Flashcards in Coordination and Response Deck (33)
what are stimuli?
stimuli are changes in an organisms environment which we detect using receptors
what are three examples of reflexes and describe their purpose
the pupil reflex - pupils get smaller in bright light to regulate the amount of light which enters the eye,
the blink reflex- eyes blink when there is near movement to potentially protect the eyes from damage,
the swallowing reflex - makes it harder to swallow straight after having swallowed just before, to prevent the throat from over filling and therefore preventing choking
what part of the hand is most sensitive and why?
the palm of the hand is most sensitive as this area is designed to detect stimuli as the palm of the hand has more receptors than the other parts.
what are the 5 sense organs
skin, tongue, nose, eyes, ears
what is the stimulus for skin
pressure, pain, temperature
what is the stimulus for tongue
chemicals in food and drink
what is the stimulus for nose
chemicals in the air
what is the stimulus for the eyes
what is the stimulus for ears
what is the central nervous system
- the central nervous system (CNS) is made up of the spinal cord and the brain.
-the peripheral nervous system carries information to or from the CNS
- when a stimulus is detected by a receptor, impulses (messages) pass down neurones to the CNS which then sends more impulses out along neurones to an effector which causes a response.
what is a reflex
a reflex is an automatic and rapid response, such as when you touch something hot or sharp.
draw a diagram of the reflex arc
- sensory neurone
- motor neurone
- relay neurone
- spinal chord
what are neurones
-specialised cells which make up nerves
- sensory neurones carry impulses from sense organ to CNS
- relay neurones are found inside the CNS and connect sensory and motor neurones
- motor neurones carry impulses from the CNS to effectors (muscles or glands)
label a diagram of a sensory and motor neurone
- cell body
- electrical impulse
- insulating sheath
- cell body
- electrical impulse
- insulating sheath
what are synapses
- the gaps between neurones are called synapses
- the impulse is transmitted from one side to the other using neurotransmitters, which travel across the gap via diffusion
- synapses mean that nerve impulses are unidirectional, meaning they only travel in one direction
- they can also connect more than one neurone
label a diagram of a synapse
- end of neurone
- sacs containing neurotransmitters
label a diagram of an eye in bright light and an eye in dim light
- radial muscles contract
- circular muscles contract
describe how the amount of light entering or leaving the eye is controlled
- the amount of light entering the eye is controlled by the iris
- this contains muscle which is able to contract and change the size of the pupil, which is a hole in the centre of the eye
- the iris contains two types of muscle; circular and radial
what happens to the muscles in the pupil in bright light
in bright light, the circular muscles contract and the radial muscles relax, making the pupil smaller. this prevents damage to the light sensitive cells on the retina
what happens to the muscles in the pupil in dim light
in dim light, the radial muscles contract and the circular muscles relax, making the pupil bigger and allowing more light into the eye
label a diagram of the eye
- choroid layer (contains dark pigment to absorb light and prevents light from being reflected back into the eye)
- sclera (protective white outer layer, contains many blood vessels which supply the retina with food and oxygen)
- ciliary muscle (circular muscles around lens which helps to change its shape when they contract)
- cornea (refracts light)
-suspensory ligament (attaches lens to ciliary muscle)
- aqueous humour (fills the front of the eye and helps bend light onto the retina)
-iris (controls amount of light entering the eye)
-pupil (hole in centre of iris which lets light in)
- lens (helps focus image)
- vitreous humour (fluid which keeps shape of eyeball)
- blind spot (where the optic nerve attaches to the retina, there are no light sensitive cells)
- optic nerve (carries electrical impulses to the brain)
- fovea (the most sensitive part of the retina- contains only cones, makes image sharper)
- retina (contains light sensitive receptor cells)
- conjuctiva- thin clear layer over surface of they and lining of the eyelids
how does the eye focus light from a distant object?
- when light enters the eye from a distance, the light rays are almost parallel when they enter the eye
- this means they need less rarefaction to be focused onto the retina
- the cornea starts to bend the rays and the lens is less involved
- to get the lens into this shape, special muscles called ciliary muscles relax and the lens is pulled thinner by the suspensory ligaments
how does the eye focus light from a close object?
- light rays from a near object are diverging when they enter the eye and so need more bending to focus them onto the retina
- to do this, the lens must change shape and become more rounded
- to enable this, the ciliary muscles contract which means that the suspensory ligaments are pulled less and the lens becomes more rounded.
what is the bending of light called?
why do peoples vision get worse when they age
their lens becomes less bendy
what is the difference between a simple and conditioned reflex?
a simple reflex is natural and automatic, whereas a conditioned reflex is learnt
in a neurone, the axon carries information along the neurone as...
what is homeostasis
the maintenance of a constant internal environment. The nervous system and hormones are responsible for this. e.g the concentration of carbon dioxide in the blood being carefully controlled, body temperature, body water content
how do plants respond to stimuli
- stems will grow towards the light stimulus (positive tropisms)
- roots grow away from light (negative tropisms)
- stem grows against the force of gravity (Negative geotropism)
- roots grow in the direction of gravity (positive geotropism)