Neurophysiology

Question 1

Glial cells general function

Answer 1

Support cells of the nervous system

Question 2

Two subdivisions of glial cells

Answer 2

Macroglia and microglia

Question 3

Types of microglia (1)

Answer 3

Macrophages (garbage collectors of the nervous system)

Question 4

Types of macroglia (3)

Answer 4

Astrocytes, oligodendrocytes, Schwann cells

Question 5

Most abundant macroglia in the brain

Answer 5

Astrocytes

Question 6

Two major functions of astrocytes

Answer 6

1. Support neurons (nutritive - provide growth factors and nutrients to neurons and physical - physically contact the neurons and hold them in place)
2. Fundamental component of the blood brain barrier (filter blood vessel content and the brain tissue itself)

Question 7

Oligodendrocyte structure

Answer 7

Cell body in middle, projections wrap around the axons of neurons many times

Question 8

Oligodendrocyte function

Answer 8

Creates myelin sheath in the CNS to assist in conduction.

Question 9

Schwann cell structure

Answer 9

Cell body of the Schwann cell is contained within the myelin sheath, instead of being in the middle like oligodendrocytes
- 1 Schwann cell can only contact one axon

Question 10

Schwann cell function

Answer 10

Creates myelin sheath in the PNS to assist in conduction

Question 11

True or false: dendrites are the only region of input in the neuron

Answer 11

False, a neuron can also get input from the cell body or axon

Question 12

Soma/cell body function

Answer 12

Integration
- Takes vast input and converges the input in the cell body. The cell body then “decides” whether or not the info gets passed down the neuron.

Question 13

Most ions will be surrounded with a _____

Answer 13

Hydration shell

Question 14

What properties contribute to the membrane potential?

Answer 14

Properties of the membrane and hydration shells

Question 15

What is potential (voltage) in general terms?

Answer 15

Separation of electric charges

Question 16

Resting membrane potential is approximately what value?

Answer 16

-65 mV

Question 17

There is more Na+ on the (inside/outside) of the neuron

Answer 17

Outside

Question 18

There is more K+ on the (inside/outside) of the neuron

Answer 18

Inside

Question 19

What causes there to be so much Na+ on the outside of the cell and lots of K+ inside the cell?

Answer 19

The Na+/K+ ATPase

Question 20

How is the resting membrane potential negative if there’s so much K+ on the inside of the cell?

Answer 20

K+ leak channels in membrane allow K+ to diffuse down concentration gradient

Question 21

Neurons are more permeable to (Na+/K+) because…

Answer 21

Neurons are more permeable to potassium due to leak channels.

Question 22

If a neuron is less permeable to K+, what happens to resting potential?

Answer 22

Resting membrane potential becomes more positive (more K+ remains in the neuron, so less flows out)

Question 23

What is driving force?

Answer 23

The force generated from concentration differences.

Question 24

What’s the driving force for Na+?

Answer 24

The driving force is into the cell.

Question 25

What’s the driving force for K+?

Answer 25

The driving force is out of the cell.

Question 26

What is electromotive force based on?

Answer 26

Coulomb’s law

Question 27

What’s the electromotive force for Na+ at resting membrane potential?

Answer 27

Into the cell because Na+ is attracted to the negativity inside the cell.

Question 28

What’s the electromotive force for Na+ when the inside of the membrane is positive?

Answer 28

Out of the cell

Question 29

What’s the electromotive force for K+ at resting membrane potential?

Answer 29

Into the cell because K+ is attracted to the negativity inside the cell.

Question 30

What’s the electromotive force for Cl- at resting membrane potential?

Answer 30

Out of the cell because Cl- is repelled by the negativity inside the cell.

Question 31

Describe the movement of K+ across the membrane if this ion could free flow

Answer 31

As potassium moves down its concentration gradient (out of the neurron), the inside of the neuron gets more negative so the emf of K+ into the cell increases. K+ would then move out until the driving force and the emf are equal and opposite -> results in “equilibrium” aka “equilibrium potential” (net movement is 0).

Question 32

Describe the movement of Na+ across the membrane if this ion could free flow

Answer 32

As sodium moves down its concentration gradient (into the neuron), the inside of the neuron gets more positive so the the emf of Na+ out of the cell increases. Na+ would then move in until the driving force and the emf are equal and opposite -> results in “equilibrium” aka “equilibrium potential” (net movement is 0).

Question 33

What’s the only thing that can change equilibrium potentials of ions?

Answer 33

Changing the ion concentrations

Question 34

If there’s more Na+ on the outside of a cell, the cell membrane potential would…

Answer 34

Increase, because of an increased driving force (some Na+ would inevitably get in)

Question 35

If you add more K+ to the outside of the cell, the cell membrane potential would become…

Answer 35

More positive, because less ions flow out (smaller driving force).

Question 36

What does the Nernst equation show?

Answer 36

The relation between the concentration difference of a permeating ion across a membrane, and the membrane potential at equilibrium
- Only looking at one ion by itself
- The ion needs to be able to move across the membrane

Question 37

Nernst equation shortcut at 18 degrees

Answer 37

E(mV)= 58log(Cout/Cin)

Question 38

Nernst equation shortcut at 37 degrees

Answer 38

E(mV)=61log(Cout/Cin)

Question 39

Nernst equation shortcut at 18 degrees with Ca2+

Answer 39

E(mV)=29log(Cout/Cin)
- just 58/2

Question 40

Nernst equation shortcut at 37 degrees with Ca2+

Answer 40

E(mV)=30.5log(Cout/Cin)
- just 61/2

Question 41

Nernst equation for Cl-

Answer 41

E=Rt/zF ln (Cin/Cout)
- Cin and Cout is flipped

Question 42

What can the Goldman equation be used to find?

Answer 42

The overall cell membrane potential
- Includes all ions, and considers permeability

Question 43

Which ion has the greatest effect on overall cell membrane potential?

Answer 43

Potassium, because it has the greatest permeability
- Why resting potential is -65 mV and equilibrium potential of K+ is -75 mV

Question 44

What is the synaptic bouton?

Answer 44

Synapse

Question 45

More Cl- on the (inside/outside) of the cell

Answer 45

Outside

Question 46

Equilibrium potential is also known as what other two things?

Answer 46

1. Nernst potential
2. Reversal potential