Neurons Flashcards
What is a neuron
a nerve cell
How do neurons communicate?
transmitting signals electrically and chemically, neurotransmitters
How big are neurons?
less than a millimetre to a metre
cell body (soma)
includes nucleus for genetic material and also branch like structures called dendrites
Dendrites
Branchlike parts of a neuron that are specialized to receive information. they carry nerve impulses from neurons towards the cell body
Axon
carries impulses away from cell body down the neuron. covered in a fatty layer of myelin sheath
Myelin sheath
Protects axon and speeds up electrical transmission of the impulse. segmented by gaps.
Nodes of Ranvier
Speed up transmission of impulse by forcing it to jump along gaps
axon terminals (terminal buttons)
communicate with the next neuron in the chain across a gap known as synapse
What are the three types of neurons?
Sensory, relay and motor
What do sensory neurons do?
Carry messages from the PNS to the CNS
What do sensory neurons have (in terms of dendrites and axons)?
Long dendrites and short axons
What do relay neurons do?
Connect sensory neurons to motor neurons or other relay neurons
What do relay neurons have (in terms of dendrites and axons)?
Short dendrites and short axons
What do motor neurons do?
They carry impulses from the CNS to effectors such as muscles and glands
What do motor neuron have (in terms of dendrites and axons)?
short dendrites and long axons
Where are sensory neurons located?
Receptors like eyes, ears, tongue and skin.
In sensory neurons, what happens to nerve impulses when they reach the brain?
They are translated into sensations such as vision, hearing, taste and touch
What happens to the sensory neurons that do not reach the brain?
They stop at the spinal cord and allow for quick reflex actions
Where are relay neurons found?
- between sensory input and motor output/response
- brain and spinal cord
What do Relay neurons do?
allow sensory and motor neurons to communicate
Where are Motor neurons found?
CNS
What do motor neurons do?
control muscle movement
What happens when motor neurons are stimulated?
They release neurotransmitters that bind to the receptors on muscles to trigger a response which leads to movement
