Module 3: Lecture 6

Question 1

True or False
The synapses can be inhibitory or excitatory?

Answer 1

True

Question 2

What is an ionotropic receptor?

Answer 2

• the ion channels that use receptors to activate them in order for ions the freely pass through
• DIRECTLY affecting the cell membrane because they are directly an ion channel that opens up

ie. neurotransmitter’s bind to the channels to allows ions through

Question 3

What are metaoblotrophic receptors?

Answer 3

• these receptors respond to a neurotransmitter binding to them, although do different tasks
• Act INdirectly on an ion channel, because it can alter its excitability
• 2nd messangers or G protein

Question 4

Where can we find the ionotropic and metabotropic receptors?

Answer 4

on the sub synaptic membrane

Question 5

What is EPSP?

Answer 5

excitatory post-synaptic potential (graded potential)

Question 6

What is responsible for an EPSP?

Answer 6

sodium bringing more positive charge into the cell to get closer to the threshold potential

Question 7

One single EPSP from a single neuron is only going depolarize the cell by how much?

Answer 7

0.5 mV

Question 8

What is an IPSP

Answer 8

inhibitory post-synaptic potential

Question 9

What ions contribute to thE IPSP?

Answer 9

Potassium K+ and Chloride Cl-

Question 10

What is Chlorides rest concentration Intracellularly and Extracellularly?

Answer 10

Intracellularly = 7
Extracellularly = 100

Question 11

Which direction chemically would chloride want to move?

Answer 11

intracellularly, down the concentration gradient

Question 12

What is chlorides resting membrane potential?

Answer 12

-70 mV or so

Question 13

What are 2 ways the cell uses to transport chloride?

Answer 13

1. Active transport of Cl- into or out of the cell (requires ATP)

• Into the cell means more “-“ charge causing a hyper polarization
• Out of the cell mean more
  “+” charge causing a depolarization

*ONLY IN CELLS THAT CAN ACTIVELY TRANSPORT CHLORIDE

2. Passive transport of Cl-

• only moving depending on its equilibrium potential relative to membrane potential

Question 14

What is the point of chloride?

Answer 14

stabilizes membrane potential, to counter other ions channels

Question 15

What is 3 causes for synaptic delay?

Answer 15

1. Presynaptic neuron
   - electrical signal
2. Chemical conversion
   - neurotransmitter receptor combination
3. Post-synaptic neuron
   - electrical signal

Question 16

How long is a synaptic delay?

Answer 16

0.5 - 1 milisec for 1 synapse

Question 17

What are the 3 mechanism that nerves use to remove neurotransmitters from the synaptic cleft?

Answer 17

1. Actively uptake back to axon terminal (endocytosis and recycled)
2. Diffuse away from the receptors site and the synaptic cleft
3. Enzymatically degraded
   (enzymes from postsynaptic neuron that will physically degrade the neurotransmitters, then retaken to presynaptic neuron to be recycled)

Question 18

What does GPSP stand for?

Answer 18

Grand Post-Synaptic potential

Question 19

What is the Grand Post-Synaptic potential?

Answer 19

The sum of thousands of inputs to the post synaptic cell being either EPSP or IPSP

Question 20

What is temporal summation?

Answer 20

When the same neuron is activated twice, sending their EXCITATORY “signal” in a close enough time frame that they summate their EPSP’s on top of one another

ie. A+A

Question 21

What is spatial summation?

Answer 21

Having two different neurons firing their EXCITATORY “signals” in a close time frame

ie. A and B

Question 22

What is spatiotemporal summation?

Answer 22

the sum of temporal summation and spatial summation will dictate weather the threshold is met

*This can be excitatory and inhibitory signals together as well

Question 23

What is presynaptic inhibition/facilitation?

Answer 23

This is when there are pre synaptic neurons acting on other pre synaptic neurons not allowing for it’s signals to pass to the postsynaptic neuron

ie. GOAL TO ACTIVATE NEURON “C”
- neuron “A” and “D” are excitatory and are pre synaptic neurons trying to pass the signal along
- neuron “B” attached to neuron “A” rather than neuron “C”
- neuron “B” has inhibitory response therefore when attached to “A” counteracts it’s effects

Question 24

True or False
Presynaptic inhibition/facilitation will effect the amount of neurotransmitter that are released either increasing or decreasing them BEFORE the synapse occurs?

Answer 24

True