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coordination and response - Coggle Diagram
coordination and response
CNS
made up of neurons
consists of the brain and spinal cord only
when receptors in a sense organ detect a stimulus they send electrical impulses along sensory neurones to the CNS
the job of the CNS is to coordinate the response. coordinated responses always need a stimulus, receptor and effector
because neurones transmit information using very high speed electrical impulses, the nervous system is able to bring about very rapid responses
reflexes
reflexes help prevent injury
reflexes are automatic responses
for example if someone shines a bright light into your eyes, your pupils automatically get smaller to protect the retina
if you get a shock, your body releases adrenaline automatically-it doesn't wait for you to decide that you are shocked
the route taken by information in a reflex is called a reflex arc
the reflex arc goes through the CNS
the neurones in the reflex arc go through the spinal cord or through the unconscious part of the brain
when a stimulus is detected by receptors, an impulse is sent along a sensory neurone to the CNC
in the CNS the sensory neurone passes on the message to a relay neurone
relay neurones relay the impulse to a motor neurone
the impulse then travels along the motor neurone to the effector
the effector (muscle) then contracts and move your hand away from the stimulus (candle)
because you don't have to think about the response, the response time in much faster
the eye
parts of the eye
the conjunctiva
lubricates and protects the surface of the eye
sclera
the tough outer layer that protects the eye
cornea
refracts light into the eye. the cornea is transparent and has no blood vessels to supply it with oxygen to oxygen diffuses in from the outer surface
iris
controls the diameter of the pupil and therefore how much light can enter the eye
lens
focuses the light onto the retina
retina
has rods and cones that are sensitive to light. they are concentrated at the fovea
optic verve
carries impulses from the receptors to the brain
iris reflex
very bright light can damage the retina
very bright light triggers a reflex that makes the pupil smaller allowing less light in
this happens by: the circular muscles contract and the radial muscles relax making the pupil smaller
the opposite happens in dim light
focusing on near and far objects
distant objects
ciliary muscles relax which allows the suspensory ligaments to pull tight. this reduces the fluid pressure around the lens, making it flatter
this makes the lens thins
this refracts light less
near objects
ciliary muscles contract which slackens the suspensory ligaments. this also increases the fluid pressure around the eye making it rounder
the lens becomes more curved
this increases how much the light is refracted
hormones
adrenaline
adrenal glands
readies the body for a fight or flight response. increases heart rate
increases heart rate, blood flow to muscles and blood sugar levels
insulin
pancrease
helps control control blood sugar levels
stimulates the liver to turn glucose into glycogen
testosterone
testes
main male sex hormone
promotes male secondary sexual characteristics
progesterone
ovaries
supports pregnancy
maintains the uterus lining
oestrogen
ovaries
main female sex hormone
controls the menstrual cycle and promotes female secondary characteristics
ADH
pituitary gland
controls water content
increases the permeability of the collecting duct in the kidneys
FSH
pituitary gland
female sex hormones
causes an egg to mature in an ovary. stimulates the ovaries to produce eostrogen
LH
pituitary gland
female sex hormone
stimulates the release of an egg from the ovary
homeostasis
when you're too hot
lots of sweat is produced, when it evaporates it transfers energy from your skin to the environment, cooling you down
blood vessels closer to the surface of the skin widen, this is called vasodilation. it allows more blood to flow to the surface so it can transfer heat energy to the surrounding
hairs lie flat
when you're too cold
very little sweat is produced
blood vessels near the surface constrict this is called vasoconstriction. this means less blood flows to the surface
you shiver which increases your rate of respiration which transfers more energy to warm the body
haris standon end to trap an insulating layer of air which helps keep you warm
37 degrees C
all enzymes work best at a certain optimum temperature. this is about 37 C in humans
a part of your brain acts as a thermometer. it is sesnitive to the blood temp in the brain
based on the signals from this and receptors on the skin, the CNS can activate necessary effectors to make sure the body temp is correct.
