biology paper 2 - b10 and b11

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what is homeostasis
the process of maintaining a constant internal environment
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why is homeostasis important
to maintain optimum conditions for enzyme actions and all cell functions
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what does homeostasis rely on
it relies on automatic control systems, such as nervous system, hormones and body organs
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what are some examples of internal conditions
water content, body temp, blood glucose concentration
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how does excess water leave the body
removed in the urine by the kidneys
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how else is water removed
sweating and breathing
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why must the core body temp stay constant
so the enzymes work properly
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what is the energy source for cells
glucose
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what organ controls the level of blood glucose
the pancreas
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what do control systems consist of
receptors, coordination centres and effectors
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what are recpetors
they detect stimuli in external/interal enviroments. the receptor cells may be part of the nervous system or hormonal control system
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what is a coordination system
areas that recieve/process info from receptors, send out signals and coordinate the response of body, like the brain, spinal cord and pancreas
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what are effectors
they are muscles/glands that bring about responses to the stimulus that has been recieved and the responses restore optimum conditions
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how does the nervous system detect stimuli
receptor cells
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where are receptor cells found
in sense organs like the eye, ear, nose, tognue and skin
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what stimulates the eye and what happens
light stimulates the receptors and electrical impulses pass to the brain along the neurons. other stimuli include sound, chemicals, temp changes, touch and pain
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how is the brain involved with the stimuli
the brain coordinates responses to many stimuli
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what is the central nervous system
the brain and spinal cord
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what is the role of sensory neurones
they carry impulses from receptors to the central nervous system
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what do nerves conatin
bundles of neurones
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what is the role of motor neurones
the carry impulses from the central nervous system to effectors that respond to the impulses, they may be glands or muscles.
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how do muscles respond to the impulses
contracting
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how do glands respond to impulses
secreting (releasing) chemicals
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summary of nervous system
stimulus > recptor > sensory neurone > coordinator (CNS) > motor neurone > effector > response
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why is the nervous system good
as it is a rapid response to allow your body to respond to your surroundings quickly
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meseauring reaction times - REQUIRED PRACTICAL
ruler drop test or digital sensors to measure how quickly you react to a visual stimulus
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what is the function of a relay neurone
in the CNS passes the impulse on
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what are reflex actions
automatic and rapid, don't ivolve the conscious parts of the brain
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what do reflexes involve
sensory, relay and motor neurones
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what is a synapse
a gap where the junction between two neurones is
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what is the sequence from the receptor to a effector called
reflex arc
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why are reflex actions important
to protect you from danger
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what is the role of the brain and what does it contain
made up of biliions of interconnected neurones and it recieves impulses from sensory neurones and coordinates the response. it controls complex behaivour and responsible for your thoughts and feelings and has different regions for different functions
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what is the function of the cerebal cortex
memory and thought
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what is the function of the cerebullum
movement, muscular activity
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what is the function of the medulla
unconcious activity- heartbeat and breathing
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what does the pituitary gland release
ADH
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how have scientists mapped the regions of the brain and linked them to particular functions
-studied patients with brain damage, electrically stimulating different parts, using MRI scanning technqiues to moniter brain activity after injury/ while doing a task
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what are some problems with the brain
delicate, complex means it is difficult to investigate and treat without causing uninteded damage. some drugs might not pass through membranes surrounding brain and surgery is difficult as some areas and their functions are not fully understood yet
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what is the sclera
the tough, white outer layer that prevents damage to the eye
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what is the cornea
transparent area at front of sclera, it lets light into the eye, the curved surface of cornea changes the direction ofl ight rays so they are refracted towards the retina
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why do the muscles of the iris contract and relax
to control pupil size, the hole that which the light enters the eye
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what happens to the pupil in dim lighting
the pupil is enlarged to let in as much light as possible
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what happens to the eye in bright lighting
the iris makes the pupil small, reduces the amount of light entering.
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how could 'too much light' damage your eye
damage the receptor cells in the retina
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what is the lens
a clear disc, held in place by suspensory ligaments and the ciliary muscles. the lens changes direction of light so the image is focused of the retina
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what do the sensory ligaments and ciliary muscles do
they hold the lens in place
