Nervous System Flashcards
What are the two main parts of the nervous system
The central nervous system
The peripheral nervous system
What is the central nervous system made up of
Brain and spinal cord
What is the peripheral nervous system made up of
All nerves outside the brain and spinal cord that carry messages to and from the CNS and other parts of your body
What is the nervous system made up of
Trillions of nerve cells or neurons
What do neurones carry
Electrical messages called nerve impulses
What direction do nerve impulses carry
In only one direction
What are the four main parts of a neurone
Cell body
Dendrites
Knobs
Axons
What does the cell body contain
The nucleus
What is the nucleus
The control centre of the cell
What are the dendrites
They branch out from the cell body and recieve messages from other nerve cells
What is the axon
The axon or nerve fibres send nerve impulses in only one direction, away from the cell body
What are the knobs
They pass messages on to the next neurone
What are motor neurones
They carry messages from the CNS to effectors, which are muscles or glands, that out the messages into effect. They cause movement in muscles and glands
What are sensory neurones
They carry messages from cells in the sense organs, (such as eyes ears tongue and skin) to brain and spinal cord
What does the motor neurone look like
They have dendrites coming off the cell body which then goes into the axon, which has myelin sheath around it and Schwanns cells which then leads into the axon terminals, or knobs where the impulse finishes.
What does the sensory neurone look like
It has dendrites which lead into the axon with myelin sheath, and the cell body comes off the axon. At the end of the axon are the knobs or axon terminals
What does the connecting neurone look like
It is much smaller and have many dendrites coming off the cell body, which goes into the axon that has no myelin sheath, and into the axon terminals or knobs
What is the connecting neurone
They are very small neurones which connect other neurones to other places. They don’t have myelin because of the short distance, and they have many dendrites.
Explain what happens when impulses reach knobs
When they reach the end a chemical called neurotransmitter is released into the space between the neurones, or synapse. The neurotransmitter carries the message from the axon of one neurone to the dendrite of the nest. The dendrite receives the chemical message and sends off an electrical signal
What is a myelin sheath
It electrically insulated the neurones from eachother and increases the speed of the nerve impulse
What are the two separate parts of the peripheral nervous system
The somatic nervous system
The autonomic nervous system
What is the somatic nervous system
It is in the PNS. It collects information about an animals surroundings through sensory organs
What are the somatic nervous systems organ
Receptors
What are receptors
They detect changes in environment. The changes stimulate the nerve endings to send messages to your brain
