BIOM 3200 UNIT 9 - Synaptic
Transmission and Muscle Physiology
Final Exam And Already Passed
Answers.
Differentiate between a chemical and electrical synapse - Answer Synapse: functional
connection between neuron and a second cell
Electrical Synapse: action potential is passed directly from one cell to the next via connections
known as gap junctions
Chemical Synapse: release of neurotransmitters from the presynaptic cell, which bind to
receptors on the postsynaptic cell - action potential
Identify different neuronal connections including: axodendritic, axosomatic, and axoaxonic -
Answer Axodendritic Synapse: a synaptic connection between the axon of one neuron and the
dendrite of a second neuron
Axosomatic Synapse: a synaptic connection between the axon of one neuron and the cell body
(soma) of a second neuron
Axoaxonic Synapse: a synaptic connection between the axon of one neuron and the axon of a
second neuron
Identify components of the synapse including: neurotransmitters, pre-synaptic membrane, post-
synaptic membrane, synaptic cleft, terminal bouton, synaptic vesicles - Answer
Neurotransmitters: stored within synaptic vesicles located in the presynaptic axon terminals
Pre-synaptic Membrane: membrane with which synaptic vesicles fuse to allow for exocytosis of
neurotransmitter into the synaptic cleft
Post-synaptic Membrane: membrane in which neurotransmitter receptors are found
Synaptic Cleft: space between the pre- and post-synaptic membranes
Terminal Bouton: name given to the presynaptic axon endings from which neurotransmitters are
released
Synaptic Vesicles: Storage vesicles for neurotransmitters
Describe electrical synapses and the role of gap junctions - Answer • electric synapse involves
direct conduction of action potential from one cell to the next via gap junctions
• cell membranes of the two neurons are very close together (2 nm) allowing for channels
formed by connexins to exist between them
, • When an action potential reaches the terminal bouton- cascade, which leads to the exocytosis
of neurotransmitter vesicles
• cross the synaptic cleft to bind to receptors on the postsynaptic cell
• causes specific ion channel to open and can lead to either excitatory postsynaptic potentials
(EPSP) or inhibitory postsynaptic potentials (IPSP) in the postsynaptic cell
Discuss the roles of calcium, synaptogamin, calmodulin, synaptobrevin, syntaxin, SNARE
complex in exocytosis of neurotransmitter vesicles - Answer • Calcium: opened by the action
potential reaching the terminal bouton - Ca2+ enters the cell and forms a complex with
synaptotagmin
• Synaptotagmin: is a calcium sensor, and complexes with Ca2+ - complex displaces components
of the SNARE, or fusion, complex allowing for neurotransmitter release via exocytosis
• Calmodulin: Activated by calcium, calmodulin activates protein kinase that is responsible for
phosphorylating other proteins involved in the cascade leading to exocytosis
• Synaptobrevin: one of the SNARE proteins
• Syntaxin: one of the SNARE proteins
• SNARE complex: responsible for holding docked vesicles to the presynaptic membrane to
allow for exocytosis
Describe how neurotransmitters function on the post-synaptic membrane in conducting nerve
impulses - Answer • Neurotransmitters bind to specific receptor proteins on the postsynaptic
membrane
• binding causes ion channels to open in the postsynaptic membrane
• opening of these channels produces are graded change in the membrane potential
Differentiate between voltage-gated and ligand gated ion channels - Answer • Voltage-Gated:
found primarily in the axon; open in response to depolarization
• Ligand (chemically) gated: found primarily in the postsynaptic membrane; open in response to
the binding of ligands to receptors
Define graded potentials - Answer • change in the membrane potential (depolarization or
hyperpolarization) with amplitudes that are varied, or graded, by gradations in the stimulus
intensity
• stimuli for graded potentials in postsynaptic neurons are neurotransmitters, and the degree of
depolarization or hyperpolarization produced depends on the amount of neurotransmitter
released by the presynaptic axon
Transmission and Muscle Physiology
Final Exam And Already Passed
Answers.
