Types of synapses. Characteristics of motor end plate. Secretion of transmitter by presynaptic varicosities. Electrical synapses

Question 1

list types of synapses

Answer 1

chemical
electrical

Question 2

chemical synapse - definition

Answer 2

released neurotransmitters from pre-synaptic terminal -> synaptic cleft -> post synaptic terminal

for neuronal communication

Question 3

chemical synapse - structure

Answer 3

already mentioned

Question 4

chemical synapse - mechanism

Answer 4

already mentioned

Question 5

chemical synapse - types

Answer 5

EPSP
IPSP
= already mentioned

Question 6

chemical synapse - characteristics - 1

Answer 6

short-term plasticity

• temporary decrease in synaptic strength
• e.g. depression

Question 7

chemical synapse - characteristics - 2

Answer 7

long-term depression

• long term decrease in synaptic strength

Question 8

chemical synapse - characteristics - 3

Answer 8

long term potentiation

• long term increase in synaptic strength
  e.g. memory/ learning

Question 9

electrical synapse - definition

Answer 9

direct communication between neurone1 + neurone 2 using via junctions

• by rapid changes in MP

Question 10

electrical synapse - structure

Answer 10

gap junctions
- formed of 6 connexin proteins forming hexagonal structure of connexon

• these connexons connect to cytoplasm of 2 adjacent neurones for direct + continous communication

synaptic cleft

Question 11

electrical synapse - mechanism

Answer 11

changes in membrane potential in neurone 1 causes changes in membrane potential of neurone 2 = rapid communication

Question 12

electrical synapse - characterisitics

Answer 12

fast/ instant/ direct/ bidirectional/synchronous transmission

reliable as no neurotransmitter involved

Question 13

electrical synapse - location

Answer 13

CNS
- retina
- thalamus
- cerebral cortex

• cardiac muscles
• smooth muscles

Question 14

motor end plate - definition

Answer 14

also called neuromuscular junction

region where motor neurone communicates with muscle fibres

Question 15

motor end plate - structure

Answer 15

pre-synaptic terminal
synaptic cleft
post-synaptic terminal

Question 16

motor end plate - presynaptic terminal

Answer 16

Voltage-gated ion channel
- opens for calcium channel influx
- triggers release of neurotransmitter Ach

Synaptic vesicles
- fluid filled sacs that contain neurotransmitter Ach

Question 17

motor end plate - synaptic cleft

Answer 17

basal lamina

• contains acetylcholinesterase enzyme
• breaking down of Ach

Question 18

motor end plate - post-synaptic terminal

Answer 18

post-synaptic membrane
- dendritic/ gland/ muscle cells all facing pre-synaptic terminal

junctional folds
- large SA to bind neurotransmitter of Ach

nicotinic receptors
- bind to Ach for opening of channels

Question 19

motor end plate - mechanism

Answer 19

1 - ARRIVAL OF AP
- action potential travels along neurone down to axon
- reaches pre-synaptic terminal which releases Ach

2 - DEPOLARISATION
- Ach binds to nicotinic receptors
= open of voltage gated sodium ion channels = influx of na+ into muscle fibres = depolarisation = AP generation = muscle contraction

3 - TERMINATION
- Ach degraded by AchE in synaptic cleft
- signal terminated

Question 20

motor end plate - characteristics

Answer 20

1 - repair + regeneration possible
2 - adapts to increase in activity levels

Question 21

Secretion of transmitter by presynaptic varicosities

Answer 21

steps 1-7