Basics of Neurophysiology

Question 1

Electrolyte

Answer 1

-fluid with a high concentration of ions

Question 2

Ions

Answer 2

-atomic particles that have an imbalance in their number of protons and electrons

Question 3

Which ion is most concentrated in the cell (intracellular)?

Answer 3

K+ (tends to want to flow outward)

Question 4

Which ions are heavily weighted to flow INTO the cell?

Answer 4

Na+, Cl-, Ca2+

Question 5

Electrical current

Answer 5

rate of flow of electric charge past a point/region

Question 6

Current (in neurons)

Answer 6

-ions flow through specialized pores in the cellular membrane

Question 7

Voltage

Answer 7

-electrical potential difference between two points/compartments

Question 8

How is an electrical potential difference used/created in neurons?

Answer 8

Sodium/potassium pumps control the concentrations of ions on either side of the membrane (more K+ in, more Na+ out)

Question 9

What is the membrane of a neuron made up of?

Answer 9

it’s a phospholipid bilayer

Question 10

What is the phospholipid bilayer impermeable to?

Answer 10

water, ions, other molecules

Question 11

How do ions move in/out of neuron?

Answer 11

transmembrane protein channels

Question 12

What are the three states a transmembrane protein channel can be in?

Answer 12

OPEN, CLOSED, INACTIVATED

Question 13

How do ligand-gated channels work?

Answer 13

-Open when they come in contact with a ligand (ion/compound)
-“lock and key”

Question 14

What effect would glutamate have on the channels?

Answer 14

EXCITATORY- would allow sodium to rush in (make membrane more positive)

Question 15

What effect would GABA have on the channels?

Answer 15

INHIBITORY- allow Cl- to rush in? (makes the membrane more negative)

Question 16

How do thermally gated ion channels work?

Answer 16

They open in response to hot/cold stimulus

Question 17

How do mechanically gated ion channels work?

Answer 17

They open in response to mechanical forces (pressure)

Question 18

Electrostatic force (Coulomb’s Law)

Answer 18

The force between two ions is related to the distance between them and the product of their charges

Question 19

Positive coulomb force

Answer 19

repulsion

Question 20

Negative coulomb force

Answer 20

attraction

Question 21

Molecular diffusion force

Answer 21

movement of particles down their concentration gradient until they are equally distributed throughout

Question 22

Define: electrochemical equilibrium

Answer 22

When electrostatic force is equal and opposite to the force of chemical diffusion

Question 23

Synonym for the inside of a cell

Answer 23

cytoplasm

Question 24

What is the Nernst equation used for?

Answer 24

Calculating the voltage at equilibrium when the membrane is permeable to just one type of ion

Question 25

What is the equilibrium potential of potassium?

Answer 25

Ek= -84mV

Question 26

What is the equilibrium potential for sodium?

Answer 26

ENa= 67mV

Question 27

What is the equilibrium potential for chloride?

Answer 27

ECl= -67mV

Question 28

What is the equilibrium potentials for calcium?

Answer 28

ECa= 116mV

Question 29

What the resting potential inside a neuron?

Answer 29

-65mV

Question 30

What two factors determine the resting potential of a neuron?

Answer 30

1) primarily permeable to K+ (leak channels)
2) K+ is more concentrated inside vs out

Question 31

What is the Goldman equation used for?

Answer 31

-calculating the resting membrane potential

Question 32

How does an action potential begin?

Answer 32

Small amount of Na+ enters the cell (making it more positive), which leads to more Na+ channels opening

Question 33

What happens simultaneously with the closing of Na+ channels?

Answer 33

K+ channels gradually (slowly) open

Question 34

What is unique about the K+ channels

Answer 34

They are slow to open/close

Question 35

The slow closure of K+ channels makes K+ more permeable than at rest, what does this lead to?

Answer 35

The voltage becomes more negative than at rest (hyperpolarization)