Neurons and Synaptic Transmission Flashcards
How many neurons are there in the human nervous system? How many are in the brain?
100 billion
80%
what are the 3 types of neurons?
1) Motor
2) Sensory
2) Relay
What does the sensory neuron do?
What are its features?
carries messages from the PNS to the CNS
Long Dendrites , Short Axons
What do Relay neurons do?
What are its features?
Connect sensory neurons to motor/other neurons
Short Dendrites, Short Axons
What do Motor Neurons do?
What are its features?
Connect the CNS to effectors like muscle and glands
Short Dendrites, Long Axons
What are the features of a typical neuron?
Cell body Nucleus Dendrites Axon Myelin Sheath Nodes of Ranvier Schwann Cells
what are nodes of ranvier?
gaps in the myelin sheath that speed up the transmission of the impulses by making it jump across the axon.
what is the myelin sheath?
a fatty layer across the axon that protects the axon and speeds up electrical impulses
Explain the process of firing a neuron (electric transmission)
1) Neuron at resting state; inside of cell is negatively charges compare to outside.
2) Neuron activated by stimulus; inside becomes positively charged for split second causing action potential to occur
3) Electical impulse created - travels down the axon to the end of the neuron
what separates each neuron?
a Synapse
how are signals transmitted during synaptic transmission?
chemically
what are neurotransmitters?
chemicals that diffuse across the synapse to the next neuron
each neurotransmitter has…
its own specific molecular structure that fits in a post-synaptic receptor site
like a lock and key
what are the 2 different effects neurotransmitters have on neighbouring neuron?
Excitatory Effect
Inhibitory Effect
Define the excitatory effect
Give an example
Increases positive charge so more likely to fire
e.g. adrenaline
