kidneys

• what controls the amount of water that is reabsorbed into the kidney nephrons?

  anti-diuretic hormones (ADH)
• what is the brain's role in osmoregulation?

  monitors the water content of the blood and instructs the pituitary gland to release ADH into the blood according to how much is needed.
• what is ADH role in osmoregulation?

  makes the collecting ducts of the nephrons more permeable so that more water is reabsorbed back into the blood. This stops the body from becoming dehydrated.
• the whole process of water content regulation is controlled by what?

  a negative feedback system.
• for example, if the amount of sodium ions in the blood increases, what happens to the concentration of water in the blood?

  it will fall. The brain will detect that the blood needs more water, so it will release more ADH. More water will be reabsorbed from the collecting duct so the water content of the blood will rise.
• what does it mean if someone has kidney failure?

  their kidneys can't filter their blood properly.
• what treatment can be used to filter people's blood who have kidney failure?

  dialysis
• what does dialysis has to be done regularly?

  to keep dissolved substances at the right concentrations, and to remove waste.
• what does dialysis have the same concentration of salts and glucose as?

  blood plasma (which means those aren't removed from the blood).
• during dialysis, what is the barrier permeable to?

  ions and waste substances, but not big molecules like proteins (just like the membranes in the kidneys).
• during dialysis, what happens to the substances that can pass through the membrane (waste substances and ions)?

  they move across the membrane into the dialysis fluid. Cells and proteins stay in the blood.
• what can cure kidney diseases?

  kidney transplant.
• for kidney transplants, who are the healthy kidneys usually transplanted from?

  people who have died suddenly and people who are on the organ donor register or carry a donor card (provided their relatives give the go-ahead).
• what is a risk of kidney transplants?

  the donor kidney can be rejected by the patient's immune system, treated like a foreign body and attacked by antibodies.
• to help prevent kidney transplant rejections, what 2 precautions are taken?

  • a donor with a tissue type that closely matches the patient is chosen.
  • the patient is treated with drugs that suppress the immune system, so that the immune system won't attack the transplanted kidney.
• what is a dialysis machine?

  it contains fluid that is designed to have the optimum concentrations of salts and glucose, as would be found in a healthy person's blood.
• how does dialysis work?

  the patient's blood passes over a partially permeable membrane in the machine that is designed to replicate the kidney tubules. The dialysis fluid is on the other side of the membrane. A concentration gradient is established, allowing excess ions and urea to diffuse from an area of high concentration in the patient' blood to an area of low concentration in the dialysis fluid.
• during dialysis, when might there be tissue damage?

  if the concentrations of urea and salts are too far away from the optimum.
• during dialysis, a patient's blood goes from concentrated to dilute.
• what are the advantages of dialysis?

  it's a life saving process that gives a patient more time to find a transplant donor.
• what are the disadvantages of dialysis?

  lasts 3-4 hours and is needed 3 times a week. It increases the risk of blood clots and infection and is expensive.
• can people have a kidney transplant from a dead person?

  if they have recently died and they are a tissue match then yes.
• why would a patient choose to have a kidney transplant from a close relative?

  they have a higher chance of being a tissue match.
• what are immunosuppressants?

  patients recieving a donor kidney often have to take these drugs for the rest of their lives. These drugs suppress the immune system to prevent it from attempting to destroy the foreign cells of the transplanted kidney.
• what are the advantages of kidney transplants?

  the patient doesn't need dialysis treatment, which is time consuming and they are cheaper in the long run.
• what are the disadvantages of transplants?

  the kidney may be rejected by the body, there can be a long waiting list and the patient will have to take immunosuppressant drugs which makes the patient prone to other infections.
• what is caused by adrenaline?

  • increased blood pressure
  • increased heart rate
  • pupil dilation