Biopsych: neurons and synaptic transmission Flashcards
What is a neuron?
The basic building blocks of the nervous system, neurons are nerve cells that process and transmit messages through electrical and chemical signals
What are sensory neurons?
Neurons which carry messages from the PNS to the CNS. They have long dendrites and short axons
What are relay neurons?
Neurons which connect the sensory neurons to the motor or other relay neurons. They have short dendrites and short axons
What are motor neurons?
Neurons which connect the CNS to effectors such as muscles and glands. They have short dendrites and long axons
What are the three types of neurons?
Sensory, motor and relay
Describe the cell body (soma)
The soma includes a nucleus, which contains the genetic material of the cell.
Describe dendrites
Dendrites protrude from the cell body. They carry nerve impulses from neighbouring neurons towards the cell body
Describe the axon
The axon carries impulses away from the cell body down the length of the neuron. It is covered in a fatty layer of myelin sheath
Describe myelin sheath
Myelin sheath is a fatty layer that protects the axon and speeds up electrical transmission of the impulse
Describe the nodes of ranvier
Gaps which segment the myelin sheath and speed up the transmission of the impulse by forcing it to ‘jump’ across the gaps along the axon
Describe terminal buttons
At the end of the axon, they communicate with the next neuron in the chain across a gap known as the synapse
What is the charge when a neuron is in resting state?
When a neuron is in a resting state the inside of the cell is negatively charged compared to the outside
What happens 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
What does an action potential create?
An electrical impulse that travels down the axon towards the end of the neuron
What groups do neurons communicate with each other within?
Neural networks
What is the gap between neurons called?
The synapse
What does an electrical impulse reaching the end of the presynaptic terminal trigger?
The release of neurotransmitters from tiny sacs called synaptic vesicles
What are neurotransmitters?
Chemicals that diffuse across the synapse to the next neuron in the chain
What is a neurotransmitter taken up by once it crosses the gap?
Postsynaptic receptor site on the dendrites of the next neuron
What does each neurotransmitter have?
It’s own specific molecular structure that fits perfectly into a postsynaptic receptor site, similar to a lock and key
What is synaptic transmission?
The process by which neighbouring neurons communicate with each other by sending chemical messages across the gap (the synapse) that separates them
What is excitation?
When a neurotransmitter, such as adrenaline, increases the positive charge of the postsynaptic neuron. This increases the likelihood that the postsynaptic neuron will pass on the electrical impulse
What is inhibition?
When a neurotransmitter, such as serotonin, increases the negative charge of the postsynaptic neuron. This decreases the likelihood that the postsynaptic neuron will pass on the electrical impulse.
What is summation?
The process by which it is decided whether a postsynaptic neuron fires
How do you calculate summation?
The excitatory and inhibitory influences are summed
What happens if the net effect on the postsynaptic neuron is inhibitory?
The postsynaptic neuron is less likely to fire
What happens if the net effect on the postsynaptic neuron is excitatory?
The postsynaptic neuron is more likely to fire
The action potential of the postsynaptic neuron is only triggered if…
The sum of the excitatory and inhibitory signals at any one time reaches the threshold.
