Neurones

What are neurones

Specialised nerve cells that transmit electrical impulses quickly throughout the body

What is the function of neurones

Transmit electrical impulses to enable rapid responses to environmental changes

What is the role of sensory neurones

Carry electrical impulses from sensory receptors to the CNS

What is the role of relay neurones

Carry electrical impulses between neurones within the CNS

What is the role of motor neurones

Carry electrical impulses from the CNS to effectors

What is the function of an effector

Produces a response to a stimulus

What is the function of the cell body

Contains the nucleus and cytoplasmic organelles

Which organelles are found in the cell body

Nucleus mitochondria and endoplasmic reticulum

What is the role of mitochondria in neurones

Provide ATP for cellular processes including neurotransmitter production

What is the role of the endoplasmic reticulum in neurones

Helps produce proteins including those involved in neurotransmitter production

What are dendrons

Short branches extending from the cell body that divide into dendrites

What is the function of dendrites

Receive nerve impulses from other neurones and transmit them towards the cell body

Why are dendrites highly branched

Increase the surface area available to receive impulses from other neurones

What is an axon

A single long nerve fibre that carries electrical impulses away from the cell body

Where do axons carry impulses

From the cell body towards other neurones or effectors

What are Schwann cells

Cells whose membranes surround parts of some neurone axons

What are three functions of Schwann cells

Form the myelin sheath remove debris by phagocytosis and aid regeneration

What is the myelin sheath

An insulating layer formed from Schwann cell membranes around parts of an axon

What is the function of the myelin sheath

Insulates the axon and prevents ions passing into or out of the covered regions

How does the myelin sheath increase conduction speed

Allows impulses to travel by saltatory conduction between nodes of Ranvier

What are nodes of Ranvier

Gaps between adjacent sections of the myelin sheath along an axon

What is saltatory conduction

The movement of an electrical impulse from one node of Ranvier to the next

Why is saltatory conduction faster than continuous conduction

The impulse jumps between nodes of Ranvier rather than travelling continuously along the axon membrane

How do non myelinated axons conduct impulses

By continuous conduction along the axon membrane

How does a sensory neurone differ structurally from a motor neurone

A sensory neurone has one axon and one dendron whereas a motor neurone has one long axon and multiple dendrites

What is the structure of a sensory neurone

One axon and one dendron with the dendron leading into several smaller dendrites

What is the structure of a relay neurone

Numerous short axons and dendrons

What is the structure of a motor neurone

One long axon and multiple dendrites

What is the typical pathway of a nerve impulse

Receptor to sensory neurone to relay neurone to motor neurone to effector

Where does a sensory neurone carry impulses

From a sensory receptor to the central nervous system

Where does a relay neurone carry impulses

Between other neurones within the central nervous system

Where does a motor neurone carry impulses

From the central nervous system to an effector

What is the central nervous system

The brain and spinal cord

What is the overall function of the nervous system

Detect stimuli process information and coordinate rapid responses through electrical impulses