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ICPP > L8- ANS > Flashcards

L8- ANS Flashcards

1
Q

A) What is the Autonomic nervous system a division of?

b) What does the ANS do?

A

a) Peripheral nervous system
b) - works automatically to regulate/control all involuntary functions
- Functions: Blood pressure, heart rate, breathing rate, body temp, digestion, metabolism, h20 balance etc

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2
Q

a) What are the divisions of the ANS ?

b) What are each divisions function?

A

a) Sympathetic nervous system and peripheral nervous system (sometimes enteric)
b)
1. Sympathetic: responds to stressful situations; fight or flight
- increase HR, Force of contraction (inotropy), BP, dilation of bronchi, dilation of pupils, inhibits saliva secretion

  1. Parasympathetic: responds to ordinary situations; rest and digest
    - lower HR, BP, contraction of bronchi, increased saliva secretion
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3
Q

What are the two main neurotransmitters found in the ANS?

A
  1. Acetylcholine (ACh)

2. Noradrenaline (NA)= Norepinephrine

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4
Q

What are the 5 anatomical divisions of the brainstem/spinal cord?

A
  1. Medullary
  2. Cranial
  3. Thoracic
  4. Lumbar
  5. Sacral
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5
Q

a) What type of neurons make up the ANS?

b) Cxtics of these in each division of the ANS

A

a) Motor neurones that are made up of preganglionic myelinated neurones and post ganglionic unmyelinated neurones
- Pre ganglionic celll bodies in CNS
- post ganglionic cell bodies in autonomic ganglia in PNS

b)

  1. Sympathetic:
    - Short preganglionic and long post ganglionic
  2. Parasympathetic:
    - Long preganglionic and short post ganglionic
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6
Q

a) Where do the neurones of each division originate?

b) Where are the ganglia of each found?

A

a)

  1. Sympathetic:
    - preganglionic short myelinated fibres originate in the: lateral horn in T1–> L2 cord segments (lumbar and thoracic cord)
  2. Parasympathetic:
    - preganglionic long myelinated fibres originate in the: lateral horn of medulla and s2-s4 sacral cord segments

b)

  1. paravertebral chain (sympathetic chain)
  2. Innervated tissues
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7
Q

Compare the Pre and Post ganglionic neurone neurotransmitter release in

a) Sympathetic neurones
b) Parasympathetic neurones

A

ALL PREGANGLIONIC NEURONES ARE CHOLINERGIC= use ACh as neurotransmitter therefore:

a) Sympathetic
1. Preganglionic neurones:
- release ACh, act on NACh (nicotinic ACh receptors) on post ganglion
2. Post ganglionic neurones: noradrenergic
- release noradrenaline, acts on alpha or beta adrenoceptors in target (effector) tissue (some are cholinergic tho)

b) Parasympathetic:
1. Preganglionic neurones:
- release ACh, act on NACh (nicotinic ACh receptors) on post ganglion
2. Post ganglionic neurones: cholinergic
- release ACh which acts on mACh (muscarinic) receptors in target (effector) tissue

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8
Q

Which sympathetic post ganglionic neurones arent noradrenergic?

A
  • Specialised ones e.g. those innervating sweat glands, hair follicles
  • they are cholinergic
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9
Q

What are some examples of other transmitters found in the ANS?

A
  • Non-adrenergic, non-cholinergic (NANC) transmitters:

- ATP, Nitric oxide (NO), Serotonin

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10
Q

What does the enteric nervous system do?

A

Control the GI system independently of the CNS

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11
Q

How are adrenal glands different in their neurotransmission?

A
  • They are sympathetic
  • Their preganglionic neurone releases ACh, acts on NACHr on post ganglionic neurones
  • The postganglionic neurones are different!!!
  • They differentiate to form neurosecretory chromaffin cells
  • They are present in the adrenal medulla
  • they release adrenaline (epinephrine) directly into the blood stream
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12
Q

What are the names of the postganglionic sympathetic neurones in the adrenal medulla

A

Chromaffin cells- secrete adrenaline

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13
Q

Outline the result of parasympathetic release of ACh in the following: (where u can name specific receptors)

a) Eyes
b) Lacrimal glands
c) Salivary glands
d) Heart
e) Lungs
f) Liver

A

a) Constrict pupils
b) M1, M3: increased secretion
c) M1,M3: Stimulates salivation
d) M2 Muscarinic: decrease heart rate
e) M3: contract/constrict bronchi smooth muscle
f) Stimulates bile release

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14
Q

Outline the result of sympathetic release of Noradenaline in the following: (where u can name specific receptors)

a) Eyes
b) Salivary glands
c) Heart
d) Lungs
e) Stomach
f) Liver
g) Arterioles
h) Adrenal glands

A

a) Dilate pupils
b) Inhibit salivation
c) B1-adrenoceptors: increase heart rate
d) B2-adrenoceptors: bronchioles dilation
e) B2-adrenoceptors: dilation of intestines
f) Glucose release
g) Alpha1 adrenoceptors: contraction
h) secrete adrenaline

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15
Q

What is the differing roles in pre-synaptic and post-synaptic receptors?

