ANS Flashcards

1
Q

ANS General

A

Controls the body’s involuntary activities. Motor system for visceral organs, blood vessels, and secretory glands.

Oversees the body’s response to immediate lie- threatening challenges and the body’s vital maintenance needs (in: cardiovascular, GI, thermal homeostasis.

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2
Q

Nerves

A

Bundles of axons of nerve cell, or neuron.

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3
Q

Axon

A

a nerve fiber; a long projection off o a nerve cell, or neuron.

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4
Q

Ganglia

A

cluster of nerve cell bodies in peripheral nervous system. synapse depot for nerves.

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5
Q

Afferent

A

an axon that carries sensory info from periphery to the CNS.`

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6
Q

Efferent

A

axon that carries motor info from the CNS to the periphery.

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7
Q

Neurotransmitter

A

endogenous chemicals that relay an action potential from one nerve, across a synapse to a target nerve or organ.

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8
Q

Synapse

A

a synpatic cleft or space between the presynaptic and postsynaptic endings/effector organ, where the action potential is carried by neurotransmitters.

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9
Q

ANs Anesthesia Concern

A

Pulmonary, cardio, thermal, endocrine, and GI

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10
Q

Organization of ANS (General)

A

Preganglionic neuron (1st neuron between cns& ganglia)

  • located in hypothalamus, brain stem or spinal cord
  • projects to an autonomic ganglia
  • Thinly myleinated axon
  • ALL release acetylcholine onto nicotinic receptors.
Postganglionic Neurons (2nd neuron goes from ganglia to the effector organ)
- unmyelinated axon
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11
Q

ANS Subsystems

A

Sympathetic Nervous System

  • Fight or Flight
  • amplification response

Parasympathetic Nervous System

  • Rest and Digest
  • discrete and narrowly targeted response
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12
Q

Ganglia Difference

A

Sympathetic Pathway

  • close to the spinal cord
  • short preganglionic fibers.
  • long postganlionic fibers

Parasympathetic Pathway

  • ganglia close to/ or in effector organ.
  • long preganglionic fibers
  • short postganglionic fibers
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13
Q

What is the first neural response?

A

Acetylcholine

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14
Q

Basal Rate

A

PsNS and SNS both are “on” at the same time: tone, allows for quick shifting from one to the other, fine control.

Predominant PsNS tone: cilliary muscle, Iris,SA node, GI tract, uterus, bladder, salivary glands.

Predominant SNS: arteriole, veins, sweat glands

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15
Q

Basal Rate

A
  • Most organs have dual innervation (accelerator & brake).
  • some patients have exagerrated effects. one or the other
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16
Q

2nd Messenger in ANS

A
  • interaction of neurotransmitters with postsynaptic receptors results in signal transduction.
  • in adrenergic (sympathetic) system, trasduction is mediated by G protein, which then regulates adenylyl cyclase, and phospholipase C to generate 2nd meengers and / or directly modulate various ion channels.
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17
Q

SYN 3 types of nerve fibers

A
  • Grouped as paired sympathetic chains (2 sets)
  • Various unpaired distal plexuses (group of nerves)
  • terminal or collateral ganglia near the target.

largest segment comes from the Thoracic

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18
Q

What is a Plexuses

A

A bundle of nerves

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19
Q

SNS response to internal or external challenges

A
  • fight or flight
  • increase heart rate, arterial pressure, and cardiac output; dilate the bronchial tree; and shunt blood away from intestine and other viscera to voluntary muscles.
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20
Q

PsNS nervous input

A

Acts primarily to conserve energy and maintain organ function and to support vegetative processes.

21
Q

What Happens in Horner Syndrome?

A

Stellate ganglion blockage with local anesthetic blocks the sympathetic fibers coursing to the ipsilateral head and neck.

This is characterized by ptosis, miosis, enopthalmos, and anhydrosis on the affected side.

22
Q

3 paths axons can take

A
  1. enter the sympathetic chain via the white ramus and synapse there
  2. enters the sympathtic chain via the white ramus and ascend or descend a few segments before synpasing.
  3. enter via the white ramus and exit the chain without synpasing, but continue on to an outlying collateral ganglion.
23
Q

Fight or Flight

A

Increased: BP, HR, and contractility, blood flow to skeletal muscles, blood glucose (via liver stimulation), mental activity (increased cortisol), metabolic rate, coagulation.

24
Q

SNS: nerve/ synapse outside the CNS

A
  1. Paravertebral: 22 paired ganglia: sympathetic chain running along the and left side of the spinal column.
  2. Prevertebral: Unpaired ganglia, ganglia are in abdomen and pelvis.
  3. collateral: terminal ganglia, few ganglia, located near organs they innervate.
    - Sympathetic preganglionic neurons can “meet up with’ their respective postganglionic partners.
25
Q

Spinal Pathways of the SNS

A
  1. Dorsal (posterior) is sensory
  2. Ventral (anterior) is muscle control.
  3. Preganglionic neurons arise from the grey matter of ther spinal cord, and exit via the ventral (anterior) nerve root.
26
Q

White and Gray Rami

A

White Rami: thoracolumbar outlow, carry preganglionic myelinated fibers; exit spinal cord via anterior spinal roots.

