Coordination and Response - GCSE Flashcards
what does the nervous system mean?
means that humans can react to their surroundings and coordinate their behaviours
what does responding with the environment help with?
it helps organisms survive
how do animals increase their chances of survival? give example
by responding to changes in their external environment. For example by avoiding places that are too hot or too cold
why do animals respond to changes in their internal environment?
to make sure that the conditions are always right for their metabolism (all chemicals reactions that go inside them)
what other organism (that is not an animal) responds to their changes in environment?
plants
what is the name of the change in external or internal environment?
it is called a stimulus
what detects a stimuli?
receptors
what are receptors?
they are groups of cells (in the sense organ) that detect external stimuli
what responds to the stimuli?
effectors
what are effectors?
they are cells that bring a response to the stimuli
what are the different ways that effectors respond?
2 ways
- muscles contract
- glands secrete hormones
what are the 5 sense organs?
- eyes
- ears
- nose
- tongue
- skin
how do receptors communicate with effectors?
it communicates via the nervous system, the hormonal system, or even both
what does CNS stand for?
central nervous system
what does the nervous system do?
it coordinates information
what is the nervous system made up of?
all the neurones (nerve cells) in your body
what are the 3 main types of neurones?
- sensory neurones
- relay neurones
- motor neurones
what are the 2 things the CNS consists of?
- brain
- spinal cord
ONLY
what is the whole process of receptors detecting and sending signals to the CNS?
when receptors in a sense organ detects a stimulus, it sends electrical impulses along sensory neurones to the CNS
what is the whole process of the effectors responding to the stimuli?
the CNS send electrical impulses to an effector along a motor neurone. The effector then responds accordingly
what does a coordinated response always need?
it needs the stimulus, the receptor, and an effector
how is the nervous system able to bring rapid responses?
because neurones transmit information using high speed electrical impulses
what is the synapses?
it is the connection between two neurones
explain a diagram of a synapse
https://www.google.com/url?sa=i&url=http%3A%2F%2Figcse-biology-2017.blogspot.com%2F2017%2F06%2F289-understand-role-of.html&psig=AOvVaw1CGizC1G88eBKMZgMkOEf1&ust=1646421900511000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCICtotbVqvYCFQAAAAAdAAAAABAJ
how is the nerve signal transferred? and what does it do?
it is transferred by chemicals called neurotransmitters which diffuses (moves) across the gap
what happens to the neurotransmitters?
they set off a new electrical signal in the next neurone
why do you have reflexes?
because sometimes waiting for your brain to make a decision can be to slow
what do reflexes help with?
with preventing injury
what is the full definition of reflexes?
automatic responses to certain stimuli, they can reduce chances of being injured
what is the route taken by the information in a reflex?
it is the reflex arc
where does the reflex arc go through?
it goes through the nervous system
explain a diagram of a reflex arc
https://www.google.com/url?sa=i&url=https%3A%2F%2Fslideplayer.com%2Fslide%2F10938436%2F&psig=AOvVaw06lKfws4oIyLgkvqZaSKV_&ust=1646422376017000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCJjs_LjXqvYCFQAAAAAdAAAAABAV
what are all the 7 steps of a reflex?
complicated version
1) neurones in reflex arc go through spinal cord or unconscious part of the brain
2) when a stimuli is detected (e.g touching a hot object) by receptors, an impulse is sent along a sensory neurone to the CNS
3) in the CNS the sensory neurone passes on the message to another type of neurone, a relay neurone
4) relay neurones relay the impulse to a motor neurone
5) the impulse then travels along the motor neurone to the effector
6) the muscle then contracts and moves your hand away from the hot object
7) because you don’t have to think about the response it’s quicker than a normal response
simple version
1) neurones (in reflex arc) -> spinal chord (or other unconscious part of the brain)
2) stimulus detected (receptor) impulse sent
explain in WORDS the reflex arc
there are 7 words
1) stimulus
2) receptor
3) sensory neurone
4) CNS
5) motor neurone
6) effector
7) response
explain the diagram of an eye
diagram 5 on hand made flash cards
what does the conjunctiva do?
it lubricates (makes it smooth) and protects the surface of the eye
what is the sclera?
it is the tough outer layer that protects the eye
what does the cornea do?
it refracts (bends) light into the eye
what is the cornea?
it is transparent and has no blood vessels to supply it with oxygen, so oxygen diffuses in from the outer surface
what does the iris do?
it controls the diameter of the pupil, therefore how much light enters the eye
what do the lens do?
focuses the light onto the retina
what is the retina?
the light-sensitive part, it’s covered in light receptors called rods and cones
what are rods?
they are receptors that are sensitive to dim light and can’t sense colour
what are cone?
they are receptors that are sensitive to colour but aren’t so good in dim light
where are cones found and where are they the most in?
they are found all over the retina but there are loads of them at the fovea
what does the optic nerve do?
it carries impulses from receptor to the brain
what does very bright light do to the eye?
it damages it
what is the reflex that protects the eye from very bright lights?
the iris reflex
what does very bright light trigger in the eye? and why?
a reflex that makes the pupil smaller (circular muscles contracted) , allowing less light in
what does a very dark (dim) light trigger in the eye? and why?
a reflex that causes radial muscles to contract, making pupils bigger and allowing more light it.
how does the eye focus light on the retina?
by changing the shape of the lens
what is the name of the reflex in which causes the eye to focus on something?
accommodation
what is the process (with 3 steps) that allows the eye to look at distant objects?
1) the ciliary muscles relax, and allows the suspensory ligaments to pull tight
2) this makes lens go thin (less curved)
3) it refracts light by a smaller amount
what is the process (with 3 steps) that allows the eye to look at near objects?
1) ciliary muscles contract, which slackens the suspensory ligaments
2) lens becomes fat (more curved)
3) this increases the amount by which it refracts light
why can’t short-sighted people focus on distant objects?
cornea or lens bends the light too much
or
eyeball too long
causes: images to be brought into focus in front of the retina