Homeostasis

Question 1

Describe the gross structure of a mammalian kidney

Answer 1

• fibrous capsule = protects the kidney
• cortex = outer region that consists of Bowman’s capsules, convoluted tubules and blood vessels
• medulla = inner region that consists of collecting ducts, loops of Henle and blood vessels
• renal pelvis = cavity collects urine into ureter
• renal artery = supplies kidney with oxygenated blood
• renal vein = returns deoxygenated blood from kidney to heart

Question 2

Describe what a nephron is and its structure

Answer 2

• functional unit in kidney
• Bowman’s capsule = start of nephron, cup-shaped, surrounds glomerulus, inner layer of podocytes
• proximal convoluted tubule (PCT) = series of loops surrounded by capillaries, walls of epithelial cells with microvilli
• loop of Henle = hairpin loop that extends from cortex to medulla
• distal convoluted tubule (DCT) = similar to PCT but fewer capillaries
• collecting duct = DCT from several nephrons empty into it and leads to pelvis of kidney

Question 3

Explain how glomerular filtrate is formed from the blood

Answer 3

• ultrafiltration in Bowman’s capsule
• high hydrostatic pressure in glomerulus forces out small molecules (urea, water, glucose etc) by pores in the endothelium
• filtrate passes through basement membrane which stops proteins as they are too large and charges repel
• filtrate passes through podocytes in the epithelium of the Bowman’s capsule

Question 4

How are cells of the Bowman’s capsule adapted for ultrafiltration?

Answer 4

Gaps between podocytes that allow fluid to pass through