13.2 neurones

5.1.3

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