neuron structure and function Flashcards
(12 cards)
What are neurons?
Nerve cells send electrical and chemical signals to communicate.
There are 100 billion of them in the human body, with 80% ‘living’ in the brain.
what are the different Types of neuron
Sensory neurons: Carry messages from PNS to CNS. Long dendrites, Short axons (LS).
Relay neurons: Connect sensory neurons to motor neurons. Short dendrites, Short axons (SS).
Motor neurons: Carry messages from CNS to muscles and glands. Short dendrites, Long axons (SL).
(Think of a way to remember S = LS, R = SS, M = SL)
what are the Structure of neurons
Cell body: nucleus containing genetic material (DNA).
Axon: Carries signals from the cell body down the neuron, covered in myelin sheath.
Myelin sheath: Fatty layer acts as insulation and gaps (nodes of Ranvier) speed up signal.
Terminal button: end of axon forming part of the synapse.
how does Electrical transmission work
neuron Resting state: Inside has a negative charge compared to outside.
When it fires: Changes to a positive charge which causes an action potential.
how do neurons comunicate with eachother through synapses
Neurons communicate with each other through the release of neurotransmitters from the presynaptic neuron to the postsynaptic neuron across the space between two neurons (the synaptic cleft).
how are neurotransmitters released
Neurotransmitters stored in vesicles at terminal buttons of presynaptic neuron.
Electrical signal releases neurotransmitters into the synaptic cleft.
how do the neurotransmitters turn back into electric messeges
Neurotransmitters released into the synaptic cleft attach themselves to the next neuron at postsynaptic receptor sites.
The chemical message is turned back to an electrical impulse.
The neurotransmitters in the synaptic cleft are broken down by enzymes and reabsorbed by the presynaptic neuron.
Excitation and inhibition in neurotransmitters
Excitatory neurotransmitters increase the postsynaptic neuron’s positive charge and make it more likely to fire.
Inhibitory neurotransmitters increase the postsynaptic neuron’s negative charge and make it less likely to fire.
what is Summation
Summation occurs if there are more excitatory signals than inhibitory signals from the thousands of signals received from other neurons.
This causes the neuron to fire creating an electrical impulse.
what are neuronds
Neurons are cells that communicate messages through electrical and chemical signals throughout the nervous system. There are three different types: sensory, relay and motor neurons (each of these is defined in the text).
what is a neurotransmitter
Neurotransmitter is a chemical that is released from synaptic vesicles. These send signals across the synaptic cleft from one neuron to another. Neurotransmitters can cause excitation or inhibition of the next neuron in the chain.
what is synaptic transmition
Synaptic transmission is the process by which neighbouring neurons communicate with each other. Neurons send chemical messages across the gap (the synaptic cleft) that separates them.
