B3.3 Homeostasis Flashcards
Where is urea produced?
in the LIVER
What happens if the water or ion content of the body is wrong?
too much water may move into or out of the cells and damage them
Then do water and ions enter the body?
When we eat and drink
Describe how a healthy kidney produces urine
- filters the blood
- reabsorbs all the sugar
- reabsorbs dissolved ions needed by the body
- reabsorbs as much water as the body needs
- releases urea, excess ions and water as urine
What are the 2 ways that people who suffer from kidney failure can be treated?
dialysis
kidney transplant
Describe how kidney dialysis works
in a dialysis machine, a person’s blood flows between partially permeable membranes.
The dialysis fluid contains the same concentration of the useful substances as the blood.
This ensures that glucose and useful mineral ions are not lost. Urea passes out from the blood into the dialysis fluid
What are some disadvantages and advantages of kidney dialysis?
it restores the concentrations of dissolved substances in the blood to normal levels
readily available, no waiting list
it has to be carried out at regular intervals
may cause blood clots or infection
Describe a kidney transplant
a diseased kidney is replaced with a healthy one from a donor
What are some disadvantages of kidney transplants
- lack of donor organs
- kidney may be rejected by the immune system unless precautions are taken
Describe why a kidney may be rejected
immune system produces antibodies
which attack the antigens on the transplanted kidney
How can you prevent rejection of a transplanted kidney?
- A donor kidney with a ‘tissue-type’ similar to that of the recipient is used
- The recipient is treated with drugs that suppress the immune system
What monitors and controls body temperature?
the thermoregulatory centre in the brain
Describe the thermoregulatory centre in the brain
it monitors and controls body temperature
It has receptors sensitive to the temperature of blood flowing through the brain
temperature receptors in the skin send impulses to the thermoregulatory centre, giving information about skin temperature
What happens if the core body temperature is too high?
blood vessels supplying the skin capillaries dilate so that more blood flows through the capillaries and more heat is lost (easier for heat to be transferred from the blood to the environment) - This is why the skin looks red when we are hot
Sweat glands release more sweat which cools the body down as it evaporates
Describe what happens if the core body temperature is too low?
- Blood vessels supplying the skin capillaries constrict to reduce the flow of blood through the capillaries
- Muscles may ‘shiver’- their contraction needs respiration, which releases some energy to warm the body
What controls the blood sugar concentration of the body?
the PANCREAS
Describe how the pancreas controls blood sugar levels
- produces a hormone called INSULIN which allows the glucose to move from the blood into the cells
- produces GLUCAGON when blood glucose levels fall. This causes GLYCOGEN to be converted into GLUCOSE and be released into the blood
What temperature do enzymes in the body work most effectively?
37 degrees
Describe type 1 diabetes and how it can be controlled
it is a disease in which a person’s blood glucose concentration may rise to a high level because the pancreas does not produce enough of the hormone insulin
it can be controlled by careful attention to diet, exercise and by injecting insulin
can have a pancreas transplant- problems of rejection ect
What is homeostasis?
the maintenance of a constant internal environment
What happens if someone with kidney failure is not treated?
may die because toxic substances accumulate in their blood
What 4 things does the body need to monitor?
body temperature
water content
ion content
blood sugar
What are 2 waste products that have to be removed from the body?
carbon dioxide- produced by respiration and removed via the lungs when we breathe out
urea- produced in the liver by the breakdown of amino acids and removed by the kidneys in the urine, which is temporary stored in the bladder
How is insulin for diabetics made?
genetic engineering
What helps to remove glucose from the blood?
vigorous exercise
What are some symptoms of kidney disease?
accumulation of toxins in blood
protein and blood in urine
Give 3 functions of the kidney
- maintain correct water concentration of the blood
- maintain correct ion concentration of the blood
- Production of urine to remove urea
What hormone is released when blood sugar levels are too high and what effect does this have on the body?
insulin
allows glucose to move into cells for respiration
and allows glucose to move into the liver where it is converted into glycogen
What hormone is released when blood sugar levels are too low and what effect does this have on the body?
Glucagon
causes glycogen in the liver to be converted to glucose and released into the blood
What happens if there is too much carbon dioxide in the blood?
makes the blood become acidic- denatures enzymes
What happens if there is too much urea in the blood?
poisons cells
Where is urea made and what is it is product of?
a product of the breakdown of amino acids in the liver
What are some advantages of a kidney transplant?
no need to control diet
high success rate
What should someone do if they are losing a lot of sodium (salt) through sweating?
Eat more food which contains sodium - (increase intake of sodium)
stay indoors + be less active so they sweat less
Suggest why someone may overheat in humid conditions
sweat is released
but it can not evaporate because of the high humidity
so less heat is lost (less cooling)
as it is the evaporation of sweat that cools the body
Explain why the levels of glucose in the blood increase if someone has not eaten for a long period of time
because glucagon (made in the pancreas) causes glycogen in the liver to be converted into glucose
glucose is then released into the blood stream
Describe the processes that prevent glucose being excreted in the urine
glucose is filtered out of the blood by the kidneys
the filtered glucose is then taken back into the blood (reabsorbed) by active transport
Explain why someone with kidney disease has protein in the urine but someone who does not have kidney disease has no protein in the urine
in a healthy person, protein is not present because protein molecules are large and so they can not pass through the filter in the kidneys
in a person with kidney disease, the protein allows protein through
What are some advantages of a kidney transplant over dialysis and some disadvantages?
advantages of transplant over dialysis:
keeps blood concentration constant, prevent high blood pressure, don’t need to restrict diet,dialysis may cause blood clots, transplant is cheaper
disadvantages of transplant over dialysis:
problems finding tissue match, rejection, dangers during operation, require immuno-suppressant drugs
Describe how the brain monitors body temperature
exam answer = learn
thermoregulatory centre has receptors which monitor blood temperature as it flows through the brain
temperature receptors in the skin send impulses to the brain
Why is drinking sports drinks bad for people with diabetes?
sports drinks contain a lot of glucose
a person with diabetes does not produce enough insulin
so blood glucose levels will rise too high
During exercise, why does the core body temperature increase?
due to increased respiration + muscle contraction
which releases energy
During exercise, why does the skin temperature decrease?
sweating
sweat evaporates and cools the skin
Describe how the body responds when the blood glucose concentration begins to decrease
pancreas detects low blood glucose
produces glucagon
glycogen is converted into glucose
