HBY 531 MEDICAL PHYSIOLOGY

Lecture Exam 3

2001

 

Section 1:  Answer the following using:

A = increase

B = not change
C = decrease

 

1.      The diameter of the ileocolonic sphincter will _________ as secretin plasma levels are elevated.

 

2.      The diameter of the sphincter of Oddi will _________ in response to elevated CCK plasma levels.

 

3.      During the gastric phase of acid secretion in the stomach the lumenal Na+ will _________.

 

4.      Chief cell secretion of pepsinogen will __________ as plasma levels of secretin are elevated.

 

5.      Following a 20% blood loss in an otherwise healthy 30 year-old individual, urinary calcium excretion will __________.

 

6.      Following a sudden increase in dietary phosphate, urinary phosphate excretion will __________.

 

7.      In the time period preceding any compensatory response, total plasma calcium will __________ following a sudden infusion of citrate (an anion).

 

8.      Compared to normal, calcium excretion will __________ following a treatment involving the diuretic furosemide.

 

9.      During the last trimester of pregnancy, 1a-hydroxylase activity within proximal tubule cells will __________.

 

10.  Following stimulation of PTH receptors on osteoblasts, the rate of bone resorption will __________.

 

11.  In the presence of a carbonic anhydrase inhibitor, the rate of bone resorption will __________.

 

12.  Following a disruption of the tight junctions forming the blood-testis barrier within seminiferous tubules, the glucose concentration in the interstitial fluids of adluminal compartments will __________.

 

13.  The number of GnRH receptors on pituitary gonadotropes will __________ following a prolonged (i.e., 24 hours) exposure to GnRH.

 

14.  FSH release from gonadotropes will __________ following exposure to activin.

 

15.  Blood flow through helicine arteries of the penis will __________ following stimulation of sympathetic nerves to these arterioles.

 

16.  As estrogen levels increase during the follicular phase of the ovary, the viscosity of cervical mucus will __________.

 

17.  Body temperature will __________ under the influence of progesterone.

 

18.  Androgen production within granulosa cells of the ovary will __________ following stimulation of LH receptors on their surface.

 

19.  Aromatase activity within granulosa cells of the ovary will__________ following stimulation of FSH receptors on their surface.

 

20.  Prolactin inhibiting hormone release will __________ as a result of a baby suckling a breast.

 

21.  Following menopause, gonadotropin levels will__________.

 

Section 2:  Answer the following using:

A = higher

B = the same

C = lower

 

The chest X-ray of a 60 year old female patient demonstrates a large (6 cm) lesion of the right upper lobe with mediastinal adenopathy. You suspect that she is suffering from an ACTH secreting carcinoma and from the effects of hypercortisolism.

(use this information for questions 22-24)

 

22.  When compared to a normal person, her 4PM ACTH level would be __________.

 

23.  Her blood ACTH levels would be __________ after a high dose dexamethasone (a potent glucocorticoid) suppression test.

 

24.  When compared to a normal person, her 8 AM cortisol level would be __________.

 

 

A female patient with a normal chest X-ray suffers from the effects of hypercortisolism. The presumptive diagnosis is that there is a dysfunction in her hypothalamic-pituitary axis (Cushing’s Disease).

(use this information for questions 25-27)

 

25.  When compared to a normal person, her 4PM ACTH level would be _________.

 

26.  Her blood ACTH level would be _________ after a low dose dexamethasone suppression test.

 

27.  Her blood ACTH level would be _________ after a high dose dexamethasone suppression test.

 

 

 

Metyrapone is a drug used to decrease cortisol secretion as it blocks the 11-beta hydroxylase step necessary for the synthesis of both cortisol and aldosterone.

(use this information for questions 28-29)

 

28.  The levels of in 11-Deoxycortisol (the precursor of cortisol) in a normal person will be _________ after taking Metyrapone.

 

29.  The late afternoon blood ACTH level in a normal person will be _________ after taking Metyrapone.

 

 

Section 3:  For each of the following, choose the single best response.

 

30.  Smooth muscle cells in the muscularis externa of the duodenum will:

a.            contract in the presence of VIP.

b.           contract in the presence of Substance P.

c.            contract in the presence of extracellular ATP.

d.           both b and c are correct.

 

31.  Secretin:

a.            stimulates the secretions of pancreatic acinar cells.

b.           causes smooth muscle cells in the fundic stomach to contract.

c.            causes smooth muscle cells in the colon to contract.

d.           causes smooth muscle cells of the gallbladder to contract.

 

32.  Receptive relaxation:

a.            is an example of a short reflex.

b.           occurs in the small intestine.

c.            will persist even if the vagus nerve is cut.

d.           none of the above is true.

 

33.  Which of the following is a feature of the gastroileal reflex?

a.            relaxation of the muscularis externa of the ileum

b.           It occurs only during fasting only.

c.            relaxation of the ileocolonic sphincter by gastrin or VIP

d.           It is triggered by distension of the colon.

