PAPER 2 - BIOPSYCHOLOGY - neurons and synaptic transmission Flashcards
what are neurons?
nerve cells responsible for sending and receiving neurotransmitters
what are the basic underlying structures of neurons?
dendrites
cell body
axon
presynaptic terminal
what do dendrites do?
receive signals from other neurons or sensory receptors
what does the cell body do?
control centre of the neuron
what does the axon do?
conducts nerve impulses away from the cell body and towards other neurons
what are the 3 types of neurons?
motor - multipolar
relay - multipolar
sensory - unipolar
what are sensory neurons?
- have cell body with 2 stems either side
- carries sensory information from the body’s sensory receptors to the spinal cord & brain
- convert information from sensory receptors to neural impulses that travel to the brain and are translated into sensations
- allows for quick reflexes
what are motor neurons?
- single axon, many dendrites HAS MYELIN SHEATH
- carries info from CNS to skeletal muscles/glands allowing control of movement & responses of internal systems
- located in CNS, their axons projected outside CNS and control muscles from synapses
what are relay neurons?
- cell body surrounded entirely by dendrites
- lie between sensory input and motor output
- they are neurons within the CNS that interconnect different parts of the CNS
- pass messages within the CNS and allow sensory & motor neurons to cocmmunicate
what are nerve impulses/action potential?
the electrical signal formed when information travels along the axon, away from cell body to axon terminal
what is synaptic transmission?
the process where a nerve impulse passes across the synaptic gap/cleft from one neuron to another
what is the synapse?
- small gap between neurons
- end of one dendrite / cell body of another where neurotransmitters are released, permitting nerve impulses transmitted between neurons
- includes end of presynaptic neuron and postsynaptic neuron
what are neurotransmitters?
chemical substance that transmit nerve impulses across a synapse
what is summation?
when multiple changes in voltage triggered by a neurotransmitter release, add up together
when does summation occur?
- if multiple nerve impulses occur in the presynaptic neuron in close succession
- if multiple nerve impulses occur at synapses on the same postsynaptic neuron at the same time
is the process of summation excitatory/inhibitory?
both - excitatory and inhibitory synaptic input on post synaptic neuron
what is the process of synaptic transmission?
- transmission of nerve impulses across the synapse is chemical, takes less than a second
- synaptic vesicles containing neurotransmitters stored at end of axon
- as nerve impulse/action potential travels down axon terminal, vesicles release neurotransmitter molecules to synapse
- neurotransmitter molecules diffuse across gap to postsynaptic membrane of next neuron & bind to specialised receptors
- the whole process has either excitatory or inhibitory effects on postsynaptic neuron
what happens after synaptic transmission?
neurotransmitter released back into synaptic space
the neurotransmitter is cleared from synaptic cleft by which processes?
diffusion - some of the neurotransmitter drifts away
break-down - some of the neurotransmitter is broken down by enzymes
re-uptake - some of it is taken back up into the presynaptic neuron, repackages & stored for later release
what are excitatory neurotransmitters?
- some neurotransmitters have excitatory effects on postsynaptic neuron (make it more likely to fire)
- excitatory synaptic connections increase neural activation in the CNS
what does an excitatory neurotransmitter binding with a postsynaptic receptor cause?
- causes an electrical change in the cell membrane
- this results in an excitatory postsynaptic potential (EPSP) making post synaptic cell more likely to fire
what are inhibitory neurotransmitters?
- some neurotransmitters have an inhibitory effect on the postsynaptic neuron (makes it less likely to fire)
- inhibitory synaptic connections decrease neural activation in the CNS
what does an inhibitory neurotransmitter binding with a postsynaptic receptor result in?
results in inhibitory postsynaptic potential (IPSP) making the postsynaptic potential less likely to fire
can a nerve cell receive excitatory or inhibitory influences?
a nerve cell can receive inhibitory or excitatory influences from several transmitters at the same time