Neurons Flashcards
Define neuron
Nerve cells that process and transmit messages through electrical and chemical signals
How many neurons are in the body
100 billion neurons
80% located in the brain
What is the size variation of a neuron
<1mm to 1m long
What does the Nucleus do
contains genetic material
What are Dendrites
Branch like structures protruding from cell body
Carry nerve impulses from neighbouring neurons toward cell body
What is the Axon
Carries impulses away from cell body down length of neuron
Covered in fatty layer of myelin sheath
What is the Myelin Sheath
Protects the axon
Speeds up electrical transmission of an impulse
Segmented by gaps called Nodes of Ranvier
What are the Nodes of Ranvier
Forces the impulse to ‘jump’ across the gaps along the axon
What are the Terminal Buttons
At the end of the axon
Communicate with the next neuron in the chain across the synapse
Sensory Neuron
Carries messages from PNS to CNS
Long dendrites, Short axon
Relay Neuron
Connect sensory neuron to motor neuron or other relay neuron (intermediary)
Short dendrites, Short axon
Motor Neuron
Connect CNS to effectors
Short dendrites, Long axon
Describe the process of Firing a Neuron
1.Electrical transmission takes place within a neuron
2. When in a resting state, the inside of the cell is negatively charged (outside is not)
3. When a neuron is activated by a stimulus, inside becomes positively charged for a split-second causing an action potential
4. Action potential creates an electrical impulse that travels down the axon to the end of the neuron
5. Signals within the neuron are transmitted electrically
6. Signals between two neurons are transmitted chemically across a synapse
