Intro to the ANS Flashcards

(35 cards)

1
Q

What would an increase in Arterial Baroreceptor firing lead to with regards to the ANS?

A

Stimulations of parasympathetic nerve; inhibits heart contraction

Inhibition of sympathetic innovation of heart and arteries to lower blood pressure and HR

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2
Q

Describe the balance of the ANS in the eye at rest:

A

Dominated by the Parasympathetic at rest.

You need your smooth muscle to be partially constricted so it can change in both directions

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3
Q

Where do parasympathetic nerves originate?

A

Cranial or Sacral regions

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4
Q

What is the neurotransmitter used in the Parasympathetic Nervous system?

A

ACh

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5
Q

What does the Preganglionic fibre of the SNS usually release?

A

ACh

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6
Q

What dies the Post-ganglionic fibre of the SNS usually release?

A

Noradrenaline

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7
Q

What post-ganglionic neurotransmitter may be secreted to innovate sweat glands?

A

ACh

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8
Q

What is the function of the SNS and PNS in the eye?

A

SNS: Pupil dilation

PNS: Constriction of pupil, Contraction of ciliary muscle

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9
Q

What is the balance of the ANS in the lungs at rest?

A

Dominated by the Parasympathetic;

There is a partial level of constriction so that it can both constrict further and dilate

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10
Q

What is the dominant branch of the ANS in the liver and what does it control?

A

Sympathetic

Glycogenolysis + Gluconeogenesis

You want glucose to be available in a fight or flight situation so sympathetic discharge will stimulate an increase in glycogenolysis and gluconeogenesis.

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11
Q

What are the effects of the SNS in the Kidneys, Bladder and Ureters?

A

Kidney: Increased renin secretion

Ureters and Bladder: Relaxes detrusor; constriction of trigone and sphincter

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12
Q

What are the effects of the ANS in the heart, and which is dominant at rest?

A

SNS: Increased rate and contractility

PNS: Decreased rate and contractility

PNS dominant at rest

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13
Q

Describe the ANS innovation of arteries and arterioles:

A

There is no parasympathetic innovation

The sympathetic is totally in control of the arterioles it controls constriction and dilation of the arterioles.

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14
Q

Where do the post-ganglionic neurones in the sympathetic limb project from, and what does this mean for their organisation?

A

Sympathetic trunk

Very divergent (1:20) neurones so the sympathetic responses are coordinated and divergent; because of the sympathetic trunk, there is a mass discharge of the SNS.

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15
Q

What are the consequences of the organisation and origins of the Parasympathetic trunk of the ANS?

A

Little divergence of neurones, so its effects tend to be discreet and localised.

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16
Q

Recall the organisation of the ANS and the neurotransmitters it uses:

17
Q

What are the two types of ACh receptor?

A

Nicotinic and Muscarinic

18
Q

Where are nicotinic receptors found?

A

At ALL autonomic ganglia

19
Q

What is the speed of Nicotinic receptors and why?

A

Rapid as they transfer the stimulus from the pre-ganglionic to the post-ganglionic neurone.

20
Q

What type of receptor is the Nicotinic receptor?

A

Type 1 - Ionotropic

21
Q

How do nicotinic receptors work?

A

Acetylcholine binds to the receptor and opens an ion channel that allows sodium/calcium influx and allows transmission.

22
Q

Where are Muscarinic receptors found?

A

At any tissue that is innervated by a post-ganglionic parasympathetic fibre

23
Q

What type of receptors are Muscarinic receptors?

A

Type 2 - G-protein coupled

24
Q

What is the speed of a muscarinic receptor?

A

Much slower than nicotinic

25
What are the sub-types of Muscarinic receptors?
* M1 – Neural (Forebrain – learning & memory) * M2 – Cardiac (Brain – inhibitory autoreceptors) * M3 – Exocrine & smooth muscle (Hypothalamus – food intake)
26
Where are Adrenoceptors located?
Most effector organs innovated by post-ganglionic sympathetic fibres
27
What type of receptors are adrenoceptors?
Type 2 - G-protein coupled
28
What are the four types of Adrenoceptors?
* Alpha 1 * Alpha 2 * Beta 1 * Beta 2
29
What are the functions of Alpha 1 and Beta 2 adrenoceptors, and what does this mean in terms of the ANS?
Alpha 1 Constricts Beta 2 Dilates - The SNS controls vasculature by itself
30
Describe the synthesis of ACh:
Acetyl CoA + Choline (from diet) with Choline Acetyl Transferase (within presynaptic bulb)
31
Describe the metabolism of ACh:
Acetylcholinesterase converts ACh in the synapse to Choline and acetate. The Choline then reenters the bulb to from more ACh.
32
What three enzymes are involved the biosynthesis of Noradrenaline, and what do they convert?
Tyrosine hydroxylase: Tyrosine to DOPA DOPA decarboxylase: DOPA to Dopamine Dopamine beta-hydroxylase: Dopamine to NA
33
What is the main difference betweent he metabolism of ACh and NA?
NA is not metabolised in the synapse!
34
How is noradrenaline removed from the synapse?
Uptake-1: Back into neuronal tissue Uptake-2: into extraneuronal tissue
35
How is NA metabolised, and where?
In neuronal tissue: Monoamine oxidase (MAO) In extraneuronal tissue: Catechol-O-Methyl Transferase (COMT)