Module 3 - Bioelectricity

Question 1

Who is credited with the discovery of bioelectricity and when?

Answer 1

Luigi Galvani in 1700s

Question 2

Describe galvanization

Answer 2

Galvani applied electric current to dissected frog legs, causing them to twitch

Question 3

Describe the public experiment conducted by Giovanni Aldini (Galvani’s nephew).

Answer 3

Used body of executed prisoner
Minutes after execution, Aldini performed galvanization on the body, causing movements of the jaw, eyes, right hand and legs

Question 4

What is electrophysiology?

Answer 4

Use of equipment to study bioelectricity

Question 5

Who developed the differential rheotome?

Answer 5

Julius Bernstein in 1902

Question 6

What is the differential rheotome?

Answer 6

Instrument used to sample membrane voltage in microsecond scale

Question 7

What are the three general paradigms for electrophysiological recording?

Answer 7

Extracellular recording
Intracellular sharp electrodes
Whole-cell patch electrodes

Question 8

What is extracellular recording?

Answer 8

Records voltage/ion fluxes along the outside surface of a cell

Question 9

How many electrodes can be used in extracellular recording?

Answer 9

Single or multiple

Question 10

What are intracellular sharp electrodes?

Answer 10

Record voltage/ion fluxes across the cell membrane

Question 11

How many intracellular sharp electrodes can be used?

Answer 11

Single or double

Question 12

What are whole-cell patch electrodes?

Answer 12

Record voltage/ion fluxes across the cell membrane

Question 13

What is a benefit to whole-cell patch electrodes?

Answer 13

Large access into cell, allowing you to change the intracellular saline

Question 14

What did protein engineers combine to create GCaMP calcium indicators?

Answer 14

1. GFP
2. The Ca2+ sensor protein calmodulin (CaM)
3. The M13 alpha helix of the muscle protein myosin light chain kinase

Question 15

What happens to GCaMP when Ca2+ levels rise?

Answer 15

Increases fluorescence

Question 16

Describe how the GCaMP calcium indicator works.

Answer 16

APs cause Ca2+ influx
Ca2+ activates CaM
CaM binds the M13 helix
This pulls on the GFP protein, changing its structure
Increased GFP fluorescence

Question 17

What is current?

Answer 17

Movement of charged particles through a conductor/resistor

Question 18

What is the symbol for current?

Answer 18

I

Question 19

What are the units for currents?

Answer 19

Amperes (A)

Question 20

What are the charged particles that move through metal wires?

Answer 20

Electrons

Question 21

What are charged particles that move through aqueous solutions?

Answer 21

Cations and anions

Question 22

What unit are charges counted/measured in?

Answer 22

Coulombs (C)

Question 23

What is the energy for charge movement?

Answer 23

Voltage

Question 24

State Ohm’s Law and define the variables

Answer 24

I = V*G
I = current
V = electrical potential energy
G = conductance

Question 25

True or false, a conductor is also a resistor?

Answer 25

True

Question 26

What is the equation that shows the relationship between resistance and conductance?

Answer 26

G = 1/R

Question 27

Outline the relationship between a conductor and a resistor.

Answer 27

A good conductor (gold) makes a bad resistance A good resistor makes a bad conductor (rubber)

Question 28

State Ohm's law with resistance

Answer 28

I = V/R

Question 29

What happens when a voltage is applied across a conductor/resistor?

Answer 29

A current is produced

Question 30

Where does membrane voltage originate from in excitable cells?

Answer 30

From ion concentration gradients across the cell membrane

Question 31

What are the conductors/resistors in cells?

Answer 31

Ion channels across the cell membrane

Question 32

Is the cytoplasm a conductor?

Answer 32

Yes

Question 33

Define a capacitor.

Answer 33

A capacitor consists of two conductive plates separated by an insulator

Question 34

What is the capacitor of cells?

Answer 34

Cell membrane

Question 35

What are the two conductive plates of the cell's capacitor?

Answer 35

cytoplasmic and extracellular salines

Question 36

What is the insulator of the cell's capacitor?

Answer 36

phospholipid bilayer

Question 37

Why must the insulator of a capacitor be thin?

Answer 37

So the charges can "sense" each other across the plates.

Question 38

What happens at a capacitor when a voltage is applied?

Answer 38

Opposite charges accumulate along opposite plates A current results from the repulsion/attraction of ions across the membrane Applied charge accumulate until energy in capacitor matches the applied voltage

Question 39

How are capacitors different than batteries.

Answer 39

Capacitors can hold and applied voltage and thus act as a voltage source, but cannot generate voltages, only borrow

Question 40

Give the equation for the capacitance of a capacitor and define the variables.

Answer 40

C = q/V C = capacitance q = charge V = electrical potential energy

Question 41

What determines capacitance?

Answer 41

Properties of the insulator Conductive plates Surface area of capacitor