topic six

• Blood enters the kidney through the renal artery
• blood leaves the kidney through the renal vein
• the ureter is a tube that carries urine from a kidney to the bladder
• the bladder stores urine
• the urethra carries urine from the bladder out of the body
• The kidneys regulate the water content of the blood using osmoregulation and remove waste products from it
• the kidneys remove urea, excess salts and water.
• the solution of wastes is urine, this drains from the kidneys down the ureters to the bladder, where it is stored until it can be eliminated from the body
• ultrafiltration

  there is a change in the diameter of the blood vessel as it gets narrower in the capillary knot. This makes the pressure in the knot very high so that ultafiltration can occur
• when ultrafiltration occurs small molecules like water, urea,glucose and salts are filtered under pressure through the capillary knot into the bowmans capsule
• big proteins and blood cells are to big to pass through the capillary wall so they stay in the blood
• selective reabsorption of ALL glucose , some salts and muc of the water takes place in the tubule so that these useful molecules, needed in the body go back into the blood.
• urine is a mixture of urea, water and salt. It travels from the collecting duct to the ureter then onto the bladder where it is stored.
• ADH is a hormone that is produced in the pituitary glad. It travels in the blood to the kidney and causes the collecting duct walls to become more permeable to water.
• Water levels in blood to low QER

  • Receptor in pituitary gland in brain detects that theres too little water in the blood
  • brain releases more ADH into the blood
  • ADH enters kidneys and makes the collecting ducts more permeable to water so more water is reabsorbed into the blood.
  • Blood water levels return to normal through negative feedback.
  • urine produced has a small volume and is more concerntrated
• water levels in blood too HIGH

  • receptor in the pituitary gland in brain detects there is too much water in the blood
  • brain releases less ADH into the blood
  • less ADH enters kidneys so the collecting duct walls are less permeable to water so less water is reabsorbed by the blood
  • Blood water levels return to normal through negative feedback
  • unrine produced has a larger volume and is less concerntrated
• The presence of blood cells or protein in the urine indicates kidney disease

  To test for protein we use biuret reagent

  If protein is present the colour change is blue -> lilac
• Kidney failure can be treated by dialysis or kidney transplant
• a diseased kidney may be replaced by a healthy one by transplant from a donor of a simular tissue type to the recipient. Usually a family member.
• a donor kidney may be rejected by the body, attacked by the immune system, unless imunosuppresent drugs are taken which suppress the immune response
• dialysis involves filtering and cleaning the blood
• a dialysis machine uses counter current flow