Neurones Flashcards
What do neurons do?
Transmit electrical and chemical messages
Sensory neurons
Carry messages from the PNS to the CNS
Have long dendrites and short axons
Relay neurons
Connect the sensory neurons to the motor neurons or other relay neurons.
They have short dendrites and short axons
Motor neurons
Connect the CNS to effectors
Have short dendrites and long axons
Size of neurons
range from less than a mm to up to 1m
Soma
The cell body
Includes the nucleus + contains genetic material
Dendrites
Branchlike structures - protrude from cell body
Carry nerve impulses from neighboring neurons towards the cell bodyq
Axon
Carries impulses away from the cell body down the length of the neuron
Myelin Sheath
A fatty layer the axon is carried in
Protects the axon and speeds up electrical transmission.
Nodes of Ranvier
Segmented gaps in the myelin sheath
Speeds up transmission by forcing it to jump along the gaps along the axon
Terminal buttons
At the end of the axon
Communicate with the next neuron in the chain across a gap (synapse)
Summation
Decides whether a postsynaptic cell fires or not
Net effect of postsynaptic neuron is inhibitory - less likely to fire
Vise Versa
- synaptic transmission
Electrical impulse in the form of action potential travels down to the axon
- synaptic transmission
The electrical impulse reaches the presynaptic terminal
- synaptic transmission
The impulse in the presynaptic terminal prompts the release of neurotransmitters from the vesicles
