Autonomic Nervous System Flashcards

1
Q

Why study the ANS?

A
  • homeostasis (internal milieu)
  • tightly controlled internal environment
  • drug actions
  • some classes of drugs work on the ANS
  • drug side effects
  • > 200 drugs that don’t work primarily at
    this site have side effects due to activation of the ANS.
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2
Q

Body functions are integrated by:

A

endocrine system
• hormones released into the blood
• eg. Insulin

nervous system
• electrical transmission with chemical “links” (neurotransmitters)

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3
Q

Describe Sensory Nerves

A
  • also known as the “afferent” division (flows to CNS)
  • information from the periphery (sensory) to the spinal cord and/or the central nervous system

(come in from outside)

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4
Q

Describe Motor Nerves

A
  • also known as “efferent” division (flows from CNS)
  • information from central nervous system or spinal chord to the periphery
  • result in some peripheral change - “motor”
  • altered muscle activity

(go outside)

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5
Q

What is the Somatic NS?

A

• largely not automatic
• consciously controlled functions
• movement - locomotion, respiration, posture
• involves electrical and chemical transmission

(going to skeletal muscles)

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6
Q

What is the ANS?

A

• “automatic” and involuntary
• control of organs and glands
• involves electrical and chemical transmission
• control of internal environment / milieu

PNS & SNS

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7
Q

What are 3 key points about the SNS/PNS?

A
  1. majority affect SNS opposed to PNS
  2. not balanced
  3. BOTH active (unless damaged) at all time
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8
Q

What are similarities b/t the PNS & SNS?

A

• Both are efferent (motor) systems: “visceromotor”

• Both involve regulation of the “internal” environment generally outside of our conscious control: “autonomous”

• Both involve 2 neurons that synapse in a peripheral ganglion

• Innervate glands, smooth muscle, cardiac muscle

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9
Q

Sympathetic vs Parasympathetic:

Basic Function

Sympathetic Nervous System

A
  • widespread or local
  • “ergotropic” – leading to energy expenditure - fight or flight
  • thoracic lumbar segments
  • cardiac stimulation, INCREASE blood sugar, cutaneous
    vasoconstriction.

(specifically for emergencies - NEED BF to brain, heart & muscles)

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10
Q

Sympathetic vs Parasympathetic:

Basic Function

Parasympathetic Nervous System

A
  • “trophotropic” – leading to growth
  • cranial sacral segment
  • energy conserving
    • slowing of heart, stimulation of digestion

(also widespread or local but never massively activated, but can also protect you long term, & you can pick organs it wants to activate)

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11
Q

SNS vs PNS Relative Lengths of Axon

A

SNS (rapid response)
- short pre-g
- long post-g

PNS (slow response)
- long pre-g
- short post-g

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12
Q

Since Symp. ganglia have short pre-g axon what does that mean?

A

ganglia are right beside the spinal column (CNS)
- rapid response

tend to be alongside CNS b/c when you get a widespread of SNS, its going to all targets

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13
Q

Since parasymp. pre-ganglia are long, what does that mean?

A

ganglia is close to a target –> imp. b/c its an anatomical analog for how the 2 work diff.

PNS: can target specific organs separately so its ganglia tends to be close to its target so it can target it separately

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14
Q

Where do the SNS ganglia run along?

A

all along SC

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15
Q

Where do the PNS ganglia run along?

A

most ganglia out from brainstem except for some at spinal column

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16
Q

What NT’s do the SNS release?

A

pregangl - ACh, +

postgangl - NE (& only place ACh @ SNS is at sweat glands), +/-, alpha & beta receptors

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17
Q

What NT’s do the PNS release?

A

pregangl & postgangl = Ach, +

18
Q

What are the target tissues for sympathetic?

A

• Organs of head, neck, trunk, & external genitalia
• Adrenal medulla
• Sweat glands in skin
• Arrector muscles of hair
• ALL vascular smooth muscle

Sympathetic system is distributed to essentially all tissues (because of vascular smooth muscle)

(GET GLOBAL COORDINATION)

19
Q

What are the target tissues for parasympathetic?

A

• Organs of head, neck, trunk, & external genitalia (whatever is necessary at a time)

Parasympathetic system never reaches limbs or body wall (except for external genitalia)

20
Q

What are SNS & PNS functional differences?

