renal blood supply

Question 1

Talk about renal blood supply?

Answer 1

• Kidneys need blood supply so regulate pH, fluid volume, osmolality, electrolytes, blood pressure….. Receive a large percent of the cardiac output 20% (1.1L of blood)
  
  • Blood arrives thought the renal artery and branches into smaller arteries
  • Some of these arteries will divide further into arterioles and will supply blood to the fist capillary network (glomerulus capillaries)
    ○ Interlobular artery branches to from the afferent artery
  • Some arterioles will divide further and become the afferent and the efferent arterioles
  • Efferent will continue and provide blood to the proximal convoluted tubal as the peritubular capillaries (subset of the vasa recta)
  • The peritubular capillaries will provide blood to the loop of Henle and be known as the vasa recta
  • Peritubular capillaries
    ○ Provide different capillaries to epithelium and interstitial cells
    ○ Capillaries also provide blood for reabsorption and secretion in the PCT
  • Vasa recta
    ○ Long hairpin shaped blood vessels
    ○ Run along the LoH
    ○ Provide nutrients to the cells
    ○ Functions as counter current exchangers
  • Blood will exit the kidney through venules then the renal vein
    *

Question 2

What is myogenic control of the GFR?

Answer 2

• GFR needs to be maintained- if too much than nutrients can be lost in urine and if too little waste can be reabsorbed
  
  • Higher blood pressure will increase the blood pressure in the kidneys
  • Kidneys can Autoregulate/self-regulate blood pressure inside the glomerus by myogenic or tubuloglomerular feedback
  • From 80-180 mmHg of blood pressure the kidneys can self-regulate (flat line=self-regulate of blood pressure) before that or after that pressure they cannot and is in the danger zone of GFR being too high or low
  • Blood pressure is too high
    ○ Afferent arteriole contact to decrease the pressure in the glomerus
    § More blood enters but same amount leaves (more blood in glomerulus) so higher hydrostic pressure
    ○ Efferent arteriole dilate to decrease the pressure in the glomerus
    § Same amount of blood enters but less amount leaves (more blood in glomerulus) so higher hydrostic pressure
  • Blood pressure is too low
    ○ Afferent arteriole dilate to increase the pressure in the glomerus
    § Less blood enters but same amount leaves (less blood in glomerulus) so lower hydrostic pressure
    ○ Efferent arteriole contact to increase the pressure in the glomerus
    § Same amount blood enters but more amount leaves (less blood in glomerulus) so lower hydrostic pressure
  • Resistance blood vessels are the Arterioles as they and constrict/dilate the lumen to increase/decrease the resistance
  • This is due to the smooth muscles in the wall of the arterioles
  • Muscles on each side of the arteriole can contract and relax to increase/decrease the lumen

Question 3

What is the importance of the vasa recta in maintaining a corticomedullary hypoosmotic gradient?

Answer 3

• Vasa recta ensures that the ions creating corticomedullary hyperostotic gradient are not moved as the corticomedullary hyperostotic gradient took a long time and lots of energy to create
  
  • Vasa recta also provides O2 and nutrients to the cells of the nephron
    1. Blood enters the vasa recta and will flow down the descending vasa recta where water moves out and solutes moves in
    2. This causes the plasma and interstitial fluid to equilibrate (destroys corticomedullary hyperostotic gradient)
    3. As blood flows up the ascending vasa recta water moves in and solutes moves out this would maintain/ recreate the corticomedullary hyperostotic gradient
    4. Slow flow through the vasa recta also maintains the corticomedullary hyperostotic gradient
    5.