L.7

Question 1

What are the 2 main types of synapses

Answer 1

electrical and chemical

Question 2

Name 5 features of chemical synapses

Answer 2

• unidirectional
• majority (most common)
• complex structure
• slower
• amplification

Question 3

Why do chemical synapses have complex structures

Answer 3

they need vesicles, receptors & neurotransmitters

Question 4

Why do chemical synapses have slower transmission

Answer 4

there is a synaptic delay because neurotransmitters need to be released and then bind to receptors

Question 5

Name 5 features electrical synapses

Answer 5

• bidirectional
• minority
• simpler structure
• faster
• no amplification

Question 6

What does axodendritic mean

Answer 6

axon connects to dendrite of post-synaptic neuron

Question 7

What does axosomatic mean

Answer 7

axon connects to soma of post-synaptic neuron

Question 8

What does axoaxonic mean

Answer 8

axon connects to axon of post-synaptic neuron

Question 9

TRUE or FALSE: axosomatic gives the most power signal between the 3 types

Answer 9

FALSE
- axoaxonic because the closer the axon connect to axon (post-synaptic) = more powerful signal is going to be

Question 10

What is a synaptic button/terminal

Answer 10

where NTs are released

Question 11

What is the function of the cytoskeleton in chemical synapses

Answer 11

• keeps vesicles in place
• maintains structure of synaptic button

Question 12

Why are there mitochondria in chemical synapses

Answer 12

provides energy for NT release ad vesicle recycling

Question 13

What is the active zone in chemical synapses

Answer 13

where synaptic vesicles dock and release NTs into synaptic cleft

Question 14

What is the synaptic cleft

Answer 14

gap between post and pre-synaptic neurons where NTs are released

Question 15

What is a neuromuscular junction

Answer 15

synapses between motor neuron and muscle fibre

Question 16

What are the features of neurotransmitters

Answer 16

• needs to be synthesised in neurons
• it needs to mimic the action endogenously released transmitter
• needs to be a specific mechanism for removing chemical from synaptic cleft

Question 17

What is the effect of an excitatory neurotransmitter

Answer 17

• depolarises membrane
• neuron more likely to fire action potential

Question 18

What is the effect of inhibitory neurotransmitter

Answer 18

• (hyper)repolarises membrane
• neuron less likely to fire action potential

Question 19

What initiates vesicle release in the presynaptic terminal?

Answer 19

• An action potential
• opening Ca²⁺ channels, allowing Ca²⁺ to influx

Question 20

What happens when Ca²⁺ binds to calmodulin?

Answer 20

It forms a Ca²⁺-calmodulin complex that activates CAMKII

Question 21

What does CAMKII phosphorylate during vesicle release

Answer 21

CAMKII phosphorylates synapsin

Question 22

What is the effect of phosphorylating synapsin?

Answer 22

It causes the release of vesicles from the cytoskeleton

Question 23

How is vesicle membrane recovered after neurotransmitter release?

Answer 23

endocytosis

Question 24

What happens to vesicles after they are recovered?

Answer 24

They are refilled with NTs

Question 25

What is the role of SNARE proteins

Answer 25

essential for vesicle fusion

Question 26

How do toxins affect synaptic transmission?

Answer 26

They cleave SNARE proteins, disrupting synaptic transmission

Question 27

What is the effect of BoTX on neurotransmitter release?

Answer 27

prevents release of Ach causing decreased/blocked muscle contraction

Question 28

What does TeTX block in the nervous system?

Answer 28

blocks release inhibitory NTs, decreasing interneuron activity

Question 29

What is the effect of Latrotoxin on neurotransmitter release?

Answer 29

triggers excessive vesicle fusion, causing NT depletion

Question 30

What condition is caused by impaired vesicle recycling?

Answer 30

Congenital myasthenic syndromes.

Question 31

What channels are attacked in LEMS?

Answer 31

Pre-synaptic Ca²⁺ channels

Question 32

How do cognitive disorders affect synaptic communication?

Answer 32

impair trans-synaptic signalling (NT flow in the synaptic cleft)

Question 33

How do Botulinum and Tetanus toxins affect vesicle fusion?

Answer 33

They disrupt SNARE proteins, preventing neurotransmitter release

Question 34

What powers vesicular transporters in synaptic vesicles?

Answer 34

A proton (H⁺) gradient created by ATPase pumping H⁺ into vesicles.

Question 35

How does a proton gradient aid vesicular transport?

Answer 35

- It increases acidity inside the vesicles - transporters use the energy from H+ gradient to carry molecules into the vesicles

Question 36

What drives plasma membrane transporters?

Answer 36

electrochemical gradient

Question 37

What maintains the electrochemical gradient across the plasma membrane?

Answer 37

Na⁺/K⁺ ATPase

Question 38

What are the three components of the tri-partite synapse?

