the ADH from binding to these receptors.  What effects would fifaceen be expected to have on urine formation?

If ADH cannot bind to receptors in the collecting ducts, no additional water can be recovered during this stage of urine formation.  The result would be the formation of large volumes of very dilute urine.

31.  Using a flow chart or a list of events, describe the hormonal pathway involved in the release of aldosterone.  Be sure to indicate (when appropriate) what triggers the release of each compound in the pathway, and what each compound’s effects are.

• Decreased blood pressure causes the kidneys to release increased amounts of renin.
• Renin converts angiotensinogen (constantly secreted by the liver) into angiotensin I.
• Enzymes in the lungs convert angiotensin I into angiotensin II.
• Angiotensin II causes the adrenal cortex to release aldosterone.  Angiotensin II also causes vasoconstriction, which helps increase BP.
• Aldosterone causes increased sodium uptake by the kidney, primarily in the distal tubule.
• Increased sodium levels in the blood help increase blood volume, which increases BP.

32.  What are the two primary components of the intersitial fluid of the renal medulla?  (Note – compounds dissociated into two ions count as one component, not two.)

Sodium chloride and urea

33.  What would be the likely respiratory response to a long-term bout of vomiting?  Why?

A long-term bout of vomiting would represent a major loss of H⁺ from the body, resulting in a metabolic alkalosis.  The respiratory response to an alkalosis is a decrease in respiration, so that increasing CO₂ levels in the blood help increase H⁺ levels again.

34.  Give an example of a buffering system in mammals, and briefly describe what a buffering system does.

The most important buffering system is the CO₂ – bicarbonate system:

      CO₂ + H₂O <---> H₂CO₃ <---> H⁺ + HCO₃^-

A buffering system tends to resist changes in pH (H⁺ concentration) by “storing” H⁺ ions when they are present in excess, and releasing them when they are in deficit.