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what is a stimulus
changes in the internal and external environment
what is the role of neurones
to transmit electrical impulses rapidly around the body so that the organism can respond to changes in its internal and external environment
what is the cell body for in a neurone
contain nucleus
large amounts of endoplasmic reticulum and mitochondria
what are dendrons for in a neurone
come from cell body
divide into dendrites
transmit electrical impulses towards the cell body
what are axons for in a neurone
transmit impulses away from cell body
can be very long
sensory neurones transmit impulses from what to what
sensory receptor cell to relay neurone, motor neurone or brain
relay neurones transmit impulses from what to what
impulses between neurones e.g sensory neurones and motor neurones
motor neurones transmit impulses from what to what
from relay neurone or sensory neurone to an effector e.g muscle or gland
where is the cell body in a sensory neurone and structure
dendron → cell body → axon
where is the cell body in a motor neurone and structure
dendrites → cell body → long axon
what is the structure of a relay neurone
cell body surrounded by short axons → dendrons → dendrites
what is the electrical impulse pathway
receptor → sensory neurone → relay neurone → motor neurone → effector cell
what type of cell makes up myelin sheaths
schwann cells - wrap around the axon many times
what is the point of myelin sheath
acts as insulating layer
allow neurones to conduct electrical impulse much faster than non-myelinated neurones
what are nodes of Ranvier
small gaps between schwann cell
