Neurons and synaptic transmission Flashcards
(16 cards)
What is a neuron?
-Nerve cells that process and transmit messages through electrical and chemical signals
What are the three types of neuron?
-Motor Neuron
-Relay Neuron
-Sensory neuron
Describe the Motor Neuron.
-They connect the CNS to the effectors (muscles and glands)
-Long axons
-Short dendrites
-soma (cell body) with nucleus
-Begin in the CNS but their long axons form part of PNS
Describe the Relay Neuron.
-They connect the sensory neurons to the motor or other relay neurons
-Short dendrites
-Short axons
-soma (cell body) with nucleus
-Make up 97% of all neurons
Describe sensory neurons.
-They carry messages from the PNS to the CNS.
-Long dendrites
-Short axons
-soma (cell body) with nucleus
-Found in clusters (ganglia) in the PNS
What is the role of an axon?
-They carry impulses down the length of the cell body of the neuron
What is a dendrite?
-Branchlike structures that protrude from the cell body which carry impulses from neighbouring neurons towards the cell body
What is a myelin sheath?
- A fatty layer which covers the axon, protecting it and speeding up rate of electrical transmission of impulse
What are nodes of ranvier?
-These are gaps in the myelin sheath which speed up the rate of transmission of electrical impulses as they have to jump across the gaps.
What are terminal buttons?
-Knobs at the end of an axon that communicate with the next neuron in the chain across the gap known as a synapse.
What is synaptic transmission?
-The process by which neighbouring neurons communicate with eachother by sending chemical messages across the synapse (the gap) that separates them
-This process is one-way (pre-synaptic release the neurotransmitter and post-synaptic receives it)
-When it reaches the Post-synaptic site it is turned back into a electrical impulse
What are neurotransmitters?
-Chemicals that are released from synaptic vesicles that relay signals across synapses to other neurons
-Neurotransmitters are either excitaory or inhibitory
-Examples = Serotonin (mood regulation) + acetylcholine(ACh) which cause muscle contraction.
What is excitation?
-When a neurotransmitter increases the positive charge of the postsynaptic neuron.
-This increases the likelihood that the neuron will fire and pass on the electrical impulse.
-Adrenaline is a excitaory neurotransmitter
What is inhibition?
-When a neurotransmitter makes the charge of the postsynaptic neuron more negative.
-This decreases the likelihood that the neuron will fire and pass on the electrical impulse.
- Serotonin is an inhibitory neurotransmitter.
What is summation?
-the sum of the overall inhibitory and excitaory influences
-if the net effect is inhibitory- neuron is less likely to be fired
-if net is excitaory it is more likely to be fired
What is action potential?
-a neural impulse a brief electrical charge that travels down an axon
-This is when the inside of the cell changes from negatively charged to positively charged because a stimulus causing the firing of a electrical impulse.
