Name: __KEY___10 points_____________________________
Synaptic Events Worksheet
Use your textbook to complete this activity…
Period: ______
Label the following parts on the diagram below:
Presynaptic neuron
Nerve impulse
Synaptic end bulb
Synaptic cleft
Neurotransmitter receptors
Voltage-gated channel
Postsynaptic neuron
Closed ion channel
Open ion channel
Synaptic vesicle
Summarize how a typical synapse operates below according to your textbook: 5 blanks @ ½ point each
(1) _nerve impulse arrives at synaptic end bulb of presynaptic axon__________________________
(2) _depolarizing phase of nerve impulse opens voltage-gated Ca2+ channels, which are present in
membrane of synaptic end bulbs; Ca ions more concentrated in intestinal fluid, Ca2+ flows into
synaptic end bulb through opened channels__________________________________________
(3) _increase in Ca2+ concentration inside synaptic end bulb triggers exocytosis of some of the
synaptic vesicles; which releases thousands of neurotransmitter molecules into synaptic cleft_
(4) _neurotransmitter molecules diffuse across synaptic cleft bind to neurotransmitter receptors in
postsynaptic neuron’s plasma membrane; binding opens ion channels; certain ions allowed to
flow across membrane___________________________________________________________
(5) _as ions flow through opened channels, the voltage across the membrane changes; depending
on which ions the channels admit, the voltage change may de depolarization or
hyperpolarization; if depolarization in postsynaptic neuron reaches threshold, then it triggers
one or more nerve impulses_______________________________________________________
Why can information only move in one direction across a synapse?
_neurotransmitters only in presynaptic neuron____1 point____________________________________
Why is this probably a good thing?
_”crossed signals”____ 1 point __________________________________________________________
Over>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Neurotransmitters
Use your textbook to fill in information about the chemicals listed below… 11 chemicals @ ½ point each
_____________________________________________________________________________________
Acetylcholine (ACh) released by many PNS neurons and some CNS neurons; excitatory neurotransmitter
at some synapse, i.e. neuromuscular junction; inhibitory at other synapses, i.e. parasympathetic neurons
slow heart rate by releasing ACh at inhibitory synapses
_____________________________________________________________________________________
Glutamate amino acid neurotransmitter in CNS; powerful excitatory
_____________________________________________________________________________________
Aspartate amino acid neurotransmitter in CNS; powerful excitatory
_____________________________________________________________________________________
Gamma aminobutyric acid (GABA) amino acid neurotransmitter in CNS; important inhibitory
neurotransmitter; it is enhanced by antianxiety drugs like: diazepam (Valium)
_____________________________________________________________________________________
Glycine amino acid neurotransmitter in CNS; important inhibitory neurotransmitter
_____________________________________________________________________________________
Norepinephrine (NE) modified amino acid neurotransmitter; plays role in arousal (awakening from deep
sleep), dreaming, and regulating mood
_____________________________________________________________________________________
Dopamine (DA) modified amino acid neurotransmitter; active during emotional responses, addictive
behaviors, and pleasurable experiences; also help regulate skeletal muscle tone and some aspects of
movement due to contraction of skeletal muscles---one type of schizophrenia due to accumulation of
excess dopamine
_____________________________________________________________________________________
Serotonin modified amino acid neurotransmitter; thought to be involved in sensory perception,
temperature regulation, control of mood, appetite, and the onset of sleep
_____________________________________________________________________________________
Neuropeptides neurotransmitter consisting of amino acids linked by peptide bonds
_____________________________________________________________________________________
Endorphins neuropeptides that are the body’s natural painkillers; linked to improved memory and
learning and to feelings of pleasure and euphoria…acupuncture may produce analgesia (loss of pain
sensation) by increasing release of endorphins
_____________________________________________________________________________________
Nitric acid (NO) simple gas neurotransmitter; different from other neurotransmitters because not
synthesized in advance and packaged into synaptic vesicles, rather formed on demand, diffuses out of
cells that produce it into neighboring cells, and acts immediately; research suggests plays a role in
learning and memory
_____________________________________________________________________________________