B5 Homeostasis and response Flashcards
what is homeostasis
regulation of the conditions inside your body that regulate your internal environment
what are the 4 key components of the nervous system
1) the CNS
2)sensory neurons
3) motor neurons
4) effectors
what is the role of a sensory neuron
to carry information as electrical impulses from the receptors to the CNS
what is the role of a motor neuron
neurons that carry electrical impulses from the CNS to effectors
what is the role of an effector
responding to nervous impulses
what is the role of a receptor
to detect stimuli
what is the CNS
a coordination centre. it recieves information from the receptors and then coordinates a response.
what is a reflex action
a rapid automatic response to certain stimuli that don’t involve conscious parts of the brain.
describe what happens in the reflex arc ( 5 steps)
1) the neurons in reflex arcs go through the spinal cord or through an unconscious part of the brain
2) when a stimulus is detected by receptors impulses are sent along a sensory neuron to the CNS
3) when the impulses reach a synapse between the sensory and relay neurons, they trigger chemicals to be released. these chemicals are sent along the relay neuron,
4)when the impulses reach a synapse between the relay and motor neuron the same thing happens. chemicals are released and send impulses along the motor neuron
5) the impulses then travel along the motor neuron to the effector
describe a negative feedback loop
1) temperature receptors detect that body temperature is too high/low
2) the thermoregulatory centre acts as a coordination centre. it recieves information from the temperature receptors and triggers the effectors automatically .
3) effectors e.g sweat glands, produce a response and counteract the change
what are the 6 glands that make up the endocrine system
pituitary gland
thyroid gland
ovary
testes
adrenal gland
pancreas
what is the role of the pituitary gland
to produce hormones which regulate body conditions
what is the role of the thyroid gland
to produce thyroxine which is involved in regulating metabolism heart rate and temperature
what is the role of the adrenal gland
to produce adrenaline which is used to prepare the body for a fight or flight response
what is the role of the ovary
to produce oestrogen which is involved in the menstrual cycle
what is the role of the testes
to produce testosterone which controls puberty and sperm production
how is glucose usually removed from the blood
the metabolism of cells
how is excess glucose stored in the body
it is stored as glycogen in the liver and in the muscles
what happens when blood glucose is too high
insulin is secreted by the pancreas
the insulin bonds to turn the glucose into glycogen which is stored in the muscles
what happens when blood glucose is too low
the pancreas secretes glucagon. glycogen is then broken down into glucose which is then released back into the blood
what are the 4 hormones in the menstrual cycle
FSH
Oestrogen
LH
Progesterone
what is FSH and what is it used for
hormone produced in the pituitary gland, it causes the egg to mature in one of the ovaries in a structure called a follicle. it also stimulates the ovaries to produce Oestrogen
what is oestrogen and what is it used for
it is produced in the ovaries, it causes the lining of the uterus to grow and also stimulates the relase of LH whilst also inhibiting the release of FSH
what is LH and what is it used for
it is produced by the pituitary glad and stimulates the release of an egg (ovulation)
what is progesterone and what is it used for
it is produced in the ovaries by the remains of the follicle after ovulation. it maintains the lining of the uterus during the second half of the cycle. when the level of progesterone falls the lining breaks down. it also inhibits the release of FSH and LH
what are the two main hormones involved in a contraceptive pill and how do they prevent pregnancy
Oestrogen is used to prevent the release of an egg by inhibiting the release of FSH which stops the development of any eggs.
progesterone is used as it stimulates the porduction of a think mucus that stops any sperm getting through and reaching an egg
what are some side effects of an oral contracteptive pill
headaches
nausea
doesnt protect against STIs
have to remember to take it
what are three non hormonal types of contraception and how do they work
condoms - worn over the penis during sex to stop the sperm entering the vagina. they are the only form of contraception that porctect against STIs
Diaphragm - a shallow plastic cup that fits over the cervix to form a barrier. it has to be used with spermicide which kills the sperm
spermicide - can also be used alone however it is not as effective
what are some ways to avoid pregnancy that dont involve contraception
sterilisation - cutting or tying the fallopian tubes in females or the sperm duct in male. this procedure is permanent
‘natural methods’ - avoiding sex when the women is most fertile - this is not very effective
abstinance - the most effective way to avoid being pregnant is to not have sex in the first place
which hormones can be used to stimulate pregnancy
FSH and LH
How does IVF work
eggs are collected from the womens ovaries and are fertilised in a lab using womens sperm. on some occasions the sperm can be injected directly into the egg which is usually done when the man has a low sperm count.
the fertilised eggs are them grown into embryos in a lab incubator
once the embryos are tiny balls of cells one or two of them are transferred to the womans uterus to improve the chance of pregnancy.
FSH and LH are given before egg collection to stimulate several eggs to mature
what are the cons of IVF
- multiple births can happen if more than one embryo grows into a baby
- there is a low success rate (about 26%)
- it is very emotionally stressful and some women can have strong physical reactions to the hormones
why are some people against IVF
- people think its unethical because lots of embryos that are unused can be destroyed and each embryo is a potential human life
- the genetic testing involved could lead to the selection of preferred characteristics
what is the role of adrenaline
-adrenaline is a hormone released by the adrenal glands.
-it is released in response to scary or stressful situations - your brain detects fear or stress and –sends nervous impulses to the adrenal glands which respond by secreting adrenaline
if the body
- it gets the body ready for fight or flight by triggering mechanisms that increase the supply of oxygen and glucose to cells in the brain or muscles .
what is thyroxine
it is a hormone released by the thyroid gland
- it plays an important part in regulating the basal metabolic rate - the speed at which chemical reactions in the body occur while the body is at rest.
- it also stimulates protein synthesis for growth and developent
-
..
