Cholinergic and Adrenergic Transmission

Question 1

How is the action of noradrenaline in the synapse terminated?

Answer 1

Reuptake into the neuronal terminal

Question 2

what are the 2 main types of adrenoreceptor?

Answer 2

alpha and beta

Question 3

how do alpha and beta adrenoreceptor differ?

Answer 3

in their affinity for various drugs

Question 4

Describe the biosynthesis of adrenaline and noradrenaline

Answer 4

• Start with Tyrosine (AA)
• hydroxyl group added by tyrosine hydroxylase to form DOPA (precursor of dopamine)
• DOPA is decarboxylated by DOPE decarboxylate to form Dopamine (neurotransitter)
• Hydroxyl group added by Dopamine B- hydroxylase to form Noradrenaline (neurotransmitter/hormone)
• Methylgroup added by phenylethanolamine N- Methyltransferase to form adrenaline (hormone/neurotransmitter)

Question 5

draw the biosynthesis of Noradrenaline and adrenaline

Answer 5

https://www.google.com/search?q=biosynthesis+of+adrenaline+and+noradrenaline&safe=active&rlz=1C1CHBF_en-gbGB767GB767&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjH25ezz-vhAhXnWxUIHVtGD3YQ_AUIDigB&biw=1280&bih=610#imgrc=bcoXKMamrZIQ1M:

Question 6

what uptakes noradrenaline in the periphery (peripheral nervous system)?

Answer 6

Neurons

Question 7

How is noradrenaline action terminated in the CNS?

Answer 7

via reuptake, then metabolism of the neurotransmitter.
This metabolism is done intraceullularly (in the neuron) by enzymes.
The 2 main enzymes that do this are monoamine Oxidase MAO and Catachol- O- methyl transferase (COMT)

Question 8

draw the structure of acetyl choline

Answer 8

https://www.google.com/search?q=acetylcholine+structure&safe=active&rlz=1C1CHBF_en-gbGB767GB767&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjymIO50uvhAhXsQRUIHS24Ci0Q_AUIDigB&biw=1280&bih=610#imgrc=SZM-PfNwgsAHHM:

Question 9

What are the 2 important components of acetyl choline?

Answer 9

• ester linkage and permanent positively charged Nitrogen

Question 10

how is Acetylcholine catabolised?

Answer 10

• The enzyme acetylcholinesterase AChE breaks down Ach into acetate and choline by cleaving the ester bond- happens extracellularly (in the synapse)
• The choline is taken back into the nerve terminal via a carrier and is made back into Ach by the enzyme choline acetyl transferase. The Ach is then transported back into vesicles and stored ready for release

Question 11

what is the Autonomic Nervous System (ANS) divided into?

Answer 11

Sympathetic (SNS) and Parasympathetic (PNS)

Question 12

What is the SNS known as commonly?

Answer 12

Fight or flight response

Question 13

what physiological changes does the activation of the SNS cause? (give 3)

Answer 13

• Increased HR
• Increased BP
• Increased BF to muscles
• Inhibits GI peristalsis
• Bronchial dilation
• Pupil dilation

Question 14

what’s the general organisation of the SNS?

Answer 14

• transmission from the CNS to the sympathetic target tissue involves 2 neurons
  1) cell body in the CNS (spinal cord) which synapses with the 2nd neuron in ganglion. Transmission at this synapse is via nAChR (Nicotinic acetylcholine receptor)
  2) neuron synapses with the target tissue. This transmission is via noradrenaline acting on adrenergic receptors

Question 15

what are the cells like in the adrenal medulla (adrenal gland)?

Answer 15

neurons that have no axons

Question 16

what do the cells of the adrenal medulla release into the blood stream?

Answer 16

adrenaline and noradrenaline

Question 17

what is the PNS more commonly known as?

Answer 17

rest and digest

Question 18

what are the physiological effects of the PNS? (give 3)

Answer 18

• reduced HR
• increased GI motility
• Bronchial constriction
• Pupil constriction
• Gastric acid secretion

Question 19

what’s the general organisation of the PNS?

Answer 19

2 neuron system

1) cell body in the CNS (spinal cord) synapses using acetylcholine to NAchR on 2nd neuron
2) neuron synapses with effector tissue where the transmitter is acetylcholine and the receptor is a muscarinic acetyl choline receptor

Question 20

In the PNS are the pre-ganglionic neurons long or short?

Answer 20

long

Question 21

in the PNS are the post-ganglionic neurons long or short?

Answer 21

short

Question 22

Parasympathetic output from the spinal cord is confined to which regions (2)?

Answer 22

medullary and sacral (top and bottom)

Question 23

How do beta-blockers affect sensitivity to insulin?

Answer 23

they reduce it