BIO 365S Lecture Notes - Lecture 7: Axon Hillock, Lipophobicity, Skeletal Muscle

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16 May 2018

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Neural Synapses

A small gap between neuron and neuron: Synaptic cleft

Electrical signal needs to be transferred to Chemical Signal

If graded potential big enough, reaches axon hillock (if not enoughh,

will decrease), if big enough makes ion channels open, generating

action potential, has potential to reach the terminal part, ready to talk

to another neuron or skeletal muscle.

Synapse: gap b/w neurons.

Synaptic cleft: need chemical signals (neurotransmitter) to work. Must

e peptide horoes eauase deliered  sapti esiles. Ca’t e

lipid. Eletrial does’t ork.

Lower serotonin: depression. SSRI = increases it as antidepressant.

Receptor enzymes: ligand gated ion channels. Once neurotransmitter

released, binds with ligand-gated soldium channels, allowing it to rush

in, causing another graded potential and etc.

Synaptic Communication

VG Ca channel open to trigger NT release

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Need voltage gated Ca2+ channel in the released part. Ca2+ high

outside (because 2nd messenger). In muscles, Ca2+ need muscle

contraction, whereas in neurons, trigger release.

Neurotransmitters

•Follo priiples of protei-based (lipophobic) ligand action

•Ca trigger heiall-gated ion channels

•Ca trigger second messenger cascade

•

•Ca e eitator or ihiitor, depedig o reeptor

•

•Iflueed  drugs ad diseases

•

Most neurotransmitters are excitatory. Some bind with GPCR. Ions

open postive charge channels open to increase positive charges on the

inside.

Some of inhibitory, like GABA, opens Cl- channel (negative charge). Cl-

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Document Summary

A small gap between neuron and neuron: synaptic cleft. Electrical signal needs to be transferred to chemical signal. If graded potential big enough, reaches axon hillock (if not enoughh, will decrease), if big enough makes ion channels open, generating action potential, has potential to reach the terminal part, ready to talk to another neuron or skeletal muscle. Synaptic cleft: need chemical signals (neurotransmitter) to work. Must (cid:271)e peptide hor(cid:373)o(cid:374)es (cid:271)e(cid:272)auase deli(cid:448)ered (cid:271)(cid:455) s(cid:455)(cid:374)apti(cid:272) (cid:448)esi(cid:272)les. Once neurotransmitter released, binds with ligand-gated soldium channels, allowing it to rush in, causing another graded potential and etc. Vg ca channel open to trigger nt release. Need voltage gated ca2+ channel in the released part. In muscles, ca2+ need muscle contraction, whereas in neurons, trigger release. Neurotransmitters: follo(cid:449) pri(cid:374)(cid:272)iples of protei(cid:374)-based (lipophobic) ligand action, ca(cid:374) trigger (cid:272)he(cid:373)i(cid:272)all(cid:455)-gated ion channels, ca(cid:374) trigger second messenger cascade, ca(cid:374) (cid:271)e e(cid:454)(cid:272)itator(cid:455) or i(cid:374)hi(cid:271)itor(cid:455), depe(cid:374)di(cid:374)g o(cid:374) re(cid:272)eptor, i(cid:374)flue(cid:374)(cid:272)ed (cid:271)(cid:455) drugs a(cid:374)d diseases.

Related Questions

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

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

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BIO 365S Lecture Notes - Lecture 7: Axon Hillock, Lipophobicity, Skeletal Muscle

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