Grey Matter, SNAB A2 biology. Nervous control key words

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Nerve impulse - an electrical impulse that is sent along a nerve to allow information to travel to effectors to carry out a response to a stimulus.

Neurone - a single cell which has dendrites, an axon, a cell body and terminal branches and make up part of the nervous system.

Nerve - contains a bundle of the axons of several neurones surrounded by a protective covering.

cell body - contains all the organelles a normal cell would have in a cytoplasm (found in different locations for different neurone types). There are 2 types of thin extensions from the cell body called dendrites and the axon.

dendrites - conduct impulses towards the cell body. Each neurone has many of these thin extensions.

axon - conduct impulses away from the cell body and is a single long process.

motor neurone - Cell body in central nervous system and axon extends out. Axons can be very long. AKA effector neurones.

sensory neurone -  carry impulses from sensory cells to the central nervous system.

relay neurone - found mostly in the central nervous system. AKA connector neurones. Have a large number of connections with other nerve cells.

myelin sheath - fatty insulating layer around the axon. Effects how fast an impulse travels. Stop the impulse escaping.

schwann cell - the myelin sheath is made up of schwann cells.

effector - produce a response when an impulse is received from motor neurones.

reflex arc - nerve impulses follow pathways, some are simple and are called reflex arcs.

reflexes - rapid, involuntary responses to stimuli.

photoreceptors - special receptors in the retina that respond to light levels which control the size of the pupil.

resting potential - (-70mV.) When the inside of the axon membrane is negative and the outside is positive. This is caused by the potassium/sodium ion pump and the movement of potassium ions in and out of the axon by the concentration gradient and the electrical gradient.

depolarisation - when an impulse travels through the…


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