Kidney!!!!

What structure in the kidney is primarily responsible for filtration?

Glomerulus (part of the nephron)

What two components make up the renal corpuscle, and where is it located in the kidney?

Glomerulus + Bowman's capsule; located in the renal cortex.

What is the primary function of the filtration barrier in the renal corpuscle?

Prevent passage of large molecules/proteins/blood cells.

Which layer of the filtration barrier is responsible for preventing the passage of large proteins?

Basement membranes – charged.

What pressure promotes filtration in the renal corpuscle?

Glomerular hydrostatic pressure.

What are the two main types of nephrons in the kidney, and how do they differ?

Cortical (85%, mostly in the cortex) and Juxtamedullary (long loop of Henle that goes deep into the medulla, functions in water reabsorption and urine concentration).

What process occurs in the glomerulus?

Filtration.

What is the glomerular filtration rate (GFR)?

Amount of fluid filtered from blood into the kidney tubules (90-120 mL/min).

Where does most tubular reabsorption occur?

Proximal tubule.

What is the key permeability difference between the descending and ascending loop of Henle?

Water is reabsorbed in descending loop; ascending loop cannot leave water but reabsorbs sodium.

What drives water reabsorption in the proximal tubule?

Osmotic gradients.

How is the concept of renal clearance best described?

Volume of plasma completely cleared of a substance in the kidneys per unit time.

How does the nephron handle glucose under normal physiological conditions in terms of clearance?

Glucose is fully filtrated and fully reabsorbed; clearance is 0, so it should not appear in urine.

What pathway allows solutes to move between cells in the renal tubule?

Paracellular pathway.

How do substances move in and out of cells in the renal tubule?

Through active (sodium pump) and passive transport (osmotic gradients).

How does the nephron regulate potassium levels?

Different cells (principal cells and intercalated cells) perform different functions for secretion and reabsorption.

Which hormone regulates water reabsorption and indirectly affects solute concentrations?

Vasopressin (ADH, antidiuretic hormone).

What is the role of the countercurrent multiplier?

Creates an osmotic gradient of increasing osmolarity deeper in the medulla, concentrating urine in the loop of Henle and allowing for slow reabsorption of water.

How does the descending loop of Henle contribute to the countercurrent multiplier?

It reabsorbs water, unlike the ascending loop.

What is the primary role of countercurrent exchange in the vasa recta?

Prevent washout of medullary osmotic gradient while allowing exchange of solutes and water.

How does the kidney respond to acidosis?

Excrete more H+, reabsorb bicarbonate, and excrete ammonium.