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MD1 SF3 - EXAM 1 > Pharmacologie: Partie 2: Pharmacologie du système nerveux autonome, Bases anatomiques et physiologiques du SNA > Flashcards

Pharmacologie: Partie 2: Pharmacologie du système nerveux autonome, Bases anatomiques et physiologiques du SNA Flashcards

1
Q

What is the job of the SNA?

A

Contrôle des fonctions viscérales du corps human —> independent

SNP “rest and digest” —> ergotropic: requires energy expenditure

SNS “fight or flight” —> trophotrophic: facilitator of metabolic processes

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2
Q

What are the different components of the nervous system and their jobs?

A

Afferent: propagation of nerve influxes to SNC

Efferent: propagation of nerve influxes from SNC to muscles and glands

  1. SNA: propagation of nerve influxes from SNC —> heart, smooth muscle and glands (INVOLUNTARY)
    1. SYMP: emergency situations
    2. PSYMP: conserve energy, normal day to day functions
  2. SNS: propagation of nerve influxes from SNC to skeletal muscle (VOLUNTARY)
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3
Q

What are the different parts of the SNA? (5)

A
  1. Cerebral cortex (frontal lobe)
  2. Limbic system (emotions)
  3. Hypothalamus (principal integration center)
  4. Reticular formation of cerebral trunk (regulation of: pupil diameter, breathing, heart, BP, etc.)
  5. Spinal cord (responsable for: miction, defecation, erection/ejaculation)
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4
Q

What is the anatomical structure of neurons in the SNA?

A

1st neuron:

  • pré-ganglionnaire, myelinated (type B)
  • synapses in the ganglion with the 2nd neuron (usually)
  • In parasympathetic: VERY LONG
  • In sympathetic: short

2nd neuron:

  • post-ganglionnaire, unmyelinated (type C)
  • synapses directly on effector organ/gland
  • In parasympathetic: short
  • In sympathetic: VERY LONG
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5
Q

Which nerves are involved in parasympathetic nervous system?

A

All of cranial/sacral origin:

  • Cranial:
    • III —> ganglion ciliaire
      • Effects: miosis et accomodation
    • VII —> ganglion pterygo-palatin et submandibulaire (splits before the ganglia)
      • Effects: augmentation des sécrétions
    • IX —> ganglion otique
      • Effects: augmentation des sécétions
    • X (vagus nerve)
      • Effect: dim. of inotropism (a bit) and chronotropy of the heart, bronchoconstriction, aug. digestive motility and secretions, dim. of tonus of sphincters (relaxation)
  • Sacral: S2, S3, S4
    • Effects: contraction of rectum and bladder, relaxation of sphincters, erection
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6
Q

Important parasympathetic information:

A
  • Activated during: calm times, rest, digestion, after sudden scary thing (vagal rxn)
  • A limited number of effects but essential for life
  • More limited distribution than that of the sympathetic
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7
Q

What is the ratio of post to pre ganglia neurons in PNS?

A

1-3:1

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8
Q

What is the primary NT in the PNS?

A

Acetylcholine

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9
Q

What is the action of the PNS on the eyes?

A

Iris (muscle sphincter): contraction (miosis)

Ciliary muscle: contraction to accommodates for viewing near objects

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10
Q

What is the action of the PNS on the lacrymal glands?

A

Increase secretions

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11
Q

What is the action of the PNS on the salivary glands?

A

Increase secretions (diluted)

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12
Q

What is the action of the PNS on the heart?

A

dim. frequency and contractility

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13
Q

What is the action of the PNS on the bronchi and trachea?

A

Bronchoconstriction and inc. secretions

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14
Q

What is the action of the PNS on the GI tract?

A

Increase motility, tonus, and secretions, relax sphincters

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15
Q

What is the action of the PNS on the bladder?

A

Contraction of the detrusor muscle, relaxation of trigone muscle and sphincter

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16
Q

What is the action of the PNS on the penis/the clitoris?

