Lecture 3.2: Cholinergic and Adrenergic Transmission

Question 1

What are the 2 Types of Cholinergic Receptors?

Answer 1

Muscarinic or Nicotinic

Question 2

How many types of muscarinic receptor?

Answer 2

• 5 types of muscarinic receptor (M1-M5)
• M1,3,5 are GPCRs (Gq) mediated by inositol lipid
  signalling
• M2,4 act through Gi to open K+ channels
  resulting in hyperpolarisation

Question 3

M1 Receptors: Where are they found? Role?

Answer 3

• Essentially neural receptors, CNS, PNS parietal
  cells
• Mediate excitatory events by reducing K+
  conductance resulting in hyperpolarisation

Question 4

M2 Receptors: Where are they found? Role?

Answer 4

• Cardiac Cells
• Work by increasing K+ conductance

Question 5

M3 Receptors: Where are they found? Role?

Answer 5

• Glandular and Smooth Muscle
• Mainly excitatory e.g. increasing secretions and
  contraction of visceral smooth muscle
• NB may also relax some vascular smooth muscle
  via the production of nitric oxide

Question 6

M4/M5 Receptors: Where are they found? Role?

Answer 6

• Located mainly in CNS
• Lack of clarity on role

Question 7

What are the 3 Types of Nicotinic Receptors?

Answer 7

• Muscular (skeletal neuromuscular junction)
• Ganglionic (SANS and PANS)
• CNS (many are presynaptic and facilitate the release of
  other transmitters)

Question 8

SANS: Where do cell bodies of preganglionic neurones originate?

Answer 8

Originate in the intermediolateral cell column of the thoracic and lumbar spinal cord (T1- L2/3)

Question 9

PANS: Where do cell bodies of preganglionic neurones originate?

Answer 9

Located in the brainstem and sacral segments of the spinal cord

Question 10

PANS: Where do cell bodies of preganglionic neurones originate?

Question 11

Where is the Enteric Nervous System (ENS) Located? (2)

Answer 11

• Submucosal Plexus (Meissners Plexus)
• Myenteric Plexus (Auerbachs Plexus)

Question 12

What does the ANS do?

Answer 12

• Regulates physiological functions
• Where parasympathetic and sympathetic divisions
  both innervate a tissue they often have opposite
  effects

Question 13

Where does the SANS outflow?

Answer 13

Thoraco-lumbar outflow

Question 14

How do axons of the SANS leave the spinal cord?

Answer 14

Axons leave the spinal cord via the ventral root and initially enter the spinal nerve

Question 15

What happens to SANS axons after they leave the spinal nerve? (3)

Answer 15

• Leave the nerve (via the white rami communicantes)
• Before synapsing with post-ganglionic neurons in
  the paravertebral ganglia
• Before renetring the spinal nerve (via grey rami
  communicantes)

Question 16

The sympathetic ganglia (…1… ganglia) form two …2… trunks of interconnected ganglia either side of the vertebral column

Answer 16

1) paravertebral
2) parallel

Question 17

Preganglionic fibres to abdominal structures form the
…1… nerves which synapse in either the coeliac,
superior and inferior …2… ganglia

Answer 17

1) splanchnic
2) mesenteric

Question 18

Innervation of the adrenal medulla: Preganglionic fibres in the splanchnic nerves synapse directly with …1… cells

Answer 18

1) chromaffin

Question 19

Where does the PANS outflow?

Answer 19

Cranio-sacral outflow

Question 20

Ganglia of PANS located close to or sometimes embedded in the…..?

Answer 20

organ they innervate

Question 21

What is Acetylcholine (ACh) is Synthesised from?

Answer 21

• Choline and Acetyl-CoA
• Reaction is catalysed by choline acetyltransferase

Question 22

Types of Cholinergic Receptors (2)

Answer 22

Nicotinic
Muscarinic

Question 23

How many types of muscarinic receptors are there?

Answer 23

• 5 types of muscarinic receptor
• M1-M5

Question 24

What muscarinic receptors are GPCRs (Gq
) mediated by inositol lipid signalling?

Answer 24

M1,3,5

Question 25

M2,4 act through ...1... to open K+ channels resulting in hyperpolarisation

Answer 25

1) Gi

Question 26

What are M1 receptors?

Answer 26

* Essentially neural receptors * CNS, PNS parietal cells * Mediate excitatory events by reducing K+ conductance resulting in hyperpolarisation

Question 27

What are M2 receptors?

Answer 27

* Cardiac * Work by increasing K+ conductance

Question 28

What are M3 receptors?

Answer 28

* Glandular and Smooth Muscle * Mainly excitatory e.g. increasing secretions and contraction of visceral smooth muscle * NB may also relax some vascular smooth muscle via the production of nitric oxide

Question 29

What are M4/5 receptors?

Answer 29

* Located mainly in CNS * Lack of clarity on role

Question 30

What are the 3 Main Types of Nicotinic Receptors?

Answer 30

* Muscular (skeletal neuromuscular junction) * Ganglionic (SANS and PANS) * CNS (many are presynaptic and facilitate the release of other transmitters)

Question 31

What is noradrenaline synthesised from?

Answer 31

Synthesised via dihydroxyphenylalanine (DOPA) and dopamine from tyrosine

Question 32

What is noradrenaline inactivated by?

Answer 32

The enzymes MAO and COMT

Question 33

What are the Classes of Adrenoceptors? (2)

Answer 33

α or β

Question 34

What are the Classes of Adarenoreceptors based on?

Answer 34

Based on the rank order of potencies of various catecholamines

Question 35

Order of potencies of catecholamines in α-adrenoreceptors?

Answer 35

Noradrenaline>Adrenaline>Isoprenaline

Question 36

Order of potencies of catecholamines in β-adrenoreceptors?

Answer 36

Isoprenaline>Adrenaline>Noradrenaline

Question 37

How are α-adrenoreceptors catagorised?

Answer 37

* 2 subdivisions of α – α1 and α2 * Each of which has 3 subdivisions (1A, 1B, 1D and 2A, 2B and 2C)

Question 38

How are β-adrenoreceptors catagorised?

Answer 38

3 subdivisions of β – β1, β2 and β3