A

Sympathetic
• “Fight or flight”
• Catabolic (expend energy) - using energy globally

Parasympathetic
• “Feed & breed”, “rest & digest”
• Homeostasis
- saving energy globally

21
Q

What is unique about the genitals?

A

both SNS/PNS work together

22
Q

What is the clinical relevance of “Pre-ganglionic neurons are located along the spinal cord? for SNS?

A

Dysfunction due to cord injury
Spinal nerve impingement & OMM

  • damage to vagus nerve will result in loss to PNS & then can kill you b/c only SNS so it’ll have a heart attack/stroke & it’ll kill you
23
Q

Catecholamine biochemistry pathways

A

L-tyrosine –(tyrosine hydroxylase)-> DOPA –(dopamine decarboxylase)-> Dopamine –(dopamine b-hydroxylase)–> Norepinephrine –(phenylethanolamine N-methyl transferase)-> Epinephrine

24
Q

What are the adrenergic receptors?

A

a1

a2

b1 &b2

25
Q

a1 adrenergic receptor is a…

A

activator

26
Q

a2 adrenergic receptor is a…

A

inhibitor (symp. drug but inhibits it)

27
Q

b-adrenergic receptors are a…

A

?

28
Q

a1 key points:

A

activates PLC
increases Ca2+

smooth muscle contraction (vasoconstriction, sphincter, mydriasis)

29
Q

a2 key points:

A

inhibits Ad Cyc
increases K+ hyperpolarization

inhibits NE release
inhibits insulin release

presynaptic neuron pancreatic B cells

30
Q

b key points:

A

activates Ad Cyc
increases PKA act.

heart, lung & energy regulation

increase HR, contractility, bronchodilation, vasodilation, glyconeogenesis, lipolysis

31
Q

What are the 6 parts of a synapse?

A
  1. Synthesis of Norephinephrine
  2. Uptake into storage vesicles
  3. Release of NT
  4. Binding to receptor
  5. Removal of norepinephrine
  6. Metabolism
32
Q

What are sites to alter activity of a NT?

A
  1. Synthesis
  2. Storage
  3. Release
  4. Receptors
  5. Degradation / termination
33
Q

What is the clinical relevance of “In cord injury, some organs/tissues will lose only SNS, while others will lose both SNS and PNS”?

A

Pre-ganglionic neurons are located in the brain stem with important exceptions
- therefore, PNS won’t be damaged with spinal damage

34
Q

___ nerve is the main one to supply

A

vagus

35
Q

What is the clinical relevance of “Surgery for colorectal cancer puts pelvic splanchnics at risk & Damage causes bladder & sexual dysfunction”?

A

b/c these nerves are difficult to see & are variable in ppl

36
Q

Which are cholinergic receptors?

A

nicotinic (ion channels) on skeletal muscle that activate pre SNS & PNS ganglion

muscarinic - hit target organs
M1, M3, M5, M2 & M4

37
Q

Muscarinic receptors (M1, M3, M5)…

A

activates contraction

activates PLC –> increases Ca2+, activates PKC
- excitation (gastric release, smooth muscl, bladder, etc.)

38
Q

Muscarinic receptors (M2 & M4)…

A

inhibitors of contraction

inhibits Ad. Cyc
activates K+ channels
inhibits PKA

inhibition (cardiac, smooth muscle)

39
Q

How does Ach go through a synapse?

A
  1. Synthesis of Ach
  2. Uptake into storage vesicles
  3. Release of NT
  4. Binding to the receptor
  5. Degradation of Acetylcholine
  6. Recycling of choline
40
Q

Variety of Interactions Between SNS and PNS

A
  1. Opposite effects at the same site
    - sinoartrial node - heart rate
    - NE (B) increases, Ach (M) decreases
  2. Opposite effects at different site - size of pupil of the eye
    - NE (a) increases (mydriasis), Ach (M) decreases (miosis)
  3. Sympathetic nerves act on parasympathetic nerve endings
    - NE (a) decreases Ach release in intestinal wall
  4. Complementary - male genital organ
    - parasympathetic (erection); sympathetic
    (ejaculation)
  5. Some organs receive only one system
    - ciliary muscles of the eye - Ach
    - arterioles of most organs - NE

or another ex is: lacrimal gland (PNS) & adrenal gland (SNS)