A

Erection

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17
Q

What is the action of the PNS on the uterus during pregnancy?

A

Variable (Symp. and parasym. both have effects)

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18
Q

What nerves are involved in the sympathetic nervous system?

A

T1-T4: head and neck

T1-T6: thorax and superior limbs

T5-L2: abdomen

T10-L2: pelvic region

T12-L2: inferior limbs

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19
Q

How many synapse options are there in the SNS?

A

4…

  1. Sympathetic trunk:
    1. Same level
    2. Different level
  2. Collateral ganglia (or prevertebral ganglia) —> between chain and organ
  3. Adrenal glands
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20
Q

Important sympathetic information:

A

“Réaction en bloc” induced by: stress, fear, low blood sugar, cold, exercise, trauma/very strong emotions

Essential for our body to adapt to changing internal and external conditions (homeostasis)

Simultaneous activity on more than one organ

NOT ESSENTIAL FOR SURVIVAL

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21
Q

What is the ratio of post to pre ganglia neurons in SNS?

A

20-30:1 —> distribution diffuse et étendue

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22
Q

What is the action of the SNS on the eyes?

A

Iris: contraction (opens up… mydriase)

Ciliary muscle: relaxation to accommodate for far away vision

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23
Q

What is the action of the SNS on the salivary glands?

A

Production of thicker secretion but in diminished quantities

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24
Q

What is the action of the SNS on the heart?

A

Increase frequency and contractility

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25
Q

What is the action of the SNS on the trachea and bronchi?

A

Dilation

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26
Q

What is the action of the SNS on the GI tract?

A

Dim. motility and overall tonus BUT contraction of sphincters

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27
Q

What is the action of the SNS on the bladder?

A

Relax detrusor muscle, contract trigone muscle and sphincter

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28
Q

What is the action of the SNS on the penis, prostate, and seminal vesicles?

A

Decrease erection and contract, ejaculation

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29
Q

What is the action of the SNS on the blood vessels?

A

Blood vessels —> follow motor neurons.. PNS doesn’t

  • Skeletal muscles: dilation or contraction depending on muscles
  • Skin, mucous membranes and splanchnic regions: constriction
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30
Q

What is the action of the SNS on the sudoriparous glands?

A

Increase sweating (due to ACh)

31
Q

What are the primary NTs in the SNS?

A

The primary neurotransmitter in preganglionic sympathetic neurons is acetylcholine (ACh), which activates neurons in the sympathetic ganglion neurons and adrenal medulla via ganglion-type nicotinic ACh receptors.

32
Q

How do the adrenal glands work? (weird form of SNS)

A

Pre-ganglionic nerve synapses directly with an organ that releases NTs that act more like hormones and have impact on the body as a whole, not just nerve endings

  • Systemic action
  • Stimulated by: pre-ganglionic neurons or directly by cortisol
33
Q

Which neurons are cholinergic (release ACh)?

A

Motor neurons of skeletal muscles

Preganglionic neurons in SNA

Postganglionic neurons in PNS

Some postganglionic neurons in SNS

Neurons in SNC

34
Q

How is acetylcholine synthesized?

A

Acetylcholine acetyltransferase catalyses the combination of choline and Acetyl-CoA in the cytoplasm of the axon terminal

35
Q

How is acetylcholine stored?

A

In vesicles in the axon terminals

36
Q

How is acetylcholine degraded?

A

By the enzyme Acetylcholinesterase (AChE) —> produces choline and acetate

37
Q

Information about cholinergic neurons:

A

Nerve endings have presynaptic receptors that can be the target of many endo and exogenous substances that can + or - impact ACh liberation

What are the two possible receptors?

  1. autoreceptors: negative feedback from ACh liberated by that neuron
  2. heteroreceptors: ligand comes from elsewhere that stimulates or inhibits ACh release
38
Q

Which neurons are adrenergic (release NA)?

A

Postganglionic neurons in SNS

Neurons in the CNS

39
Q

How is noradrenaline synthesized?

