Synpases and neuromuscular control

Question 1

What are the two types of synapses?

Answer 1

Electrical and Chemical

Question 2

How do electrical synapses transmit signals?

Answer 2

Via electric current that passes directly through gap junctions between pre- and postsynaptic cells

Question 3

How do chemical synapses transmit signals?

Answer 3

Electrical signals are converted into chemical signals via neurotransmitters

Question 4

What forms gap junctions in synpases?

Answer 4

Docking of two hemichannels made of connexin or innexin proteins

Question 5

What are the three main categories of neurotransmitters?

Answer 5

Classical
Peptides
Unconventional

Question 6

Name examples of classical neurotransmitters

Answer 6

Acetylcholine
Biogenic amines (norepinphrine, dopamine, serotonin, histamine)
Amino acids (glutamate, GABA, glycine)

Question 7

Name examples of peptide neurotransmitters

Answer 7

Substance P
Endorphins
Enkephalins

Question 8

Name examples of unconventional neurtransmitters

Answer 8

Nitric oxide
ATP
Cannabinoids

Question 9

What is an excitatory postsynaptic potential

Answer 9

Adepolarising response that may lead to an action potential

Question 10

What is an inhibitory postsynaptic potential?

Answer 10

A hyperpolarising response that makes action potentials less likely

Question 11

What triggers neurotransmitter release at the synpase?

Answer 11

Action potential opens volagte-gates Ca2+ channels, allowing Ca2+ entry, which triggers exocytosis

Question 12

What happens after neurotransmitter release?

Answer 12

It diffuses across the synpatic cleft and binds to postsynaptic receptors, initiating a response

Question 13

What are the precursors of ACh?

Answer 13

Choline and acetyl-CoA

Question 14

What enzyme synthesise ACh?

Answer 14

Choline acetyltransferase

Question 15

What enzyme degrades ACh?

Answer 15

Acetylcholinesterase, breaking it into acetic acid and choline

Question 16

What are ionotropic receptors?

Answer 16

Chemicalls-gated ion channels that open directly

Question 17

What are metabotropic receptors?

Answer 17

G-protein coupled recepotrs that trigger second messengers

Question 18

What type of receptor is nAChR?

Answer 18

Ionotropic; allows Na+, K+, and Ca+ in when activated

Question 19

What type of receptor is mAChR?

Answer 19

Metabotropic, uses G-proteins to affect second messenger system

Question 20

What do M1, M3, N5 mAChRs do?

Answer 20

Activate phospholipase C –> DAG + IP3 –> increase Ca2+, kinase activation

Question 21

What do M2, M4 mAChRs do?

Answer 21

Inhibit adenylate cyclase –> decrease cAMP; affect K+, Ca2+ channels

Question 22

What is an agonist?

Answer 22

A molecule that binds to and activates a receptor

Question 22

What is an antagonist?

Answer 22

A molecule that blocks or interferes with receptor activation

Question 23

What does a1 receptor activation do?

Answer 23

Activates phospholipase C –> IP3 and DAG

Question 24

What does a2 receptor do?

Answer 24

Inhibits adenylate cyclase --> decrease cAMP

Question 25

What do B1-B3 receptros do?

Answer 25

Activate adenylate cyclase --> increase cAMP

Question 26

How are neuotrasnmitters inactivated?

Answer 26

Reuptake Enzymatic breakdown Glial uptake

Question 27

Is there reuptake for ACh?

Answer 27

No, but choline is recycled

Question 28

What does the somatic motor pathway control?

Answer 28

Skeletal muscle via single, exciatory neurons from the CNS

Question 29

What is a motor unit?

Answer 29

One motor neuron and all the muscle fibres it innervates

Question 30

What neurtransmitter is used at the NMJ?

Answer 30

Acetylcholine

Question 31

What receptor is at the NMJ?

Answer 31

Nicotinic ACh receptor (nAChR)

Question 32

What triggers ACh release?

Answer 32

Ca2+ influx due to an action potential

Question 33

What happens after ACh binds nAChRs?

Answer 33

Na+ influx --> depolarisation of muscle fibre

Question 34

What diseases are linked to impaired neurotransmission?

Answer 34

Alzheimer's Parkinson's Depression Anxiety Schizophrenia Epilepsy

Question 35

How do drugs affect neurotransmission?

Answer 35

Alter enzyme activiy, reuptake, or receptor interactions

Question 36

What are the general symptoms of Myasthenic Disorders?

Answer 36

Muscle weakness Fatigability

Question 37

What is Myasthenia Gravis?

Answer 37

Postsynaptic defect; antibodies attack nAChRs

Question 38

How is MG treated?

Answer 38

What acetylcholinesterase inhibitors

Question 39

What is Lambert-Eaton Myasthenic Syndrome

Answer 39

Presynaptic defect; antibodies attack Ca2+ channels --> decrease ACh release

Question 40

WHat causes ACh receptor deficiency?

Answer 40

Mutation in nAChR genes --> fewer/altered receptors (postsynaptic)

Question 41

What cause Congenital Myasthenic Syndromes? (CMSEA)

Answer 41

Mutation in choline acetyltransferase (presynaptic)

Question 42

What causes AChE deficiency?

Answer 42

Mutation in AChE gene --> overstimulation of muscle (synaptic defect)

Question 43

What is endogenous depression?

Answer 43

No clear cause, possibly genetic

Question 44

What is exogenous depression?

Answer 44

Triggered by life events (PTSD)

Question 45

What neurotransmitter imbalance is seen in depression?

Answer 45

Decrease in noradrenaline, serotonin, dopamine Increase in cholinergic activity

Question 46

How do tricyclin antidepressant work?

Answer 46

Block reuptake of noradrenaline

Question 47

How do SSRIs work?

Answer 47

Blcok reuptake of serotonin

Question 48

How do MAO inhibitors work?

Answer 48

Prevent breakdown of monoamines