Differentiate between a chemical and electrical synapse - Answer Synapse: functional
connection between neuron and a second cell
Electrical Synapse: action potential is passed directly from one cell to the next via connections
known as gap junctions
Chemical Synapse: release of neurotransmitters from the presynaptic cell, which bind to
receptors on the postsynaptic cell - action potential
Identify different neuronal connections including: axodendritic, axosomatic, and axoaxonic -
Answer Axodendritic Synapse: a synaptic connection between the axon of one neuron and the
dendrite of a second neuron
Axosomatic Synapse: a synaptic connection between the axon of one neuron and the cell body
(soma) of a second neuron
Axoaxonic Synapse: a synaptic connection between the axon of one neuron and the axon of a
second neuron
Identify components of the synapse including: neurotransmitters, pre-synaptic membrane, post-
synaptic membrane, synaptic cleft, terminal bouton, synaptic vesicles - Answer
Neurotransmitters: stored within synaptic vesicles located in the presynaptic axon terminals
Pre-synaptic Membrane: membrane with which synaptic vesicles fuse to allow for exocytosis of
neurotransmitter into the synaptic cleft
Post-synaptic Membrane: membrane in which neurotransmitter receptors are found
Synaptic Cleft: space between the pre- and post-synaptic membranes
Terminal Bouton: name given to the presynaptic axon endings from which neurotransmitters are
released
Synaptic Vesicles: Storage vesicles for neurotransmitters
Describe electrical synapses and the role of gap junctions - Answer • electric synapse involves
direct conduction of action potential from one cell to the next via gap junctions
• cell membranes of the two neurons are very close together (2 nm) allowing for channels
formed by connexins to exist between them
, • When an action potential reaches the terminal bouton- cascade, which leads to the exocytosis
of neurotransmitter vesicles
• cross the synaptic cleft to bind to receptors on the postsynaptic cell
• causes specific ion channel to open and can lead to either excitatory postsynaptic potentials
(EPSP) or inhibitory postsynaptic potentials (IPSP) in the postsynaptic cell
Discuss the roles of calcium, synaptogamin, calmodulin, synaptobrevin, syntaxin, SNARE
complex in exocytosis of neurotransmitter vesicles - Answer • Calcium: opened by the action
potential reaching the terminal bouton - Ca2+ enters the cell and forms a complex with
synaptotagmin
• Synaptotagmin: is a calcium sensor, and complexes with Ca2+ - complex displaces components
of the SNARE, or fusion, complex allowing for neurotransmitter release via exocytosis
• Calmodulin: Activated by calcium, calmodulin activates protein kinase that is responsible for
phosphorylating other proteins involved in the cascade leading to exocytosis
• Synaptobrevin: one of the SNARE proteins
• Syntaxin: one of the SNARE proteins
• SNARE complex: responsible for holding docked vesicles to the presynaptic membrane to
allow for exocytosis
Describe how neurotransmitters function on the post-synaptic membrane in conducting nerve
impulses - Answer • Neurotransmitters bind to specific receptor proteins on the postsynaptic
membrane
• binding causes ion channels to open in the postsynaptic membrane
• opening of these channels produces are graded change in the membrane potential
Differentiate between voltage-gated and ligand gated ion channels - Answer • Voltage-Gated:
found primarily in the axon; open in response to depolarization
• Ligand (chemically) gated: found primarily in the postsynaptic membrane; open in response to
the binding of ligands to receptors
Define graded potentials - Answer • change in the membrane potential (depolarization or
hyperpolarization) with amplitudes that are varied, or graded, by gradations in the stimulus
intensity
• stimuli for graded potentials in postsynaptic neurons are neurotransmitters, and the degree of
depolarization or hyperpolarization produced depends on the amount of neurotransmitter
released by the presynaptic axon