 

34.  A key manifestation of the enterogastric inhibitory reflex is:

a.            that it is triggered by distension of the colon.

b.           that it is mediated by Auerbach’s plexuses only making it a short reflex.

c.            relaxation of the pyloric sphincter by gastrin.

d.           it is triggered by acid and hypertonic solutions entering the duodenum.

 

35.  Doubling the activity of the Na+/H+ exchanger, found on the lumenal surface salivary duct cells, would result in:

a.            lower levels of Na+ in saliva secreted at maximal flow rates.

b.           a more alkaline saliva.

c.            a more hypertonic saliva.

d.           an increase in the concentration of Cl- in the saliva.

 

36.  What is the fate of a chylomicron remnant?

a.            transcytosis into tissues from capillaries

b.           It is further acted on by endothelial lipoprotein lipase (LPL) to become an IDL.

c.            It is sequestered via endocytosis into hepatocytes.

d.           It is converted into VLDL by endothelial lipase.

 

37.  With regard to crypt cell secretion:

a.            if the apical Cl- channels are open, the Cl- equilibrium potential is –40 mV, and the resting potential is –40 mV; then the flux of Cl- between cell and lumen will be outward.

b.           if the apical Cl- channels are open, the Cl- equilibrium potential is –40 mV, and the resting potential is –60 mV; then the flux of Cl- between cell and lumen will be inward.

c.            if all the apical Cl- channels are closed, the Cl- equilibrium potential is          –40 mV, and the resting potential is –60 mV; then the net flux of Cl- between cell and lumen will be inward.

d.           none of the above are true.

 

38.  Inhibition of the enzyme enterokinase would result in:

a.            diarrhea.

b.           no change in carboxypeptidase A activity.

c.            an increase in phospholipase A activity.

d.           the inhibition of pancreatic amylase.

 

Inorganic content has been determined from fluid samples taken from your patient in the duodenum, jejunum, ileum and from fecal material and compared with normal. The data (mM) are shown in the following Table.

(use this information for questions 39-40)

 

Normal

                                    Na+                  K+        Cl-                    HCO3-

Duodenum                      60                  15          60                  15

Jejunum                        140                    6        100                  30

Ileum                            140                    8          60                  70

Feces                             40                  90          15                  30

 

Patient

                                    Na+                  K+        Cl-                    HCO3-

Duodenum                      95                    8          90                  15

Jejunum                        140                    6        100                  30

Ileum                            140                    8          90                  40

Feces                             40                  90          90                  10

 

39.  The elevated Na+ in the duodenum for the patient most likely results from:

a.            too much mucus being secreted by the columnar cells lining the stomach mucosa.

b.           lowered secretion of H+ by parietal cells.

c.            increased salivary secretions.

d.           increased activity of the H+/K+ pump.

 

40.  The elevated Cl- concentration in the ileum and fecal sample of the patient indicate that:

a.            Na+ absorption/resorption is dysfunctional.

b.           the apical Cl-/HCO3- exchanger on the columnar absorptive cells of the ileum and colon is dysfunctional.

c.            the basolateral Na+/HCO3- cotransporter on the columnar absorptive cells is dysfunctional.

d.           either b or c.

 

41.  Bile salts:

a.            are recycled at most once a day.

b.           are resorbed only by active transport.

c.            are synthesized by hepatocytes only.

d.           are lost in the feces at a rate of approximately 30% per day.

 

42.  A deficiency of ApoC-2 will result in:

a.            a decrease of VLDL plasma levels during the absorptive state.

b.           an increase in chylomicrons remnants during the absorptive state.

c.            an elevated chylomicron concentration during the absorptive state.

d.           an elevated LDL concentration during the absorptive state.


An individual has ingested 0.7L of fluid with a pH of 6.9 at the 1hour mark. You are monitoring stomach pH, stomach volume and small intestine volume.

(use this information for questions 43-46)

 

43.  The reduction in small intestine volume between hours 5 and 6 is most likely due to:

a.            reduced bile secretion

b.           the myenteric reflex.

c.            defecation.

d.           none of the above.

 

44.  The number of moles of H+ produced at the 2hour mark is:

a.            2 x 10-6 moles

b.           2 x 10-5 moles

c.            1 x 10-4 moles

d.           2.5 x 10-7 moles

 

45.  The volume of stomach secretions is:

a.            0.1 L

b.           1.3 L

c.            2.0 L

d.           0.5 L

 

46.  With regard to the small intestine volume vs. time relationship, which reflex is missing?

a.            gastro-gastric

b.           enterogastric inhibitory

c.            gastroileal

d.           myenteric

 

47.  During a complicated delivery, the mother experienced excessive blood loss and suffered from a significantly lowered blood pressure for at least one hour. Even though she has not been nursing her child, she reports that three months post partum she had not begun her previously normal menstrual cycles and that she feels fatigued and cold all the time. Which of the following is likely to be noted on laboratory examination of this patient?

a.            A normal rise in the levels of ACTH after a standard Metyrapone test which markedly decreases the production of cortisol.

b.           A normal circadian rhythm for ACTH and cortisol.

c.            An increase in circulating levels of TSH.

d.           A decrease in circulating levels of TSH after a TRH stimulation test.

e.            A high level of blood cortisol at 8 AM.