Answer 38

- Pre-synaptic neuron - post-synaptic neuron - astrocyte (glial cell).

Question 39

How do astrocytes participate in synaptic plasticity?

Answer 39

- synapse formation/elimination - involved in learning and memory.

Question 40

What is reactive gliosis, and when does it occur?

Answer 40

It's a glial response to injury, where glial cells become reactive.

Question 41

What are the categories of neurotransmitters

Answer 41

- amino acids - monoamines - neuropeptides

Question 42

Where are amino acid neurotransmitters synthesised?

Answer 42

pre-synaptic terminal

Question 43

Where are monoamines stored

Answer 43

Stored in synaptic vesicles

Question 44

Where are neuropeptides synthesised

Answer 44

cell soma

Question 45

Where are neuropeptides stored

Answer 45

secretory granules

Question 46

What are the names of the main excitatory and inhibitory neurotransmitters

Answer 46

excitatory = glutamate inhibitory = GABA (and glycine)

Question 47

Where is serotonin produced

Answer 47

Raphe nuclei (brainstem)

Question 48

What does serotonin regulate

Answer 48

mood, sleep, emotion & appetite

Question 49

What is a special feature of serotonin neurons

Answer 49

they have a large outreach (1 neurons contact 100 000 other neurons)

Question 50

How is glutamate transported in vesicles

Answer 50

by vesicular glutamate transporters (VGLUT)

Question 51

How is glutamate reabsorbed and recycled

Answer 51

1. reabsorbed by excitatory amino acid transporters in pre-synaptic cell 2. glial cells convert glutamate into glutamine 3. glutamine is converted to glutamate (in nerve terminals)

Question 52

How is glutamate synthesised

Answer 52

- from glucose in Krebs cycle - glutamine is converted to glutamate by glutaminase

Question 53

How is GABA synthesised

Answer 53

it is synthesised from glutamate by glutamic acid decarboxylase

Question 54

How is GABA transported

Answer 54

stored in vesicles by vesicular GABA transporter

Question 55

How is GABA cleared from the synaptic cleft?

Answer 55

Through reuptake mechanisms by transporters on glial cells and both GABAergic and non-GABAergic neurons

Question 56

TRUE or FALSE: a higher proportion of GABA is synthesised to novo rather than recycling

Answer 56

TRUE

Question 57

What happens to the electrochemical gradient during cerebral ischemia?

Answer 57

- metabolic events maintaining gradient are disrupted - Na+/K+ gradient reverses --> releasing glutamate - Excessive calcium release causes excitotoxic cell death

Question 58

What is GHB?

Answer 58

a metabolite of GABA that can be converted back to GABA

Question 59

how does GHB affect GABA levels?

Answer 59

It increases the GABA levels

Question 60

What happens if there is an excess of GHB

Answer 60

unconsciousness and coma

Question 61

How do neuropeptides differ from small molecule neurotransmitters?

Answer 61

- mediate slow transmission - differ in their synthesis and release methods - short polypetide chains

Question 62

how do soluble gases function as neurotransmitters?

Answer 62

They act quickly in the synaptic environment

Question 63

What is retrograde signalling by soluble gases?

Answer 63

- Soluble gases are released from post-synaptic neurons - They diffuse back to pre-synaptic neurons, influencing neurotransmitter release

Question 64

What are endocannabinoids

Answer 64

active component of marijuana

Question 65

what effect do endocannabinoids have?

Answer 65

reduce GABA release

Question 66

What are the 4 main types of neurotransmitters?

Answer 66

- amino acids - monoamine - acetylcholine - neuropeptides

Question 67

What are the two main types of post-synaptic receptors?

Answer 67

ionotropic & metabotropic

Question 68

How do ionotropic receptors work?

Answer 68

1. NT bind to receptor to open it 2. receptor changes conformation and ions flow through

Question 69

Which one has faster transmission: ionotropic or metabotropic

Answer 69

ionotropic

Question 70

How do metabotropic receptors work?

Answer 70

They transduce signals (relay signal from outside the cell to inside the cell) via activation of a G-protein triggering a series of intracellular events

Question 71

What is the difference between ionotropic and metabotropic receptors?

Answer 71

- ionotropic: faster - metabotropic: longer lasting effects

Question 72

What does an antagonist do

Answer 72

blocks the normal activity of a neurotransmitter, preventing its effect

Question 73

What is the role of an agonist

Answer 73

enhances the effect of a neurotransmitter by mimicking or increasing its action

Question 74

How does kinetics affect neurotransmitter function?

Answer 74

how fast neurotransmitters bind to a receptor, which determines the duration of their effect

Question 75

What does selectivity in receptors mean?

Answer 75

refers to which ions (e.g., Na+, Cl-) pass through the receptor channels

Question 76

What is conductance in receptor function?

Answer 76

how quickly ions flow through the receptor, which determines the magnitude of the effect