Renal Physiology

Question 1

What are the four components of the MDRD equation for calculating eGFR?

Answer 1

Age
Gender
Ethnicity
Creatinine levels

Question 2

Each kidney contains how many nephrons?

Answer 2

One million

Question 3

Where is renin secreted from?

Answer 3

Juxtaglomerular cells of the afferent arteriole

Question 4

Where is angiotensinogen secreted from?

Answer 4

Liver

Question 5

What is the function of the thin descending limb?

Answer 5

Water absorption only

Question 6

What is the function of the macula densa cells?

Answer 6

Part of the DCT
Detect elevated sodium levels in the tubule
Act by vasoconstriction of the afferent arteriole to reduce filtration

Question 7

What is the function of the juxtaglomerular cells?

Answer 7

Part of the afferent arteriole

Secrete renin when pressure in the afferent arteriole falls

Question 8

Which part of the nephron does Aldosterone act upon?

Answer 8

DCT

Distal convoluted tubule

Question 9

Which part of the nephron does ADH act upon?

Answer 9

Collecting duct

Question 10

Where is the site of uric acid reabsorption in the nephron?

Answer 10

Proximal convoluted tubule (PCT)

Question 11

Where is ADH produced and secreted from?

Answer 11

Produced by the hypothalamus

Secreted from the posterior pituitary gland

Question 12

What is the function of ADH?

Answer 12

Released in response to reduced circulating volume/increased plasma osmolality

Acts by expression of Aquaporin channels in the collecting duct for water reabsorption

Question 13

What is the function of Aldosterone?

Answer 13

Acts on the DCT to stimulate sodium reabsorption and potassium excretion

Question 14

Outline the steps of the RAAS

Answer 14

Renin converts angiotensinogen to angiotensin 1
ACE converts angiotensin 1 to angiotensin 2
Angiotensin 2 stimulates aldosterone secretion and vasoconstriction

Question 15

Where is angiotensin 1 converted to angiotensin 2?

Answer 15

Lung