Autonomic nervous system and neurotransmission Flashcards

1
Q

Autonomic nervous system definition

A

Effector system that controls viscera

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2
Q

Functions of the autonomic nervous system

A

Maintain homeostasis and respond to external stimuli

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3
Q

Subdivision of the ANS

A

Sympathetic, parasympathetic, and enteric

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4
Q

Major neurotransmitters in the ANS

A

Acetylcholine and norepinephrine

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5
Q

Other NT’s in the ANS

A

ATP, nitrous oxide, serotonin, GABA, dopamine, and glutamate

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6
Q

Differences between ANS synapses and CNS synapses

A

ANS are not as well-defined, have variable synaptic cleft distances, and are all metabotropic

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7
Q

Synthesis/degradation of NE

A

Synthesized in vesicles from Dopa, degraded in the cytosol by MAO and COMT (also some degradation enzymes in the mitochondria and in circulation)

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8
Q

NE release

A

Occurs somewhat near the target cell, but is not closely coupled

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9
Q

ACh synthesis and degradation

A

Synthesized by/broken back down to choline in the cytosol. Broken down by acetylcholinesterase

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10
Q

Choline is found frequently in these foods

A

Egg yolks, liver, and soybeans

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11
Q

Mechanism of nerve agents

A

Inhibit AChE and prevent ACh degradation, causing rapid death by overstimulation

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12
Q

Treatment for nerve gas agents

A

Drug cocktail with Diazepam to prevent seizures, atropine to block muscarinic AChRs, and pralidoxime (2PAM) to recover AChE function

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13
Q

Location of both ganglionic neurons

A

Preganglionic is within the CNS and synapses with a postganglionic neuron in an autonomic ganglion

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14
Q

All preganglionic neurons secrete ___

A

acetylcholine

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15
Q

Basal tone

A

Target organs have a resting level of activity that permits both increases and decreases from that set point.

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16
Q

Location of preganglionic somas

A

Lateral horn in the thoracic and upper lumbar segments of the spinal cord and in the C8 segment (thoracolumbar)

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17
Q

Type of receptors in the preganglionic-postganglionic synapse

A

Nicotinic (ionotropic, fast-acting)

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18
Q

ANS: ipsilateral or contralateral?

A

Mostly ipsilateral, except for the intestines and pelvis, which are bilateral

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19
Q

Two types of ganglia in the ANS

A

Paravertebral (sympathetic) and prevertebral (parasympathetic)

20
Q

Path of preganglionic neurons in the sympathetic system

A

Go usually into the ganglion at the corresponding level, but they can travel up and down. Enter through the white communicating ramus

21
Q

Superior cervical ganglion

A

Fused paravertebral ganglia from C1-C4 that control the head and neck

22
Q

Middle cervical ganglion

A

Fused paravertebral ganglia from C5-C6 that control the heart, lungs, and bronchi

23
Q

Stellate ganglion

A

Fused paravertebral ganglia from C7-C8 (T1) that also control the heart, lungs, and bronchi

24
Q

Gray communicating ramus

A

Postganglionic neurons send out their axons to spinal nerves through these

25
Sympathetic postganglionic fibers secrete ___ and activate ___ ___ receptors in target organs
Norepinephrine, metabotropic adrenergic
26
The special case of the adrenal medulla
Preganglionic axons pass through the splanchnic nerve and directly synapse with the medulla, so it doesn't have a post-ganglionic neuron
27
Chromaffin cells
Cells in the adrenal medulla that secrete epinephrine and NE directly into the blood stream as a response from the direct activation from cholinergic pre-ganglionic fiber
28
The adrenal medulla is responsible for the secretion of __% of epinephrine and __% of norepinephrine into the circulation
80% and 20%
29
Metabotropic receptors are coupled to these
G protein cascade
30
Exception to the sympathetic activation of postganglionic adrenergic receptors
Sweat glands - innervated by the sympathetic branch, but are activated via ACh binding to muscarinic metabotropic receptors
31
Location of parasympathetic preganglionic fibers
Cranial nerves in the brainstem and in the S3 and S4 sacral divisions of the spinal cord
32
Which cranial nuclei contain preganglionic somas?
Cranial nerves II, VII, IX, and X.
33
Type of receptors in parasympathetic post-ganglionic cells
Nicotinic (fast, ionotropic)
34
Parasympathetic ganglia are typically close to or far away from their target organs?
Close to
35
Parasympathetic postganglionic fibers typically activate these types of receptors with this NT
Metabotropic, ACh
36
Important muscarinic receptors
M1 - gastric secretion | M2/M3 - smooth muscle function
37
Parasympathetic smooth muscle activation generally causes ___, except . . .
dilation, except GI, where it causes contraction
38
Parasympathetics of the glossopharyngeal
Baroreceptor afferent fibers from the carotid sinus, which go through the nucleus solitarius and eventually control heart rate and blood pressure
39
Afferent fibers use this as their preferred nuerotransmitter
Glutamate
40
Common neuromodulators
Angiotensin II, arginine vasopressin, substance P, enkephalin, oxytocin, somatostatin, vasoactive intestinal polypeptide
41
Definition of referred pain
Pain in the viscera that is perceived by the CNS as somatic pain
42
Why does referred pain happen?
Convergence of somatic and visceral afferent fibers from the same SC level
43
Baroreceptor reflex
Negative feedback loop that controls arterial pressure
44
Location of baroreceptors
Nerve terminals in the carotid sinus and the aorta
45
Where afferent baroreceptor fibers end
Vasomotor and cardioregulatory centers of the medulla in the brainstem
46
Effect of stimulation of the vasomotor and cardioregulatory centers
- Decrease in sympathetic input to the heart - Increase in parasympathetic input - Decrease of sympathetic input to vascular smooth muscle - Decreased sympathetic input to adrenal chromaffin cells