Chapter 4 - Week 3

Question 1

What is the membrane potential?

Answer 1

The difference in electrical charge between the inside and outside of a cell.

Question 2

What is a neuron’s resting potential?

Answer 2

Around -70 mV

Question 3

What is the abbreviation for sodium ions?

Answer 3

Na+

Question 4

What is the abbreviation for potassium ions?

Answer 4

K+

Question 5

What do the plus signs indicate in the abbreviation of neurons?

Answer 5

That it carries a single, positive charge.

Question 6

Describe the ions when the neurons are at resting potential.

Answer 6

There are more Na+ (sodium) ions outside the cell than inside and more K+ (potatssium) ions inside than outside.

Question 7

At resting potential, describe what push Na+ ions to enter the neuron.

Answer 7

1. Electrostatic pressure (because opposite charges attract, the negative 70 mV charge attracts the Na+ postitive charge) and
2. pressure from random motion pressure for Na+ ions to move down their concentration gradient.

Question 8

What are the two effects that neurotransmitter molecules have when they bind to postsynaptic receptors?

Answer 8

1. Either depolarize (decrease the resting potential) or

2. Hyperpolarise it (increase the resting membrane potential from -70mV to -72 for example)

Question 9

What is the threshold of excitation that causes an action potential to fire?

Answer 9

Around -65 mV.

Question 10

How long does an action potential last?

Answer 10

1 millisecond

Question 11

Before an action potential is fired, positive and negative neurons are added to the “membrane sum”. They might add together making a greater charge, or cancel each other out. What is this called

Answer 11

Integration.

Question 12

Substance nigra produces a substance called what?

Answer 12

Dopamine

Question 13

The difference in electrical charge between the inside and the outside of a cell is called the what?

Answer 13

Membrane potential.

Question 14

When a neuron is in its resting state, there is a greater concentration of what ions outside the neuron?

Answer 14

Sodium.

Question 15

The ‘what’ channels are open during a neurons resting potential?

Answer 15

Potassium

Question 16

Ions pass through neural membranes via specialised pores called what?

Answer 16

ion channels

Question 17

The firing of neurons releases chemicals at their button terminals called what?

Answer 17

neurotransmitters

Question 18

Neurotransmitters typically have one of two effects on postsynaptic neurons. They either depolarise them or what?

Answer 18

hyperpolarise

Question 19

What is the sum of the postsynaptic potentials produces in rapid succession at the same synapse to form a greater signal called?

Answer 19

temporal summation

Question 20

An action potential is elicited when the depolarisation of the neuron reaches the what?

Answer 20

threshold of excitation

Question 21

Neurons integrate postsynaptic potentials in two ways: through spatial summation and through what other summation?

Answer 21

temporal

Question 22

What is the period called after the absolute refractory period, wherein it is possible to fire the neuron again but only in higher than normal levels of stimulation?

Answer 22

The relative refractory period.

Question 23

What are the four steps of an action potential?

Answer 23

1. Sodium channels open and sodium rushes in
2. potassium channels open and potassium flows out
3. At peak, sodium channels close
4. At the end, potassium channels start to close.

Question 24

In myelinated axons, where is the only place that ions can pass through?

Answer 24

At the nodes of ranvier

Question 25

The Hodgkin- Huxley model gives a supposedly factual account of neural conduction and its mechanisms. What was the problem with this theory?

Answer 25

The neurons and mechanisms are not representative of the variety, complexity and plasticity of many of the neurons in the mammalian brain

Question 26

What does exocytosis mean?

Answer 26

The process of neurotransmitter release.

Question 27

What is reuptake?

Answer 27

Once released, the neurotransmitters are drawn back into the presynaptic buttons by transporter mechanisms.

Question 28

What are the four most studied amino acid neurotransmitters called?

Answer 28

1. glutamate
2. GABA
3. aspartate
4. glycine

Question 29

What is the most prevalent excitatory neurotransmitter in the mammalian central nervous system?

Answer 29

Glutamate

Question 30

Which is the most prevalent inhibitory neurotransmitter?

Answer 30

GABA

Question 31

What are the four monoamine neurotransmitters?

Answer 31

1. dopamine
2. epinephrine
3. norepinephrine
4. serotonin

Question 32

What are the four groups of small-molecule neurotransmitters?

Answer 32

1, amino acids

2. monoamines
3. acetylcholine
4. unconventional neurotransmitters

Question 33

Drugs that facilitate the effects of a particular neurotransmitter are said to be what of that neurotransmitter?

Answer 33

agonists

Question 34

What are the drugs that inhibit the effects of a particular neurotransmitter called?

Answer 34

antagonists

Question 35

How does botox work?

Answer 35

It blocks the release of acetylcholine at neuromuscular junctions