 

48.  Which of the following is true regarding thyroid hormone regulation?

a.            MIT and DIT (mono and diiodotyrosines) released by the thyroid gland are activated by enzymes in the liver.

b.           T4 binds to TSH receptors on the plasma membranes of liver cells to directly induce the synthesis of malic enzyme.

c.            T4 is converted to rT4 (reverse T4) by brain cells to provide for normal functioning of these cells, particularly during starvation.

d.           In hypothyroidism, frequently an auto antibody mimics the action of TSH on the thyroid gland to increase the synthesis, storage and release of T4.

e.            During starvation brain cells increase the production of T3 from T4 by an increase in the activity of a specific deiodinase.

 

49.  In a patient with hyperthyroidism, which of the following would be expected?

a.            An increased systolic pressure with a relatively low diastolic pressure.

b.           A warm wet skin with a dislike for warm temperatures.

c.            An increase in the basal metabolic rate.

d.           An increase in circulating T4 levels.

e.            all of the above

 

50.  A patient suffers from Addison’s Disease which is caused by the auto immune mediated destruction of the adrenal cortex. In this patient you would expect:

a.            a lower level of serum Na+ and a higher level of serum K+ than normal.

b.           very low levels of epinephrine in the blood.

c.            a lower blood level of ACTH and TSH.

d.           a decrease in the pigmentation of the mucous membranes and skin.

e.            hypotension and hyperglycemia.

 

51.  A patient is treated for three months with pharmacologic doses of dexamethasone.  In this patient you would expect:

a.            blood ACTH levels to be high in the 8 AM blood sample.

b.           blood cortisol levels to be high throughout the 24 hour period.

c.            aldosterone levels to be higher than normal.

d.           blood TSH levels to be high throughout the 24 hour period.

e.            the patient to demonstrate glucose intolerance to an oral glucose load.

 

52.  All hormones act as allosteric effectors. As such they are involved in regulating processes related to:

a.            production, use and storage of metabolic energy.

b.           reproduction of the species.

c.            maintenance of the internal milieu (homeostasis).

d.           differentiation, growth and development of the organism.

e.            All of the above.

 

53.  In a patient with a deficiency of the 21-hydroxylase enzyme during embryogenesis or early childhood you would expect:

(Reminder: 21-hydroxylase converts progesterone to 11-deoxycorticosterone (DOC) and 17-OH-progesterone to 11-deoxycortisol, controlling the production of cortisol and aldosterone.)

a.            higher than normal levels of Na+ and lower than normal levels of K+ in the blood.

b.           hyperplasia of the zona fasciculata and zona reticularis of the adrenal cortex.

c.            abnormal genital development in the male fetus during embryogenesis.

d.           higher than normal levels of cortisol at 8 AM.

e.            hypotension often leading to syncope (fainting spells).

 

54.  Many hormones bind to blood proteins. Which of the following is a purpose and/or consequence of this binding?

a.            Binding of the hormone to protein makes it more readily accessible to the interior of the target cell as there are specific plasma membrane transporters for the hormone protein complex.

b.           Binding of the hormone to protein makes it more easily filtered, and then reabsorbed in the kidney, limiting its excretion in the urine.

c.            Binding of the hormone to protein makes unnecessary to measure “free hormone” in the blood.

d.           Binding of hormone to protein in the blood, in some cases, provides a large reservoir of hormone and as such can serve to buffer acute changes in total hormone levels.

e.            During pregnancy there is an increase in thyroid hormone binding globulin, which decreases the total level of circulating T4.

 

55.  The following is NOT an effect of growth hormone?

a.            Fat cells are rendered more sensitive to epinephrine.

b.           During starvation it increases muscle’s uptake of glucose for a given concentration of insulin.

c.            It increases the production of somatomedins (IGF1 and IGF2).

d.           It facilitates the growth of long bones in children.

e.            After ingestion of protein, it promotes the synthesis of muscle.

 

56.  Which of the following stimulates release of a hormone from the anterior pituitary?

a.            hyperosmolality

b.           suckling during lactation

c.            IGF1 and IGF2

d.           elevated T4 levels

e.            somatostatin

 

57.  Sequencing of a patient’s insulin gene revealed a substitution of both lys-62 and arg-63 into alanine.  Which of the following statements would BEST describe the consequences of these mutations?

a.            The circulating connecting C-peptide to insulin ratio would remain high after a meal.

b.           Exocytosis of granules from the pancreatic b-cells in response to glucose would be decreased.

c.            The patient would require periodic insulin injections to properly regulate blood glucose levels.

d.           The glucose tolerance curve would be normal to slightly elevated, since there is only a small change in the biological activity of the insulin.

 

58.  In humans, the adaptation to fasting requires:

a.            the proper secretion of insulin in response to increased circulating amino acids.

b.