Physiology II Exam III > Autonomic Nervous System > Flashcards

Autonomic Nervous System Flashcards

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1
Q

What are the two sequential neurons that compose the ANS?

A
  • preganglionic neuron

- postganglionic neuron

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2
Q

Describe the preganglionic neuron.

A
  • cell bodies are located within CNS
  • axons are myelinated
  • neurotransmitter is ACh
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3
Q

Describe the postganglionic neuron.

A
  • cell bodies are located in peripheral ganglia
  • axons are not myelinated

-neurotransmitter is
+ACh is parasympathetic
+NE in sympathetic

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4
Q

What some generalizations regarding the ANS?

A
  • most parasympathetic and almost all sympathetic postganglionic fibers merely touch or pass near to the effector cells of the organs they innervate
  • terminal ends of these fibers usually have enlarged varicosities where neurotransmitter and large numbers of mitochondria are stored
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5
Q

Cell body of each sympathetic preganglionic neuron lies where?

A

-intermediolateral horn of the spinal cord (T1-L2)

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6
Q

Describe how the sympathetic preganglionic fibers travel.

A
  • can synapse with postganglionic neurons upward or downward in the paravertebral chain
  • preganglionic fiber can pass for variable distances through the chain and then through one of the sympathetic nerves to synapse in a peripheral sympathetic ganglion
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7
Q

What are some characteristics of postganglionic sympathetic fibers?

A
  • pass through the gray rami
  • are type C fibers
  • make up about 8% of the fibers in the average nerve
  • control blood vessels, sweat glands, piloerection muscles
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8
Q

Where is the thoracic sympathetic chain?

A

Lies against neck of ribs and costovertebral junctions

-12 thoracic ganglia pairs
+first one often fused with inferior cervical ganglion
+referred to as stellate ganglion collectively

-cervical ganglion
+superior, middle, inferior

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9
Q

The preganglionic sympathetic supply to the thoracic viscera are from _________.

A

T1-5

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10
Q

The postganglionics are from the thoracic sympathetic chain are from where? How do they exit?

A
  • superior, middle, and inferior cervical ganglia
  • T1-T5 paravertebral ganglia
  • they exit the chain as direct fibers and travel downwards to enter the thorax -> as cardiopulmonary splanchnic nerves
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11
Q

The cardiopulmonary splanchnic nerves travel on their own and do not accompany other nerves or vessels.

A

:)

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12
Q

What is the function of the thoracic sympathetic chain?

A
  • coronary artery dilation
  • increase HR
  • bronchodilation
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13
Q

What are splanchnic nerves??

A
  • composed of preganglionic fibers and visceral sensory fibers
  • supply abdominal viscera
  • synapse in prevertebral ganglia
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14
Q

Location and synapses of greater splanchnic nerves?

A
  • T5-T9

- synapses in celiac ganglion

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15
Q

Location and synapses of lesser splanchnic nerves

A
  • T10-T11

- synapses in the superior mesenteric ganglion

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16
Q

Location and synapses of the least splanchnic ganglion

A
  • T12

- synapses in the aorticorenal ganglion

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17
Q

When the adrenal medulla is stimulated by the sympathetic system what does it secrete?

A
  • secrete about 80% epi and 20% NE

- hormones last 5-10x longer than neurotransmitter versions

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18
Q

What does circulating NE do?

A

-constricts most blood vessels of the body
+greater effect on blood vessels in skeletal muscles so greater effect on raising arterial pressure

  • increases heart activity
  • inhibits GI tract
  • dilates pupil
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19
Q

Secretory cells of the adrenal medulla are what?

A
  • postganglionic neurons

- have rudimentary fibers that secrete epi and NE

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20
Q

What does circulation epinephrine do?

A
  • raises arterial pressure to a lesser extent than NE
  • increases cardiac output more than NE
  • has 5-10x as great effect on metabolism as NE
  • can increase metabolic rate of whole body as much as 100% above normal
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21
Q

What is the alarm or stress response?

A

-occurs when there is a mass discharge of the entire sympathetic system

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22
Q

What does the alarm response induce physiologically?

A
  • increased arterial pressure
  • reroute get of blood flow to active muscles
  • increased rates in cellular metabolism
  • increased blood glucose conc
  • increased glycolysis in liver and muscle
  • increased muscle strength
  • increased mental activity
  • increased blood coagulation
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23
Q

About 75% of all parasympathetic fiber are in what?

A

Vagus nerve

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24
Q

Most preganglionic fibers pass all the way to the organ that is to be innervated.

A

;)

