Neurotransmission Flashcards
what does the phospholipid bilayer prevent?
ion exchange
what regulates the movement of ions?
ion channels
what are the main ion specific channels?
sodium, potassium, chloride channels
what is the membrane potential?
the difference in electrical charge between the inside and outside of the neuron
what will change the membrane potential?
movement of ions through the channels
what is the membrane potential of the average neuron?
-65mV
depolarization occurs when…
the membrane potential becomes more positive
hyperpolarization occurs when…
the membrane potential becomes more negative
what are the two ion gradients?
concentration and electrical
what is equilibrium potential?
when the flow of ions in and out has the same pull
which gradients is sodium drawn in by?
electrical and concentration
what is the equilibrium potential of Na+?
+60mV
what is the equilibrium potential of K+?
-85mV
what is the equilibrium potential of Cl-?
-65mV
which gated ion channels are open at rest?
mostly K+, half as many Cl-, very very few Na+
what is the sodium potassium pump?
ATP activated pump that moves 3 Na+ out of the cell and 2 K+ into the cell
what happens if there is an excitatory postsynaptic potential?
sodium channels open and will come into the cell to cause depolarization
what happens if there is an inhibitory postsynaptic potential?
chloride channels open and decrease the likeliness of depolarization
what is temporal summation?
when the stimulus is applied repeatedly in succession from one input
what is spatial summation?
when many stimulus are applied from multiple input sources?
what happens when the membrane potential decreases past threshold (-50mV)?
creates a sudden opening of voltage gated sodium channels (rising phase)
what happens after the rising phase?
falling phase
sodium channels are deactivated and voltage gated potassium channels are active, causes rapid repolarization
what returns the neuron back to its resting membrane potential after the falling phase?
the falling phase undershoots, Na+K+ pump rises the membrane potential back to resting
what is the absolute refractory period?
time after the membrane potential has crossed the threshold when another action potential cannot begin
when will sodium channels reopen?
when the membrane potential is below threshold
what is the relative refractory period?
potassium channels remain open for a moment to undershoot the resting membrane potential, requires a stronger stimulus to reach threshold
how is the action potential released?
progressively along the axon
what helps increase the rate of impulse?
thicker myelin, larger axons
what are nodes of Ranvier
gaps between myelin
what are signals traveling along the nodes of Ranvier called?
saltatory conduction
what happens when an action potential reaches the end of an axon?
neurotransmitters are released
when will a postsynaptic neuron start an action potential?
when enough neurotransmitters reach the receptors on the postsynaptic membrane
neurotransmitters
can be inhibitory, excitatory, or neuromodulatory
some have different effects on different receptors
multiple neurotransmitters can be released within a single synapse
what are neurotransmitters composed of?
molecules or amino acids
glutamate
most common excitatory neurotransmitter
found and acts throughout CNS
allows Na+ into membrane, leads to depolarization
histamine effect
excitatory, neuromodulatory function
gamma-aminobutyric acid (GABA)
most common inhibitory neurotransmitter
found and acts throughout CNS
allows Cl- through membrane
glycine action and location
inhibitory
found in and acts on the spinal cord, acts on the brainstem
what do neuromodulators do?
change how neurons function:
change firing rate
synaptic efficacy
+/- currents
dopamine location
substantia nigra and ventral tegmental area
serotonin location
raphe nuclei
where is histamine found
hypothalamus and reticular formation
norepinephrine location
sympathetic ganglia and locus ceruleus
where are neuropeptides found
entire CNS
acetylcholine
primary neurotransmitter in neuromuscular junctions
what kind of synapses does Ach have?
preganglionic autonomic and postganglionic parasympathetic
where does Ach have a neuromodulator effect?
in small areas of the CNS
