Homeostasis and response Flashcards
What is homeostasis?
Regulation of the internal conditions of a cell or organisms to maintain optimum conditions for function in response to internal and external changes
How does thermoregulatory centre send electrical impulses to the centre?
Thermoregulatory has receptors which is sensitive to the temp of blood & skin also has receptors which send electrical impulses down sensory neurones to the centre
What is vasodilation?
When body temp is too high
What is vasoconstriction and what happens?
Body temp is low
Blood vessels constrict (narrow)
less blood flows and less heat is lost
and you start to shiver
What is the endocrine system?
Consists of number of glands and the glands secrete hormones into the bloodstream directly
Blood carries hormones around the body but each hormones acts on specific target organs and produces an effect
*Hormones acts slower but longer
What glands make the Endocrine system?
PITUATARY GLANDS
THROID GLANDS
ADRENAL GLAND
What happens when blood glucose is to high?
- Pancreas produces insulin into the bloodstream all around the body and triggers body cells to take up glucose from the blood
- Insulin can trigger liver and muscles cells to store excess glucose (glycogen)
What is type 1 diabetes?
- Pancreases does not produce enough insulin
- Results in uncontrolled high blood glucose levels
- Treated with insulin injections
What is type 2 diabetes?
- No longer respond to insulin
- Obesity as a risk factor
- Treated with carbohydrate controlled diet & regular exercise
What happens if the level of water in blood falls?
1) ADH travels to the kidney & kidney tubules become more permeable to water
2) So more water is reabsorbed from tubules back into the blood=less urine produced
What happens when the conc of water in blood rise?
Conc of blood rises & pituitary gland stops releasing ADH
*So kidney reabsorbs less water into the blood=more urine produced and conc of water is normal
Explain the process of kidney dialysis?
1)Patients blood passes over a semi-permeable membrane allowing urea, ions and water through but not large particles
2) urea diffuses from the blood into dialysis fluid & dialysis fluid is constantly refreshed.
*always is a large conc of
gradient for urea
What are advantage and disadvantage of Kidney transplant?
shortage of kidney donors-dis
Allows patient to have a normal life-adv
Anti-injection drug to be taken for rest of their life-dis
Where is auxin produced/what does light do?
1) Auxin is produced at the very tip of the roots(auxin triggers cell growth)
2) Light causes auxin to concentrate on the darker side of the shoot tip
What is gravitropism?
roots grow towards force of gravity, involves auxin and is produced in the roots
Name 2 plant hormones
GIBERELLINS-start the germination of seeds
ETHENE-Control cell division and ripening of fruit
What do you do to start the practical for newly germinated seeds?
1) take a number of small plastic boxes and make a hole on one side .All holes must be the same side
2) Put some soil in the container and plant 10 crest seeds
What does homeostasis control?
- body temp
- Blood glucose conc
- water and ion levels
Where is the thermoregulatory system ?
Normal human temp is 37
Control of body temp is in the brains
What happens when you body temp is too high?
Sweat glands release sweat on the surface of the skin
- Sweat evaporates and takes energy from the body and cools the body down
- Blood vessels widen, directing more blood to the surface of the skin
What happens when you shiver?
-Skeletal muscles contract to generate energy for the contraction the muscle cell increase their rate of respiration which release heat.
What does the pituitary gland do?
- In the brain
- Different hormones in the blood
- Act on other glands making them secret hormones this triggers a range of effects
What does the thyroid gland do?
*increases metabolic rate
Controls growth and development in young animals
*Controlled by negative feedback
What hormone does adrenal produce and when?
- Releases the hormone adrenaline which is produced in times of fear and stress
- Prepares body for fight or flight
What does adrenal gland do?
*Increases heart rate, oxygen and glucose goes to the brain and muscles
What happens when blood conc is to low?
pancreases releases glucagon
*Glucagon stimulates glycogen to be converted into glucose and released into the blood
Where is blood glucose controlled and monitored?
in the pancreases
What hormone is released when water in blood levels falls?
pituitary gland releases the hormone ADH in the blood stream
When does pituitary gland stop releasing water?
3)*Amount of water in the blood rises back to its normal level and pituitary gland stop releasing ADH
What are the disadvantage of kidney dialysis?
- Inconvenient
- Visit hospital 3 time a week
- Controlled diet
- Expensive
What are the advantages of kidney dialysis?
No shortage of dialysis machines
What does dialysis fluid contain?
normal conc of water and ions but no urea
Why does the root auxin stop cell growth?
so lower side now grows more slowly than the upper side
How does the shoot grow towards the light?
3) Auxin spreads down the shoot
4) Cells on the darker side grow faster than cells on the lighter side-causing the shoot to grow towards the light
What are the variables for the practical?
CV-number and type of seeds
IV-position of hole
DV-Direction of which the seeds grow
What do you do after planting the crest seeds?
3) Put the lid on and leave in even lighting with the holes pointing at different directions
4) Water the soli leave for several days
What is the difference between positive/negative gravitropism?
POSITIVE-towards the ground
NEGATIVE-Grows away from the ground
What is the difference between positive/negative phototropism?
POSITIVE-towards the light
NEGATIVE-away from the light
What happens if the kidney produces little urine?
cell swells and becomes damaged
What organ produces urea/why do people drink sports drinks before a race?
liver
Have sports drink to replace water / ions / salt (that is) lost in sweat
