Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

FoM - normal function > autonomic physiology and pharmacology > Flashcards

autonomic physiology and pharmacology Flashcards

1
Q

what’s the difference between autonomic and somatic nervous system efferent pathways?

A

somatic - to skeletal muscle

autonomic
- ganglion split into pre-ganglionic (small myelinated) fibre and post-ganglionic (unmyelinated) fibre
- goes to smooth muscle, cardiac muscle, glands, GI neurones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

whats the difference between autonomic and somatic nervous system target connection?

A

somatic
- specialised neuron muscular junction

  • alpha motor neurons release ACh directly onto the nicotinic receptors on the end plate
  • ionotropic receptors with integral ion channels, depolarization always excites the skeletal muscle

autonomic
- neurotransmitter released from varicosities

  • metabotropic receptors (G-protein coupled), they either depolarize or hyperpolarize
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

describe the outflow from CNS and location of ganglia of parasympathetic nervous system (rest and digest system):

A

Cranio-sacral outflow (in the brain and sacrum)

Ganglia lie close to or near the target

(long preganglionic fibres & short postganglionic fibres)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are 2 autonomic neurotransmitters?

A

Acetylcholine acts on cholinergic receptors

e.g. Nicotinic receptors (ionotropic) & Muscarinic receptors (metabotropic)

Noradrenaline acts on adrenergic receptors

e.g. alpha receptors & beta receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

describe the outflow from CNS and location of ganglia of sympathetic nervous system (fight or flight system):

A

Thoracolumbar outflow (in thoracic and lumbar segments)
(T1-T12 & L1-L2)

Ganglia close to the spinal cord in the sympathetic trunk
(para-vertebral ganglia)

(short preganglionic fibres & long postganglionic fibres)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

all preganglionic fibers release acetylcholine, which acts on nicotinic cholinergic receptors.

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what do parasympathetic and sympathetic post ganglionic fibers release?

A

parasympathetic - acetylcholine which acts on cholinergic muscarinic receptors on the target.

Sympathetic postganglionic fibres release noradrenaline, which acts on either alpha or beta-type adrenergic receptors.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the one exception to preganglionic fibres that go straight through?

A

There is one exception of preganglionic fibres that go straight through
sympathetic trunk → celiac ganglia → postganglionic cells on adrenal gland

This releases adrenaline & noradrenaline into the blood.
(mass hormonal activation if this works)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are 2 exceptions to the rule in sympathetic post-ganglionic fibres?

A

There are two exceptions to the rule in sympathetic postganglionic fibres:

1- Sympathetic cholinergic fibers that innervate sweat glands

2- Non-adrenergic non-cholinergic (NANC) transmitters e.g. peptides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

using the eye as an example, describe what the sympathetic system does:

A

Noradrenaline activates a1 receptors on the radial muscle of the iris

Radial muscle contracts & makes the pupil larger

  • Noradrenaline activates b2 receptors on ciliary muscle around the lens

The ciliary muscle relaxes & eye focuses far away

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

using the eye as an example, describe what the sympathetic system does:

A

Acetylcholine activates muscarinic receptors on the sphincter (circular) muscle of the iris

Contracts sphincter muscle & makes pupil smaller

  • Acetylcholine activates muscarinic receptors on ciliary muscle around the lens

Ciliary muscle contracts & eye focuses close-up

An example of two different types of antagonistic actions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

using the heart as an example, describe what the sympathetic system does:

A

Noradrenaline activates {{c1::b1 receptors}} on the pacemaker cells

Increases heart rate

  • Noadrenaline activates {{c1::b1 receptors}} on the myocytes

Increases strength of contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

using the heart as an example, describe what the parasympathetic system does:

A
  • Acetylcholine activates muscarinic receptors on pacemaker cells
    > Decreases heart rate
  • Little effect on myocytes
    > Little effect on the strength of contraction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Explain the sympathetic and parasympathetic effect on the lungs

A

Sympathetic system

  • Noradrenaline activates b2 receptors on the smooth muscle of airways
    > Makes smooth muscle relax & dilates airways

Parasympathetic system

  • Acetylcholine activates muscarinic receptors on the smooth muscle of airways
    > Makes smooth muscle contract & constricts airways
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why do patients with asthma and heart problems take salbutamol?

