Where are the kidneys located?

→ In the posterior abdominal wall, in the retroperitoneal space, within the lumbar region.

What are the two main regions of the kidney?

→ The renal cortex and renal medulla.

3. What does the renal cortex contain?

→ Renal corpuscles and much of the nephron, including parts of the renal tubules.

What does the renal medulla contain?

→ Mainly the loops of Henle and collecting ducts.

What is the pathway of urine drainage within the kidney?

→ Collecting ducts → minor calyces → major calyces → renal pelvis → ureter.

What is the renal pelvis?

→ A funnel-shaped structure that collects urine from the major calyces and passes it into the ureter.

7. What is the retroperitoneal space?

→ The anatomical space behind the peritoneum where the kidneys are located.

What is the nephron?

→ The basic structural and functional unit of the kidney.

What is the main function of the nephron?

→ Filtration and modification of filtrate to produce urine.

3. What structures make up the renal corpuscle?

→ The glomerulus and Bowman's capsule.

4. Where does filtration occur?

→ At the glomerulus and Bowman's capsule.

5. What is the function of the glomerulus?

→ It filters the blood, allowing small substances to pass into Bowman's capsule

What is Bowman's capsule?

→ A cup-shaped structure surrounding the glomerulus that collects the filtrate.

What is the PCT?

→ The proximal convoluted tubule, where extensive reabsorption and secretion occur.

What does the PCT reabsorb?

→ Large amounts of water, glucose, amino acids, and ions are reabsorbed back into the blood.

What is secretion?

→ The movement of substances from the blood into the nephron tubule.

10. What is reabsorption?

→ The movement of substances from the nephron tubule back into the blood.

11. What is the function of the Loop of Henle?

→ It helps regulate water and salt balance and allows the kidney to concentrate urine.

What happens in the descending limb of the Loop of Henle?

→ Water is reabsorbed from the filtrate.

What happens in the ascending limb of the Loop of Henle?

→ Salts are reabsorbed, while the limb is relatively impermeable to water.

What is the DCT?

→ The distal convoluted tubule, where further reabsorption and secretion modify the filtrate.

What is the function of the collecting duct?

→ It carries the filtrate toward the renal calyces and allows final adjustment of water content.

Which hormone increases water reabsorption in the collecting ducts?

→ ADH (antidiuretic hormone).

What is the pathway through the nephron?

→ Glomerulus → Bowman's capsule → PCT → Loop of Henle → DCT → collecting duct.

18. What is the pathway of urine after the collecting duct?

→ Collecting duct → renal papilla → minor calyx → major calyx → renal pelvis → ureter.

19. What are the three major processes involved in forming urine?

→ Filtration, reabsorption, and secretion.

What is the difference between filtration, reabsorption, and secretion?

→ Filtration: blood → nephron → Reabsorption: nephron → blood → Secretion: blood → nephron

What is the glomerulus?

→ A network of fenestrated capillaries where blood filtration occurs.

What are fenestrations?

→ Small pores/openings in capillary walls that allow small substances to pass through during filtration.

What are the two layers of Bowman's capsule?

→ Parietal (outer) layer and visceral (inner) layer.

What is the function of the parietal layer?

→ It helps maintain the shape of Bowman's capsule.

What is the visceral layer made of?

→ Podocytes.

What are podocytes?

→ Specialised cells that surround the glomerular capillaries and have filtration slits

What is the function of podocytes?

→ They help form the filtration barrier, allowing small substances to pass while restricting larger substances.

What is Bowman's capsule?

→ The enlarged end of the renal tubule that surrounds the glomerulus and collects the filtrate.

What happens at the glomerulus and Bowman's capsule?

→ Blood is filtered, and the resulting filtrate enters Bowman's capsule.

Where does the proximal convoluted tubule (PCT) begin?

→ It leaves Bowman's capsule and is tightly coiled.

What are microvilli in the PCT for?

→ They increase surface area, allowing more efficient reabsorption.

Why does the PCT contain many mitochondria?

→ Mitochondria produce ATP, which provides energy for active transport during reabsorption and secretion.

What are the main functions of the PCT?

→ Reabsorption and secretion.

What happens in the descending limb of the nephron loop?

→ It is highly permeable to water, so water is reabsorbed into the surrounding tissue/blood.

What happens in the ascending limb of the nephron loop?

→ It is relatively impermeable to water and transports Na⁺ and other salts out of the filtrate.

Why are the descending and ascending limbs different?

→ Their different permeabilities help create the osmotic gradient needed to concentrate urine.