Homeostatis And Hormonal Control Flashcards
What are hormones
chemical messengers released by glands and into the bloodstream, where it’s carried to target cells or organs.
what is the endocrine system made up of
made up of glands which secrete hormones directly into the bloodstream to target cells
What does the endocrine system control
Water levels in blood
blood glucose levels
body temperature and metabolic rates
what do receptors do
detect change in stimuli
what do co-ordinators do
process information from receptors
what do effectors do
bring about responses
what glands does the endocrine system consist of
-pituitary glands (master gland)
- thyroid
-adrenal glands
-pancreas
-testes
-ovary
what does the pancreas secrete
Insulin and glucagon, to control blood glucose levels
what does the thyroid secrete
thyroxine, to control metabolic rate, heart rate and temperature of body
What kind of feedback are thyroxine levels controlled by
negative feedback
how are thyroxine levels kept relatively stable
by the pituitary glands that secrete TSH (thyroxine stimulating hormone)
What happens when thyroxine levels fall?
change is detected by the hypothalamus and more TSH is secreted by the pituitary gland, and more thyroxine is secreted
What happens when thyroxine levels rise?
Change is detected in hypothalamus, Less TSH is secreted from the pituitary glands, and less thyroxine is secreted.
Why do hormones only affect certain tissues or organs
Target cells in the certain tissue/organ have special chemical receptors for the particular hormone
Those who have an underactive thyroid may be what?
Overweight, since the rate of metabolism is slower
those who have an overactive thyroid may be what?
underweight, since the rate of metabolism is faster
what is diabetes
a non-communicable disease and there are two types
What is the cause of type 1 diabetes
it is genetic. The body’s immune system destroys any insulin producing cells. auto-immune disease. diagnosis tends to be in childhood/adolescence
Cause of type 2 diabetes
The body becomes resistant or no longer responds to insulin produced by the pancreas, leading to uncontrolled glucose levels.
treatment for type 1 diabetes
insulin injection
treatment for type 2 diabetes
-losing weight
-healthy or balanced diet
-exercising more often
3 ways of managing type 1 diabetes
-glucose sticks (where you urinate on it)
-glucose meter
-continuous glucose monitor (continuously monitors blood glucose levels and it is wearable
disadvantages of a glucose strip test
- the data it provides is qualitative -> the data is not numerical and can be subjective.
- Unhygienic as you need to collect a urine sample
- doesn’t measure current blood glucose levels
- you can’t do it in public
disadvantages of a glucose meter
people may have a fear of needles ( you need to have a blood sample)
advantages of glucose meter
quantitative data
gives an exact reading of blood glucose levels in numbers
Can be used anywhere
When doing an investigation on blood glucose levels, why must the person not eat within a certain amount of time
Food can cause blood glucose levels to change, affecting results (we don’t know the original blood glucose level)
excretion of waste - examples
carbon dioxide, urea, water and mineral ions
Why is carbon dioxide a waste product and how is it produced
Carbon dioxide is a product of aerobic respiration. It causes the blood to become acidic, affecting enzymes. it is removed by exhalation (gas exchange)
why is urea removed and how is it produced
The liver turns excess amino acids from proteins into ammonia. Ammonia is toxic, so it is converted into urea. A build up of urea can cause damage to cells.
The kidneys filter urea out of the bloodstream into urine or sweat.
why are water and mineral ions removed and how are they produced
water: product of aerobic respiration
mineral ions: excess in our diet, dissolved in water
They must be removed so cells don’t take up the water via osmosis and burst.
WATER POTENTIAL IN CELLS AND BLOOD MUST BE THE SAME, or body won’t function properly
how are water and mineral ions removed
by sweating, urination and exhalation.
what does digestion of protein result in
excess amino acids
The higher the BMI the ….?
the higher the BMI, the more likely you are to develop type 2 diabetes.
risk factor of type 2 diabetes?
obesity
Two ways of managing kidney failure
Dialysis
Transplant
What is dialysis
When a patients blood is drawn through a dialysis machine, where dialysis fluid runs over the blood, allowing urea to be diffused out
advantages of dialysis
-patient is kept alive
-patients blood is clean
-shorter waiting time for treatment
disadvantages of dialysis
-diet is restricted
- patients blood must be thinned
- higher risk of infection as the patient is punctured constantly
-more time spent in hospital
advantages of a kidney transplant
-donors can be alive so there’s a larger volume of donors
- no dietary restrictions
-concentration of urea is automatically controlled
single operation
-less visits to the doctor
-patient is kept alive
-flexible lifestyle
disadvantages of a kidney transplant
-risk of rejection
-tissue type of donor must be the same as the patient
-patient and donor need to take immunosuppressants for life
-long recovery from surgery
-risk of infection
what processes does the kidney do
-reabsorption
-filtration
-osmoregulation
-excretion
what happens during ultrafiltration
- glucose, mineral ions, water and urea all move from the blood and into the nephron.
