Neurones and reflex arcs Flashcards
What does the central nervous system comprise of?
The brain and spinal cord
What makes up the peripheral nervous system?
Neurones
What is the function of the dendrites?
They pick up electrical signals from nearby neurones
What is the function of the axon?
Allows neurones to send impulses around the whole body
What is the function of the node of ranvier?
Help to propagate an impulse faster down the axon
What is the function of the myelin sheath?
It is a layer of fat and protein that acts as an insulator so that impulses travel faster
What is the order of the reflex arc?
Stimulus → Receptor → Sensory neurone → Relay neurone in spinal cord → Motor neurone → Effector
What is a synapse?
The junction between two neurones
How do electrical impulses reach the axon terminal(end of neurone)?
Electrical transmission
What happens after the impulses reach the axon terminal of the presynaptic neurone?
Vesicles move towards and fuse with the presynaptic membrane, releasing neurotransmitters into the synapse
What kind of transmission takes place across the synapse
Chemical transmission
What happens after neurotransmitters diffuse across the synapse?
They bind to receptor molecules on the postsynaptic membrane. This generates an electrical impulse at the dendrite of the postsynaptic neurone. It is transmitted down the neurone.
What are receptors?
Specialised cells that sense a change in the environment
What is a stimulus?
A change in an organisms environment
What are effectors?
Muscles, glands or organs that bring about the responses to the stimulus that has been received
