from blood plasma to urine

Question 1

The renal corpuscle – a closer look

Answer 1

• Glomerulus
– Tuft of capillaries
– Surrounded by podocytes
• Bowman’scapsule
– Funnel for catching filtrate
• Plasma enters via afferent arteriole and exits via efferent arteriole

Question 2

Glomerular filtration

Answer 2

• Highpressureinglomerulus
• As blood travels through glomerulus some plasma is pushed out into Bowman’s capsule
– Glomerular filtration
• Solution is called filtrate
– Filtrate = plasma without proteins

Question 3

filtrate

Answer 3

Water
• Electrolytes (eg. Na+, K+, Cl-)
• Nutrients (glucose, amino acids)
• Waste products (drugs, food additives)
• Urea

Question 4

Glomerular membrane (1)

Answer 4

• Filtrate must pass through 3 layers of glomerular membrane

1. Glomerular capillary wall
2. Basement membrane
3. Podocyte filtration slits

Question 5

Glomerular membrane (2)

Answer 5

• Filtrate must pass through 3 layers of glomerular membrane
1. Glomerular capillary wall
• Has fenestrations (pores) - holes inside the cell
• Allows passage of most plasma components except large proteins and cells

Question 6

Glomerular membrane (3)

Answer 6

• Filtrate must pass through 3 layers of glomerular membrane
2. Basement membrane
• Gel-like zone
• Physical barrier: proteins can’t fit
through
• Electrical barrier: Negative charge repels proteins

Question 7

Glomerular membrane (4)

Answer 7

3. Podocyte filtration slits
   • Capillaries lined with podocytes (cells with long foot processes
   • Adjacentpodocytesinterlace
   • Spaces between processes called filtration slits

• cells have long feet that wrap around capillary, interwind with
  eachother and spaces between called filtration slits

Question 8

Forces involved in glomerular filtration

Answer 8

• The rate at which filtrate is produced depends on opposing forces in the renal corpuscle
  – Hydrostatic pressure (pushing force) • Glomerular capillary blood pressure
  • Bowman’s capsule hydrostatic pressure
  – Osmotic pressure (pulling force) • Plasma-colloid osmotic pressure
  • Netfiltrationpressure
  – Forces favouring filtration minus forces opposing filtration

Question 9

Forces involved in glomerular filtration

Glomerular capillary blood pressure

Answer 9

– Pressure of blood inside the glomerular capillaries – Efferent arteriole has a smaller radius than afferent
arteriole = high pressure – 50mmHg
– Favours filtration

• just know it’s high pressure

Question 10

Forces involved in glomerular filtration

• Plasma-colloido smotic pressure

Answer 10

– Plasma proteins suck in glomerular capillaries
– Osmolarity is greater inside the capillaries than Bowman’s capsule
– Pulls fluid back into capillaries
– Opposes filtration

Question 11

Forces involved in glomerular filtration

• Bowman’s capsule hydrostatic pressure

Answer 11

– Pressure of fluid inside Bowman’s capsule

– Opposes filtration