Nerves Flashcards
What are nerves
A nerve is a group of special nerve cells grouped together in parallel.
What do nerves do
They convey information in the form of the nerve impulses the neurons link together to form a network.
How are nerves important in the nervous system
The nervous System is made up of specialised cells called neurons (nerves).
What are the parts of a neuron
Cell Body, Dendrites, Axon, Schwann cells, Myelin sheath, Nodes of Ranvier and Synaptic terminal
What is the cell body of a neuron
- Contains the nucleus
- Expanded portion of cytoplasm
- Controls and maintains cell activities
- Thin cytoplasmic fibres (dendrites and axons) extend from here.
- Main receiving area for input of impulses from other neurons
What are the dendrites of a neuron
- Carry signals from adjacent neurons INTO the cell body
- Short
- Greatly branched
What is the axon of a neuron
- long, usually unbranched
* Main pathway for conduction of nerve impulses away from the cell body
What is the schwann cells of a neuron
- Special non-nervous cells that wrap tightly around and cover axons
- Produce myelin
What is myelin sheath of a neuron
- Fatty substance that surrounds some axons
- Protects and insulates the nerve fibre
- Increases the rate of transmission of nerve impulses
What is nodes of ranvier of a neuron
- Gaps between Schwann cells where the axon is exposed
* Allows nutrients and wastes to enter/leave the neuron
what is synaptic terminal of a neuron
- End of the axon
* Contains vesicles with neurotransmitters
what are sensory nerves and their structure
Associated with everything, conducts impulses towards central nervous system (relays messages from receptors to central nervous system). The dendrites of theses nerves are long and myelinated. The axon is short and ends in the central nervous system. The cell body is near the central nervous system.
what are motor neurons and their structure
Bring about a response, it conducts impulses away from the central nervous system (relays messages from receptors to muscles/organs). The dendrites are short and not myelinated. The cell body is in the central nervous system and the axon goes to the effector organ. Usually long, myelinated.
what are interneurons and their structure
Found only within in the central nervous system. They make up the brain and spinal cord, they link sensory and motor neurons. They usually have a short axon. Interneurons conduct impulses within the central nervous system. Run the length of the spinal cord into the brain and they may also be called ‘association’ or ‘relay neurons.
