BIOL 3P34 Lecture Notes - Lecture 14: Ligand-Gated Ion Channel, Chemical Synapse, Nicotinic Acetylcholine Receptor

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7 Nov 2016

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Release of a chemical from the pre-synaptic cell that acts on ionotropic receptors (also ion channels) on post synaptic cell. Cation-selective channel activated by the binding of ach increase in cation permeability (na and ca) produces a depolarization or an excitatory post-synaptic potential (epsp) Glutamate is the most prevalent excitatory neurotransmitter. Acts on different types of cation-selective ionotropic receptors (ampa vs. Serotonin and ach also have excitatory actions on ionotropic receptors to produce excitation. Direct or fast inhibition occurs by the activation of anion channels (e. g. increased permeability to cl) Inhibitory input produces hyperpolarization of vm (moves away from threshold. Examples: gaba and glycine activate anion channels to produce inhibition. Epsps drive vm toward threshold potential for ap firing. Ipsps drive vm away from threshold for ap firing. Reversal potentials: help determine the permeability of channels to various ions nachr: voltage clamp muscle and stimulate nerve to produce synaptic current nachr: Non-selective cation channel (permeability to na, ca, and k)

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.

Assume you have an experimental set up with two neurons connected via a chemical synapse-Neuron A is presynatptic and Neuron B is postsynaptic. Also, assume that there is a stimulating electrode in Neuron A that brings it to threshold and produces an EPSP in Neuron B. (1)First state, which specific mechanism(s)/events(s) involved in chemical synaptic transmission WOULD be affected, e.g. what would be stopped, disrupted, enhance, dimished,ect.. (2) What WOULD NOT be affected, e.g. what would happen as usual, e.g. still have APs, neurotransmitter release, ect (3) Third, explain WHY these mechanisms and or events would or would not be affected. JUSTIFY.

(A) if presynaptic Na+ channels are blocked, then...

(1)

(2)

(3)

(B) if external K+ concetration becomes equal to internal K+ , then....

(1)

(2)

(3)

jadehippopotamus844

Sensory systems

1.All sensory input arrives at the central nervous system in the same form, as ____________ propagated by afferent neurons. Perception of the type and intensity of a stimulus depends on which part of the brain the impulse projects to and the firing frequency the sensory neuron.

A.action potentials B.receptor potentials C.reflexes D.frequency localizations E.thresholds

2.The simplest sensory receptors are __________ that respond to mechanical distortion,changes in temperature, or specific chemicals.

A.nociceptors B.free nerve endings C.gated channels D.photoreceptors. E.ganglia

3.When membrane proteins on an olfactory neuron are stimulated by the binding of a specific chemical, what is the immediate result?

A.membrane depolarization B.membrane repolarization C.active ion transport D.membrane hyperpolarization E.neurotransmitter release

5.The lateral line system provides ________ with a sense of "distant touch," enabling these animals to sense objects that reflect pressure waves and low-frequency vibrations.

A.adult amphibians B.reptiles C.birds D.mammals E.fish

6.Which correctly represents the sequence of steps involved to convey sensory information to the CNS?

A.stimulation and ion flow through the synaptic cleft B.neurotransmitter release and interpretation
C.neurotransmitter release and ion flow through the synaptic cleft D.stimulation, transduction, transmission, and interpretation E.stimulation, transmission, and neurotransmitter release

7.Which of the following stimuli do vertebrates NOT have a specialized receptor for?

A.hearing B.taste C.smell D.humidity E.vision

8.Which of the following is NOT an example of a mechanoreceptor?

A.Meissner's corpuscles B.Ruffini endings C.Merkel cells D.red corpuscles E.Pacinian corpuscles

9.What are the receptors called that transmit impulses that are perceived by the brain as pain?
A. baroreceptors B. chemoreceptors C. nociceptors
D. thermoreceptors E. propioceptors

10. Which of the following do humans NOT have taste buds specialized to sense?

A. salty B. sour. C. sweet. D. vitamins E. bitter

BIOL 3P34 Lecture Notes - Lecture 14: Ligand-Gated Ion Channel, Chemical Synapse, Nicotinic Acetylcholine Receptor

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