Unit 3 (K4) - Cells of the Nervous System & Neurotransmitters at Synpases Flashcards
What are nerves?
Nerves are bundles of nerve fibres which carry electrical impulses from one part of the body to the other.
What are some parts found on a neurone?
- Cell body
- Dendrite
- Axon
What does a dendrite do?
They receive nerve impulses and carry them towards the cell body.
What does an axon do?
They carry nerve impulses away from the cell body.
What direction does a nervous impulse always travel from?
Dendrite > Cell body > Axon
What does the myelin sheath do?
- Insulate the axon
- Speed up impulse conduction.
What is the myelin sheath made up of?
Cells that lie around the fibre.
What is myelination?
The development of myelin around axon fibres of individual neurons.
What does myelination increase?
Increases the speed of nerve conduction.
Give an example of a disease that destroys the myelin sheath
Multiple Sclerosis.
What happens when the myelin sheath is destroyed?
It causes a loss of co-ordination.
What are the 3 types of neurons?
- Sensory neuron
- Inter neuron
- Motor neuron
What is the purpose of glial cells?
- Providing physical support
- Production of myelin sheath
What is a synpase?
A synapse is a tiny gap between 2 neurons.
Where do neurons connect with other neurons?
At the synaptic cleft.
How are messages relayed across the synaptic cleft?
By chemicals called neurotransmitters.
Where are neurotransmitters stored?
In vesicles in the axon endings of the presynaptic neuron.
Where do neurotransmitters bind when they diffuse across the synaptic cleft?
They bind to receptors on the membrane of the postsynaptic neuron.
What determines whether a nervous impulse can pass a synpase?
If a certain minimum number of neurotransmitters molecules are released at the synaptic cleft.
What is a summation?
This is a series of weak stimuli from many neurons at once which can trigger enough neurotransmitters to fire an impulse.
How are transmitter molecules removed from the synaptic cleft?
- Enzyme degradation
- Re-uptake
Name an example of a neurotransmitter than can affect mood and behaviour
- Endorphins
- Dopamine
What does endorphins do in the body?
- Reduce the intensity of pain.
How is endorphin production increased?
- In response to severe injury
- Prolonged and continuous exercise