homeostastis Flashcards
what is homeostasis
the maintenance of constant internal conditions
Normal body temperature?
37 degrees celsius
where is the thermoregulatory system
The thermoregulatory centre is in the hypothalamus of the brain
what is the use of thermoreceptors in the skin
they send impulses to the thermoregulatory centre sending information on skin temperature
what happens when youre core body temperature rises
This is detected by the thermoreceptors in the hypothalamus
Impulses are sent out from the hypothalamus to the body
blood vessels that supply the skin surface - capillaries - open wide - lets more blood flow through
Skin warms, so more energy is transferred to surroundings, cooling the body
Sweat glands produce more sweat and energy is used to evaporate it off. In humid conditions when it can’t evaporate, it is hard to cool down
what is vasodilation
vaso - vessels dilation - getting wider
What happens when core body temperature falls
- impulses are sent from the hypothalamus to the body
- vasoconstriction occurs
vasoconstriction = blood vessels that supply the skin cappillaries constrict (close up). This reduces blood flow through the capillaries and so reduces energy loss in the form of heat - Sweat production is reduced or stopped –> reduces the amount of energy lost from water evaporating
- Skeletal muscles contract and relax rapidly –> causes shivering
Muscle contractions need a lot of respiration, which is an exothermic process, so this raises body temperature
what is vasoconstriction
vasoconstriction = blood vessels that supply the skin cappillaries constrict (close up).
Why is CO2 bad?
CO2 produces an acidic solution –> this can be harmful as it affects the pH of the environment of enzymes, affecting their function
How is CO2 removed?
- CO2 diffuses out of the cell (where it is made via respiration) down a concentration gradient
- Diffuses from the blood to the air in alveoli
- This air is excreted when you exhale
A side effect of this is that water is also lost when moist air is breathed out.
what is urine?
Urine = urea dissolved in water
what is urea?
Urea = the waste product of deamination
what is deamniation?
Deamination = the process of excess amino acids being broken down in the liver
Why does urea need to be excreted?
Urea is poisonous –> if it accumulates, it will greatly damage cells
How is urea removed?
- Urea passes from the liver cells to the blood
- Filtered out of the blood by the kidneys
- Passed out of the body in urine, produced by the body with any excess water and salt
When is urea produced?
. when excess protein is eaten
2. muscle tissues are worn out
- Deamination occurs as excess protein cannot be stored
Process where water/minerals/urea loss cannot be controlled:
1. Sweat - lose water, mineral, urea
2. Water leaves the lungs when you exhale
Process where water/minerals/urea loss cannot be controlled?
- Sweat - lose water, mineral, urea
- Water leaves the lungs when you exhale
what is selective reabsorortion
This process where the body determined the varying amount of water or mineral ions reabsorbed is called selective reabsorption
wha size molecules that can be filtered through the kidney
ALL small molecules are filtered out of the blood
what process must happen for reabsorption to happen
for ALL of the glucose to be reabsorbed back into the blood, diffusion AND active transport must take place
what happens when the body is dehydrated (urine)?
When the body is dehydrated, a lot of water molecules are also reabsorbed back into the blood
If a lot of water is reabsorbed, this would result in very concentrated urine
what happens when the body is hydrated
when the body is hydrated a lot more water molecules will not be reabsorbed into the blood
This means that the urine would be dilute
what is the use of the kidneys
ALL small molecules are filtered out of the blood, in the kidneys
Then, useful molecules, such as glucose, are reabsorbed back into the blood
what do osmoreceptors do
Osmoreceptors detect the concentration of solutes in the plasma –> this tells it how high or low water levels are
what happpens if the blood becomes too concentrated
If blood becomes too concentrated:
1.the pituitary gland releases lots of ADH into the blood
2.ADH binds to the kidneys and causes the kidney tubules to reabsorb a lot more water
3.Results in a small volume of concentrated urine
what happens if the blood becomes too dilute
If blood becomes too dilute:
1.the pituitary gland releases less adh into the blood
2.ADH binds to the kidneys and causes kidney tubules to reabsorb less water
3.this results in a larger dilute amount of urine released
what happens in dialysis (4 points)
blood of the patient is removed for cleaning
Anti-coagulant prevents any blood clots
new dialysis fluid is placed in the machine for fresh blood the dialysis fluid contains the right amount
of useful solutes so that when the blood passes through no diffusion occurs and no useful substances from the blood are lost
the dialysis machine also contains a semi-permeable membrane so it ensures that the substances that need to be filtered
are filtred
4. this process repeats so for every new batch of fresh blood dialysis fluid is removed and replaced
name 4 disadvantages of dialysis
Disadvantages of Dialysis:
You have to follow a carefully controlled diet
You have to spend long regular hours connected to it
As the next session approaches, the patient may tired
Over time it gets more difficult to keep the balance
what are the risks of kidney transplant
The risk with this: the patient’s immune system’s antibodies will attack the antigens on the donor organ
what are ways we can reduce the risks of kidney transplants
match organ donor with a similar tissue type to the patient
recipient is given immunosuppressants for the rest of their life –> this means that the patient’s immune system won’t reject the organ
what is a disadv of immunosuppressants
a disadv of immunosuppressants = prevenys patients from dealing effectively with infectious diseases (they can become more seriously ill from minor illnesses like the common cold because they won’t really have a proper immune system)
how long does an average kidney last
The average transplanted kidney lasts 1 year - at the end the patient goes back to dialysis and waits for a new kidney
what is one disadv of longterm dialysis
Long term dialysis is much more expensive than transplant and causes serious damage to the body
a kidney transplant means an almost normal life, however you need to constantly take immunosuppressants
