Structure + Function Neurons Flashcards
How many neurons and what is their job role? (General)
There are 100 billion neuron’s and 80% are located in the brain. By transmitting signals electrically and chemically these neuron’s provide the nervous system with its primary means of communication
What are the three types of neuron? (+ their appearance)
- Sensory: carry messages from the PNS to CNS, they have long dendrites and short axons
- Relay: They connect the sensory neuron’s to the motor or other relay neuron’s. They have short dendrites and axons
- Motor: These connect the CNS to effectors such as muscles and glands. Short dendrites and long axons
What is the structure of a neuron?
The cell body includes the nucleus which contains the genetic material of the cell.
Branchlike structures called dendrites protrude from cell body carry nerve impulses from neighbouring neuron’s towards the cell body.
The axon carries impulses away from the cell body down the length of the neuron
The myelin sheath protects the axon, speeding up electrical transmission and is segmented by gaps called nodes of ranvier speeding up transmission by forcing to jump across gap.
Terminal buttons are at the end of an axon they communicate with the next neuron in the chain across the synapse.
What is the location of neurons?
The cell bodies of motor neurons may be in the central nervous system (CNS) but they have long axons which from part of peripheral nervous system (PNS). Sensory neurons are located outside of the CNS in PNS in cluster known as ganglia. Relay neurons make up 97% of all neurons and are found most within brain and visual system.
What is electrical transmission?
When a neuron is in a resting state inside of the cell it is negatively charged compared to the outside. When a neuron is activated by a stimulus, inside of the cell become positively charged for a split second causing action potential to occur. This creates an electrical impulse that travels down the axon towards the end of the neuron.
