Neurons Flashcards
What is a neuron?
A highly specialised nerve cell that sends electrical and chemical signals around the nervous system
What is a cell body?
The control centre of the neuron, containing the nucleus and other cell organelles
What is a dendrite?
Long fine branches protruding from cell body which receive information from neighbouring neurons and transport the message towards the cell body as an electrical impulse
What is an axon?
What is a terminal button?
A larger branch coming off cell body carrying information away
At the end of the axon communicating with next neuron in chain across synapse
What is a myelin sheath?
What are nodes of ranvier ?
Fatty layer encasing the axon which protects the axon and enables nerve impulses to travel quickly along axon
Small gaps breaking up myelin sheath which force electrical signals to jump across gaps and help speed up transmission of nerve impulses
What does a sensory neuron do?
What does a sensory neuron look like?
Carry information from sensory receptors (pns) to CNS and converts information into a neural impulse that is then decided in brain to produce appropriate sensation so we can react appropriately
Long dendrites and short axons
What does a relay neuron do?
What does a relay neuron look like?
Communicate between motor and sensory neurons
Short dendrites and short axons
What does a motor neuron do?
What does a motor neuron look like?
Carry messages from CNS to effectors by connecting with muscles and influencing their contraction
Short dendrites and long axons
How is information transmitted within a neuron?
By an electrical impulse based upon action potential where the inside of a neuron is negatively charged in comparison to the outside but as soon as the neuron is activated, it becomes positively charged for a fraction of a second so that the electrical impulse can travel
How is information transmitted between neurons?
Chemically by neurotransmitters:
1) electrical impulse moves along axon
2) inside of neuron becomes positively charged relative to outside
3) vesicles release neurotransmitters
4) neurotransmitter crosses synapse
5) neurotransmitter binds to receptors
6) electrical impulse is triggered or prevented from being triggered in post-synaptic neuron
What is excitation?
What are some examples?
Neurotransmitters cause depolarisation causing post-synaptic neuron to be more likely to trigger an electrical impulse (action potential), stimulating brain into action
Adrenaline, dopamine
What is inhibition?
What are some examples?
One neurotransmitters cause hyperpolarisation causing post synaptic neuron to be less likely to trigger an electrical impulse (action potential), calming the brain and balancing mood
Serotonin, GABA
What is summation?
Receptors on post-synaptic neuron can be stimulated by excitatory and inhibitory neurotransmitters at the same time, so effects are summed and if net effect is excitatory, neuron will be more likely to generate an electrical impulse. If net effect is inhibitory, neuron will be less likely
