Lecture 3 - Basics of Neurophysiology I

Question 1

Ions

Answer 1

Imbalance of protons/electrons

High concentration of positive ions action potential

Question 2

What are neurons and the nervous system filled with

Answer 2

bathed in electrolyte, a fluid with high/different concentrations of ions

Question 3

What are the 4 ions

Answer 3

Potassium
Sodium
Chloride
Calcium

Question 4

Why do sodium channels open faster?

Answer 4

Sodium channels open faster because of there flaps meaning they can open/close faster. (Inactivated)

Question 5

Which ion is the only one with a heavy concentration intracellularly?

Answer 5

Potassium. All the other ins have a heavy concentration extracellularly.

Question 6

What is a current?

Answer 6

Flow of electricity and the rate it is flowing at past a point or region (water flowing under a bridge).

In terms of neurons a current results when ions flow through specialized pores in cell membrane

Question 7

what is voltage?

Answer 7

voltage is electrical potential difference between two points.

By controlling concentrations of ions on either side of cell membrane, neurons create EPD (sodium and potassium pump)

Question 8

How do neurons create voltage?

Answer 8

Voltage is created between intra and extracellular points by moving ions across the membrane (currents) through specialized pores (ion channels)

Question 9

what kind of membranes do neurons have

Answer 9

Phosphid bi-layer membranes. These membranes are impermable to water, ions and more.

Active transport, moves selected ions against concentration gradients.

Question 10

What kind of channels allow movment?

Answer 10

Transmembrane protein channels.

Ion channels allows ions to diffuse down concentration gradient. Uses charge to see which ions can come in

Question 11

States and Gates

Answer 11

States:
Sodium has three states: open, closed and inactive. Potassium only has open closed. This is what makes sodium gates faster

Gates: what causes the ion channels to change states in first place. this is due to change is membrane potential

Question 12

Ligand-Gated ion channels
(lock) (key)

Answer 12

Once the ion binds to the channel it opens up allowing for ions to flow in (Na) or out (K) out the neuron

Question 13

Gaba vs Glutamine

Answer 13

Gaba blows positive ions from entering, this is decreasing the firing rate (inhibitory neurotransmitter)

Glutamine allows for sodium to rush in and is most excited neurotransmitter by increasing firing rate.

Question 14

Thermally and Mechanical gates

Answer 14

thermal: ion channels open in response to hot/cold force. responds to heat and allows for sodium to enter as a response

mechanical: ion channels open when mechanical force opens it

Question 15

Electrostatic force (coulombs law)

Answer 15

Electrochemical diffusion. Opposites attract, same repels, closer the hard the force/pull is

Question 16

Molecular diffusion

Answer 16

Electrochemical diffusion .Outside the cell. Due to thermal motions of particles the dye becomes equally distrubted. as a result ions tend to move down the concentration gradient from a region of high to lower concentration

Question 17

What is the cell membrane capable of?

Answer 17

The cell membrane is capable of creating voltage between the inside and out of fluids.

Question 18

How is electrochemical equilibrium reached?

Answer 18

Forces of attraction must be equal and opposite to ion concentration

Question 19

What is equilibrium

Answer 19

when diffusion and force are equal

Question 20

What is action potential

Answer 20

the electrical potential difference across the plasma membrane