L11- synaptic transmission

Question 1

how can APs be transmitted (between cells)

Answer 1

synapses

gap junctions

Question 2

explain the mechanism of synaptic transmissiom

Answer 2

1. depolarisation arrives at pre SM and causes opening of voltage gated Ca2+ channels
2. Ca2+ influx causes NT vesicles to fuse with pre S membrane
3. NT released into cleft and diffuses to post SM

Question 3

what are some structural features of a synapse

Answer 3

mitochondria
vesicles
channels

Question 4

what is an end plate potential

Answer 4

a sub threshold potential - no AP generated

Question 5

what happens to propagation of an end plate potential

Answer 5

decreases away from the site

Question 6

what is a MEPP and how can it lead to an AP

Answer 6

minature end plate potential

1. summation of MEPPs leads to end plate potential (EPSP)
2. several end plate potentials may reach threshold
3. threshold = AP

Question 7

explain knee jerk reflex

Answer 7

1. hit to tendon in knee causes stretch, which sends signal to CNS
2. sends EPSPs to extensor muscle
3. sends IPSPs to antagonist muscle (flexor)
4. knee jerks

Question 8

define EPSP

define IPSP

Answer 8

excitatory post synaptic potential

inhibitory post synaptic potential

Question 9

what do EPSPs do

Answer 9

add to generate depolarisation

Question 10

what do IPSPs do

Answer 10

add to generate repolarisation

Question 11

what do EPSPs and IPSPs do to eachother

Answer 11

cancel eachother out

Question 12

define temporal summation

Answer 12

several small potentials (EPSPs) arrive successively from one neuron and combine to produce (possible) AP

Question 13

define spacial summation

Answer 13

several EPSPs arrive from several different neurons (eg dendrites) to combine and produce (possible) AP

Question 14

what can cause inhibition of a neuron

Answer 14

opening cl- channels