PHARM 1: Introduction to the ANS

Question 1

What are the 3 principal efferent outputs from the CNS?

Answer 1

1. ANS
2. Somatic NS
3. Neuroendocrine system

Question 2

Give 3 examples (tests) that determine which ANS branch is dominant

Answer 2

1. Pupillary constriction
2. Cephalic + Gastric phase of gastric secretion
3. Basal Control of Heart Rate

Question 3

What neurotransmitters are released from the

a) Presynaptic neurones
b) Postsynaptic neurones

IN THE PNS?

Answer 3

a) Presynaptic neurones –> Ach

b) Postsynaptic neurones –> Ach

Question 4

What neurotransmitters are released from the

a) Presynaptic neurones
b) Postsynaptic neurones

IN THE SNS?

Answer 4

a) Presynaptic neurones –> Ach

b) Postsynaptic neurones –> NA / A (adrenal medulla) + Ach

Question 5

Sympathetic effects tend to be ________ + ________

Answer 5

Sympathetic effects tend to COORDINATED + DIVERGENT

Question 6

Parasympathetic effects tend to be ______ + _____

Answer 6

Parasympathetic effects tend to be DISCRETE + LOCALISED

Question 7

Compare between Nicotinic Receptors + Muscarinic Receptors

Answer 7

NICOTINIC receptor:

• propagates signal
• found in ALL autonomic ganglia
• ion channel linked
• Rapid

MUSCARINIC receptors:

• influences end target effect
• found in all effector organs innervated by post ganglionic Parasympathetic fibers
• Type 2 G-Protein Coupled
• Much Slower

Question 8

What effect would blocking nicotinic Ach receptors have on HR (at rest) ?

Answer 8

at rest:

• PNS is dominating
• so blockage –> increase in HR

Question 9

What effect would blocking nicotinic Ach receptors have on HR (during exercise) ?

Answer 9

during exercise:

• SNS = dominating
• so blockage –> decrease in HR

Question 10

What is the effect of PNS on:

a) lungs
b) Gut
c) Urinary frequency
d) sight

Answer 10

What is the effect of PNS on:

a) lungs –> Bronchoconstriction
b) Gut –> increased motility
c) Urinary frequency –> Increase
d) sight –> Short sightedness

Question 11

What are the 3 main sub-types of Muscarinic Receptor?

and where do they act on?

Answer 11

• M1 (Neural)
• M2 (Cardiac)
• M3 (Exocrine + Smooth Muscle)

Question 12

What are the different subtypes of adrenoreceptor?

Answer 12

a1, a2, b1, b2

Question 13

What type of receptor are adrenoreceptors?

Answer 13

G-Protein coupled receptors

Question 14

Blockade of which receptor subtype would induce both an INCREASED HR + a REDUCTION in sweat production during exercise?

Answer 14

• Muscarinic receptors

Question 15

How is NA removed? What are the 2 methods of uptake of NA?

Answer 15

1. –> back into neuronal tissue

2. –> into extra neuronal tissue

Question 16

Once NA has been taken up, what enzymes break it down? and where are they located in?

Answer 16

1. MAO (mainly neuronal tissue)

2. COMT (mainly extra neuronal tissue)

Question 17

A blockade of which target would cause the most significant rise in synaptic NA conc?

Answer 17

• Uptake 1 transport protein

Question 18

In dark room which nervous system becomes more dominant?

Answer 18

• SNS kicks in
• causes pupil dilation
• increases light coming in

Question 19

Note: enteric nervous system
has sensory + motor neurones that work quite independently of the brain
but
brain still exerts ANS control of the ENS

Answer 19

-

Question 20

Describe the synthesis of NA

Answer 20

• Tyrosine –> DOPA (enzyme: tyrosine hydroxylase)
• DOPA –> dopamine (enzyme: DOPA decarboxylase)
• Dopamine –> Noradrenaline (enzyme: dopamine beta-hydroxylase)