Lesson 3 - Synaptic Transmission

Question 1

What do neurons transmit

Answer 1

• Electrical impulses
-action potentials

• Between pre-synaptic neuron
-neuron transferring action potential

• And post-synaptic neuron
-neuron receiving action potential

Question 2

What is released when action potential reaches pre-synaptic terminal

Answer 2

• Neurotransmitters
• From sacs on pre-synaptic membrane
• vesicles
• during exocytosis

Question 3

What does the neurotransmitter do

Answer 3

• Diffuse across synaptic cleft
-physical gap between pre-synaptic membrane & post-synaptic membrane)

• Binds to specialised post-synaptic receptor sites

Question 4

How long is synaptic transmission

Answer 4

• Fraction of a second

-effects terminated by re-uptake

Question 5

What is re-uptake

Answer 5

• Neurotransmitter taken back by vesicles on pre-synaptic neuron
• Stored for later release
• Quicker neurotransmitter taken back = shorter the effects

Question 6

What are excitatory neurotransmitters

Answer 6

• Cause electrical charge in membrane of post-synaptic neuron
• Resulting in excitatory post-synaptic potential (EPSP)

Question 7

What are inhibitory neurotransmitters

Answer 7

• Cause inhibitory post-synaptic potential (IPSP)

Question 8

Are excitatory or inhibitory neurotransmitters more likely to fire an impulse

Answer 8

Excitatory

• Post-synaptic neuron more likely to fire impulse

Question 9

What determines the chance of a neuron firing an impulse when it receives EPSPs and IPSPs at the same time

Answer 9

Summation
-net result of adding up excitatory and inhibitory synaptic input

-If net effect is inhibitory then no fire & vice versa

Question 10

Which way does synaptic transmission occur

Answer 10

• Pre-synaptic to post-synaptic

• Vesicles only present in pre-synaptic membrane
-Receptors only present in post

Question 11

What is a vesicle

Answer 11

Sac-like structures in neurons that store neurotransmitter molecules before releasing them into synapse

Question 12

What causes the information to be transmitted to the next neuron

Answer 12

Binding of neurotransmitter to receptor

Question 13

Why does synaptic transmission occur from pre to post

Answer 13

Diffusion of neurotransmitters mean they can only go from high to low concentration

Question 14

What are psychoactive drugs

-what is an example

Answer 14

Medication that affects brain function to alter alter perception, mood, or behaviour
-SSRIs

Question 15

How do SSRIs work

Answer 15

Affecting transmission of neurotransmitters across synapse

Question 16

Why do some pain meds mimic the effects of inhibitory neurotransmitters
(1/3)

Answer 16

Stimulation of postsynaptic receptors by inhibitory neurotransmitter result in inhibition of postsynaptic membrane

Question 17

What happens when an inhibitory neurotransmitter binds to the post-synaptic receptors
(2/3)

Answer 17

Makes the post-synaptic neuron less likely to fire

Question 18

(3/3)

Answer 18

• Due to summation action potential is prevented

• Therefore pain meds would decrease overall activity
- & reduced brain activity may lead to less pain