Why do patients with hypertension and lung problems take atenolol?

A

Because salbutamol is a b2 agonist

→ dilates airways, but does not affect the heart.

Because atenolol is a b1 antagonist

→ decreases heart rate, but does not affect airways.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Explain the redirection of blood during exercise

Explain the sympathetic and parasympathetic effects on the blood vessels

A

Sympathetic System

Tissues that contain b2 receptors e.g. heart and skeletal tissue

→ vasodilation & increase in blood flow during fight or flight

Tissues that contain a1 receptors e.g. kidneys, GI tract …etc.

→ vasoconstriction & decrease in blood flow during fight or flight

Parasympathetic System

Does not affect the majority of blood vessels

Exceptions - salivary glands & genitalia

12
Q

Explain the sympathetic and parasympathetic effects on the salivary glands:

A

Sympathetic system

  • Noradrenaline activates b receptors
    Stimulates thick secretion rich in enzymes

Parasympathetic system

  • Acetylcholine activates muscarinic receptors
    Stimulates profuse watery secretion

An example of dual innervation with non-antagonistic actions i.e. no relax vs contract

12
Q

Explain the sympathetic and parasympathetic effect on the blood vessels:

A

Sympathetic system

  • Noradrenaline activates a1 receptors on the smooth muscle of vessels
    > Makes smooth muscle contract (vasoconstriction) & blood flow decreases
  • Noradrenaline activates b2 receptors on the smooth muscle of vessels
    > Makes smooth muscle relax (vasodilation) & blood flow increases

Parasympathetic system

Usually no effect, except in genitalia and salivary glands. (EXCEPTIONS)

i.e. the response depends on what receptors each tissue expresses

Single-system (sympathetic) innervation of the blood vessels means that a tone is continually maintained, so you either increase activity or decrease it.

12
Q

using the bladder as an example explain the sympathetic and parasympathetic effects:

A

Sympathetic system

  • Noradrenaline activates a1 receptors on the smooth muscle of the sphincter
    Contracts smooth muscle and stops urination
  • Noradrenaline activates b2 receptors on the smooth muscle of the bladder wall
    Relaxes smooth muscle and reduces pressure

Parasympathetic system

  • Acetylcholine activates muscarinic receptors on the smooth muscle of the sphincter
    Relaxes smooth muscle and causes urination
  • Acetylcholine activates muscarinic receptors on the smooth muscle of the bladder wall
    Contracts smooth muscle and increases pressure
13
Q

explain the effects of parasympathetic & sympathetic on the reproductive tract as an example:

A

Sympathetic system

  • Noradrenaline activates a1 receptors on the smooth muscle of the urethra
    Contracts smooth muscle and causes ejaculation

Parasympathetic system

  • Acetylcholine activates muscarinic receptors on the smooth muscle of the corpus cavernosum
    Relaxes smooth muscle & causes erection

An example of dual innervation with complementary effects

14
Q

what is the baroreceptor reflex?

A

a type of autonomic reflex that detects blood pressure, and sends info to the integrating centre in the brain, then that centre coordinates sympathetic and parasympathetic outflow to the tissues accordingly..

14
Q

what does the hypothalamus do?

A

it’s a portion of the brain responsible for central control, it coordinates autonomic, somatic, and endocrine activity.

Both of them together control the sympathetic and parasympathetic systems

15
Q

what type of receptors does the neuromuscular junction use?

A

nicotinic

16
Q

what are the 8 steps of synaptic transmission?

