Jonathon Williams

Question 1

What are neurotransmitters

Answer 1

Chemical messengers released by nerve cells
The bind to receptors on target cells
Binding causes a biological response in the target cell

Question 2

What do the sensory nerves do

Answer 2

Take messages from the body to the CNS

Question 3

What do the motor nerves do

Answer 3

Carry messages from the CNS to the rest o the body

Question 4

What are the three principle motor nerves

Answer 4

Somatic motor nerve - skeletal muscle
Autonomic motor nerve (sympathetic)
Autonomic motor nerve (parasympathetic)

Question 5

What happens at chemical synapses

Answer 5

Nerve signal travels down neurone until it reaches a synapse
Neurotransmitters released from presynaptic membrane into synaptic cleft
Neurotransmitter diffuses across cleft to bind to receptors on postsynaptic membrane

Question 6

How are receptors activated

Answer 6

Neurotransmitter binds to receptor
Non covalent interactions cause receptors to change shape
This is known as induced fit
Change in shape of receptor binding site causes further conformational changes which ultimately result in a biological response

Question 7

How are ion channel receptors activated

Answer 7

Ion channel complexes are made of 5 protein subunits that transverse the cell membrane
Controlled by lock gate mechanism
Resting state is closed. When a messenger binds to the receptor the induced fit causes a conformational change which opens the ion channel

Question 8

How do kinase linked receptors work

Answer 8

Directly linked to kinase enzymes
Ligand binding causes a conformational change which opens the kinase active site inside the cell
Kinase enzymes catalyse phosphorylation reactions within the cell

Question 9

How do receptor agonists work

Answer 9

Mimic the natural neurotransmitter
Activate the target receptor
Induce the same biological response

Question 10

How to receptor antagonists work

Answer 10

Bind to target receptor
Do not induce biological response
Block the action of the neurotransmitter

Question 11

How do reuptake inhibitors work

Answer 11

Bind to transport proteins that return neurotransmitters to presynaptic membrane
This increases the concentration of the neurotransmitter for longer periods of time
Prolongs biological response of neurotransmitter

Question 12

How do hydrolysis inhibitors work

Answer 12

Prevent neurotransmitter from being hydrolysed in synaptic gap
Increases concentration of neurotransmitter
Same effect as receptor agonist

Question 13

How do Biosynthesis inhibitors work

Answer 13

Prevent correct neurotransmitters from being synthesised

Reduces the effect of the neurotransmitter

Question 14

What is acetyl choline

Answer 14

A neurotransmitter that acts on cholinergic receptors

Question 15

What are the two main types of cholinergic receptors

Answer 15

Nicotinic receptor

Muscarinic receptors

Question 16

How do G protein couples receptors work?

Answer 16

When a ligand binds to a G-protein coupled receptor there is a conformational change which exposes a new binding site within the cell
This binding site interacts with a G-protein
When the G-protein binds it releases GDP and binds GTP
The GTP breaks the G-protein into its subunits
The released subunits activate other processes within the cell
The activated G-protein coupled receptor can activate several G-proteins before the original ligand leaves allowing signal amplification

Question 17

Describe the binding of propantheline

Answer 17

Propantheline has the same core as acetylcholine with additional binding sites so binds more strongly

Question 18

What are nicotinic receptor antagonists used for?

Answer 18

Neuromuscular blocking agents

Question 19

Give three examples of nicotinic antagonists?

Answer 19

Suxamethonium
Pancuronium
Atracurium

Question 20

How do anticholinesterases work?

Answer 20

Inhibit the action of acetylcholinesterase
This prevents hydrolysis of acetyl choline which has a similar effect to that of a cholinergic agonist
Acetylcholinesterase enzyme is bound to the post-synaptic membrane close to the receptor

Question 21

What do nerve gases do?

Answer 21

Such as dyflos and sarin
Inhibit acetylcholinesterase by irreversibly phosphorylating the serine residue in the active site
Acetylcholine cannot be hydrolysed causing the cholinergic system to be continuously stimulated. This results in permanent contraction of skeletal muscle

Question 22

Describe adrenaline and noradrenaline

Answer 22

Both catecholamines
Adrenaline is a hormone released by the adrenal medulla and activates adrenergic receptors throughout the body
Noradrenaline is a neurotransmitter released by nerve cells that control smooth muscle and cardiac muscle

Question 23

Describe noradrenaline biochemistry

Answer 23

Biosynthesised from L-tyrosine in the presynaptic nerve and is released upon arrival of a signal
Activates target receptor it is then transported back using a carrier protein
Some noradrenaline is metabolised by methylation and oxidation
Adrenaline is biosynthesised from noradrenaline in the adrenal medulla

Question 24

How does alpha methyltyrosine work?

Answer 24

Inhibits the enzyme tyrosine hydroxylase preventing the synthesis of noradrenaline reducing the adrenergic response

Question 25

Facts about dopaminergic receptors

Answer 25

Dopamine is an intermediate in the biosynthesis of noradrenaline but is also neurotransmitter itself
G-protein coupled receptors
Prominent in the CNS and are involved in cognition learning and motor control
The dopaminergic system has been targeted using agonists, antagonists, biosynthesis inhibitors, metabolism inhibitors, storage inhibitors and reuptake inhibitors

Question 26

What are serotonin receptors

Answer 26

Neurotransmitter biosynthesised from tryptamine
Serotonin receptor subtypes consist of both G-protein coupled receptors and ligand gated ion channels
Serotonin receptors are thought to influence aggression cognition learning memory and mood