homeostasis Flashcards
what is homeostasis
the regulation of the bodies internal conditions so the it can work at an optimum rate
what is a stimulus
a change in the environment
what organs form the censtal nervous system
the brain and the spinal cord
what is the cerebral cortex and its function
it is the folded outermost part of the brain and holds the information for language memory and consciousness
what is the cerebellum and its function
it controlls are balance and coordinates our movements and is found underneath the cerebral cortex
what is the medulla and its function
it controls our heart rate and breathing rate and other subconscious actions
how can you investigate the brain
- look at brain damadge and its affect on the person
- electrically stimulate certain areas of the brain
- use MRI scanning
what is the cornea
the transparent front of the eye that allows light to pass through
what is the lens
the function of the lens is to focus the light rays onto the retina at the back of the eye. the lens can change shape to focus on distant or near objects (acoomodation
what is the retina
the retina contains receptor cells for light intensity and colour which then sends electrical impulses down the optic nerve to the brain
what is the sclera
it is the white part of the eye which is the tough outer layer to protect the eye
what are the cilliary muscles and the suspensory ligament’s function
they allow us to focus on distant or near objests
what is the iris
the coloured part of the eye which controls the size of the pupil
what is the pupil
the pupil is the center of the iris which light passes through
how do we focus on near objects
the cilliary muscles contract and the suspensory ligaments relax causing the lens to become thicker and refreact light more
how do we focus on distant objects
the cilliary muscles relax and the suspensory ligaments contract causing the lens to become thin not refracting light as much
how can we correct hyperopia (long sighted)
people with long sight have no problem focussing on distant object. This is usually caused by have an eyeball that is too short whcih causes the light to be focussed at a point behind the retina . This can also be caused by having a lens taht is less elastic. hyperopia can be corrected using a convex lens
how can we correct myopia (short sighted)
people with short sight have no problem focussing on nearby object. This is usually caused by have an eyeball that is too long whcih causes the light to be focussed at a point infront the retina . This can be because the lens is too thick. myopia can be corrected using a concave lens
how does the body respond to having high temperatures
1) the sweat glands release sweat which evapotaes which takes energy out of the body
2) the body can cool itself through flushing. This is when the blood vessels supplying the capilaries dialate to increase amount of heat loss. this is called vasodilation
how does the body respond to having low temperatures
1) the body can cool itself through flushing. This is when the blood vessels supplying the capilaries constric to decrease amount of heat loss. this is called vasoconstriction
2) we also shiver. this constrics our skeletal muscles by increasing the rate of respiration
what are the differences between the endocrine system and the nervous system
the nervous system uses electrical impulses whereas the endorcrine system uses chemicals (hormones)
the nervous system uses neurones whereas the endocrine system uses the bloodstream
signaling in the nervous system is very fast whereas in the endocrine system it is very slow
what is the function of the thyroid gland
it is located in the neck and produces hormones involved in growth and in regulating the bodies base metabolic rate
what is the function of the adrenal glands
they are located above easch kidney and produce adrenaline in times of fear or stress
what is the function of the pituitary gland
it is located in the brain and releases a number of different hormones into the blood which affect other glands triggering a range of different effects in the body
what hormone is produced when the pancreas detects a rise in levels of glucose
insulin
what is the function of insulin
it triggers body cells to take up glucose from the blood and also triggers liver and muscle cells to store excess glucose in the form of glycogen
why does type 1 diabetes affect the body
it is because the person’s pancreas does not produce enough insulin causing a high blood sugar level
why does type 2 diabetes affect the body
it is because the patients body cells do not respond to the insulin
how does the body respond to low blood sugar levels
the pancreas releases the hormone glucagon t
what is deamination
when the liver breaks down excess amino acids into ammonia (this is then converted to urea)
how do the kidneys ensure that useful molecules do not get lost
they selectively reabsorb molecules into the bloodstream using active transport such as glucose and mineral ions
what is the function of testosterone
it stimulates the testes to produce sperm
what is the function of oestrogen and where is it produced
Stops FSH being produced (so that only one egg matures in a cycle). Repairs, thickens and maintains the uterus lining. Stimulates the pituitary gland to release LH.
what happens in ovulation
the uterus lining becomes spongy. then an egg travels down the fallopian tubes. if sperm is present the egg becomes fertilised and implants into the uterus wall. If not the egg and uterus lining are released
what is FSH
it causes the egg to mature in the ovary and stimulates the ovaries to release LH
what is LH
causes ovulation (an egg to be released)
what is the function of oestrogen and progesterone in the menstrual cycle
involved in maintaining the lining of the uterus
how do the reproductive hormones interact with eachother
first the pituitary gland releases FSH which travells to the ovaries to mature the eggs. FSH triggers the ovaries to produce oestrogen which causes the lining of the uterus to become thick and also stops the pituitary gland from releasing FSH and instead releases LH which triggers ovulation. Once the ovary has released its egg it triggers the pituitary glands to release progesterone wich stops the pituitary gland from releasing LH and FSH to prevent anymore eggs from being released
- FSH causes eggs to mature and triggers production of oestrogen.
- LH is released to trigger ovulation and causes release of progesterone to stop production of LH and FSH
how do oral contraceptive pills work
oral pills stop the body from producing FSH therefore inhibiting the eggs from maturing. These are very effective however needs to be taken daily and some have side effects such as breast cancer or blood clots and does not protect agains STD’s
how do hormonal contraceptives such as implants skin patches and injections work
these contain progesterone which stops egges from maturing or being released. These last for longer implants last for 3 years. The injection lasts for 3 weeeks and the skin patch lasts for a week.these do not protect agains STD’s
what are barrier methods and how do the work
these include condoms and diaphrams and provide a physical barrier to ensure the sperm does not reach the egg. There is not risks from STI’s or side effects. They however can break.
what is a spermicide
it is a chemical that can kill or disable sperm and can be paired with barrier methods to increase effectiveness
what is an IUD (intrauterine device)
it prevents embryos from implanting by releasing copper and some can release hormones to further reduce the chances of fertilistation. This has very few side effects however does not preotect the user from STI’s.
what is steralisation
in women it prevents the egg from reaching the uterus and in men prevents the sperm leaving the penis. This is very difficult to reverse and does not protect from STI’s
how can infertility be solved in women
take an injection containing LH and FSH to cause the woman to ovulate more
what are the disadvantages of IVF
IVF is expensive
low succes rates
emotionaly stressfull
physically demanding
can lead to multiple births
not all of the embryos are transferred
what is the independant, dependant and control variables in the plant hormones practical
indpendant - light intensity
dependant - height of seedling
control varialbes - amount of seeds, water, temperature
how do we conduct the plant hormones practical
first place cotton wool in three petri dishes and soak them with water
then place 10 of the same type of seed in the cotton wool
then ensure that there is the same amount of seedling in each petri dish
then use a ruler to measure the height of the seedlings ensuring the stem is straight without damadging the seedlings
then place the seedling in different light intensities
what will happen to seedling in the dark
they will grow rapidly as seeds usually germinate underground trying to reach light
how can auxins be used
weedkillers
rooting powers
promoting growth in tissue culture
how can gibberellins be used
ending seed domancy
encouraging plants to flower
causes fruit to grow larger
how can ethene be used
One use is in bananas where they are transported before they are ripe and then ethene is used to ripen them
