Kidneys Flashcards
What is the function of the renal vein?
takes “cleaned” blood away from kidneys
What is the function of the aorta?
main artery supplying oxygenated blood to body
What is the function of the renal artery?
brings blood containing “waste” to the kidneys
What is the function of the urethra?
carries urine out of the body
What is the function of the ureter?
carried urine to the bladder
What is the function of the bladder?
muscular sac that stores urine (~700cm³)
What is the function of the sphincter muscle?
keeps bladder closed
What is the function of the medulla?
lighter middle layer of kidney
What is the function of the pelvis (kidney)?
central cavity which collects urine
What is the function of the cortex (kidney)?
darker outer layer
What is the function of the nephron?
filtration unit (where urine is produced)
What is the function of the vena cava?
main vein returning blood to the heart
How is waste removed throughout the body?
- Mouth (exhalation) - carbon dioxide and water.
- Skin (sweat) - urea, water and salt.
- Kidneys (urine) - urea, water and salt.
Why do we need to remove urea, water, and salt?
- Urea is toxic.
- Excess water has an osmotic effect.
- Excess salt (mineral ions) has an osmotic effect.
How does drinking water affect urine production?
- A high water concentration in the blood is bad because it can go into the body cells and make them explode.
- Urine volume increases, so the blood water concentration drops.
How does being thirty affect urine production?
- Low water concentration in the blood is bad because water then leaves the cells.
- The urine volume decreases, so the blood water concentration increases.
How does eating salty food affect urine production?
- High solute concentration in the blood is bad because water leaves the cells and so they shrink.
- The urine volume decreases, so the blood water concentration increases.
Why does the blood become deoxygenated in the PCT?
• Active transport happens in the PCT, and that requires energy. The energy comes from respiration, which requires oxygen. The oxygen is taken from the blood and therefore the blood becomes deoxygenated.
What happens when one eats a meal with protein?
- The protein is broken down into amino acids.
- The amino acids go through the ileum and most are taken to the cells.
- The excess amino acids are taken to the liver and become urea.
Where does ultrafiltration take place?
• The glomerulus and Bowman’s capsule.
What happens during ultrafiltration?
- Uncleaned blood arrives at a high pressure in the glomerulus.
- Small molecules are squeezed through gaps in the wall of the glomerulus and the Bowman’s capsule.
- Large molecules and cells stay in the blood as they are too large to fit through the gaps.
- The result is a filtrate contains small molecules and there is filtered blood containing large molecules.
Where does selective reabsorption take place?
• In the proximal convoluted tubule (PCT).
What happens during selective reabsorption?
- Useful molecules such as glucose, amino acids and salt are re-absorbed into the bloodstream by active transport.
- Some water moves back into the bloodstream by osmosis.
- Urea stays in the filtrate.
- The result is a filtrate containing urea.
Why do th cells lining the PCT have lots of mitochondria?
• Mitochondria have lots of energy (powerhouse of the cell), which is needed for active transport.
Why is urea not reabsorbed?
• The carrier proteins are specific to one molecule, and there are no carrier proteins for the urea.
Why would there be glucose found in the urine?
• If someone has diabetes, there will be too much glucose in their bloodstream because the insulin in their body is not effective. The PCT doesn’t have enough carrier proteins to take away the excess of glucose in the blood - not all the glucose is filtered out.
How does being thirsty affect ADH production?
- There is a low water concentration in the blood.
- Osmoreceptors in the hypothalamus detect this.
- Hypothalamus stimulates pituitary gland to release ADH.
- ADH works on the collecting ducts so that they are more permeable to water.
- More water is reabsorbed into bloodstream.
- Less urine is produced.
- Water concentration increases, no more ADH released.
How does drinking water affect ADH production?
- High water concentration in blood.
- Osmoreceptors in the hypothalamus detect this.
- Hypothalamus does not stimulate pituitary gland to release ADH.
- Collecting ducts are less permeable to water.
- Less water is reabsorbed into bloodstream.
- More urine is produced.
- Water concentration decreases, ADH is produced once we need it again.
How does eating lots of salty food affect ADH production?
- There is a high solute concentration in the blood.
- Osmoreceptors in the hypothalamus detect this.
- Hypothalamus stimulates pituitary gland to release ADH.
- ADH works on the collecting ducts so that they are more permeable to water.
- More water is reabsorbed into bloodstream.
- Less urine is produced.
- Water concentration increases, no more ADH released.
Why is kidney failure a threat to life?
- Urea is toxic - must be removed.
* Water and salt affect solute concentration, too much of either could have a bad osmotic effect.
How does a dialysis machine work?
- Uncleaned blood taken from a vein enters the dialysis machine and flows between dialysis membranes.
- Dialysis fluid contains salt, amino acids, glucose and water in normal blood concentration but no urea.
- Urea, excess salt and excess water diffuse from the blood through the selectively permeable membranes into the dialysis fluid.
- Dialysis fluid is discarded as waste while cleaned blood leaves the dialysis machine and travels back to the body.
Why is the blood taken from a vein rather than an artery into the dialysis machine?
- Veins have a lower pressure than arteries, so the blood flow speed can be controlled.
- Veins are closer to the surface and therefore more easily accessed.
Why is a warm water bath used for dialysis?
• The blood needs to return to the body at a normal temperature, otherwise the cold blood would kill you.
Why is there a blood thinner for dialysis?
• To ensure the blood doesn’t clot.
What are the disadvantages with kidney transplants?
- Lack of donors.
- Risk of rejection - patient has to be on immunosuppressant drugs for the rest of their life.
- Anti-rejection drugs mean that the patient will have a worse immune system - higher risk of infection.