- proteins, enzymes and antibodies which are too large remain in the bllood
what happens during reabsorption or selective reabsorption
- all glucose and amino acids are reabsorbed back into the blood
- volume of water and mineral ions reabsorbed back into the blood stream depends on what the body needs.
the water moves back via osmosis and mineral ions move back via active transport
what happens during excretion
all urea is excreted with excess water and mineral ions
what happens to cells if blood is too dilute
water from the plasma moves into cells via osmosis, causing cells to burst
what happens to cells if blood is too concentrated
water moves from the cells to the blood, causing the cells to shrivel up
what is osmoregulation
the control of water levels in the blood.
receptors detect change in water potential and instructs the pituitary glands to release more ADH
what is ADH and what does it do
Anti Diuretic Hormone and it makes nephron/kidney tubules more or less permeable, changing the volume of water being reabsorbed into the blood
describe what happens if the blood is too dilute
(osmoregulation)
- receptors detect that the water potential is too high and instructs the pituitary gland to release less ADH
-Kidney tubules become less permeable, so less water is reabsorbed back into the blood stream
-larger volume of dilute urine goes to bladder
describe what happens if the blood is too concentrated
(osmoregulation)
receptors detect that water potential is too low and instructs pituitary gland to release more ADH
- kidney tubules become more permeable, allowing more water to be reabsorbed back into the blood stream
-blood becomes less concentrated and more dilute.
explain how a kidney may be rejected during a transplant
- the immune system sees the kidney as a foreign body
-antibodies are produced
-antibodies bind to the antigens on the kidney’s surface and they bind, destroying the kidney
describe how a healthy kidney produces urine
- kidney filters urea, glucose, water, mineral ions and urea from the blood
- ALL glucose which was originally filtered out is reabsorbed into the blood stream
- some water and some mineral ions are reabsorbed to maintain a constant water level.
- urea, which is a toxic substance is removed by the kidneys and excreted in urine
why do plants produce hormones
to co-ordinate and control growth and responses to gravity
what stimuli are plants sensitive to
-light
-moisture
-gravity
what is a positive response
when growth movement is towards stimuli
what is a negative response
when growth movement is away from stimuli
what is phototropism
a plant’s response to light
SHOOTS
positively phototropic and negatively gravitropic
ROOTS
negatively phototropic and positively gravitropic
what is gravitropism or geotropism
a plant’s response to gravity
what happens to the roots and shoots if a plant pot is knocked over
the shoots still grow up and the roots grow down
what does an uneven distribution of auxin cause
uneven growth in the shoot
what do high levels of auxin cause
shoot cells to elongate, but auxin inhibits the growth of root cells.
what is auxin
a hormone responsible for the growth in plants
what light conditions does auxin distribute evenly in?
all round light or in the dark, causing the shoot to grow directly upwards
what happens if the light is unilateral (coming from one side)
auxin accumulates on the shaded side, causing the shoot cells to elongate and bend towards the light
uses of auxins
rooting powders
weed killers
uses of ethene
causes fruit to ripen
controls cell divison
uses of gibberellins
promotes flowering and seed germination
ends seed dormancy
increases fruit size
RP 8: independent variable
light condition or light intensity or direction of light
RP 8: dependent variable
height of seedlings
RP 8: control variables
number of seedlings
type of seedlings
temperature seedlings are kept at
volume of water given to seedlings
RP 8: METHOD 1
1) put cotton wool into 3 petri dishes and add same volume of water to each dish
2) add 10 seeds to each dish, evenly spread out and let them germinate
3) once seeds have germinated, ensure each dish contains the same number of seeds
4) place one dish where there is full light, one in complete darkness and one in partial light
5) measure height of each seedling everyday for one week and record results
6) calculate mean height of the ten seedlings for each day, and compare the mean heights in the 3 different light conditions
