Renal System

Aldosterone stimulates the active absorption of sodium (and the secretion of potassium) from the filtrate.

Filtration which is driven by the hydrostatic pressure difference between blood (at high pressure) in the glomerular capillaries and the filtrate (at lower pressure) in the Bowman’s capsule.

Efferent arteriole leaves the glomerulus and enters the peritubular capillaries.

The majority of reabsorption occurs in the proximal convoluted tubule which is before the loop of Henle.

Angiotensinogen II causes choices A, B and C to happen. While aldosterone does cause Na+ to be reabsorbed from the filtrate and if ADH is present to promote the insertion of aquaporins into the tubule cell plasma membranes, water will be absorbed from the filtrate. But this is not a direct result, so “D” is the best choice of answer.

PCT is permeable to urea, so as volume of filtrate in PCT decreases due to absorption of water, urea concentration in filtrate increases. This promotes passive reabsorption of urea along its concentration gradient.

Renin catalyses the formation of angiotensin I from angiotensinogen. ACE then converts angiotensin I to angiotensin II. Aldosterone is released from the adrenal cortex due to angiotensin II. Angiotensin II also promotes systemic vasoconstriction (not just in efferent arteriole).

The ascending limb is impermeable to water. ADH and ANP have no effect on the loop of Henle.

The PCT absorbs the bulk of the water and solutes.

Carina is in the trachea; renal pelvis refers to the ureter; reno-atrio notch does not exist.