Chapter 3 Flashcards
What is a neuron?
the specialized conducting cell of the nervous system
What is a dendrite?
branchlike or root like extensions from a neuron that connect to other neurons or axons to RECEIVE INFORMATION
What is an axon?
Extension of a neuron used to CONDUCT electrical impulses
What is a Glial cell?
it is the support cell of the nervous system
What do Glial cells do?
surround neurons and hold them in place
manufacture nutrient chemicals
absorb toxins and waste
Explain what a tripartite synapse includes?
presynaptic axon
postsynaptic dendrite
Glial cell that surrounds the area and helps clear the neurotransmitters more efficitently
What is the absolute refractory period?
the time when the membrane is not excitable and cannot generate another action potential
What is the action potential threshold?
-55mv
needs to change from -70 to -55 in order to trigger action potential (minimum change)
What is the all or none law?
action potentials occur at a uniform and maximum intensity or they do not occur at all
Explain the resting state of a neurons membrane
Abundant Na+ outside membrane and K+ and negative molecules inside.
creates a resting potential of -70mV
explain the process of an axon stimulating a dendrite
action potential travels down the axon.
the change in voltage of the axon terminal from -70 mV to +40 mv triggers the release of neurotransmitters from synaptic vesicles in the axon terminal into the synaptic cleft
these neurotransmitters then quickly diffuse across the synaptic cleft and bind to receptor proteins in the dendritic membrane.
these proteins then trigger the opening of gated Na+ channels to generate an action potential in the dendrite
What is a graded potential?
it is when the membrane depolarizes slightly, but not enough to reach the action potential threshold and thus not enough to generate an action potential
What is a myelin sheath?
a fatty white layer of insulation derived from glial cells during development
What is a node of ranvier?
an area where the myelin is either extremely thin or absent..
What does multiple sclerosis do?
it is when the immune system attacks the myelin sheath
What is an excitatory transmitter?
A neurotransmitter that depolarizes the neuron’s membrane when it binds to a receptor protein by opening Na+ channels
What is an inhibitory neurotransmitter?
a neurotransmitter that causes the neuron to hyperpolarize by allowing k+ to flow out or negative ions to flow in making it more negative
makes it more difficult for the action potential threshold to be reached
allows fine tuning and reduces the chance of uncoordinated discharges
At what point is the action potential threshold?
-55mV
What are the two ways that a neurotransmitter can be deactivated?
Breakdown by chemicals in the synaptic cleft
Reuptake into the pre synaptic axon terminal
approximately how many neurotransmitters are there?
100-150
What does acetylcholine affect?
memory and muscle activity
underproduction of ACh linked to Alzheimer’s
botulism blocks it at muscles resulting in paralysis
it is excitatory
What does dopamine do?
many things including:
motivation, reward, pleasure, voluntary motor control
it is excitatory
What neurotransmitter does Parkinson’s disease deplete?
dopamine
What does serotonin influence?
mood, eating, sleep, and sexual behaviour
What does the medication Prozac do?
block the reuptake of serotonin to allow it to exert its effects for longer
What do endorphins do?
block pain and increase feelings of well being
explain the difference between neurotransmitters and neuromodulaters
neurotransmitters have a very specific effect that effect a very specific area
neuromodulators have a generalized effect of enhancing or inhibiting receptors that is widespread over a large area often the whole brain
