Homeostasis Flashcards
What is homeostasis?
The maintenance of a constant internal environment,
What are the three main things the body keeps constant?
- Water and ion content
- Body temperature
- Blood glucose level
Why does carbon dioxide need to be removed from the body?
It is highly toxic in large quantities.
How is carbon dioxide removed from the body?
The blood carries it to the lungs where it gets breathed out.
What is urea?
The waste products from when excess amino acids are broken down and used to make fats and carbohydrates.
Why does urea need to be removed from the body?
It’s poisonous.
How is urea removed from the body?
The liver releases it into the blood stream an then the kidneys filter it out. It’s temporarily stored in the bladder in urine and then excreted.
What are the three functions of the kidneys?
- The removal of urea
- Adjustment of ion content
- Adjustment of water content
How do ions enter the body?
In food
How does water enter the body?
Food and drink
What are the three ways water is lost from the body?
- Urine
- Sweat
- Exhaled air
What are nephrons?
Tiny structures in the kidney that filter the blood and produce urine. There are thousands in each kidney.
What is stage one of urine production?
Ultrafiltration
What happens during ultrafiltration?
Blood from the renal artery enters the kidney. High pressure builds up in the blood vessels which squeezes water, urea, ions and sugar into an area called the capsule in the nephron.
Why aren’t proteins and blood cells absorbed during ultrafiltration?
They are too large to fit through the membrane between the renal artery and the capsule.
What is stage two of urine production?
Reabsorbtion
What happens during reabsorption?
- All glucose is reabsorbed using active transport
- Sufficient ions are reabsorbed using active transport
- Sufficient water is reabsorbed
What is stage three of urine production?
The release of waste products
What happens during the release of waste products?
The urea, excess ions and excess water go down the ureter to the bladder to be stored as urine. The urine is then excreted when it reaches a certain level.
What two treatments are available for kidney failure?
Dialysis and transplant
What is dialysis?
A treatment in which a dialysis machine takes over the role of a failing kidney to filter the blood.
Why does dialysis need to happen regularly?
To keep the concentrations of dissolved substances in the blood at normal levels.
How does a dialysis machine work?
1) The patient’s blood flows alongside a partially permeable membrane surrounded by dialysis fluid.
2) The partially permeable membrane allows the dissolved substances through that the kidney would.
3) Only the right amounts of water and ions diffuse across along with all the urea and the clean blood returns to the patient.
What enables the dialysis machine to only take the right amount of ions and water?
The dialysis fluid has the same concentration of dissolved substances as healthy blood so only the waste amounts will diffuse across.
What are five disadvantages of dialysis?
- Can require three 3-4 hour sessions a week
- Can cause infections and blood clots
- Restricted diet go patients too stop too much of one ion building up between sessions
- Patients have to limit fluid intake as kidneys usually regulate water content
- Expensive
What is a kidney transplant?
When a healthy kidney replaces someone’s diseased kidney.
Where do kidney donations come from?
- People who have died suddenly i.e. In a car crash
- Registered organ donors who die
- Living donors as we can survive with one kidney
What is rejection?
When antigens on a donated organ are recognised as foreign bodies by the immune system so the white blood cells produce antibodies to attack the donor cells.
What are two ways that rejection can be prevented?
- A donor with a similar tissue-type can be used
* Immunosuppressant drugs can be used to stop the body attacking the donated organ
What are four problems with kidney transplants?
- Rejection
- Immunosuppressive drugs can be dangerous
- Long waiting lists
- Operation-based issues
What temperature should the body be kept at?
37 degrees
What part of the brain controls your internal temperature?
The thermoregulatory centre
In what three ways does the body react to a high core body temperature?
- Hairs lie flat to trap less air
- Sweat is produced as evaporation removed heat
- Blood vessels dilate - take a path closer to the surface of the skin
In what four ways does the body react to a low core body temperature?
- Hairs stand up to trap an insulating layer
- No sweat is produced
- Blood vessels construct to reduce amount of heat from the blood emitted to the surroundings
- Shivering to instigate respiration which releases energy to warm the body
What happens when blood glucose gets too high?
1) The pancreas detects high blood glucose levels and secretes insulin into the bloodstream
2) Insulin instigates the liver to take in glucose as its stored form - glycogen
3) Blood glucose level falls
What happens when there is not enough glucose in the blood?
1) The pancreas detects low blood glucose levels and secretes glucagon
2) Glucagon causes the glycogen in the liver to be converted back into glucose
3) Blood glucose level rises
What is type one diabetes?
When the pancreas cannot produce any/enough insulin.
What three ways is type one diabetes controlled by?
- Limit intake of simple carbohydrates as they cause a sharp rise in glucose levels. Starchy carbohydrates take longer to break down so are encouraged
- Regular exercise
- Insulin therapy
What is insulin therapy?
When insulin is manually injected into the blood stream to make sure excess glucose is being stored.
What two things determine how much insulin someone needs to inject during insulin therapy?
Diet and exercise
What are two modern treatments to type one diabetes?
- Pancreas transplant
* Artificial pancreases and stem cell research
