Question

1. Explain 2 ways that autoregulation within the kidneys could deal with a drop in GFR.

2. If the kidney receives lower than normal levels of oxygen via the renal artery,
explain why higher levels of EPO would be released into the blood.

Answer 1

Answer 1:

Autoregulation in kidney to manage drop in GFR is done in following two ways:

Low GFR activates Renin Angiotensin Aldosterone system (RAAS) due to which renin gets released from juxtaglomerular apparatus of kidney. Renin acts on angiotensinogen and converts it to angiotensin I. Then angiotensinogen converting enzyme (ACE) converts angiotensin I to angiotensin II. Angiotensin II then causes constriction of efferent arteriole of glomerulus thereby increasing GFR.

When there is decrease in GFR then there is less Na+ in the formed urine and most are reabsorbed before they reach macula densa this results in decreased ATP and adenosine which causes afferent arteriole of glomerulus to dilate and cause increase in GFR.

Answer 2:

When kidney receives less oxygen then it starts to secrete more erythropoietin (EPO) so that more red blood cells (RBCs) are produced. When more RBC are produced then more oxygen will be carried in the RBC and delivered to body tissues including kidney.