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what happens when light hits the retina
the light sensitive cells are stimulated,which send impulses to the brain along the sensory neurones in the optic nerve and when the brain recieves theseit interprets them as a visual image
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what is the retina
at the back of the eye, is a special light sensitive layer
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what is a blind spot
the point where the optic nerve leaves the eye has no retina
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what happens if the the light is focused infront or behind the retina
the image will be blurred
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what process is used to focus light
refraction
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how can the shapes of the lens be changed
by the contraction or relaxation of ciliary muscles
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what does the change in lens shape affect
it affects the amount the lens refracts the light
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how is an image formed on the retina
upside down
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what does the optic nerve do
carries impulses from the retina to the brain
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to focus on distant objects
ciliary muscles - relax so suspensory ligaments tighten and lens pulled flat/thin. it only refracts light rays slightly so focused on retina
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to focus on near objects
ciliary muscles contract, so suspensory ligaments loosen. the lens is thicker/curved it refracts light rays strongly so focused on the retina
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what happens to peoples lenses as they age
they get harder, and cannot focus easily on close objects
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myopia
short sighted- can see close objects clearly, not far away. the light is focused in front of the retina, this may be because the lens is too curved or particuarly long eyeball.
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how can myopia be treated
glasses with concave lens, spreading out the light from distant objects before reaching the eye
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hyperopia
long sighted - can see far away clearly, not close. this may be becayse the lens is too flat/thin or the eyeball is particularly short. therefore the lens cannot refract the light rays strongly enough and the light is rocused behind the retina.
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how can hyperopia be treated
by wearing glasses with convex lenses which brings the light rays together before they reach the eye and the thinner lens can focus the light perfectly on the retina
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contact lenses
hard contact lenses are made of rigid material and last a long time, removed overnight and kept sterile to prevent infections. soft conytact leses, worn every day for month, left in sterile solution overnight, and some are disposable
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laser eye surgery
adults only, as eyes have stopped growing/stable vision. treats myopia by reducing thickness of cornea, refracts the light less strongly, nowthe lens focuses distant light on retina, not infront. and to treat hyperopia, chnages curve of cornea
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replacement lenses
add another lens inside the eye to correct visual defect permanently.
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replacement lens method 1
permanent contact lens implanted into eye, and natural lens is left in place
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replacement lens method 2
the faulty lens is replaced by an artificial lens
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risks of lens replacements
damage to retina, cataracts developing if natural lens remains, and infections
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what is the endocrine system made up of
glands that secrete hormones directly into the blood stream
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what role does the blood play in the endcrine system
it carries the hormone to the effector or taget organ/organs
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whta hormones can act rapidly
adrenaline and insulin
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whatnhormones are slow acting but have long lasting effects
growth and sex hormones
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how does a hormone travel from the endocrine system to the target organ
the glands secrete the hormone directly to the bloodstream which carries it to the organ
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what do the secreted hormones provide
they provide chemical coordination and control for the body
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what stimulates the ovaries to secrete oestrogen
FSH follicle stimulating hormone
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what stimulates the thyroid gland to secrete thyroxine
TSH
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what does the thyroid gland secrete
thyroxine
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what does TSH stimulate
the thyroid gland
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what does ADH affect
the amount of urine is produced by the kidney
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where is ADH produced
hypothalamus
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what gland produces serval hormones
pituitary gland
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what is the role of the thyroid gland
controls the metabolic rate of the body
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what is the role of the pancreas
controls and moniters the level of glucose in the body
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what is the role of the pituitary gland
controls child's growth, stimulates thyroid gland - thyroxine, in women it stimulates ovaries to produce and release eggs, and oestrogen and in males stimulates testes to make sperm and testosterone
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what do the receptors in the pancreas do
the detect the level of blood glucose
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what does the body do if there is too much glucose in the body
the pancreas produces insulin, which causes to lower it, as insulin causes glucose to move from the blood into the cells
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what does the body do if there is not enough blood glucose in the body
the pancreas will produce another hormone, glucagon, which causes glycogen in the liver to change to glucose which is released back into the blood
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what does glucagon do
it changed glycogen, in the liver to glucose which is needed in the blood
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type 1 diabetes
if the pancreas produces no/ little inulin the blood glucose level may become very high
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type 2 diabetes
devlops when the body does not respond to it's own insulin. obesity is a signifcant factor that can lead to type 2
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blood glucose too high