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25
Where are postganglionic parasympathetic fibers found? What do they use as their neurotransmitter?
- are located in the wall of the organ | - use ACh as their neurotransmitter
26
What cranial nerves carry parasympathetic signals?
- oculomotor (III) - facial (VII) - glossopharyngeal (IX) - vagus (X)
27
What are the functions of the oculomotor nerve?
- supplies fourth of the six extrinsic muscles of the eye and the levator palpebrae superioris - preganglionic: from Edinger-Westphalia nucleus to the ciliary ganglion - postganglionic: from the ciliary ganglion to the sphincter pupillae muscle
28
What are the functions of the facial nerve?
- primary motor nerve to muscles of facial expression - carries sensation of taste from anterior 2/3 of tongue Preganglionics: from superior saliva tort and lacrimal nuclei to submandibular/sublingual ganglia -postganglionics: to lacrimal glans, submandibular gland, sublingual gland, adn mucus glands of mouth and nose
29
What is the function of the glossopharyngeal nerve?
- carries general sensation and sensation of taste from posterior 1/3 of the tongue - preganglionics: from inferior saltatory nucleus to otic ganglion - postganglionics: to parotid gland
30
What is the function of the vagus nerve?
-motor supply to muscles of the 4th and 5th pharyngeal arches and is important in swallowing and speaking
31
Outline the parasympathetics of the vagus nerve.
-major parasympathetic supply to thoracic and abdominal organs Preganglionics: from dorsal motor nucleus Postganglionics: myenteric plexus of wall of gut tube all the way to the left colic fissure
32
What is the course if the vagus nerve?
- runs parallel to esophagus (innervates esophagus) - passes posterior to root of lung on each side - pierces diaphragm with esophagus - becomes gastric nerve - supplies viscera in thoracic cavity
33
What are the vagus nerve branches?
- cardiac branches to cardiac plexus - pulmonary branches to pulmonary plexus - esophageal branches to esophageal plexus - left recurrent laryngeal nerve from left vagus (hooks around arc of aorta to left of ligamentum arteriosus) - right recurrent laryngeal nerve from right vagus (raisers in neck, not thorax)
34
How is ACh produced? Broken down?
- acetyl CoA + choline -> ACh (choline acetyl transferase) | - ACh -> choline + acetate ion (acetylcholinesterase)
35
Describe how NE is produced?
- hydroxylation of tyrosine to dopa - decarboxylation of dopa to dopamine - transport of dopamine into the vesicles - hydroxylation of dopamine to NE * in the adrenal medulla, 80% of NE is methylated to form epi
36
How is NE removed?
- reuptaken - diffusion - destruction by monoamine oxidase -> found in nerve endings - destruction by catechol-O-methyl transferase (COMT) -> present in all tissue * NE/epi is active for only a few seconds when secreted directly into the tissues, but is active in blood until destroyed by COMT
37
What are muscarinic ACh receptors?
- muscadine is a poison from toadstools | - receptors are found on all effector cells stimulated by postganglionic cholinergic neurons
38
What are nicotinic ACh receptors?
- found in autonomic ganglia at synapses between preganglionic and postganglionic neurons - present in neuromuscular junctions in skeletal muscle
39
What are alpha adrenergic receptors?
- NE excited mainly alpha receptors but also beta receptors to a lesser extent - epi excited both alpha and beta almost equally - certain alpha receptors are excitatory; others are inhibitory
40
What are alpha receptors associated with?
- vasoconstriction - iris dilation - intestinal relaxation - intestinal sphincter contraction - pilomotor contraction - bladder sphincter contraction - inhibition of neurotransmitter release
41
What do beta1 adrenergic receptors do?
- cardio acceleration - increased myocardial strength - lipolysis
42
What do beta2 adrenergic receptors do?
- vasodilation - intestinal relaxation - uterus relaxation - bronchodilation - calorigenesis - glycogenolysis - bladder wall relaxation
43
What do beta3 adrenergic receptors do?
-thermogenesis
44
What are the sympathomimetic drugs?
- NE - epi - methoxamine - phenylephrine (alpha receptors) - isoproterenol (beta receptors) - albuterol (beta2 receptors)
45
What drugs cause release of NE?
- ephedrine - tyramine - amphetamine
46
What does reserpine do?
-blocks synthesis and storage of NE
47
What does guanethidine do?
-blocks release of NE
48
What does phenotype amine/phentolamine do?
-block sympathetic alpha receptors
49
What does propranolol do?
-blocks sympathetic beta1 and beta2 receptors
50
What does metoprolol do?
-blocks mostly sympathetic beta1 receptors
51
What does hexamethonium do?
-blocks transmission through autonomic ganglia
52
What do parasympathetic drugs that act of cholinergic effector organs do?
- not rapidly destroyed by cholinersterase - include pilocarpine and methacholine - act directly on muscarinic receptors
53
What drugs inhibit acetylcholineesterase?
- neostigmine - pyridostigmine - ambenonium
54
What are drugs that block cholinergic activity?
- atropine - homatropine - scopolamine
55
What are the effects the ANS on the eye?
Sym: pupil dilation Para: pupil constriction, lens focusing
56
Sympathetic stimulation of glands
-causes secretion of large amounts of sweat +cholinergic to most sweat glands (few adrenergic fibers in palms and soles) +actually a parasympathetic function distributed via sympathetic fibers
57
Parasympathetic stimulation of glands
- strongly stimulates lacrimal, nasal, salivary, and many GI glands - strongly stimulates GI glands of upper tract - lower tract mostly stim,halted via the enteric system
58
ANS stimulation on GI tract
Sym: strong stimulation inhibits peristalsis, normally not dependent on sympathetic stimulation Para: promotes peristalsis, relaxes sphincters
59
ANS on heart
Sym: increases HR and strength of contraction Para: decreases HR and strength of contraction
60
ANS of systemic blood vessels
Sym: constricts most blood vessels Para: has almost no effect
61
ANS on arterial pressure
Sym: results in acute increase in arterial pressure but little effect long term Para: decreases pumping of heart but little effect on blood pressure
62
General effects of ANS
Sym: inhibits most endodermal structures Para: excited most endodermal structures
63
What are some characteristics of the ANS?
-can change visceral function rapidly and intensely +HR can be increased to twice normal within 3-5 secs +arterial pressure can be doubled within 10-15 secs +sweating can begin within seconds
Physiology II Exam III
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