L03

Question 1

Who won the Nobel prize in 1906 for their work on the structure of the nervous system?

Answer 1

Camillo Golgi and Santiago Ramon y Cajal.
Their work was made possible by the discovery of the Golgi stain that causes 2% of brain cells to darken in color.

Question 2

What is the Golgi stain mixture made of?

Answer 2

Silver nitrate and potassium chromate

Question 3

What is it that creates the Golgi stain?

Answer 3

The silver chromate that crystallizes inside of the brain cells

Question 4

What is electrostatic pressure?

Answer 4

The attractive force between molecules that are oppositely charged (i.e., positive and negative) or repulsive force between molecules that are similar charged (e.g., positive and positive)

Question 5

What are ion channels?

Answer 5

Specialized protein molecules (receptors) that sit in the cell membrane. They have a pore (hole) in them through which specific ions can enter or leave cells.

Question 6

What are leak channels?

Answer 6

An ion channel protein that is in the membrane and has a pore that is always open (e.g., potassium leak channel).

Question 7

Neurons sit in and are full of _____ _____.

Answer 7

salt water

Question 8

What are the 2 proteins that are responsible for setting up and maintaining the resting membrane potential?

Answer 8

Sodium-Potassium transporters and the leak channels (potassium)

Question 9

What is the function of the sodium-potassium transporter?

Answer 9

It is to pump Na+ atoms out of the cells and K+ atoms in.

Question 10

What is diffusion?

Answer 10

If there is a concentration gradient and no forces or barriers to prevent free movement of molecules, then
molecules will move, on average, from regions of high concentration to regions of low concentration.

Question 11

What is a membrane potential?

Answer 11

Electrical charge across a cell membrane; difference in electrical potential inside and outside the cell.

Question 12

What is the resting potential?

Answer 12

Membrane potential of a neuron when it is not being altered by signaling molecules that cause excitatory or inhibitory postsynaptic potentials

Question 13

What is the range of the resting membrane potential?

Answer 13

At rest, the membrane potential ranges between -40 and -90 mV across different types of neurons

Question 14

What are receptors?

Answer 14

Proteins that act as sensors and that are specific to specific features of the extracellular environment.

Question 15

What stimuli can receptor proteins detect in the external world?

Answer 15

1. The presence of certain molecules (ex: neurotransmitters)
2. Physical pressure (movement, touch)
3. Electrical pressure (voltage)
4. Temperature
5. pH
6. Electromagnetic radiation (light)

Question 16

Are ion channels receptors?

Answer 16

Yes

Question 17

What is depolarization?

Answer 17

When the membrane potential of a cell becomes less negative than it normally is at rest.

Question 18

What 3 proteins are involved in the action potential?

Answer 18

1. Voltage-gated sodium channels
2. Voltage-gated potassium channels
3. Voltage-gated calcium channels

Question 19

Voltage-gated channels have _____ _____ on their doors, such that they open or close when the charge difference across the membrane is greater or smaller than some number.

Answer 19

electrical charges

Question 20

What is the action potential?

Answer 20

A brief electrical impulse that provides the basis for conduction of information along the axon. It is a rapid change in the membrane potential caused by the opening and closing of voltage-gated ion channels.

Question 21

What do we call the value of the membrane potential that must be reached to produce an action potential?

Answer 21

The threshold of excitation

Question 22

Once the voltage-gated Na+ channels are open, how long does it take them to close again (get inactivated)?

Answer 22

1 ms

Question 23

What is hard to do during the refractory period?

Answer 23

Trigger another action potential

Question 24

When do voltage-gated calcium channels open?

Answer 24

When the axon terminal becomes depolarized

Question 25

Is calcium more concentrated inside the cell or outside?

Answer 25

Outside the cell (1000x more concentrated)

Question 26

What is the primary mean of communication between neurons?

Answer 26

Synaptic transmission

Question 27

What is synaptic transmission?

Answer 27

The transmission of messages from one neuron to another via the presynaptic release of a chemical (neurotransmitter) that crosses the synapse and binds to receptors located on the post-synaptic membrane

Question 28

What does the all-or-none law state?

Answer 28

That the action potential occurs or does not occur, and once triggered, will propagate down the axon without growing or diminishing in size, to the end of the axon.

Question 29

Is the conduction of an action potential bidirectionnal or unidirectionnal?

Answer 29

Unidirectionnal

Question 30

What do we call the movement of the information along the axon?

Answer 30

The conduction of the action potential

Question 31

What does the rate law state?

Answer 31

That the strength of the stimulus is represented by the rate of the firing axon.

Question 32

Does the size of the action potential remain constant or is it inconstant?

Answer 32

It remains constant