10. Endocrine Sytem

Question 1

1. Which statement below about hormones is true?
   A. Hormones are enzymes that catalyse reactions.
   B. Hormones are released into the blood circulation.
   C. Hormones affect all cells of the body.
   D. Hormones are released by neurones at synapses.

Answer 1

Answer is B: Hormones are circulating messengers that are transported in blood. A particular hormone does not necessarily affect every cell in the body. Some (but not all) hormones are released by neurones, for example, in the hypothalamus.

Question 2

2. Which hormones are soluble in blood?
   A. Steroid hormones
   B. Hormones produced by the adrenal cortex
   C. The sex hormones
   D. Those released by the pituitary gland

Answer 2

Answer is D: The pituitary gland releases peptide hormones which are soluble in blood. The other choices refer to steroid hormones which are insoluble in blood. They require transport via plasma proteins.

Question 3

3. Which statement about the hypothalamus is correct?
   A. The hypothalamus is connected to the brain by the infundibulum.
   B. The hypothalamus is composed of glandular epithelial tissue.
   C. The hypothalamus secretes “releasing hormones”.
   D. The hypothalamus secretes epinephrine and norepinephrine.

Answer 3

Answer is C: The hypothalamus is part of the brain so is composed of neural tissue. Epinephrine and norepinephrine are released from the adrenal medulla.

Question 4

4. What hormone does the thyroid produce?
   A. Thyroid-stimulating hormone
   B. Calcitriol
   C. Thyroxine
   D. Parathyroid hormone

Answer 4

Answer is C: Thyroxine (or tetraiodothyronine) is converted to triiodothyronine in target tissues.

Question 5

5. What hormone(s) does the adrenal medulla produce?
   A. Aldosterone
   B. Epinephrine and norepinephrine
   C. Corticosteroids
   D. Glucocorticoids

Answer 5

Answer is B: Epinephrine and norepinephrine are produced in the adrenal medulla (the deep or inside part). Aldosterone is a mineralocorticoid, which like corticosteroids and glucocorticoids, as the “cortico” in the name suggests, are all produced in the adrenal cortex.

Question 6

6. What is produced by the beta cells of the pancreas?
   A. Angiotensin-converting enzyme
   B. Glucocorticoids
   C. Glucagon
   D. Insulin

Answer 6

Answer is D: Beta cells of the pancreatic islets produce insulin. The alpha cells produce glucagon.

Question 7

7. Which gland or organ releases erythropoietin?
   A. The kidneys
   B. The adrenal glands
   C. The anterior pituitary D. The pancreas

Answer 7

Answer is A: Kidneys produce erythropoietin (EPO) – which signals the red bone marrow to increase production of RBC.

Question 8

8. What effect does parathyroid hormone have?
   A. It increases plasma Ca2+ concentration.
   B. It decreases plasma Ca2+ concentration.
   C. It increases the rate of ATP formation.
   D. It stimulates the thyroid gland to produce thyroxine.

Answer 8

Answer is A: PTH increases plasma Ca2+ (calcitonin aids in lowering blood calcium).

Question 9

9. Which one of the following is NOT part of the endocrine system?
   A. The islets of Langerhans (pancreatic islets)
   B. The thyroid gland
   C. The acini cells of the pancreas
   D. The parathyroid glands

Answer 9

Answer is C: The acini cells produce digestive enzymes.

Question 10

10. What is the difference between an exocrine gland and an endocrine gland?
    A. An endocrine gland secretes neurotransmitters (an exocrine gland does not).
    B. An endocrine gland secretes via a tube to the destination (an exocrine gland does not).
    C. An exocrine gland secretes into the blood (an endocrine gland does not).
    D. An endocrine gland secretes into the blood (an exocrine gland does not).

Answer 10

Answer is D: Endocrine glands secrete “circulating” hormones, that is, secrete into the blood.

Question 11

11. By what term are hormones derived from tyrosine also known?
    A. Amino acid derivatives B. Peptide hormones
    C. Steroid hormones
    D. Corticosteroids

Answer 11

Answer is A: Catecholamines (adrenaline, noradrenaline), dopamine and thyroid hormone are all derived from tyrosine.

