Question

1.

Which of the following is TRUE about the functions of atrial natriuretic peptide (ANP)? There may be more than one answer.

Select one or more:

a. ANP increases the glomerular filtration rate by binding at the afferent arteriole to cause the walls to vasoconstrict.

b. ANP binds at the posterior pituitary gland to suppress the secretion of ADH into the blood.

c. ANP binds at the adrenal cortex to suppress the secretion of aldosterone.

d. ANP binds at the distal convoluted tubule and collecting duct to suppress the Na⁺ reabsorption.

e. ANP binds at the juxtaglomerular apparatus to suppress the secretion of renin.

f. All of the above

2.

Which of the following is TRUE about the signal transduction for diacylglycerol (DAG) and inositol triphosphate (IP₃)?  

Select one:

a. Epinephrine and norepinephrine are first messengers that bind to Alpha 1 receptors to activate protein kinase C at the cell membrane.

b. Phospholipase C, an amplifier enzyme, converts membrane phospholipid into two second messengers, diacylglycerol and inositol triphosphate.

c. Inositol triphosphate remains in the cell membrane and activates protein kinase C, which phosphorylate other proteins for cellular response.

d. Diacylglycerol diffuses from the cell membrane into the cytoplasm to activate the sarcoplasmic reticulum to secrete calcium into the cytosol for cellular response.

3.

Which of the following statements associated with the Renin-Angiotensin-Aldosterone System (RAAS) is TRUE?

Select one:

a. The granular cells of the afferent arteriole in the juxtaglomerular apparatus secrete renin, an enzyme, when the afferent arteriole detects a lower blood pressure.

b. The liver cells would secrete angiotensinogen which is converted by the renin into angiotensin I.

c. Angiotensin I is converted into angiotensin II by the angiotensin converting enzyme (ACE) which is an enzyme secreted by the lungs.

d. Angiotensin II can cause arteriolar vasoconstriction and stimulate the adrenal cortex to secrete aldosterone.

e. Aldosterone binds at the principal cells of the distal convoluted tubule and the collecting duct to promote the production of Na⁺ channels and the opening of Na⁺ channels in order to increase the Na⁺ reabsorption which will increase the plasma osmolarity, blood pressure, and blood volume while it will decrease the urine flow rate.

f. All of the above

g. None of the above

Answer 1

1. The true statements are the following :

b. ANP binds at the posterior pituitary gland to suppress the secretion of ADH into the blood

c. ANP binds at the adrenal cortex to suppress the secretion of aldosterone

d. ANP binds at the distal convoluted tubule and collecting duct to suppress the Na⁺ reabsorption

e. ANP binds at the juxtaglomerular apparatus to suppress the secretion of renin

• ANP increases the glomerular filtration rate by binding at the afferent arteriole to cause the walls to vasodilate.
• ANP receptors are present in posterior pituitary and they modulate the release of ADH from posterior pituitary.
• ANP inhibits aldosterone secretion by adrenal cortex by interfering with appropriate changes in calcium flux and cell calcium concentration.
• ANP reduces sodium reabsorption by DCT and CD by inhibiting cyclic nucleotide-gated cation channels and epithelial sodium channels.
• ANP inhibits renin release from JG cells by cGMP-dependent process