kidney

• function of the kidneys


  filter the blood to remove any waste products and regulate water potential in the blood.
• what is the structure of the kidney?

  kidney:

  A) renal cortex

  B) renal medulla

  C) renal capsule

  D) minor calyx

  E) major calyx

  F) renal collumns

  G) renal pyramids

  H) ureter

  I) renal pelvis

  J) renal vein

  K) renal artery

  
• label the diagram of the nephron

  nephron:

  A) glomerulus

  B) afferent arteriole

  C) Bowmans capsule

  D) descending limb of Henle

  E) Loop of Henle

  F) Ascending Limb of Henle

  G) Collecting duct

  H) DCT

  I) PCT

  J) efferent arteriole

  K) renal medulla

  L) renal cortex

  
• what is the process of ultrafiltration in the Bowman's capsule?


  Afferent arteriole diameter>efferent

  Causes high hydrostatic pressure in the glomerulus

  Forcing small molecules (urea,water,glucose,amino acids) into Bowmans capsule.

  Podocytes around capillaries act as additional filter.
• Explain the process of selective reabsorbtion in the PCT?


  Active transport moves sodium ions from epithelial cells of PCT into bloodstream.

  Low conc of NA+ in epithelial cells.

  By faciliated diffusion, NA+ and useful molecules (glucose)from PCT, move into epithelial cells.

  Glucose now diffuses into bloodstream.

  Water also reabsorbed into blood by osmosis.

  Fluid now moves to loop of Henle and DCT
• How are the epithelial cells in the proximal convoluted tubule (PCT) adapted for efficient selective reabsorption?


  Contains lots of microvilli, increases SA for absorption

  Lots of infoldings, increases SA for molecules to diffuse into bloodstream.

  Lots of mitochondria, provide ATP for active transport
• what is the role of the loop of Henle?


  is to lower the water potential of the tissue in the medulla
• How does the loop of Henle and the collecting duct function?

  Na+ and Cl- actively pump out of ascending loop, creates low water potential in medulla.

  Water diffuses out of descending loop.

  More Na+ and Cl- diffuse out of ascending loop, further lowing water potential.

  Water diffuses out of the collecting duct into medulla, where it is then reabsorbed back into collecting duct
• Explain the process of osmoregulation in the collecting duct?


  hypothalamus synthesises the hormone ADH, it is then transported to the posterior pituitary gland.

  Osmoreceptors detect the change in water potential of the blood
• Explain what happens when a person becomes dehydrated (osmoregulation)


  dehydrated

  water potential of blood decreases

  water leaves osmoreceptor cells

  osmoreceptor cells shrink

  posterior pituitary gland is stimulated to release ADH into the bloodstream
• what is the role of ADH in osmoregulation?


  in walls of collecting duct near blood capillary.

  ADH binds to specific receptors on collecting duct membrane

  cAMP is produced (secondary messenger)

  this triggers vesicles containing aquaporins to fuse with membrane, allowing water molecules to move into collecting duct walls and then to bloodstream

  urea also allowed through into medulla, decreasing the water potential which increases reabsorption of water
• What is the effect of kidney failure on glomerular filtration rate(GFR)?


  if the rate increases, kidney is not filtering properly.
• what are the symptoms of kidney failure?


  protein in the urine - podocytes damaged

  Blood in the urine - filter not working
• What are the effects of kidney failure?


  waste products build up (urea)

  swelling can occur due to excess water building up

  loss of electrolytes balance - brittle bones

  long term damage causes anaemia
• what are the two types of renal dialysis? (inside or out of body)


  Haemodialysis - outside the body

  Peritoneal dialysis - inside the body
• explain haemodialysis?


  blood filtration

  dialysis machine

  3-5hrs and 2-3 sessions per week at hospital
• explain peritoneal dialysis?


  dialysis fluid put through a tube into patient

  done at home, several times a day

  risk of infection
• How can urine be used in medical diagnosis for Anabolic steriods?

  use of gas chromatography and mass spectrometry
• how is urine used in medical dialysis for drug testing?


  test strips contain antibody that bind to the drug and change colour