Question 12

12. Which hormones have their receptors inside their target cell?
    A. Amino acid-based hormones
    B. Hormones with a membrane carrier mechanism or that are lipid soluble
    C. Steroid hormones and peptide hormones of less than 50 amino acids
    D. Lipid-soluble hormones

Answer 12

Answer is B: Choice D is also correct, but B is the better answer as thyroid hormones cross membrane by a carrier mechanism.

Question 13

13. Where in the body is the hypothalamus located?
    A. On the inferior surface of the brain
    B. In the cortex of the adrenal gland
    C. In the anterior pituitary gland
    D. On the dorsal surface of the thyroid gland

Answer 13

Answer is A: The hypothalamus is below the thalamus, more or less on the “floor” of the brain, but above the pituitary gland.

Question 14

14. From where are antidiuretic hormone and oxytocin released?
    A. The anterior pituitary B. The posterior pituitary C. The adrenal cortex
    D. The adrenal medulla

Answer 14

Answer is B: ADH and OT are produced in the hypothalamus and transported to the posterior pituitary.

Question 15

15. Which hormone has the element iodine as part of its molecule?
    A. Calcitonin
    B. Haemoglobin
    C. Thyroxine
    D. Parathyroid hormone

Answer 15

Answer is C: Thyroxine or thyroid hormone contains iodine.

Question 16

16. What effect does aldosterone have?
    A. It causes glucose to be absorbed from the blood.
    B. It cause Na+ to be absorbed in the kidneys.
    C. It causes Ca++ to be absorbed from the gut.
    D. It causes K+ to be absorbed from the filtrate.

Answer 16

Answer is B: Aldosterone cases reclamation of sodium ions from the filtrate and potassium to be secreted in exchange.

Question 17

17. Which of the following is a part of the endocrine system?
    A. The thalamus
    B. The pancreatic islets (islets of Langerhans)
    C. The renal glands
    D. The salivary glands

Answer 17

Answer is B: The pancreatic islets secrete the hormones insulin and glucagon.

Question 18

18. Which of the following is an amino acid derivative hormone?
    A. Epinephrine
    B. Tyrosine
    C. Testosterone
    D. Prostaglandin

Answer 18

Answer is A: Epinephrine is derived from the amino acid tyrosine (so tyrosine is a wrong answer).

Question 19

19. Which statement below is true of steroid hormones?
    A. They do not have a specific receptor to bind with.
    B. They are not lipid soluble to bind to receptor proteins on the cell
    membrane.
    C. They are lipid soluble so diffuse through the cell membrane.
    D. They cross the cell membrane via a carrier mechanism.

Answer 19

Answer is C: Steroids are lipid soluble so diffuse through the plasma membrane to bind to a receptor within the cell.

Question 20

20. Which structure controls the endocrine system and integrates the activities of the nervous and endocrine systems?
    A. The infundibulum
    B. The pituitary gland
    C. The thalamus
    D. The hypothalamus

Answer 20

Answer is D: Hypothalamus secretes regulatory hormones that control endocrine cells in the ant pit gland, produces ADH and oxytocin and contains “autonomic centres” that exert neural control over endocrine cells of the adrenal medullae.

Question 21

21. One of the statements below is true. Which one?
    A. The anterior pituitary produces testosterone from cholesterol and releases it when releasing hormones arrive from the hypothalamus.
    B. The hypothalamus produces ADH and oxytocin which are stored in the pos- terior pituitary.
    C. The posterior pituitary contains autonomic centres that exert neural control over the adrenal glands.
    D. The thalamus produces ADH and oxytocin which are stored in the anterior pituitary.

Answer 21

Answer is B: Testosterone is not produced in the pituitary nor does the pituitary contain autonomic centres.

Question 22

22. Iodine is an essential component of which hormone?
    A. Thyroid hormones
    B. Aldosterone
    C. Thyroid-stimulating hormones
    D. Parathyroid hormone

Answer 22

Answer is A: Thyroid hormones T3 and T4 contain three and four iodine atoms, respectively.

