Final Exam Flashcards
(137 cards)
what is a synapse?
site of communication between a neuron and another cell
types of synapses
1) electrical
2) chemical
how do electrical synapses work?
- direct physical contact between cells
how do chemical synapses work?
- signal transmitted across a gap (synaptic cleft) by chemical neurotransmitters
what does the production of action potential depend on in chemical synapses?
- amount and type of neurotransmitter released
- sensitivity of postsynaptic cell
what are the steps of action potential in chemical synpases?
1) action potential arrives & depolarizes synaptic knob
2) synaptic vesicles are exocytosed & neurotransmitter molecules are released
3) neurotransmitter crosses synaptic cleft & binds to receptor
4) ion channels open, depolarizing membrane & producing a graded potential
5) neurotransmitter removed & depolarization ends
what are cholinergic synapses?
- synapses that use acetylcholine as a neurotransmitter
- most common type of synapse
how does a cholinergic synapse work?
1) AP depolarizes synaptic knob
2) Ca2+ channels open
- Ca2+ enter
- Ach exocytosed
3) Ach binds to receptor
- Na+ enters
- depolarize membrane
4) AchE breaks down Ach (acetate + choline)
what are the 2 types of neurotransmitters?
1) excitatory
2) inhibitory
how do excitatory neurotransmitters work?
- cause depolarization of post-synaptic membranes
(excitatory postsynaptic potential = EPSP)
how do inhibitory neurotransmitters work?
- cause hyperpolarization of postsynaptic membranes
(inhibitory postsynaptic potential = IPSP)
effect on postsynaptic membrane depends on what?
the RECEPTOR
what are the 2 types of summation of postsynaptic potential (PSPs)?
1) spatial
2) temporal
do fewer synapses mean faster response?
yes
what is synaptic fatigue?
- occurs when neurotransmitter cannot be recycled fast enough to meet demands of intense stimuli
what are some major neurotransmitters?
- norepinephrine (NE)
- dopamine
- serotonin
what are some characteristics of norepinephrine?
- released by adrenergic synapses
- excitatory & depolarizing effect
- brain & portions of ANS
what are some characteristics of dopamine?
- CNS neurotransmitter
- excitatory or inhibitory
- involved in Parkinson’s diseases, cocaine use
what are some characteristics of serotonin?
- CNS neurotransmitter
- affects attention & emotional states
what are the 2 types of electrical signals?
1) graded potentials
2) action potentials
what are graded potentials?
- affect only a small portion of a cell membrane
- allows communication over short distances
how do action potentials work?
- affect the entire surface of a cell membrane
- allow communication over long distances
what are the 3 phases of graded potentials?
1) resting
2) stimulation
3) depolarization
what are the 5 phases of action potentials?
1) resting
2) threshold
3) activation/depolarization
4) inactivation/repolarization
5) return to resting