A

Tyrosine (diet) —> dihydroxyphenylalanine (by tyrosine hydroxylase) —> dopamine —> noradrenaline —> adrenaline (in adrenal glands)

noradrenaline —> inhibition of tyrosine hydroxylase if there is too much

40
Q

Comment est-ce qu’on peut mettre fin à l’action de la NA? (3 ways)

A
  1. Reuptake into adrenergic neuron (most impact mechanism)
  2. Diffusion towards circulation/other nearby tissues
  3. Metabolism by enzymes into vanillylmandelic acid (important in dx)
    1. MAO: nerve endings
    2. COMT: liver and tissues
41
Q

What are receptors?

A

NT binding to specific receptor —> modification of its configuration

  • Activate/inhibit enzyme (adenylate cyclase)
  • Alter ionic flow

What is the net effect?

transduction of an external stimulus into an intracellular signal —> action

42
Q

What are the two main types of cholinergic receptors?

A

Nicotinic and muscarinic

43
Q

What are the main types of nicotinic receptors?

A

N1: ganglionic nicotinic receptors

  • What? Ionic canals: open Na, Ca and K, neuronal depolarization
  • Where? ANS ganglia, adrenal medulla (inside of adrenal gland)

N2: muscular nicotinic receptors

  • What? Ionic canals: open Na, Ca and K, sarcolemma depolarization
  • Where? Neuromuscular junctions

OTHERS: ionic canals in CNS

44
Q

What are the main types of muscarinic receptors?

A
  1. M1, M3, M5 —> protein coupled (Gq), activation of phospholipase
  2. M2 and M4 —> protein coupled (Go and Gi), inhibition of adenylate cyclase
45
Q

Where are cholinergic receptors found?

A

N1: ANS ganglia (including adrenal medulla)

N2: Neuromuscular junction

M: (4 ish)

  1. Postsynaptic parasympathetic and sympathetic (sweat glands)
  2. Presynaptic
  3. SNC
  4. Vessels
46
Q

What are the two main types of adrenergic receptors?

A

Alpha and beta

47
Q

What are the main types of alpha receptors?

A

α1: post-synaptic

α2: post-synaptic

α2: pre-synaptic (between 2nd neuron and organ)

48
Q

Effect of a-1 post-synaptic receptors on SNS?

A

Vasoconstriction of vessels, mydriase, contraction of GI and vesical sphincters

49
Q

Effect of a-2 post-synaptic receptors on…?

A

Peripheral receptors (SNS)… effect?

platelet aggregation, inhibition of insulin release, stimulation of GH, and inhibition of ADH

Central receptors… effect?

Sedation, analgesic effect, diminish perfusion of tissues and CV function

50
Q

What are the functions of a-2 pre-synaptic receptors?

A

Sympathetic: autoreceptors —> inhibit release of NA

Parasympathetic: heteroreceptors —> inbibit release of ACh

51
Q

What are the main types of beta receptors?

A

β1: post-synaptic

β2: post-synaptic

β2: pre-synaptic

52
Q

Effect of B-1 post-synaptic receptors?

A

Sympathetic nervous system… effect?

Increase speed, automaticity, and contractility of heart and lipolysis (β3)

53
Q

Effect of B-2 post-synaptic receptors?

A

Sympathetic nervous system.. effects?

Vasodilation of vessels and bronchi,

GI, uterine and bladder relaxation,

Glycogenolysis and secretion of insulin

54
Q

What are the functions of B-2 pre-synaptic receptors?

A

Sympathetic: heteroreceptors —> increase release of NA

Parasympathetic: autoreceptors —> increase release of ACh

55
Q

How and where do auto and heteroreceptors work?

