The Cells Of The Nervous System And Neurotransmitters At Synapses Flashcards
What makes up the neuron? (5 things)
Dendrites, cell body, axons, myelin sheath, glial cells.
What is the myelin sheath?
The myelin sheath surrounds axons and insulates the axon which increases the speed of impulse conduction
What is myelination?
Myelination is the production of the myelin sheath
When does myelination occur?
From birth to adolescence
What are responses to stimuli like in the first two years of life?
The responses to stimuli are not as rapid or coordinated as those of an adult.
The responses are slow and uncoordinated
What does MS ( multiple sclerosis ) do?
MS destroys the myelin sheath which results in a loss of coordination
What are glial cells?
Glial cells produce the myelin sheath and support neurons
What is the purpose of the cell body in the neuron?
To produce proteins such as neurotransmitters
What is the function of a dendrite?
Dendrites receive information from pre-synaptic neurons across the synaptic cleft.
Where do neurons connect with other neurons or muscle fibres at?
The synaptic cleft
What is the function of neurotransmitters?
Neurotransmitters relay impulses across the synaptic cleft
Where are neurotransmitters stored?
Neurotransmitters are stored in vesicles in the axon endings of the presynaptic neuron
When are neurotransmitters released?
Neurotransmitters are released on the arrival of an impulse by the vesicles of an axon into the synaptic cleft
What do neurotransmitters do during diffusion?
Neurotransmitters diffuse across the synaptic cleft and then bind to receptors on the membrane of the postsynaptic neuron
How can neurotransmitters be removed if they are sent in excess?
By degradative enzymes or reuptake to prevent continuous stimulation of postsynaptic neurons
What do receptors on the postsynaptic neuron determine?
Receptors determine whether the signal is excitatory or inhibitory
What happens to weak stimuli in the synapses?
Synapses can filter out weak stimuli which arise from insufficient secretion of neurotransmitters
What is meant by the threshold on the postsynaptic membrane?
Threshold is the minimum number of neurotransmitter molecules that must attach to receptors in order to transmit the impulse to the PS membrane
How can weak stimuli trigger an impulse?
Summation of a series of weak stimuli can release enough neurotransmitter to trigger an impulse
How can convergent neural pathways trigger impulses
Convergent neural pathways can release enough neurotransmitter molecules to reach the threshold and trigger an impulse
What is meant by an excitatory effect from neurotransmission?
An effect that switches on the next nerve cell
What is meant by an inhibitory effect on neurotransmission?
The neurotransmitters cause an effect that switches off the post synaptic neuron
