Neurons & Synapses Flashcards
How many neurons are there in the body and where are they located?
100 billion
80% are located in the brain
How are neurons transmitted ?
Electrically and chemically
What does the neurons provide for the nervous system?
Primary means of communication
What is the role of the sensory neuron?
- carry messages from PNS to CNS
What are the features of a sensory neuron?
Long dendrites and short axon
What is the role of a relay neuron?
- connect the sensory neuron to the motor or relay neuron.
What are the features of a relay neuron?
- short dendrites and short axons
What is the role of a motor neuron?
Connect the CNS to the effectors such as muscles and glands
What are the features of motor neuron?
Short dendrites and long axons
Cell body
Include a nucleus which contains genetic material of the cell.
Dendrites
Carry nerve impulses to neighbouring neurons towards the cell body.
Axon
Carry impulses away from the cell body.
Myelin Sheath
The fatty layer that covers and protect the axon.
Node of Raniver
Gaps in the myelin sheath to speed up electrical impulses.
Terminal buttons
Communicate with next neuron in the chain across the synaptic gap.
What is the process of neuron firing?
Neuron resting = postive charge outside and negative inside.When a neuron is activated by a stimulus, the inside becomes postivitely charged for a split second causing an action potential to occur.Creates an electrical impulse travels down the axon towards the end of neuron.
What is the process of synaptic transmission?
- Neurons separated form the next by tiny gap (synapse).
- Signals within neurons are transmitted electrically and signals neurons are transmitted chemically across the synapse.
- when electrical impulse reaches the end of the neuron( presynaptic terminal)
- triggers the release of neurotransmitter from tiny sacs (synaptic vesicles)
-once the neurotransmitter crosses the gap, it is taken up by the postsynaptic receptor site then it is converted back into an electrical impulse.
What is an excitatory neuron?
Adrenaline- they make the next neuron more likely to fire as neuron becomes more positively charged.
What is an inhibitory neuron?
Serotonin- they make they next neuron less likely to fire as neuron becomes more negatively charged.
