Coordination and response Flashcards
Nerve impulse
an electrical signal that passes along nerve cells called neurones
Human nervous system
Allows for coordinated movement and constant internal environment to be maintained.
-CNS: Central nervous system, consisting of
brain and spinal cord
-PNS: peripheral nervous system, made up of nerves and receprtors
Mylein sheath
-fatty layer that surrounds the axon. The sheath acts as an insulator and speeds up nerve impulses.
voluntary and involuntary actions
- Voluntary actions uses conscious control, and is slower response
- Involuntary actions does not use conscious control and is faster response.
Identify motor (effector), relay (connector) and sensory neurones from diagrams
- sensory neurones: Carries impulses from a receptor to brain and spinal cord
- relay (connector): Carries impulses between different parts of the central nervous system
- motor (effector)
simple reflex arc
- Receptor: Stimulus such as heat is detected by recptors
- Sensory neurone: Receptor send an impulse down sensory neuron to spinal cord
- Relay neurone: In CNS passes the impulse to motor neuron
- Motor neurones: Impulse travels along motor neuron to effector
- Effector:
reflex action
A means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands)
Synapse
a junction between two neurones
structure of a synapse, How impulse arrives is passed at a synapse
- An impulse arrives at the end of the presynaptic neuron
- Vesicles move towards, and fuse with the presynaptic membrane, this releases neurotransmitters into the synaptic cleft.
- The neurotransmitters diffuse across the synaptic cleft (down concentration gradient)
- Neurotransmitters attach to the receptors of the postsynaptic membrane
- This triggers an impulse which travels along the postsynaptic neuron
- The neurotransmitters are recycled or destroyed after an impulse is sent.
how an impulse triggers the release of a neurotransmitter from vesicles into the synaptic gap and how the neurotransmitter diffuses across to bind with receptor molecules, in the membrane of the neurone after the synaptic gap, causing the impulse to continue
Fusion of a vesicle with the presynaptic membrane causes neurotransmitters to be released into the synaptic cleft.
- The neurotransmitters diffuse across the synaptic cleft (down concentration gradient)
- Neurotransmitters attach to the receptors of the postsynaptic membrane
- This triggers an impulse which travels along the postsynaptic neuron
- The neurotransmitters are recycled or destroyed after an impulse is sent.
in a reflex arc
the synapses ensure that impulses travel in one direction only
Many drugs, e.g. heroin, act upon synapses
Stimulants such as caffeine, cause a release of neurotransmitters such as dopamine and serotonin into the synapses, whereas depressants such as heroin and alcohol, inhabits synapses by blocking the receptors on the presynaptic neuron so that impulses cannot be sent
Sense organs
groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals
Identify the structures of the eye, limited to cornea, iris, pupil, lens, retina, optic nerve and blind spot
…
Function of each part of the eye
– cornea: clear layer that coats the iris and refracts light
– iris: controls how much light enters pupil, by contacting and dilating the pupil
– lens: focuses light onto retina
– retina: contains light receptors, some sensitive to light of different colours Rod and cone cells, AKA photoreceptors
– Optic nerve: carries impulses to the brain