Kidney 1 - Structure & Glomerular Filtration

Question 1

What are the functions of the kidney?

Answer 1

• Excretory organs: process blood and remove waste products of metabolism via urine
• Maintain internal homeostasis of fluid and electrolytes (also affects blood pressure)
• Creating hormones like erythropoietin (red blood cell production)

Question 2

What are the 3 macroscopic parts of the kidney and what is the function of each?

Answer 2

Cortex - Contains 85% of all kidney tubules (nephrons: filtration, reabsorption, secretion, and excretion occurs

Medulla- Site where urine is concentrated and prevents excessive water loss

(Renal) Pelvis - Collection area for urine which is funnelled into the ureter

Question 3

What is the main blood supply to the kidney?

Answer 3

Renal artery (branched off abdominal aorta)

Question 4

What are the main microscopic structures in the kidney & functions of each? (in order of first to last)

Answer 4

Glomerulus: network of fine capillaries, single layer of endothelial cells, surrounded by Bowman’s capsule

Bowman’s capsule: cuplike structure surrounding glomerulus, contains parietal & visceral layer

Proximal convoluted tubule (PCT): selective reabsorption of Glucose, water, maintains pH balance by exchanging H+ for bicarbonate ions

Loop of Henle: U-shaped portion, reabsorbs water and concentrates urine

Distal convoluted tubule (DCT): filtrate is fine tuned - Na+ & water, regulated by Antidiuretic hormone and aldosterone

Collecting ducts: collects urine from nephrons and moves to renal pelvis

Question 5

What are the two types of nephron and what is the difference between them?

Answer 5

Cortical nephron & Juxtamedullary nephron

Cortical nephrons have a short Loop of Henle which only slightly penetrates the medulla of the kidney

Juxtamedullary nephrons have a long Loop of Henle which deeply extends into the medulla of the kidney

Question 6

Where does filtration (removal) primarily occur in the kidneys?

Answer 6

Glomerulus & Bowman’s capsule = Renal Corpuscle

Question 7

What is glomerular filtration and what is filtered?

Answer 7

First step in urine production

Water, glucose, amino acids, urea, creatinine, electrolytes (sodium, chloride, calcium, phosphate, potassium, bicarbonate)

Question 8

What is the glomerular filtration rate (GFR) and what drives it?

Answer 8

The rate at which blood is filtered through the glomerulus into the Bowman’s capsule

Primarily driven by Glomerular hydrostatic pressure

Question 9

How does GFR relate to kidney function/health?

Answer 9

Kidney damage reduces the GFR

Reduced GFR = inefficient blood clearance and waste removal therefore reduced kidney function/health

Question 10

Where does most of the reabsorption occur in the kidney?

Answer 10

Renal tubule/Nephron