6 Renal System Physiology Free Online FlashCards

What key aspects of the internal environment do the kidneys regulate?

The kidneys regulate water and electrolyte levels, blood volume and pressure, and blood pH while removing metabolic wastes and excess substances.

What are the main parts of a nephron?

A nephron consists of a renal corpuscle—its glomerulus and Bowman’s capsule—and a tubule: the proximal tubule, loop of Henle, distal tubule, and collecting duct.

How does blood flow into and out of the glomerulus?

Blood enters the glomerulus through the afferent arteriole and leaves through the efferent arteriole.

What passes into Bowman’s capsule during filtration?

Blood pressure drives water and small dissolved substances into Bowman’s capsule. Blood cells and most proteins remain in the bloodstream.

How are filtration, reabsorption, and secretion related to excretion?

$\text{Excretion} = \text{filtration} - \text{reabsorption} + \text{secretion}$.

What does the proximal tubule reabsorb?

The proximal tubule reclaims most filtered water and sodium, along with nearly all glucose and amino acids under normal conditions.

What is tubular secretion, and what can it remove?

Secretion moves selected substances from blood into the tubule. Examples include hydrogen ions, potassium, some drugs, and metabolic wastes.

How does the loop of Henle support water conservation?

The loop of Henle helps establish a concentration gradient in the kidney’s medulla, enabling collecting ducts to conserve water when needed.

How does high ADH affect the collecting ducts and urine?

When blood is concentrated or water is scarce, ADH increases collecting-duct permeability to water. More water returns to the blood, producing a smaller volume of more concentrated urine.

What happens to urine when ADH levels are low?

When ADH is low, less water is reabsorbed, so the urine is more dilute.

How does aldosterone affect sodium and potassium handling?

In response to low blood pressure or reduced kidney blood flow, aldosterone increases sodium reabsorption in the distal nephron and promotes potassium secretion. Water tends to follow sodium.

How do the kidneys help stabilize blood pH?

The kidneys provide longer-term pH control by reabsorbing filtered bicarbonate and secreting hydrogen ions into the tubules.