Endocrine Functions of the Kidney

Question 1

What are the primary endocrine functions of the kidney?

Answer 1

Production of erythropoietin, renin, activation of vitamin D, and production of prostaglandins.

Question 2

What hormone is primarily produced by the kidneys in response to hypoxia?

Answer 2

Erythropoietin (EPO).

Question 3

How does erythropoietin (EPO) function in the body?

Answer 3

EPO stimulates the production of red blood cells in the bone marrow.

Question 4

Which cells in the kidney produce erythropoietin?

Answer 4

Peritubular fibroblasts in the renal cortex.

Question 5

How does erythropoietin regulate red blood cell production?

Answer 5

By binding to erythroid progenitor cells in the bone marrow and promoting their maturation into red blood cells.

Question 6

What triggers the release of erythropoietin from the kidneys?

Answer 6

Low oxygen levels (hypoxia) in the blood.

Question 7

What is the role of the kidneys in the renin-angiotensin-aldosterone system (RAAS)?

Answer 7

The kidneys release renin, which activates the RAAS to regulate blood pressure and fluid balance.

Question 8

How do the juxtaglomerular cells contribute to the endocrine function of the kidneys?

Answer 8

Juxtaglomerular cells produce renin in response to decreased blood pressure or blood flow to the kidneys.

Question 9

What stimulates the secretion of renin from the kidneys?

Answer 9

Decreased renal perfusion, sympathetic nervous system activation, and low sodium chloride concentration in the distal tubule.

Question 10

Describe the process by which renin leads to the production of angiotensin II.

Answer 10

Renin converts angiotensinogen to angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme (ACE) in the lungs.

Question 11

How does angiotensin II affect blood pressure?

Answer 11

Angiotensin II constricts blood vessels, increasing blood pressure and stimulating aldosterone release.

Question 12

What is the role of aldosterone in kidney function?

Answer 12

Aldosterone increases sodium reabsorption and potassium excretion in the kidneys, promoting water retention.

Question 13

How does the activation of RAAS contribute to sodium and water retention?

Answer 13

By increasing aldosterone secretion, which enhances sodium and water reabsorption in the distal tubules and collecting ducts.

Question 14

What enzyme do the kidneys produce that is involved in vitamin D metabolism?

Answer 14

1-alpha-hydroxylase.

Question 15

Describe the role of 1-alpha-hydroxylase in the kidneys.

Answer 15

It converts 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D (calcitriol), the active form of vitamin D.

Question 16

How do the kidneys convert vitamin D into its active form?

Answer 16

By hydroxylating 25-hydroxyvitamin D in the proximal tubules.

Question 17

What is the active form of vitamin D produced by the kidneys?

Answer 17

1,25-dihydroxyvitamin D (calcitriol).

Question 18

How does active vitamin D (calcitriol) affect calcium homeostasis?

Answer 18

Calcitriol increases calcium absorption from the gut, reabsorption in the kidneys, and release from bones.

Question 19

What is the role of the kidneys in phosphate metabolism?

Answer 19

By regulating the reabsorption and excretion of phosphate in response to various hormones.

Question 20

How does parathyroid hormone (PTH) influence kidney function in relation to calcium and phosphate?

Answer 20

PTH increases calcium reabsorption and decreases phosphate reabsorption in the kidneys.

Question 21

What is the relationship between kidney function and the regulation of blood pressure?

Answer 21

By regulating the RAAS and producing vasodilatory prostaglandins.

Question 22

How does the kidney’s endocrine function impact systemic vascular resistance?

Answer 22

Angiotensin II and aldosterone, products of the RAAS, increase systemic vascular resistance and blood volume.

Question 23

What is the function of prostaglandins produced by the kidneys?

Answer 23

Prostaglandins act as vasodilators, increasing renal blood flow and counteracting vasoconstriction.

Question 24

How do renal prostaglandins affect renal blood flow?

Answer 24

They help maintain adequate blood flow to the kidneys, particularly during stress or injury.

Question 25

What role do the kidneys play in the regulation of acid-base balance through endocrine mechanisms?

Answer 25

By secreting hydrogen ions and reabsorbing bicarbonate, influencing systemic acid-base balance.

Question 26

How does the kidney produce and utilize ammonia in acid-base balance?

Answer 26

Ammonia is produced and secreted by the kidneys to buffer hydrogen ions in the urine.

Question 27

What is the significance of the kidney’s production of kallikrein?

Answer 27

Kallikrein is involved in the production of kinins, which are vasodilators.

Question 28

How does kallikrein contribute to blood pressure regulation?

Answer 28

Kinins produced from kallikrein activity lower blood pressure by dilating blood vessels.

Question 29

What are the effects of atrial natriuretic peptide (ANP) on kidney function?

Answer 29

ANP increases glomerular filtration rate and sodium excretion, lowering blood pressure.

Question 30

How does the endocrine function of the kidney influence fluid and electrolyte balance in the body?

Answer 30

By regulating the balance of sodium, potassium, calcium, phosphate, and water through various hormonal mechanisms.