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

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5 Jan 2018

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Neurons have between 10,000 >150,000 synapses on their dendrites and cell body: capable of storing huge amounts of info in the brain, synaptic cleft: between the presynaptic axon terminal and postsynaptic junction. Components of a synapse: synaptic vesicles contain the neurotransmitter that is released into the synaptic cleft. Because energy is required for movement of synaptic vesicles, the mitochondria generate. Atp to provide energy to allow the movement of synaptic vesicles from inside presynaptic neuron to synaptic membrane: synaptic cleft and synaptic junction contains receptors where neurotransmitters bind to. Information transfer at the synapse: action potential conducted down the axon, each neurotransmitter binds to a specific receptor, activation of a receptor could be responsible for the depolarization response that initiates the greater potential in a cell body/dendrite. Receptor activation initiates a downstream signalling cascade signal transduction: conformational change triggers downstream response. Ionotropic = ion-loving: downstream can cause responses like depolarization, activation of greater potential.

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.

a) Which of the following statements about the autonomic nervous system is INCORRECT?

A The preganglionic fibres in the parasympathetic division are usually long compared to the postganglionic fibres

B The sympathetic division mediates responses that allow the body to respond to âflight and frightâ situations

C The ganglia of the sympathetic division are usually close to the spinal cord

b) Glutamate is an example of an excitatory amino acid neurotransmitter that acts via direct synaptic transmission when it is released from presynaptic neurons in the brain

Based on the background information, which of the following is a CORRECT statement regarding events at the synaptic cleft after glutamate is released?

A Glutamate acts by stimulation of receptors on the presynaptic neuron

B The postsynaptic glutamate receptors are in the family of tyrosine-kinase linked receptors

C On the postsynaptic membrane, glutamate activates ligand-gated sodium channels, which are an example of ion-channel linked receptors

D The events at this synapse are an example of electrical transmission

E The pathway of receptor activation includes activation of a signal transduction pathway and production of second messengers

D The adrenal medulla is a sympathetic ganglion

E The parasympathetic nerves arise from the brain stem and the sacral region of the spinal cord

fuchsiafish404

The junction specialized for the transmission between a neuron and another cell is called a (1) _____ ______. Usually, the signal being sent to the receiving cell is carried by chemical messengers called (2) _____. (3) _____ is an example of this type of chemical messenger, which diffuses across the synaptic cleft, combines with protein receptor molecules on the muscle cell membrane, and soon thereafter is rapidly broken down by enzymes. At an (4) ____ synapse, the membrane potential is driven toward the threshold value and increases the likelihood that depolarization and an action potential will occur. At an (5) ____ synapse, the membrane potential is driven away form the threshold value, and the receiving neuron becomes hyperpolarized and is less likely to achieve an action potential. A specific transmitter substance can have either excitatory or inhibitory effects depending on which type of protein channel it opens up in the (6) ____ membrane. (7) ____ are neuromodulators that inhibit perceptions of pain and may have roles in memory and learning, emotional states, temperature regulation, and sexual behavior. (8) ____ ________ at the cellular level is the moment-by-moment tallying of all excitatory and inhibitory signals acting on a neuron. Incoming information is (9) ____ by the cell bodies, and the charge differences across the membranes are either enhanced or inhibited. Some narrow-diameter neurons are wrapped in lipid-rich (10) _______ produced by specialized neuroglial called Schwann cells; each of these is separated from the next by a(n) (11) ________ ________ - a small gap where the axon is exposed to extracellular fluid. A (12) ____ is an involuntary sequence of events elicited by a stimulus. During a (13) _______ ________, a muscle contracts involuntary whenever conditions cause a stretch in length; many of these help you maintain an upright posture despite small shifts in balance. Imbalances can occur at chemical synapses; a neurotoxin produced by Clostridium tetani blocks the release of GABA and glycine, thus freeing the motor neurons from (14) _____ control, which may cause tetanus â a prolonged, spastic paralysis that can lead to death. A. Excitatory H. Stretch reflex B. Inhibitory I. Summed C. Myelin J. Neurotransmitters D. Chemical synapse K. Postsynaptic E. Synaptic integration L. Endorphins F. Exposed node M. Acetylcholine (ACh)

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

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