Synapse

Question 1

What 3 factors determine the electrical activity of the cell?

Answer 1

1. How well ions move across the membrane
2. Gradients
3. When the ions move

Question 2

Which ion is the membrane more permeable too?

Answer 2

Potassium (rather than sodium)

Question 3

What are the 2 gradients that influence ion movement?

Answer 3

• Concentration

- Electrical

Question 4

Why is a neuron negatively charged at rest?

Answer 4

There is more negative ions inside the cell than outside

Question 5

Where are neurotransmitters stored?

Answer 5

In the presynaptic terminal

Question 6

What happens to the equilibrium when the neuron is stimulated?

Answer 6

The equilibrium is upset and if the excitatory stimulation is large enough (above 50mV), the resting potential becomes an action potential

Question 7

What happens when an AP reaches the presynaptic terminal?

Answer 7

A chemical (neurotransmitter) is released into the junction between the neurons

Question 8

How is the synapse formed?

Answer 8

The termination of an axon from one neuron onto the dendrite of another neuron

Question 9

Where do most synapses occur?

Answer 9

Between neurons (that result in neuron becoming excited or inhibited)

Question 10

What is the area between neurons and muscles?

Answer 10

Neuro-muscular junction

Question 11

What is the function of synapses at the neuromuscular junction?

Answer 11

Cause muscles to contract and allow us to move

Question 12

Where are the axons from neurons that activate muscles located?

Answer 12

In the spinal chord

Question 13

What is the disease that effects neurons that activate muscles?

Answer 13

ALS

- gradually restricts movement

Question 14

Where are neurotransmitters made?

Answer 14

Cell body

Question 15

Where are neurotransmitters packaged?

Answer 15

Vesicles

Question 16

When do vesicles release their contents?

Answer 16

When AP reaches those vesicles (dormant until then)

Question 17

What type of ion channels open at the synapse?

Answer 17

Calcium (Ca++)

Question 18

Where does the incoming Ca++ bind to?

Answer 18

Binds to the synaptic vesicles, causing them to release their neurotransmitters into the synapse

Question 19

What do the neurotransmitters bind to once they are released?

Answer 19

They bind to receptor sites that then become activated

Question 20

How does habituation/adaptation occur e.g. n sea snails that begin to withdraw their gills less in a defensive manner when confronted with water?

Answer 20

This process can result from a reduction in the influx of calcium at the axon’s pre-synaptic terminal and the release of less neurotransmitter

Question 21

What are neurotransmitter receptors?

Answer 21

Proteins that are found on dendrites

Question 22

What are ionotropic neurotransmitter receptors composed of?

Answer 22

1) Binds neurotransmitter

2) Ion channels

Question 23

What happens when a neurotransmitter binds to a receptor?

Answer 23

The ion channel opens, allowing ions into the cell

Question 24

How to metabotropic neurotransmitter receptor influence ion channels indirectly?

Answer 24

When a neurotransmitter binds to a binding site, a subunit detaches and causes the ion channel to open allowing ions to pass through

Question 25

What are EN’s?

Answer 25

• Released at type 1 synapses and bind to receptors that cause an influx of positive ions (Na +)
• Makes post-synaptic cell more likely to fire

Question 26

What are IN’s?

Answer 26

• Released at type 2 synapses and cause an influx of negative ions (Cl-)
• Less likely to fire

Question 27

Why do neurotransmitters need to be removed/inactivated following release?

Answer 27

Otherwise they would keep on stimulating (prolonged activation)

Question 28

What does mustard gas do?

Answer 28

Prevents the deactivation of acetylcholine

Question 29

What is glutamate?

Answer 29

Brains major excitatory neurotransmitter

- vital in forming links between neurons that are the basis of learning and memory

Question 30

What is GABA?

Answer 30

Brains main inhibitory neurotransmitter

Question 31

What is dopamine?

Answer 31

Involved in reward control and in reward circuits

Question 32

What is serotonin?

Answer 32

Profound effect on mood/anxiety

Question 33

What is acetylcholine?

Answer 33

Neurotransmitter used at the neuro-muscular junction

Question 34

What is schizophrenia thought to be caused by?

Answer 34

Overactivity of the dopaminergic pathways

Question 35

What is tetrodotoxin?

Answer 35

A venom that targets and deactivates ion channels

- produces a potent inactivation of Na+ channels, paralysing animals who eat it

Question 36

How does the tetanus toxin work?

Answer 36

By preventing inhibitory neurotransmitters to be released in the spinal chord
- causes hyperactivity of the muscles

Question 37

What do psychoactive drugs do?

Answer 37

Mimic the effect of neurotransmitters by binding directly to neurotransmitter receptors

Question 38

How does alcohol have a sedative-like effect?

Answer 38

Stimulates GABA receptors, increasing the increasing the effect of this inhibitory neurotransmitter leading to a sedative effect

Question 39

How does cocaine affect neurotransmitters?

Answer 39

It prevents the reuptake of dopamine, which prolongs the effect of dopamine when it is released = feeling of arousal/euphoria

Question 40

Why is there an association between drug taking and reward circuits in the brain?

Answer 40

Many highly addictive drugs activate the ‘reward system’ circuit in the brain