What is meant by homeostatis?
This means keeping the body in the same/a steady state.
How do the kidneys keep the body the same?
Kidneys keep water and ion concentration constant.
Why is body temperature kept the same?
The body is kept at 37o so that enzymes can work quickly, but do not denature.
How is blood glucose level kept the same?
The pancreas releases insulin when blood glucose rises, and glucagon when blood glucose falls.
What does a healthy kidney do?
A healthy kidney:
1. Filters the blood.
2. Reabsorbs all the sugar.
3. Reabsorbs as much water and ions as the body needs.
4. Releases urea, excess ions and water in the urine.
What is urea?
Urea is produced in the liver when excess protein is taken in. This cannot be stored so the protein is broken down in urea.
How is blood filtered in the kidneys?
How can kidney disease be treated?
Either by dialysis or transplant.
What is a dialysis machine?
A dialysis machine carries out the same job as the kidneys. It filters the blood using a partially permeable membrane, and restores the concentration of substances in the blood back to normal.
What is in dialysis fluid?
Dialysis fluid contains the same concentration of useful substances as the body needs (water, glucose and ions) so the substances do not diffuse into the dialysis fluid.
There is no urea in the fluid, therefore urea in the blood diffuses into the fluid and so is removed from the blood.
Why must immunosuppressants be taken after a kidney transplant?
The antigens on the donor organ may be attacked as the recipient's immune system sees the antigens as 'foreign'. Therefore immunosuppressant drugs must be taken to prevent rejection.
What are the advantages and disadvantages of using dialysis for kidney disease?
A- Available to all patients (no shortage).
A- No need for immunosuppressant drugs.
D- Patients must limit salt and protein intake.
D- Expensive for the NHS.
D- Regular dialysis sessions➡️Impact on the patient's life.
What are the advantages and disadvantages of having a kidney transplant?
A- Patients can lead a more normal without having to watch what they eat and drink.
A- Cheaper for NHS overall.
D- Must take immunosuppressant drugs which increase risk of infection.
D- Shortage of organ donors.
D- Kidney only lasts 8-9 years on avergae.
D- Any operation carries risk.
Where is blood temperature monitored?
Thermoregulatory centre in the brain (hypothalamus). This centre has receptors which detect the temperature of the blood flowing through the brain.
What happens when the body is too hot?
-Arteries supplying capillaries dilate (muscles relax). This increases blood flow into capillaries and near the surface of the skin to increase the amount of heat loss by radiation.
-Sweat glands secrete swear➡️Evaporation of sweat requires energy which comes from the skin's surface so cools the skin down.
What happens when the body is too cold?
-Arteries supplying capillaries constrict (muscles contract). This means less blood flows in capillaries and near the surface of the skin, so less heat is lost by radiation.
-We shiver (muscles contract quickly) which increases the rate of respiration and some energy released warms the blood.
-Hair stands erect➡️Traps warm layer of air (more in animals).
What happens if body temperature is not kept constant?
-If body temperature is too low the respiratory ezymes work too slowly and too little energy is released.
-If body temperature is too high enzymes can denature.
Why is insulin produced, and what does it do?
Insulin is produced when there is too much glucose in the blood.
Insulin converts glucose to glycogen for storage in the liver and muscles.
Why is glucagon produced, and what does it do?
Glucagon is produced when there is not enough glucose in the blood.
Glucagon converts glycagen back to glucose.
What causes type 1 diabetes and how is it treated?
If the pancreas is unable to produce enough insulin, the blood glucose level may become too high.
Type 1 diabetes is traditionally treated with human insulin produced by genetically engineered bacteria. The diabetic must inject themselves with insulin before meals.
What new methods are being developed to treat type 1 diabetes?
-Transplanting pancreas cells.
-Using embryonic stem cells to produce insulin secreting cells.
-Using adult stem cells from diabetic patients.
-Genetically engineering pancreas cells to make them work properly.
During exercise, why would the core body temperature increase?
Increased respiration, so more energy released.
During exercise, why would the skin surface temperature decrease?
Increased sweating (1) which evaporates and uses energy, so cools the skin (1).