A
  1. Synthesis and packaging of neurotransmitters (usually) in presynaptic terminals
  2. Na+ action potential invades the terminal
  3. Activates voltage-gated Ca2+-channels
  4. Triggers Ca2+-dependent exocytosis of pre-packaged vesicles of transmitter
  5. Transmitter diffuses across cleft and binds to ionotropic and metabotropic receptors to evoke
    a postsynaptic response
  6. Presynaptic autoreceptors inhibit further transmitter release by closing calcium channels
  7. The transmitter is (usually) inactivated by an enzyme or is uptaken into glia or neurones
  8. Transmitter is metabolised within cells
17
Q

what are the 5 ways to inhibit AP transmission, targeting NMJ transmission?

A

1- inhibit choline transporter
e.g. hemicholinium

2- Block voltage-gated Ca2+ channels
e.g. black widow spider venom

3- Block vesicle fusion
e.g. botulinum

4- Use non-depolarising nicotinic receptor blockers
(competitive antagonists → high affinity & low/zero efficacy)
e.g. d-tubocurarine

5 - Use depolarising nicotinic receptor blockers
(keep muscle depolarised and stop voltage-gated sodium channels from working again)
e.g. succinylcholine

18
Q

How does an anticholinesterase work?
e.g. eserine

A

An anticholinesterase blocks acetylcholinesterase

→ stops breakdown of ACh so it hangs around in the synaptic cleft for longer.

18
Q
A
18
Q
A
18
Q

when targeting postsynaptic parasympathetic transmission, what do muscarinic receptors do?

A

Muscarinic receptor agonists - e.g. carbachol, pilocarpine

  • mimic the effect of the parasympathetic system

(slow heart rate, contract smooth muscle in airways and bladder, increase gut motility, increase bronchial secretions and salivation, constrict pupil)

Muscarinic receptor antagonists - e.g atropine

  • will block effects of the parasympathetic system i.e. mimic the effect of the sympathetic system

(increase heart rate, relax smooth muscle in airways and bladder, reduce gut motility, bronchial secretions and salivation, dilate pupil)

19
Q

What is Glaucoma and how are muscarinic agonists used to relieve it?

A

Glaucoma is raised intraocular pressure.

Muscarinic agonists contract the ciliary muscle supporting the lens and the sphincter muscle of the pupil to increase drainage of the aqueous humour through the canal of Schlemm

19
Q

what are 5 ways to inhibit AP transmission when targeting postganglionic sympathetic transmission?

A

1- Blocking the enzymes that produce NA
e.g. carbidopa

2- Blocking the transporter that fills the vesicles with NA
e.g. reserpine

3- introducing a “false” transmitter
e.g. methyldopa

  • looks like NA but doesn’t bind to receptor

4- Activating inhibitory presynaptic (α2) autoreceptors

  • inhibits voltage gate Ca2+ channels, so reduces the release of vesicles.

e.g. methyldopa

5- Blocking α or β postsynaptic receptors

e.g. doxazosin or propranolol

19
Q

how does the mechanism of removing neurotransmitters differ in NMJ than in postganglionic cleft?

A

NMJ - usage of an enzyme called acetylcholinesterase to break down acetylcholine and then it’s taken up the presynaptic terminal

Postganglionic cleft - usage of a reuptake molecule to take noradrenaline back into the presynaptic terminal

20
Q

what are 3 ways to potentiate AP transmission when targeting postganglionic sympathetic transmission?

A

1- Stimulate NA release
e.g. amphetamine

2- Inhibit uptake into:
Neurones

e.g. cocaine & tricyclic antidepressants

Glia

e.g. phenoxybenzamine

  • Allows NA to hang out around the cleft longer

3- Activate postsynaptic receptors

e.g. phenylephrine and salbutamol

All of the above-mentioned drugs are known as sympathomimetics

20
Q

summary: Mention some clinical applications of alpha and beta agonists:

A

α1 agonists (contraction of muscle) can be used as decongestants and dilate the pupil (mydriatics)

  • α2 agonists can be used in the treatment of hypertension
  • β2 agonists (relaxation of muscle) can be used in the treatment of asthma
  • β1 antagonists can be used in the treatment of hypertension, angina and cardiac arrhythmias

FoM - normal function (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions