GPT Renal Notes

Question 1

Where does most solute and water reabsorption occur?

Answer 1

Proximal convoluted tubule (PCT).

Question 2

What substances are 100% reabsorbed in the PCT?

Answer 2

Glucose and amino acids.

Question 3

What is the function of the descending limb of Henle’s loop?

Answer 3

Reabsorbs water (impermeable to solutes).

Question 4

What does the thick ascending limb of Henle do?

Answer 4

Reabsorbs Na+, K+, and Cl−; impermeable to water.

Question 5

What is the role of the distal convoluted tubule (DCT)?

Answer 5

Fine-tunes Na+, Cl− reabsorption; site of thiazide diuretic action.

Question 6

What hormones act on the collecting duct?

Answer 6

ADH (increases water reabsorption) and aldosterone (increases Na+ reabsorption and K+ excretion).

Question 7

What maintains the kidney’s medullary osmotic gradient?

Answer 7

The countercurrent multiplier system of the loop of Henle and the vasa recta.

Question 8

What transporter is inhibited by loop diuretics?

Answer 8

Na-K-2Cl cotransporter in the thick ascending limb.

Question 9

What is the function of the Na+/H+ exchanger in the PCT?

Answer 9

Reabsorbs Na+ in exchange for secreting H+, aids in bicarbonate reclamation.

Question 10

What part of the nephron is impermeable to water?

Answer 10

The thick ascending limb of Henle.

Question 11

Where does the majority of phosphate reabsorption occur?

Answer 11

In the proximal tubule (regulated by PTH).

Question 12

What happens to glucose reabsorption in diabetes mellitus?

Answer 12

It exceeds the transport maximum (Tm), leading to glucosuria.

Question 13

What triggers renin release from the juxtaglomerular cells?

Answer 13

Low BP, low Na+, or sympathetic stimulation.

Question 14

What does angiotensin II do?

Answer 14

Vasoconstriction, stimulates aldosterone, increases Na+/water reabsorption, raises BP.

Question 15

What does aldosterone do in the kidney?

Answer 15

Increases Na+ reabsorption and K+ secretion in the DCT and collecting duct.

Question 16

What does ADH do?

Answer 16

Promotes water reabsorption by inserting aquaporins in the collecting duct.

Question 17

What hormones oppose the RAAS system?

Answer 17

ANP and BNP – promote natriuresis and lower BP.

Question 18

What role does the kidney play in vitamin D metabolism?

Answer 18

Converts calcidiol to active calcitriol (1,25-dihydroxyvitamin D).

Question 19

What enzyme converts angiotensin I to angiotensin II?

Answer 19

Angiotensin-converting enzyme (ACE), mainly in the lungs.

Question 20

What is the effect of ANP on the nephron?

Answer 20

Inhibits Na+ reabsorption in the collecting duct and dilates afferent arterioles → ↑ GFR.

Question 21

What triggers ADH release?

Answer 21

Increased plasma osmolality or decreased blood volume.

Question 22

What enzyme activates vitamin D in the kidney?

Answer 22

1-alpha hydroxylase.

Question 23

What inhibits renin secretion?

Answer 23

High blood pressure, high sodium levels, or angiotensin II (negative feedback).

Question 24

What percentage of cardiac output do the kidneys receive?

Answer 24

~20–25%.

Question 25

What arteriole supplies blood to the glomerulus?

Answer 25

Afferent arteriole.

Question 26

What arteriole drains the glomerulus?

Answer 26

Efferent arteriole.

Question 27

What capillary network surrounds the proximal and distal tubules?

Answer 27

Peritubular capillaries.

Question 28

What structure maintains the countercurrent exchange in the medulla?

Answer 28

Vasa recta.

Question 29

How does the kidney respond to metabolic acidosis?

Answer 29

Increases H+ secretion and new HCO₃⁻ generation via ammoniagenesis.

Question 30

How does the kidney respond to metabolic alkalosis?

Answer 30

Decreases H+ secretion and increases HCO₃⁻ excretion.

Question 31

What part of the nephron is key for bicarbonate reabsorption?

Answer 31

The proximal tubule.

Question 32

What is the role of alpha-intercalated cells in acid-base balance?

Answer 32

Secrete H+ and reabsorb HCO₃⁻ during acidosis.

Question 33

What is the role of beta-intercalated cells?

Answer 33

Secrete HCO₃⁻ and reabsorb H+ during alkalosis.

Question 34

What are the five primary functions of the renal system?

Answer 34

Filtration, fluid & electrolyte balance, acid-base regulation, hormone production (EPO, renin, calcitriol), and excretion of waste.

Question 35

What hormone produced by the kidney stimulates red blood cell production?

Answer 35

Erythropoietin (EPO).

Question 36

Where are the kidneys located?

Answer 36

Retroperitoneal, spanning vertebral levels T12–L3 (right lower due to liver).

Question 37

What is the order of structures at the renal hilum (anterior to posterior)?

Answer 37

Renal vein, artery, ureter (VAU).

Question 38

What is the pathway of urine from nephron to ureter?

Answer 38

Papilla → Minor calyx → Major calyx → Renal pelvis → Ureter.

Question 39

What is the blood supply sequence within the kidney?

Answer 39

Renal artery → Segmental → Interlobar → Arcuate → Interlobular → Afferent arteriole → Glomerulus → Efferent arteriole → Peritubular capillaries/vasa recta.

Question 40

What structure surrounds the kidney for protection?

Answer 40

The renal capsule.

Question 41

What separates the renal cortex from the medulla?

Answer 41

The arcuate arteries and veins.

Question 42

What part of the kidney contains the renal pyramids?

Answer 42

The renal medulla.

Question 43

What is the function of the renal pelvis?

Answer 43

Acts as a funnel for urine flowing to the ureter.

Question 44

What is the significance of the juxtaglomerular apparatus (JGA)?

Answer 44

It regulates blood pressure and GFR via renin secretion and tubuloglomerular feedback.

Question 45

What is the functional unit of the kidney?

Answer 45

The nephron.

Question 46

What are the two types of nephrons?

Answer 46

Cortical (85%) and juxtamedullary (15%).

Question 47

What is the primary function of the juxtamedullary nephrons?

Answer 47

Concentration of urine via long loops of Henle.

Question 48

What are the main components of the nephron in order?

Answer 48

Glomerulus → PCT → Loop of Henle → DCT → Collecting duct.

Question 49

What drives glomerular filtration?

Answer 49

Starling forces: hydrostatic and oncotic pressures.

Question 50

What is the normal GFR?

Answer 50

~125 mL/min.

Question 51

How is GFR clinically estimated?

Answer 51

Using creatinine or inulin clearance.

Question 52

What three layers form the filtration barrier in the glomerulus?

Answer 52

Fenestrated endothelium, basement membrane, podocyte slit diaphragm.

Question 53

What type of molecules are filtered freely at the glomerulus?

Answer 53

Small molecules: water, glucose, electrolytes, urea.

Question 54

What restricts filtration of large or negatively charged molecules?

Answer 54

The basement membrane and podocyte slit diaphragm (charge and size barrier).