8. Which of the following statements about vasopressin and oxytocin is NOT CORRECT?

a. The active forms of vasopressin and oxytocin are 9 amino acid peptides that contain a disulfide bond.

b. Vasopressin is a key hormone involved in the control of whole body water balance.

c. An increase in blood volume stimulates vasopressin secretion.

d. Vasopressin binds receptors in the kidney that inhibits loss of water in the urine.

e. Oxytocin is a key hormone in female physiology. Oxytocin binds receptors in smooth muscle in the uterus and myoepithelial cells in the mammary gland. In each case, oxytocin binding to membrane receptors stimulates cell contraction.

c. An increase in blood volume stimulates vasopressin secretion.

9. The most abundant chemical in the body (as a % of body weight) is:

a. Water

b. Calcium

c. Fat

d. Protein

e. Carbohydrate

a. Water

10. Which of the following statements about the anterior pituitary is NOT CORRECT?

a. Neurosecretory cells with axonal termini ending at the level of the median eminence secrete protein, peptide or catecholamine hormones that enter the local pituitary circulation. These hypothalamic hormones control the secretion of anterior pituitary hormones.

12. Which of the following steps IS NOT involved in the synthesis and secretion of thyroid hormones, T4 and T3?

a. Dietary iodine is required for T4 and T3 synthesis.

b. Iodide (I-) is covalently attached to tyrosines in thyroglobulin by a peroxidase at the apical surface of thyroid follicular cells.

c. Iodinated tyrosines within the thyroglobulin protein are coupled together to form iodothyronines.

d. Iodinated thyroglobulin is secreted into the blood. The thyroid hormones (T4 and T3) are released from thyroglobulin by blood proteases.

e. Iodinated thyroglobulin is stored in the colloid. Secretion of thyroid hormones (T4 and T3) requires thyroglobulin to be taken up by the thyroid follicular cell (endocytosis) and degraded by lysosomal proteases. T4 and T3 are secreted into the blood.

d. Iodinated thyroglobulin is secreted into the blood. The thyroid hormones (T4 and T3) are released from thyroglobulin by blood proteases.

13. Which of the following BEST describes the regulation of calcium (Ca+2) absorption by the intestine.

a. Dietary Ca+2 in the intestinal lumen is transported into intestinal mucosa cells through a Ca+2 channel.

b. Intracellular Ca+2 binds calbindin and is transported into the interstitial space and blood by a Ca+2-ATPase (a pump).

c. 1,25 (OH)2-Vitamin D3 will bind receptors in nuclei of intestinal mucosal cells and stimulate the transcription of genes encoding calbindin and Ca+2-ATPase.

b. Glucocorticoids, mineralocorticoids and androgens are synthesized in the adrenal cortex; cholesterol is the precursor for steroid synthesis.

c. Catacholamines are synthesized in the adrenal cortex; serine is the precursor for catecholamine synthesis.

d. Adrenal hormones coordinate the body’s response to stress.

e. Glucocorticoids dampen the immune system.

c. Catacholamines are synthesized in the adrenal cortex; serine is the precursor for catecholamine synthesis.

15. The endocrine system plays a role in which of the following physiological processes:

a. growth and development

b. reproduction

c. energy metabolism, utilization and storage

d. maintenance of the internal environment

e. all of the above are correct

e. all of the above are correct

16. Thyroid hormone plays a major role in whole body metabolism. Which of the following statements about thyroid hormone is NOT CORRECT?
a. Hashimoto’s disease is an autoimmune disease. Patients with Hashimoto’s disease are hyperthyroid with elevated blood T3 levels.

b. T3 is the active form of the hormone. T3 binds nuclear receptors and regulates gene expression leading to changes in protein abundance and cell function.

c. T3 and T4 are hydrophobic hormones that are transported in the circulation in association with binding proteins like thyroxine binding globulin.

d. T3 regulates the basal metabolic rate, (BMR). T3 effects on BMR include control of fat and carbohydrate oxidation which impacts oxygen consumption and respiration, as well as cardiac output.

e. T3 is a feedback regulator of thyroid function by inhibiting the secretion of TRH from the hypothalamus and TSH from the anterior pituitary.

b. Phenylethanolamine-N-methyl transferase is the rate limiting enzyme in the pathway for synthesis of epinephrine.

19. A patient is fasted from 8 PM in the evening to 8 AM (post-absorptive phase) the next morning. The patient consumes no caloric food or beverage during this time. Which statement about whole body metabolism is NOT CORRECT?

a. So long as blood glucose is sufficient, the brain uses glucose at a rate of 6 grams/hour regardless of the time of day.

b. At 8 AM, blood levels of insulin will be elevated, while blood levels of glucagon, epinephrine and cortisol will be suppressed.

c. At 8 AM, glucagon and epinephrine stimulate glucose production by increasing glycogen breakdown and gluconeogenesis in the liver.

d. At 8 AM, cortisol stimulates skeletal muscle protein breakdown; the amino acids are used as substrates for gluconeogenesis.

e. At 8 AM, epinephrine and cortisol stimulate lipolysis (triglyceride breakdown) in adipose tissue to release fatty acids. Fatty acids are used as a fuel source for muscle and other tissues.

b. At 8 AM, blood levels of insulin will be elevated, while blood levels of glucagon, epinephrine and cortisol will be suppressed.

20. Thyroid stimulating hormone (TSH) plays an important role in controlling blood levels of thyroid hormone. Which of the following statements about TSH is NOT CORRECT?

a TSH stimulates the conversion of T4 to T3 by deiodinases in non-thyroidal tissues, like the liver.

b. TSH stimulates all facets of T4 and T3 synthesis and secretion from thyroid follicular cells.

d. TSH secreted from anterior pituitary thyrotrophs is stimulated by TRH and inhibited by T3 and somatostatin.

e. TSH levels decrease in Graves disease.

a TSH stimulates the conversion of T4 to T3 by deiodinases in non-thyroidal tissues, like the liver.

21. Body mass is related to energy balance. We are in balance (constant body weight) when energy input (calories consumed as protein, carbohydrate and fat) equals energy output (all biochemical reactions in the body).
Which of the following statements about metabolism and appetite control is NOT CORRECT?

a. The 3 macronutrients are carbohydrate, protein and fat. Fat contains the most energy (9.4 kcal/g).

c. Appetite is controlled by the ventromedial nucleus of the hypothalamus.

d. Leptin is a hormone secreted from the liver that stimulates appetite.

e. Obesity is associated with positive energy balance. At least 30% of the US population is obese, i.e., BMI > 30.

d. Leptin is a hormone secreted from the liver that stimulates appetite.

22. Glucose regulates insulin secretion form pancreatic beta-cells. Which of the following statements about the glucose-sensing mechanism regulating insulin secretion from pancreatic beta-cells is NOT CORRECT?

a. Glucose is transported into pancreatic beta-cells through a glucose transporter, GLUT4.

c. Increased skeletal growth is associated with increased bone mass and length, widening of the epiphyseal plates where osteoblast activity predominates over osteoclast activity, as well as elevated blood levels of growth hormone and IGF-1.

d. Steroids are important for growth. Cholesterol is a precursor for all steroids. The diet is the only source of cholesterol for steroid synthesis.

e. Insufficient dietary iodine will lead to goiter formation, hypothyroidism and impaired growth and development.

d. Steroids are important for growth. Cholesterol is a precursor for all steroids. The diet is the only source of cholesterol for steroid synthesis.