Biopsychology - Neurons & Synaptic Transmission Flashcards
What is a neuron?
Nerve cells that process & transmit messages through electrical & chemical signals
What are the 3 types of neurons?
Relay
Motor
Sensory
Where are relay neurons located?
In the central nervous system
What is the function of the relay neuron?
Connect sensory neurons to the motor & other relay neurons
What are the characteristics of relay neurons?
Have short dendrites & axons
Where are motor neurons located?
The peripheral nervous system
What is the function of motor neurons?
Connect the central nervous system to effectors (muscles/glands)
What are the characteristics of motor neurons?
Short dendrites & long axons
Where are sensory neurons located?
The peripheral nervous system
What is the function of a sensory neuron?
Carry messages from the peripheral nervous system to the central nervous system
What are the characteristics of sensory neurons?
Have long dendrites & short axons
What are the characteristics of all neurons?
Dendrites
Cell body
Nucleus
Node of ranvier
Myelin sheath
Schwann cell
Axon
Terminal buttons
Describe how an electrical signal is sent over neurons
A dendrite receives a signal from another neuron which is passed down the axon. The myelin sheath & Schwann cells surrounding the axon, increases the speed at which the signal is transmitted which ends up reaching the terminal buttons at the end of the neuron. The electrical impulse is then sent to the next neuron.
What is stage 1 of synaptic transmission?
An action potential arrives at the axon terminal. The vesicles with the neurotransmitter merge with the membrane
What is stage 2 of synaptic transmission?
The neurotransmitters are released into the synaptic cleft and diffuse across the synapse to reach the post synaptic cleft
What is stage 3 of synaptic transmission?
Summation
What is summation?
The combined effect of all the excitatory & inhibitory neurotransmitter influences on the post synaptic neuron
What happens if the threshold is reached during summation?
if a threshold is reached then a new action potential is formed in the post synaptic cell
What are excitatory neurotransmitters?
Neurotransmitters that increase the likelihood of a new action potential forming in the cell.
They make the charge of the cell more positive & more likely to fire when detected (depolarisation)
Positively charged sodium ions enter the post synaptic cell
What are inhibitory neurotransmitters?
Neurotransmitters that decrease the likelihood of a new action potential forming in the cell.
They make the charge of the cell more negative & less likely to fire when detected (hyperpolarisation)
Positively charged potassium ions leave the post synaptic cell
What is stage 4 of synaptic transmission?
Some neurotransmitters are reabsorbed into the presynaptic cell after transmitting neurotransmitters which happens between transport proteins -> SSRIS
