Synpases

Question 1

where do chemical synapses occur?

Answer 1

between neurons, muscle cells and gland cells

Question 2

what is the first step in a chemical synapse?

Answer 2

AP depolarises presynaptic ending

Question 3

what is the second step in a chemical synapse?

Answer 3

influx of Ca2+ into presynaptic ending

Question 4

what is the third step in a chemical synapse?

Answer 4

vesicles migrate towards plasma membrane

Question 5

whats is the fourth step in a chemical synapse?

Answer 5

release of transmitter into cleft (exocytosis)

Question 6

what is the fifth step in a chemical synapse?

Answer 6

transmitter (Tx) diffuses in cleft

Question 7

what is the sixth step in a chemical synapse?

Answer 7

Tx binds to receptors on post-synaptic cell

Question 8

what is the seventh step in a chemical synapse?

Answer 8

changes in post-synaptic cell

Question 9

what is the eighth step in a chemical synapse?

Answer 9

inactivation of transmitter - reuptake into presynaptic cell and enzymic destruction

Question 10

name 3 amino acid derivatives transmitters

Answer 10

acetylcholine, dopamine, glycine

Question 11

name 3 peptide transmitters

Answer 11

vasoactive intestinal polypeptide, enkephalins, endorphins

Question 12

what are the effects of transmitters on post-synaptic cells determined by?

Answer 12

type of receptors and 2nd messengers in post-synaptic cell

Question 13

what happens when the cell is depolarised?

Answer 13

increased activity (excitatory)

Question 14

what happens when the cell is hyperpolarised?

Answer 14

decreased activity (inhibitory)

Question 15

what happens in an excitatory synapse?

Answer 15

transmitter causes depolarisation, excitatory post-synaptic potential, brings MP nearer to firing threshold

Question 16

what happens in an inhibitory synapse?

Answer 16

transmitter causes hyperpolarisation, inhibitory post-synaptic potential, takes MP further from firing threshold

Question 17

where do inputs synapse onto on the neuron?

Answer 17

cell body and dendrites

Question 18

comment on the effect of postsynaptic potentials on the MP of postsynaptic cells?

Answer 18

single ones have little effect on the MP of postsynaptic cells

Question 19

what do EPSPs do?

Answer 19

summate (add together)

Question 20

what happens if EPSPs and IPSPs summate?

Answer 20

they will tend to cancel each other out

Question 21

what is the condition for a post-synaptic cell to fire?

Answer 21

it must receive sufficient excitation to drive the MP beyond threshold

Question 22

when does the post-synaptic cell receive sufficient excitation?

Answer 22

when it receives many excitatory inputs (and few inhibitory inputs) within a short time period

Question 23

what is convergence?

Answer 23

each neuron receives many inputs from other cells

Question 24

what is divergence?

Answer 24

each neuron synapses with many other cells

Question 25

what do convergence and divergence produce?

Answer 25

a complex network of neurons

Question 26

when is the neuron more likely to fire?

Answer 26

if the excitatory inputs predominate the inhibitory inputs

Question 27

what is a neuromuscular junction?

Answer 27

synapse between a motor nerve and a muscle fibre

Question 28

comment on the area of contact on a neuromuscular junction

Answer 28

it is greater than in a nerve-nerve synapse

Question 29

what is the transmitter for a neuromuscular junction?

Answer 29

acetylcholine

Question 30

what is acetylcholine broken down by?

Answer 30

acetylcholinesterase

Question 31

what is the first event at a neuromuscular junction?

Answer 31

AP depolarises motor nerve ending

Question 32

what is the second event at a neuromuscular junction?

Answer 32

influx of Ca2+ into nerve ending

Question 33

what is the third event at a neuromuscular junction?

Answer 33

vesicles migrate towards plasma membrane

Question 34

what is the fourth step at a neuromuscular junction?

Answer 34

release of ACh into cleft (exocytosis)

Question 35

what is the fifth step in a neuromuscular junction?

Answer 35

ACh diffuses in cleft

Question 36

what is the sixth step in a neuromuscular junction?

Answer 36

ACh binds to receptors on post-synaptic cell

Question 37

what is the seventh step in a neuromuscular junction?

Answer 37

action potential in muscle cell causes contraction

Question 38

what is the eighth step in a neuromuscular junction?

Answer 38

ACh transmitter broke down by acetyl cholinesterase

Question 39

what is the ninth step in a neuromuscular junction?

Answer 39

choline and acetate taken up by the neuron

Question 40

what can synaptic activity be affected by?

Answer 40

drugs

Question 41

what do drugs do to the synapse?

Answer 41

enhance or suppress

Question 42

how do drugs block the synapse?

Answer 42

affecting synthesis/storage of Tx, release of Tx, action of Tx on receptor, second messenger system, inactivation of Tx

Question 43

what does botox do?

Answer 43

paralyse facial muscles to remove wrinkles

Question 44

how does botox work?

Answer 44

it prevents the release of transmitter from motor nerves