responses in plants
Auxins are plant growth hormones
Auxins are plant hormones which control the growth at the tips of shoots and roots. they move through the plant in solutions
Auxin is produce at the tips and diffuses backwards to stimulate cell elongation process which happens just behind the tips
Auxins promote growth in the shoot but it actually inhibits growth in the shoots
Auxins are involved in growth responses of plants to light (phototropism) and gravity (geotropism)
Auxins change the direction of root and shoot growth
shoots are positively phototropic
when a shoot tip is exposed to light, it accumulates auxin on the shaded side
this makes the cells elongate (grow) faster on the shaded side so that the shoots grow towards the light
shootsare negatively geotropic
when a soot is growing sideways, gravity produces causes more auxin to accumulate on the lower side
this causes the lower side to grow faster, bending the shoot upwards
roots are positively geotropic
a root growing sideways will also have more auxins on its lower side
but in roots, the extra auxin inhibits growth. this means the cells on top elongate faster and the root bends downwards
roots are negatively phototropic
if a root starts to be exposed to some light, more auxin accumulates on the shaded side
the auxin inhibits cell elongation, this bends the root downwards. roots that are underground aren't exposed to light. they grow downwards due to positive gravitropism
human reproductive systems
male reproductive system
sperm are male gametes
sperm mix with a liquid to make semen, which is ejaculated from the penis into the vagina of the female during sexual intercouse
parts of the male reproductive system
urethra-a tube which carries sperm through the penis during ejaculation. urine also passes through the urethra to exit the body
erectile tissue-swells when filled with blood to make the penis erect
testis-where sperm are made
glands-produce the liquid that is added to sperm to make semen
sperm duct-muscular tube that carries sperm from the testis towards the urethra
scrotum-hangs behind the penis and contains the testes
female reproductive system
ova are female gametes. an ovum is produced every 28 days from one of two ovaries
it then passes into the fallopian tube. This is were is might meet sperm that have entered the vagina during sexual intercourse
if it isn't fertilised by sperm, the ovum will break up and pass out of the vagina
if it is fertilised, the ovum starts to divide. the new cells will travel down the fallopian tube to the uterus and attach to the endometrium. a fertilised ovum develops into an embryo
parts of the female reproductive system
fallopian tube-a muscular tube that carries ovum from the ovary to the uterus
ovary-the organ that produces ova and sex hormones
endometrium-has a good blood supply for implantation of an embryo
cervix-the neck of the uterus
vagina-where the sperm are deposited
uterus-the organ where an embryo grows
menstrual cycle
menstrual cycle has 4 stages
the uterus lining breaks down for about four days
the uterus lining builds up again, from day4 to 14, into a thick spongy layer full of blood vessels, ready to receive a fertilised egg
an egg develops and is released from the ovary at day 14-this is called ovulation
the wall is then maintained from about 14 days until 28. if no fertilised egg has landed on the uterus wall by day 28, the spongy lining starts to break down and the whole cycle starts again
it is controlled by 4 hormones
FSH
produced in the pituitary gland
causes an egg to mature in one of the ovaries in a structure called a follicle
stimulates the ovaries to produce oestrogen
oestrogen then inhibits the release of FSH
oestrogen
produced in the ovaries
causes the lining of the uterus to grow
stimulates the release of LH
LH
produced in the pituitary gland
stimulates the release of an egg on day 14
progesterone
produced in the ovaries by the remains of the follicle after ovulation
maintains the lining of the uterus during the second half of the menstrual cycle. when the level of progesterone falls, the lining breaks down
inhibits the release of LH and FSH
embryo develops during pregnancy
once an ovum has been fertilised, it develops into an embryo and implants in the uterus. in later stages of pregnancy the embryo is called a fetus
once the embryo has implanted, the placenta develops-this lets the blood of the embryo and mother get very close to allow the exchange of food, oxygen and waste
the amnion membrane forms-this surrounds the embryo and is full of amniotic fluid. amniotic fluid protects the embryo against knocks and bumps