homeostasis and response Flashcards
what is homeostasis?
maintaining internal conditions of a cell or organism, in response to internal and external changes
what does the body control?
blood glucose concentration
water levels
body temperature
what are receptors?
cells which detect stimuli (changes in environment)
what do coordination centres do?
they receive and process information from the receptors
what do effectors do?
they bring about responses which restore optimum levels.
what does the nervous system do?
enables humans to react to their surroundings and coordinate their behaviour.
what does the information from receptors pass along as?
cells(neurones) as electrical impulses to the cns
what is the CNS?
the brain and spinal cord
what does the CNS do?
coordinates the response of effectors which may be muscles contracting or glands secreting hormones.
reflex actions
automatic and rapid responses which dont involve the conscious part of the brain
what does the brain do?
control complex behaviour
what are the 4 main areas of the brain?
cerebellum
cerebrum
medulla
hypothalamus
cerebellum
controls balance,coordination of movement and muscular activities
cerebrum
split into two hemispheres and is highly folded.controls intelligence,personality, conscience and high level functions
medulla
controls unconscious activities
hypothalamus
the regulating centre for the temperature and water balance within the body
what is the endocrine system?
its composed of glands which secrete chemicals (hormones) into the bloodstream
what does the pituitary gland do?
secretes hormones in response to body conditions.(some of the hormones act on other glands to stimulate other hormones)
adrenaline
produced by adrenal glands during times of fear or stress.
prepares the body for fight or flight
thyroxine
produced by the thyroid gland.
increases metabolic rate,controls growth and development in young animals.
controlled by negative feedback
blood glucose concentration
monitored and controlled by the pancreas
responses to high blood glucose concentration?
-the pancreas produces more insulin(insulin causes the blood to move from the blood into the cells.
-the excess insulin in liver and muscles is converted to GLYCOGEN for storage.
responses to low blood glucose concentation?
-the pancreases releases GLUCAGON
-GLUCAGON stimulates GLYCOGEN to be converted into glucose and be released into the blood.
type 1 diabetes
-caused from the pancreas not producing enough insulin.
-results in uncontrolled high blood glucose levels which are treated with insulin injections.
type 2 diabetes
-caused from the body not responding to insulin.
-obesity is a risk factor
-treated with a healthy diet and regular exercise
how does water leave body?
via the lungs during exhilation
what is lost from the skin in sweat?
-water
-ions
-urea
there is no control over…
water, ions or urea loss by lungs or skin
excess … are removed via … in the …
-water, ions and urea
-the kidneys
-the urine
what happens if body cells lose or gain too much water by osmosis?
they don’t function efficiently
what does the digestion of proteins from food result in?
excess amino acids
in the liver what happens because of this?
excess amino acids are converted to ammonia in a process called DEAMINATION
ammonia is ?
toxic so its converted to urea for safe excretion.
the kidneys produce urine by:
-filtering the blood
-selective reabsorption of useful substances (glucose,ions,water)
what are water levels in the body controlled by?
ADH
ADH?
-released by the pituitary gland when the blood is too concentrated
-it passes in the blood, to the kidney tubules where it causes more water to be reabsorbed back into the blood.(controlled by NEGATIVE FEEDBACK)
kidney failure
-treated by organ transplant or kidney dialysis
dialysis
-a machine which takes over the role of the kidneys
-used to remove waste products from the blood
(3x a week)
oestrogen
the main female reproductive hormone produced in the ovary.
ovulation
when eggs begin to mature and one is released
approximately every 28 days.
testosterone
the main male reproductive hormone produced by the testes and it stimulates sperm production.
Follicle stimulating hormone
causes maturation of an egg in the
ovary
Luteinising hormone
stimulates the release of the egg
Oestrogen and progesterone
involved in maintaining the uterus
lining.
3 hormonal and non hormonal forms of contraception
oral contraceptives( contain hormones to inhibit FSH production so that no eggs mature)
injection, implant or skin patch ( slow release progesterone to inhibit the maturation and release of eggs for months or years)
barrier methods( condoms and diaphragms which prevent the sperm reaching an egg)
doctors may give..
FSH and LH in a ‘fertility drug’ to a woman. She
may then become pregnant in the normal way.
