BIOC32H3 Lecture Notes - Lecture 5: Exon, Ligand-Gated Ion Channel, Signal Transduction

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12 Nov 2014

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Neuronal signalling involves three signalling mechanisms: graded potential, action potential, chemical neurotransmission. Neurotransmission- conversion of the action potential into a chemical signal which is released from the presynaptic axon terminal a response (graded potential) is triggered in the dendrites/cell body of the target neuron at the postsynaptic junction. The components of a synapse include: pre-synaptic components: Presynaptic axon terminal, synaptic vesicles, neurotransmitters (in vesicles), ca+ channels, mitochondria: synaptic cleft (between pre and post, post-synaptic components: Once the receptor is activated, signal transduction is initiated. *note: the high specificity for each receptor and neurotransmitter is referred to as the lock-key hypothesis. Directly coupled to ion channels; allow movement of ions. Causes fast postsynaptic responses and quick to and not of great impact channels across the postsynaptic membrane inactivate effects are short-lasting: g-protein coupled receptors (gpcr) Has slow synaptic responses; slow to activate and inactivate effects are longer-lasting and has a greater impact.

Related Questions

Which one of the following is an experimental evidence that demonstrates the reverse-transport model of amphetamine action? At high concentration of amphetamine,

a. it shows saturation kinetics when all the transporters are occupied and reversed.

b. it requires Ca++ ions entry to release neuotransmitters.

c. it requires action potential firings at the pre-synaptic terminal

. d. it is broken down by the COMT enzyme at the synapse, rendering it useless.

e. it is synthesized by the presynaptic neuron

33. When the reuptake of dopamine is blocked by the Ritalinâ¢ or cocaine molecule, what would happen?

a. increase in dopamine synthesis by the presynaptic neuron

b. decrease in dopamine synthesis by the presynaptic neuron

c. dopamine level at the synaptic cleft would be prolonged

d. dopamine level at the synaptic cleft would be decreased

e. enhance the release of dopamine from the presynaptic terminal.

Which experiment is used to prove that release of dopamine induced by amphetamine is not coming from vesicular release? a. dopamine is released by activation of action potentials in the presynaptic neuron without amphetamine. b. dopamine release only in the presence of magnesium. c. dopamine release is dependent on depolarization of post-synaptic cell. d. dopamine release from axon terminal can occur in Ca++ free medium. e. dopamine release is quantal in amount.

Tetraethylammonium (TEA) is a drug that blocks voltage-gated potassium channels. What effect would this have on an action potential?

(a)Prevent the rising phase

(b)Prevent the cell from reaching the threshold to trigger an action potential

(c)Prevent or prolong the falling phase

(d)None of the above

The hyperpolarization phase of the action potential is due to:

(a)The opening of voltage-gated Cl- channels

(b)Prolonged opening of voltage gated K+ channels

(c)The closure of resting Na+ channels

(d)Rapid inactivation of voltage-gated K+ channels

The period when it is difficult to initiate another action potential for several milliseconds due to voltage-gated sodium channel inactivation is referred to as the:

(a)Relative refractory period

(b)Absolute refractory period

(c)Resting period

(d)Hyperpolarization period

In the human central nervous system, Gap junctions are found:

(a)Only between neurons

(b)Only between astrocytes

(c)In both neurons and astrocytes

(d)In all cells

Small molecule transmitters such as acetylcholine are synthesized in:

(a)The nerve terminal

B) The cell body and transported to the nerve terminal

C) Synaptic vesicles

D) Endoplasmic reticulum

Prior to Otto Loewiâs classical experiment, which of the following was not known:

(a)stimulation of the vagus nerve slows the heart

(b)extracts of frog heart, made following vagal nerve stimulation, slow the heart

(c)some acetylcholine effects are similar to those produced by muscarine

(d)vagal nerve stimulation releases a substance which slows the heart

Which of the following is most important in determining if neurotransmission is excitatory or inhibitory?

(a)The structure of the synapse

(b)The neurotransmitter released by the presynaptic neuron

(c)The neurotransmitter receptor

(d)The strength of the stimulus

Benzodiazepines such as Valium allosterically regulate GABA receptors by:

(a)Binding at receptor sites other than the transmitter binding site

(b)Binding at the transmitter (GABA) binding site on the receptor

(c)Blocking the action of the endogenous transmitter

(d)Mimicking the action of the endogenous transmitter

GABA-A receptors are ligand-gated Cl- channels. The equilibrium potential of Cl- is -65 mV. At the neuronal resting membrane potential of -65 mV, GABA binding to the GABA-A receptor would result in the opening the Cl- channel, resulting in:

(a)no net flow of Cl- ions

(b)Cl- inflow and hyperpolarization

(c)Cl- outflow and depolarization

(d)Cl- outflow and hyperpolarization

At the mammalian neuromuscular junction, the released neurotransmitter acts on:

(a)muscarinic receptors

(b)nicotinic receptors

(c)adrenergic receptors

(d)Beta receptors

Neurotransmitters are packaged into synaptic vesicles by:

(a)endocytosis following transmitter release

(b)presynaptic membrane transporters

(c)vesicular transporters

(d)all of the above

. Which of the following are NOT types of ion channels?

Voltage-gated

(a)Ligand-gated

(b)G protein coupled receptor (GPCR)-gated

(c)Leak channels

(d)NONE of the above

NMDA receptors are unique in that their ion channel is:

(a)Ligand-gated

(b)Voltage-gated

(c)Ligand- and voltage-gated ion channels

(d)GPCR-gated

. Which of the following is INCORRECT regarding Catecholamine neurotransmitters

(a)Includes Dopamine, Norepinerphrine, and Epinephrine

(b)Contain a Catechol Ring

(c)Synthesized from Tryptophan

(d)Are produced by neurons whose cell bodies are located in the upper brainstem

The largest and most diverse group of receptors in eukaryotes is:

(a)Ligand gated receptors

(b)Glutamate receptors

(c)G-Protein coupled receptors

(d)Allosteric receptors

The most abundant G-protein coupled receptor in the brain is:

(a)Glutamate receptors

(b)Acetylcholine receptors

(c)Cannabinoid receptors

(d)Dopamine receptors

Which of the following drugs DOES NOT block voltage-gated Na+ channels

(a)Lidocaine

(b)Riluzole

(c)Reserpine

(d)Tetrodotoxin

Sarin, a nerve gas, exerts its toxicity by:

(a)blocking nicotinic receptors

(b)inhibiting choline acetyltransferase

(c)inhibiting acetylcholinesterase

(d)inhibiting voltage-gated Na+ channels

Botulinum Toxin (BoTox) interferes with transmitter release by:

(a)cleaving protein(s) involved in transmitter release

(b)blocking voltage-gated Ca2+ channels

(c)blocking voltage-gated Na+ channels

(d)blocking voltage-gated K+ channels

Atropine is:

(a)An agonist of the acetylcholine ionotropic receptor

(b)An antagonist of the acetylcholine ionotropic receptor

(c)An agonist of the acetylcholine metabotropic receptor

(d)An antagonist of the acetylcholine metabotropic receptor

BIOC32H3 Lecture Notes - Lecture 5: Exon, Ligand-Gated Ion Channel, Signal Transduction

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