Question

How does the renin-angiotensinogen-aldosterone system (RAAS) respond in the case of an excessive loss of both salt and body fluids?

a. It activates the hormone atrial natriuretic peptide, which increases blood volume and pressure.

b. It responds to the drop in blood volume and pressure by increasing water and Na+ reabsorption.

c. It stimulates the production of ADH in the posterior pituitary, lowering blood Na+ concentration.

d. It inhibits the production of angiotensin converting enzyme (ACE), suppressing the production of angiotensin II.

A difference between class I MHC and class II MHC molecules is _____.

1. most body cells have class I and class II MHC molecules, but antigen-presenting cells have only class II
2. only class I MHC molecules are important for recognition of antigen-presenting cells
3. CD4 protein on helper T cells binds class II MHC molecules on the antigen-presenting cell
4. class II MHC molecules interfere with effector cell production
5. only class I MHC molecules are displayed on cell surfaces; class II MHC molecules are subcellular molecules

Answer 1

Q. 1. C. It stimulates production of ADH in posterior pituitary ,lowering blood Na+ concentration.

ADH ( anti diuretic hormone) lowers osmolarity or reduces sodium concentration by increasing water reabsorption in the kidney.

Also to maintain osmolarity from decreasing below normal, the kidney reabsorb sodium in the distal nephron.

Q. 2. C.  CD 4 protein on T helper cellbinds class II MHC molecules on the antigen-presenting cell

Class I present antigen to CD8