A

Muscarinic:

  • PNS: autoreceptor —> inhibits release of ACh
  • SNS: heteroreceptor —> inhibits release of NA

a2:

  • SNS: autoreceptors —> inhibit release of NA
  • PNS: heteroreceptors —> inhibit release of ACh

​β2:

  • PNS: heteroreceptors —> increase release of ACh
  • SNS: autoreceptors —> increase release of NA
56
Q

What impacts regulation of receptors?

A

Repeated stimulation of a receptor can lead to what?

  • Desensitization to stimulus… decrease response
  • Decrease of number of receptors (downregulation)

Absence of stimulation of a receptor can lead to what?

  • Hypersensitivity: increase the response of the same effect
  • Increase of number of receptors (upregulation)
57
Q

What are the baroreceptor reflexes?

A

Receptors:

  • baroreceptors in sinus carotidien and aortic arch

Neurones sensitifs (afferent)

  • IX —> carotid sinus
  • X —> aortic arch

SNC

Autonomic neurons (efferent)

  • Parasympathetic (X)
  • Sympathetic

Effectors:

  • Cardiac muscles and muscles surrounding blood vessels
58
Q

What is the pupillary reflex?

A

Receptors:

Cells in retina

Sensitive neurons (afferent)

  • II optic nerve

SNC

Autonomic neurons (efferent)

  • Parasympathetic (III)
  • Sympathetic

Effectors:

  • Muscles in the iris
59
Q

What are the potential targets for Rx in SNA?

A

Synthesis, storage, release, inactivation, action of neurotransmitters (agonists/antagonists)

60
Q

Which classes of medications target the SNA? (4)

A

Cholinomimetics, anticholinergics, sympathomimetics, sympatholytics

61
Q

Iris:

A

Sphincter muscle: parasympathetic

  • Myosis

Radial muscle: sympathetic (alpha-1 receptors)

  • Mydriasis
62
Q

Ciliary muscle:

A

Sympathetic (beta-2 receptor)

  • relaxation

Parasympathetic STRONGER RESPONSE

  • contraction
63
Q

Salivary glands:

A

Sympathetic (alpha-1 receptor)

  • Thickening of saliva

Parasympathetic STRONGER RESPONSE

  • Dilution of saliva
64
Q

Heart:

A

Sympathetic (beta-1 receptors) STRONGER RESPONSE

  • increase HR and contractility

Parasympathetic

  • decrease HR and contractility
65
Q

Arterioles:

A

Artérioles (alpha-1)

  • sympathetic: constriction

Artérioles (beta-2 except beta-1 in coronary arteries)

  • sympathetic: dilation
66
Q

Veins:

A

Sympathetic

  • Constriction
67
Q

Lungs:

A

Sympathetic (beta-2 receptors)

  • Bronchodilation

Parasympathetic STRONGER RESPONSE

  • Bronchoconstriction
68
Q

GI tract:

A

Sympathetic (alpha-1 and beta-2)

  • Decrease motility and secretions
  • Constriction of sphincters (alpha-1 only)

Parasympathetic STRONGER RESPONSE

  • Increased motility and secretions and relaxation of sphincters
69
Q

Sudoriparous glands:

A

Sympathetic ACh (IMPORTANT EXCEPTION)

  • Sweating
70
Q

Urinary system:

A

Sympathetic

  • beta-2: relaxation of detrusor muscle
  • alpha-1: contraction or trigone, sphincters, and ureters
  • beta-1: renin secretion

Parasympathetic STRONGER RESPONSE

  • Contraction of detrusor, relaxation of trigone, sphincters, and ureters
71
Q

Genital tract:

A

Sympathetic

Ejaculation

Parasympathetic

Erection

72
Q

Adrenal medulla:

A

Sympathetic (ACh)

liberation of catecholamines

73
Q

Liver:

A

Sympathetic (beta-2)

glycogenesis and gluconeogenesis

74
Q

Pancreas:

A

Sympathetic

  • alpha-1 —> decrease secretions from beta cells
  • beta-2 —> increase secretions from beta cells
  • beta-1 —> lipolysis

MD1 SF3 - EXAM 1 (11 decks)

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