Kidney

Question 1

The blood supply of the kidney

Answer 1

• Blood enters kidney via the renal artery
  
  • divides into segmental arteries
  • divide into interlobar arteries
  • divide into arcuate arteries
  • give rise to cortical radiate arteries (c.r.a.)
• Each c.r.a. gives rise to numerous afferent arterioles, which give rise to glomerular capillaries.
• Each glomerular capillary gives rise to an efferent arteriole, which give rise to peritubular capillaries.
• The peritubular capillaries drain into venules.
• The venous drainage is largely in the same pattern as the arteries in reverse…
  cortical radiate vein → arcuate vein → interlobar vein → renal vein
• NOTE: NO SEGMENTAL VEINS

Question 2

Microcirculation of kidney

Answer 2

FLOW CHART:
Renal artery –> segmental arteries –> interlobar arteries –> arcuate arteries –> cortical radiate arteries –> afferent arterioles –> (start of nephron) glomerulus –> efferent arteriole –> peritubular capillaries (end of nephron) –> venules –> cotricol radiate veins –> arcuate veins –> interlobar veins –> renal vein

Question 3

The Nephron

Answer 3

• The nephron is the function unit of the kidney
• nephron = vital role in filtering the blood + producing the urine
• Approx 85% of nephrons are cortical and 15% are juxtamedullary
• There are about 1 mil nephrons in a human kidney, and 85% of them are cortical nephrons, so 850,000 are cortical nephrons and 150,000 (15%) are juxtamedullary nephrons
• glomerulus + renal corpuscle + Bowman’s capsule –> proximal convoluted tubule –> loop of Henle –> distal convoluted tubule –> collecting duct –> papillary duct

Question 4

The circulation of the nephron

Answer 4

• The circulation of the nephron is unique + allows for the high filtration of substances from the blood
  It comprises:
• a (relatively) low resistance arteriole (afferent arteriole)
• a high pressure capillary network (glomerular capillaries)
• a high resistance arteriole (efferent arteriole)
• a low pressure capillary network (peritubular capillaries)

Question 5

Blood supply of nephron

Answer 5

The afferent arteriole supplies the glomerular capillary which in turn feeds the efferent arteriole –> the efferent arteriole gives rise to the peritubular capillaries, which surrounds the tubule

• In juxtamedullary nephrons, capillary loops called vasa recta dip down into the renal medulla
• where loop of Henle is located

Question 6

radius of arterioles

Answer 6

• Radius of afferent arteriole is greater than the efferent = less resistance
• Pressure higher in gemeroular capillary then peritubular capillaries