Biopsychology : Neurons And Synaptic Transmission Flashcards
(28 cards)
Definition of neuron
The basic building blocks of the nervous system
They are nerve cells that process and transmit messages through electrical and chemical signals
Definition of sensory neurons
Carry information from the PNS to the CNS
They have LONG dendrites and SHORT axons
Definition of relay neurons
Connect sensory neurons to the motor or other relay neurons
SHORT dendrites and SHORT axons
Definition of motor neurons
Connect the CNS to effectors such as muscles and glands
SHORT dendrites and LONG axons
What does the cell body include
A nucleus which contains the genetic material of the cell
Branchlike structures called dendrites prelude from the cell body - these carry nerve impulses from neighbouring neurons towards the cell body
Function of dendrites
Carry nerve impulses from neighbouring neurons towards the cell body
Function of axons
Carries impulses AWAY from the cell body down the length of a neuron
Function of myelin sheath
Covers the axon and is a fatty layer
Protects the axon and speeds up electrical transmission of the impulse
Why does the mycelia sheath need nodes of ranvier
Otherwise it would be continuous and have the reverse effects and slow down electrical impulses
Function of nodes of ranvier
Speed up transmission by forcing it to ‘jump’ across the gaps along the axon
Function of terminal buttons
Found at the end of axons
They communicate with the next neurons chain across a gap called a synapse
Where are motor neurons found
May be in the CNS
But they have long axons which form part of the PNS
Where are sensory neurons found
Outside of the CNS in the PNS known as ganglia
Where are relay neurons found
Make up 97% of all neurons and are most found within the brain and visual system
What is electrical transmission and how does it occur
The firing of a neuron
When a neuron is at resting state the inside of the cell is negatively charged compared to the outside
When a neuron is activated by a stimulus the inside of the cell becomes positively charged for a split second causing an action potential to occur
This creates an electrical impulse that travels down the axon towards the end of a neuron
Definition of synaptic transmission
The process by which neighbouring neurons communicate with each other by sending chemical signals across a synapse
What is chemical transmission
- neurons communicate with each other within groups (neural networks)
- each neuron is separated from the next by a synapse
- signals within the neuron are transmitted electrically
- signals between neurons are transmitted chemically across the synapse
- when the electrical impulse reaches the end of the neuron it triggers the release of a neurotransmitter from synaptic vesicles
What is a neurotransmitter
Chemicals that diffuse across the synapse to the next neurons chain in chain
What happens once the neurotransmitter crosses the synapse
It is taken up by a postsynaptic receptor site on the dendrites of the next neurons
Here the chemical message is converted back into an electrical impulse and the process of transmission begins again in the next neurons
Why can the direction of travel be ONE WAY
Neurotransmitters are released from the presynaptic neuron terminal and received by the postsynaptic neuron
What is a feature of neurotransmitters
They have their own specific molecular structure that fits perfectly into a postsynaptic receptor site
Similar to lock and key
LOL BIOLOGY
Example of a neurotransmitter (PE)
Ach ( acetylcholine)
Found at each point where a motor neuron meets a muscle and upon to release it causes the muscle to contract
What effects do neurotransmitters could have on a neighbouring neurons
Excitatory or inhibitory
What is an example of inhibitation
Serotonin causes inhibition in the receiving neuron, resulting in the neuron becoming more negatively charged and less likely to fire