Gray Rami; arise from ganglia; carry postganglionic fibers to spinal nerves for distribution to glands and muscles.

27
Q

What Does the Adrenal Medulla Release

A

epinephrine
-80% secreted

Norepinephrine
-20%

28
Q

Sympathetic Diffuse Attack

A

allows for amplifcation

29
Q

Where does Adrenergic nerved release norepinephrine?

A

the neuro effector junction.

30
Q

SNS Receptors: Adrenergic receptors

A

Norephrine acting as neurotransmitter, interacts with receptors in lipid cell membrane.

Alpha 1 receptors: located on blood vessels, smooth muscle vasoconstriction.

Alpha 2 receptors: (presynaptic): inhibits NE release

Beta 1 receptors: located on the heart and other places, increased heart rate and contractility, bronchial dilation, glycogenolysis.

Beta 2: located in the lungs increased bronchodilatation, smooth muscle relaxation.

31
Q

What Couples Adrenoreceptors

A

G-proteins

alpha and beta receptors are coupled to G-protein. When activated, G proteins can modulate the synthesis or availability of intracellular second messengers.

32
Q

What controls Sympathetic Activation

A

The sympathetic center in the Hypothalamus.

  • sympathetic activation
  • affects included increased alertness, energy, and euphoria, increased cardiovascular and respiratory activities, elevation in muscle tone, mobilization of energy resources.
33
Q

Neurotransmitter Release

A

-Preganglionic neurons in the SNS are cholinergic (same as acetycholine (*Ach)); secrete Ach as neurotransmitter, carrying the action potential to the post ganglionic neuron.

Stimualtion of Sympathetic division has 2 distinct results

  • Release o Ac or NE at specific location
  • Secretion of E and NE into general circulation.
34
Q

Adrenal Medulla

A
  • Large sympathetic ganglion w/ NO parasympathetic innervation.

Liberation of Ach from the preganglion, results in epinephrine(80%0 and norephirine (20%). most of the synthesized NE is converted to E by action of phenylethanolamine-N-methyltransferase. Cortisol enhances this enzymes activity

Is an endocrine gland: secrets product into circulations (verses a duct) NE and E are hormones not neurotransmitters.

35
Q

Postganglionic Neurons are involved with what/

A

Thermoregulation and release of Achs

36
Q

Kidneys exception of SNS

A

-Postganglionic neurons to the smooth muscle of the renal vascular bed release dopamine.

37
Q

making of Epinephrine (E)back

A

Tyrosine (Tyr) is converted to DOPA by tyrosine hydroxylase in the cytoplasm of the postganglionic SNS nerve endings.

38
Q

Termination of Action of NE

A

-Termination of the action of norepinepherine uptake(reuptake) back into the postganglionic sympathetic nerve endings dilution by diffusion from receptors metabolism by the enzymes MAO and COMT.

39
Q

Final Metabolism Product NE

A

The final metabolic product of inactivation vanillymandelic acid (VMA) .

40
Q

Dopamine Receptors

A

D1 receptors are postsynaptic and act on renal mesenteric, splenic, and coronary vascular smooth muscle to mediate vasodilation through stimulation of adenylate cyclase and increased production of cAMP.

41
Q

PNS

A
  • More specific
  • The Vagus nerve
  • Postganglionic neurons are short
  • Ach primary neurotransmitter.
  • Nerve fibers that secrete Ach are called cholinergic
42
Q

PNS

A

“breed and freed”…“rest and digest”

43
Q

Vagus Nerve

A

most important of parasympathetic nerves and transmits fully 3/4 of the traffic in PNS.

44
Q

Pathway of Preganglionic Neurons

A

Output simpler than SNS.

2 Outputs

  • cranial nerve
  • sacral outflow
45
Q

Muscarinic Recptors

A

M1. Important in autonomic ganglia and for salivary and stomach secretion.

M2. Expressed in the heart where activation slows heart rate and nodal activity and decreases atrial contractility.

M3. Involved in smooth muscle contraction and eye accomdations. Activation includes emesis andtheir anatgonism with scoplamine has antiemetic properties.

Atropine broad-spectrum muscarinic agoinist.

46
Q

ACh Synthesis

A
  • choline enters presynaptic nerve endings.
  • Acetyl coenzyme A is synthesized in mithochodria
  • Ach can bind to either nicotinic (N) or muscarinic (M) postsynaptic receptors to elicit an effector response.

Ach is rapidly broken down in the synapse by acetylcholine esterase (AChE) hydrolysis.

47
Q

What makes up Acetylcholine

A

Coenzyme A (acetyl CoA) + Choline

48
Q

Classification of drugs affecting ANS

A

PsNS

  • mimic acetylcholine
    • cholinergic= muscarinic agonis=Parasympathomimetic.
  • Block Acetylcholine
  • anticholinergic= muscarinc antagonist= Parasympatholytic Atropine

SNS

  • mimics NE
    • adrenergic= adrenergic agonsit= sympathometic Adrenaline, E
  • Blocks NE
    • antiadrenergic= adrenergic antagonist= sympatholytic Beta-blockers.