Functions of the Kidneys and Regulation Mechanisms

A comprehensive set of flashcards covering key concepts related to the functions of the kidneys and their regulatory mechanisms.

What are the primary functions of the kidneys?

Filters blood plasma, separates waste from useful chemicals, and returns useful substances to blood.

How do the kidneys regulate blood volume and pressure?

By eliminating or conserving water.

What role do the kidneys play in regulating osmolarity?

They control the relative amounts of water and solutes eliminated.

What enzyme do the kidneys secrete to help control blood pressure?

Renin.

What hormone is secreted by the kidneys to stimulate red blood cell production?

Erythropoietin.

How do kidneys collaborate with lungs?

To regulate PCO2 and acid-base balance of body fluids.

What is the final step in synthesizing calcitriol?

It contributes to calcium homeostasis.

What metabolic function do kidneys serve during extreme starvation?

Gluconeogenesis from amino acids.

What happens to glomerular filtration rate (GFR) if it is too high?

Chance of dehydration and electrolyte depletion increases, resulting in a rise in urine output.

What occurs if glomerular filtration rate (GFR) is too low?

Wastes are reabsorbed, potentially leading to azotemia.

What mechanisms control GFR?

Renal autoregulation, sympathetic control, and hormonal control.

What does renal autoregulation maintain?

A dynamic equilibrium where GFR fluctuates within narrow limits.

What is the effect of blood pressure changes on GFR?

They do affect GFR and urine output somewhat.

What is the upper limit for mean arterial pressure (MAP) where GFR remains stable?

90 to 180 mm Hg.

What occurs below 70 mm Hg MAP?

Glomerular filtration and urine output cease.

What is the renin-angiotensin-aldosterone mechanism?

A hormonal mechanism that regulates blood pressure and fluid balance.

What does angiotensin II do?

It is a potent vasoconstrictor that raises blood pressure throughout the body.

What role does aldosterone play in the kidneys?

Promotes Na+ and H2O reabsorption in the distal convoluted tubule (DCT) and collecting duct.

What stimulates thirst and H2O intake?

Angiotensin II.

What hormone increases the permeability of the collecting duct to water?

Antidiuretic hormone (ADH).

Under what condition is ADH secreted?

In response to dehydration and rising blood osmolarity.

What is the normal urine volume for an average adult?

1 to 2 L/day.

What is polyuria?

Urine output in excess of 2 L/day.

What is oliguria?

Urine output of less than 500 mL/day.

What is anuria?

Urine output of 0 to 100 mL/day.

What causes low urine output in anuria?

Kidney disease, dehydration, circulatory shock, or prostate enlargement.

What are the symptoms of urinary tract infection (UTI)?

Cystitis (infection of the bladder), pyelitis (infection of the renal pelvis), and pyelonephritis (infection reaching the cortex and nephrons).

Why are UTIs especially common in females?

Due to the short length of the female urethra.

What can trigger cystitis?

Frequent sexual intercourse.

What can pyelitis lead to?

Potential progression to pyelonephritis.