A

Pre-synaptic receptors can control the release of neurotransmitter into the synapse, post synaptic receptors control the response in target tissues

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16
Q

How is Acetylcholine

a) synthesised
b) Degraded?

A

a) acetyl CoA + choline —> ACh + coenzyme A
- Catalysed by: choline acetyl transferase (CAT)

b) ACh –> acetate + choline
- catalysed by acetyl choline esterase

17
Q

What are the 3 fates of ACh?

A
  1. Recycled
  2. Degraded by AChE
  3. Attached to post synaptic receptors
18
Q

What are the two ways in which we can pharmacologically intervene to alter ANS activity?

A
  1. Manipulate cholinergic function

2. Manipulate adrenergic function

19
Q

Major drug classes that affect Cholinergic transmission?

A
  1. Ganglion-blocking drugs at nACHrs: trimethaphan, used to control hypotension
  2. Cholinesterase inhibitors: decrease ACh degradation e.g. pyridostigmine to treat myasthensia gravis (allows more Ach to bind) and donepezil to treat alzhemiers
  3. Muscarinic ACh receptor agonists: pilocarpine (treat glaucoma, intraocular pressure) and bethanechol (stimulate bladder emptying)
  4. Muscarinic ACh receptor antagonists; Ipratropium and tiotropium to treat some forms of asthma and COPD
20
Q

What is the problem with a lack of selectivity of cholinergic drugs?

A

Unwanted side effects occur

21
Q

a) What is “SLUDGE”?

b) Spell it out

A

a) - Pathological effects of massive discharge of the parasympathetic nervous system
- due to chronic over stimulation of muscarinic ACh receptors
- irreversible deactivation of AChE, raises ACh levels

b)

  • Salivation: stimulation of salivary glands
  • Lacrimation: stimulation of lacrimal glands
  • Urination: relaxation of urethral internal muscle and detrusor muscle contraction
  • Defecation
  • GI upset: smooth muscle tone changes- diarrhoea
  • Emesis; vomiting
22
Q

a) When would you see sludge syndrome?

b) How could it be treated?

A

a) - drug overdose
- ingestion of magic mushrooms
- exposure to organophosphorus insectisides

b) - Atropine, pralidoxime or other anti-cholinergic agents

23
Q

a) How is noradrenaline synthesised?
b) Where do adrenoceptors in the ANS occur?
c) What is the structure of them related to function?

A

a) Tyrosine –> Dopa –> dopamine –> noradrenaline
b) Post-ganglionic sympathetic nerves
c) - highly branching axonal network with numerous varicosities, each a specialised site for calcium depdendant noradrenaline release

24
Q

What is the fate of released noradrenaline?

A
  1. NA diffuses across synapse and interacts with adrenoceptors on post synaptic memb
  2. NA interacts with presynaptic receptors to regualte processes in nerve terminal
  3. Metabolism: taken up into vesicles and metabolised
25
Q

What are the 2 enzymes that can metabolise noradrenaline

A
  1. monoamine oxidase (MAO)

2. Catechol-O-methyltransferase (COMT)

26
Q

What are the major drug classes that are used to affect adrenergic transmission?

A
  1. B-2-adrenoceptor-selective agonists e.g. salbutamol: used in asthma to reverse/oppose bronchoconstriction
  2. A-2-adrenoceptor selective antagonists (e.g. doxazosin) and B-1- adrenoceptor-selective antagonists (e.g. atenolol) used to treat hypertension
27
Q

What are the main categories of drugs that are used to treat asthma and why?

A
  1. M3- Muscarinic antagonists e.g. ipratropium
    - Block muscarinic receptors in the airways so that ACh cannot bind, prevents innervation of these, hence prevent constriction of bronchi
  2. B2-adrenoceptor agonists: e.g. Salbutamol
    - bind to b2-adrenoceptors in the airways, stimulate sympathetic innervation of airways and hence dilates bronchioles to allow more airway in and out
28
Q

a) What is thyrotoxicosis?
b) What are the symptoms
c) Drugs?

A

a) Excess thyroid hormone in body
b) - Increased heart rate
- increased sweating
- muscle aches
- anxiety
c) Beta blockers to lower heart rate e.g. propanolol and atenolol

29
Q

What are the main categories of drugs that are used to treat hypertension and why?

A

Hypertension = high blood pressure

  1. A-1 adrenoceptor selective antagonists (e.g. doxazosin)- block adrenaline from binding hence block innervation of arterioles hence prevent arteriole contraction to lower BP
    (found in arterioles)
  2. B-1- adrenoceptor- selective antagonists (e.g. atenolol)
    - these receptors are found in the heart
    - hence these drugs bind to them and block adrenaline from binding
    - prevent heart rate from increasing hence lower bP

ICPP (8 decks)

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