pancreas > insulin released > glucose taken in by cells > glucose converted to glycogen in liver
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blood glucose too low
pancreas > glucagon released > glycogen broken down > amino acids/fats broken down
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what is glucose
sugar used in respiration
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what is glycogen
a storage carbohydrate found in muscles and liver
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what is glucagon
a hormone that stimulates the liver to break down glycogen to glucose
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what does insulin do
allows glucose to move from blood into cells and stored as glycogen in liver and muscles
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what does glucagon interact with a what system
glucagon interacts with insulin in a negative feedback system
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what happens to your body without insulin
you kidneys will excrete glucose in your urine, and lots of it until, you feel dehydrated, glucose also can't get into the cells, and you then feel tired and have no energ, you will then break down fats/protein for fuel instead and loose weight
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how is type 1 diabetes treated
injecting insulin to replace the hormone that isn't made. glucose can be taken into cells, and converted into glycogen in the liver, stopping concentratration to get too high. then as it falls, glycogen back to glucose and it is stable
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what is insulin
a protein that is digested in the stomach
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how can type 1 be cured
pancreas transplant, difficult and risky, not enough donors for every patient and will have to take imunosuppressants
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what do you need to do if you have type 1 diabetes
levels of carbohydrates, regular meals, exercise to keep heart and blood vessels healthy. when exercising you need enough glucose to respire more rapidly to produce the energy required for muscles to work
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how do you treat type 2
regular exercise, balanced diet and controlled amounts of carbohydrates, loosing weigh, some drugs that help insulin work better, help pancreas make more insulin and reduce amount of glucose absorbed from gut
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what does the negative feedback system do
maintains a steady state, the response causes you to do the opposite. if something increases, changes take place to decrease it and restore to orignial level
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what does the thyroid gland use to produce thyroxine
iodine from your food
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what happens if levels of thyroxine falls
detected by sensors, so the amount of TSH released from pituitary gland increases, a negative feedback system, as thyroxine levels increases, it is detected, and TSH decreases to make it stable
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what does adrenaline cause
heart rate/ breathing increases, stored glucogen (liver) converted to glucose for respiration, pupils dilate more, mental awareness increases, once adrenaline is not produced everything else stops and returns to original, no negative feedback system
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which one involves a negative feedback system - adrenaline or thyroxine
thyroxine (metablic rate, how quickly your body breaks things down or is built up)
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how does the menstrual cycle work
each month, eggs begin to mature in the ovary and the uterus produces a thicker lining ready for pregnancy, every 28 days a mature egg is released from the ovary.
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what is ovulation
when a mature egg is released every 28 days
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what happens if the egg is not fertilised
the lining of the uterus, along with the egg, is shed around 14 days later
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what hormones control the menstrual cycle
FSH, LH, Oestrrogen and Progestorone
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what does the Follicle stimulating hormone do
it causes the eggs in the ovary to mature
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what does the luteinising hormone do
stimulates the release of an egg at ovulation
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what does oestrogen and progestorone do
stimulates the build up and maintainance of the uterus lining
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what is the male sex hormone and where is it produced
testosterone is produced in the testes
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FSH, where it is secreted, what is it's function
secreted by the pituitary gland, makes eggs mature in their follicles in ovaries and stimulates the ovaries to produce hormones such as oestrogen
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oestrogen, what is it, where is it secreted and due to what hormone, and what does it do
female repoductive hormone is made/ secreted in ovaries due to FSH. Oestrogen stimulates lining of uterus to grow again after menstruation, prep for pregnancy. also inhibits production of more FSH, stimulates release of LH, when Oestrogen is too high
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LH, where is it secreted, what does it stimulate and what happens to it when ovulation takes place
secreted by pituitary gland, stimulates release of a mature egg from ovary, and when ovulation happens the levels fall again
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progesterone, where is it produced, what is it's function, what does it inhibit
secereted by empty egg follicle in ovary after ovulation, it helps to maintain pregnancy if egg is fetilised, it also inhibits both LH and FSH. maintains the lining of uterus, ready to recieve a developing embryo if egg is fertilsied
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name two hormones produced by the pituitary gland that are involved when controlling the menstrual cycle
LH and FSH
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which hormone inhibits just FSH
Oestrogen
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what happens when oestrogen levels rise
productiong of FSH is inhitbited, LH production is stimulated, when this reaches it's peak, in middle of cycle, ovulation occurs
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what happens to the hormones and the lining of the uterus if the egg is not fertilised
the levels of all hormones fall, lining of uterus is lost from body. FSH is no longer inhibited, so level rises and stimulates oestrogen to be produced again
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Card 2

Front

why is homeostasis important

Back

to maintain optimum conditions for enzyme actions and all cell functions

Card 3

Front

what does homeostasis rely on

Back

Preview of the front of card 3

Card 4

Front

what are some examples of internal conditions

Back

Preview of the front of card 4

Card 5

Front

how does excess water leave the body

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Preview of the front of card 5
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