The Structure and Function of Neurons Flashcards
What is a Sensory Neuron?
Carry messages from the PNS to the CNS.
Long dendrites and short axons.
The Function of Sensory Neurons
Found in receptors such as eyes, ears, tongue and skin, and carry nerve impulses to the spinal cord and brain.
When these nerve impulses reach the brain, they are translated into ‘sensations’ such as vision, hearing, taste and touch.
Not all sensory neurons reach the brain, as some neurons stop at the spinal cord, allowing for quick reflex action.
What is a Motor Neuron?
Connect the CNS to muscle and glands.
Short dendrites & long axons
The Function of Motor Neurons
Found in the Central Nervous System and control muscle movements.
When motor neurons are stimulated they release neurotransmitters that bind to the receptors in muscles to trigger a response, which lead to movement.
What is a Relay Neuron?
Connect sensory neurons to motor or relay neurons.
Short dendrites and Short axons.
The Function of Relay Neurons
Found between sensory input and motor output/response. Relay neurons are found in the brain and spinal cord and allow sensory and motor neurons to communicate.
The Structure of a Neuron (components)
They vary in size but have the same structure. Made up of:
- Cell body
- Dendrites
- Axon (Myelin sheath) (nodes of Ranvier)
Cell body (soma)
Includes a nucleus which contains the genetic material of the cell
Dendrites
Branch like structure.
Protrude from the cell body
Axon
Carries the impulse’s away from the cell body down the length of the Neuron.
Covered in a fatty layer of myelin sheath that protects the Axon and speeds up electrical transmission of the impulse.
Myelin Sheath is segmented by gaps called nodes of Ranvier; these speed up the transmission of impulses by forcing it to jump across gaps along the axon.
Terminal Buttons
The end of the axon.
Communicate with next neuron in the chain across a gap known as the synapse.