Question 23

23. Which hormone(s) increases the reabsorption of Ca++ from the filtrate in the kidney tubule?
    A. Calcitonin
    B. Mineralocorticoids
    C. Parathyroid hormone D. Aldosterone

Answer 23

Answer is C: PTH causes increased calcium absorption and hence increases blood calcium level.

Question 24

24. What effect does aldosterone have? It causes:
    A. Angiotensin to be formed from angiotensinogen
    B. Na+ to be absorbed from the filtrate
    C. Na+ and Ca++ to be absorbed from the filtrate and K+ to be secreted into
    the filtrate
    D. Na+ to be absorbed from the filtrate and K+ to be secreted into the filtrate

Answer 24

Answer is D: Aldosterone promotes the absorption of sodium from the filtrate, while potassium (also a positively charged ion) is secreted to maintain electrical neutrality.

Question 25

25. Which of the following is NOT part of the endocrine system? A. The thymus B. The pineal gland C. The acini cells of the pancreas D. The posterior pituitary gland

Answer 25

Answer is C: The acini cells produce digestive enzymes.

Question 26

26. Peptide hormones are produced (and/or released) by which structure? A. The adrenal cortex B. The gonads C. The hypothalamus D. The kidneys

Answer 26

Answer is C: The hypothalamus produces peptide hormones.

Question 27

27. Which statement applies to steroid hormones? A. They are transported dissolved in blood. B. They bind to receptor proteins on the outside of the plasma membrane. C. They cross the plasma membrane by using a protein carrier mechanism. D. They bind to receptors in the cell cytoplasm or nucleus.

Answer 27

Answer is D: As steroid hormones are lipid soluble, their receptors are inside the cell as they can cross the plasma membrane.

Question 28

28. Which endocrine organ produces “releasing hormones” and “inhibitory hormones”? A. Thyroid B. Anterior pituitary C. Hypothalamus D. Thalamus

Answer 28

Answer is C: The hypothalamus controls the secretion of the anterior pituitary by the use of “releasing hormones” and “inhibitory hormones”.

Question 29

29. What hormone is produced by the parafollicular cells of the thyroid gland? A. Parathyroid hormone B. Calcitonin C. Thyroid hormone D. Thyroxine

Answer 29

Answer is B: Parafollicular (or “C”) cells of the thyroid produce calcitonin which aids in lowering of blood calcium.

Question 30

30. What hormones are produced by the adrenal medulla? A. Epinephrine and norepinephrine B. Insulin and glucagon C. Aldosterone and erythropoietin D. Testosterone and estrogen

Answer 30

Answer is A: The medulla is the deeper part of the adrenal gland.

Question 31

31. What is one mechanism of hormone action? A. They act as second messengers in the cytoplasm. B. They act as enzymes for reactions. C. They act as receptor proteins. D. They activate genes in the nucleus.

Answer 31

Answer is D: Some hormones (corticosteroids) determine which genes are transcribed in the nucleus.

Question 32

32. What is the effect of ADH (antidiuretic hormone)? A. Allows walls of collecting duct to become permeable to water. B. Inhibits the reabsorption of Na+. C. Causes an increase in the volume of urine produced. D. It promotes diuresis.

Answer 32

Answer is A: ADH causes more aquaporins to be inserted into the collecting duct walls which allow water molecules to pass through along the osmotic gradient.

Question 33

33. Which one of the following is NOT true of peptide hormones? A. They are water soluble. B. They are derived from amino acids. C. Their receptors are located in the cell cytoplasm. D. They are transported dissolved in blood.

Answer 33

Answer is C: The receptors for peptide hormones are located on the plasma membrane as they are unable to penetrate the plasma membrane.

Question 34

34. Which hormones are produced by the adrenal medulla? A. Gonadocorticoids B. Steroid hormones C. Mineralocorticoids D. Catecholamines

Answer 34

Answer is B: Steroid hormones are lipid soluble so can enter the cell to bind to receptors located inside the cell. Amino acid-based hormones are not lipid soluble so their receptors are located outside the cell on the plasma membrane.