Coordination And Response Flashcards
Stimulus
A change in the environment that can be sensed
Response
An action caused by the effector due to the stimulus
Receptor
A special structure that allows living organisms to sense the conditions of their internal or external environment
Central nervous system
Consists of the Brian and spinal cord
Effectors
These are the parts of the body that create a response, for example muscles or glands
Sensory neurone
Nerve cell that carries messages form cells in the sense organs to the CNS
Motor neurone
Carry an impulse from the CNS to the effectors
Relay neurone
Sometimes called a connector, these are neurones in the central nervous shyster that transmit impulses from sensory to motor neurons
Cell body
Largest part of a typical neurone; contains the nucleus and much of the cytoplasm
Axon
the elongated part of a neurone, insulated by a fatty sheath, carries information along in the form of electrical impulses, sometimes called nerve fibres
Myelin sheath
A fatty cover over the axon, insulates axon and speeds up impulse
Sense organs
Groups of receptor cells that respond to specific stimuli: light, sound, touch, temperature and chemicals
Synapse
a junction between two nerve cells, consisting of a small gap across which impulses pass by diffusion or a neurotransmitter (chemical) - impulse continues on 2nd axon.
Neurotransmitter
Chemical messengers that cross the synaptic gaps between neurones, eg dopamine
Dendrites
Branchlike parts of a neurone that are specialised to receive information
Reflex arc
The pathway an impulse travels to initiate a super quick unconscious reaction, involves relay neurones
Spinal cord
Nerves that run up and down the length of the back and transmite most messages between the body and brain
Peripheral nervous system
A division of the nervous system consisting of sensory and motor nerves that are not part of the brain or spinal cord
Ciliary muscles
Muscles to control the size of the lens. Contract to make the lens short and fat for near vision
Iris
Controls the size of the pupil and the amount of light entering the eye. Made of circular and radial muscles.
Córnea
Front part of the eye that bends the light into the eye
Lens
Focuses the light onto the retina
Fovea
Focus point on the retina. Area of most cones and so responsible for colour vision
Optic nerve
Carries the signals form the retina to the visual cortex of the brain
Simple reflex arc
Stimulus -> receptor -> sensory neurone -> relay neurone -> motor neurone -> effector -> response
