Topic 12 - Role of the Kidneys in Homeostasis Flashcards
What is the function of the excretory system?
To remove cellular waste (CO2 + urea), filter blood and control water content in the body
What is urea?
Excess amino acids broken down in the liver to form ammonia which bonds with CO2 in a process called deamination
Why is deamination important?
Urea/Ammonia can be toxic to the body and is very soluble
What is ultrafiltration?
When high-pressure blood is filtered of salts, water, urea, amino acids and glucose in the glomerulus and Bowman’s capsule
What is selective reabsorption?
When useful substances are reabsorbed into the blood in the nephron
What is excretion?
When water, urea and excess salt goes to the ureter (via the collecting duct) and then the bladder
What makes up the excretory system? (8)
Aorta, Vena Cava, Renal Artery, Renal Vein, Kidney, Ureter, Bladder and Urethra
What makes up the kidney?
Cortex, Pelvis, Medulla, Ureter, Renal Vein, Renal Artery
What does the presence of urea in the blood or cells indicate?
Disease in the kidney
What does the presence of glucose in the kidney indicate?
Diabetes
What does the presence of blood or glucose or proteins in urine indicate?
Disease in the kidney
Why is a blood thinner used in dialysis?
To prevent clotting
What is the role of the dialyser?
Removes waste products from the blood by filtration
What is dialysis fluid?
A fluid without salt and urea that flows in the opposite direction to the blood in the dialyser
What is dialysis tubing?
Strands of tubing with a large surface area and a semi-permeable membrane to maximise osmosis/diffusion of salt, water and glucose from high to low concentration
Why is a bubble trap used?
To prevent air from getting into the bloodstream
What are the advantages of dialysis?
- Survival
- Allows for a wait
What are the disadvantages of dialysis?
- Must be checked often
- Uncomfortable (12 hours a week)
- Disrupt social/work life
- Possibility of infection
- Rigid diet
- Impermanent
What are the advantages of transplants?
- No toxin build-up
- No high blood pressure
- No blood clotting
- Survival
What are the disadvantages of transplants?
- Expensive operation
- Immunosuppressants/Rejection
- Availability of donors/Right tissue type
- Infection/anaesthetic
- Payment for donors (ethical issues)
What is the hormone that controls osmoregulation?
Anti-Diuretic Hormone
From where is ADH released?
Pituitary gland
What suppresses ADH production?
Alcohol (leading to dehydration)
What increases ADH production?
Ecstasy (leading to overhydration)
What happens when there is too much salt or sweating?
Low water content -> More ADH -> High volume reabsorbed by kidney -> Low volume, concentrated urine
What happens when too much water is drunk?
High water content -> Less ADH -> Low volume reabsorbed by kidney -> High violume, dilute urine
What is rejection?
When the body’s immune system attacks the foreign cells of a donated kidney -> immunosuppressants must be taken
