Resting Membrane Potential

Question 1

what is the cell membrane made out of?

Answer 1

phospholipid bilayer

Question 2

what does the cell membrane contain?

Answer 2

channel proteins, receptor proteins, and ion pumps/pump proteins

Question 3

what are channel proteins?

Answer 3

quaternary structures of proteins containing subunits that act as channels for the passage of select ions

Question 4

what are receptor proteins?

Answer 4

ionotropic-like receptors that bind to neurotransmitters, causing the release of something else within the cell

Question 5

what are ion pumps/pump proteins?

Answer 5

enzymes that use ATP to move ions across the membrane

Question 6

what is membrane potential?

Answer 6

difference in electrical charge between the inside and the outside of the cell, voltage

Question 7

what is current?

Answer 7

the rate of flow of ions

Question 8

what are the cations and anions that control current?

Answer 8

cations: sodium (Na+) and potassium (K+)
anions: chloride (Cl-) and proteins (A-, too large to cross membrane)

Question 9

what is membrane potential determined by?

Answer 9

differences in ion concentrations across the membrane (active transporters) and the membrane being selectively permeable to some ions (ions channels)

Question 10

what are the 7 components of the electrophysiology rig and what do they do?

Answer 10

faraday cage: blocks outside electric signals
air table: prevents vibrations
amplifier: compares signals of recording and reference electrode
oscilloscope/digitizer: visualizes the voltage
microscope/stereotax: allows you to visualize and move the electrode
microelectrodes: electrolyte filled micropipette that measures charge
reference (ground) electrode: records reference charge

Question 11

what are the three types of electrophysiology techniques?

Answer 11

extracellular recording, intracellular recording, and patch clamp recording

Question 12

ex vivo vs in vivo

Answer 12

ex vivo: tissue slices, cultured cells, or cell lines
in vivo: anesthetized or freely moving animals

Question 13

what is extracellular recording?

Answer 13

least sophisticated, measurements are taken away from the cell so that only the strongest signals (action potentials, uV) are recorded, single/multi unit recordings can be taken, the spike pattern of each cell can be analyzed in order to identify cell types, local field potentials are recorded to determine if a certain cell population is active or not

Question 14

what is intracellular recording?

Answer 14

more precise than extracellular, measures graded local potentials (IPSPs and EPSPs, mV), voltage clamp allows you to fix voltage and measure current, current clamp allows you to inject a current and measure the resulting membrane potential (voltage)

Question 15

what is patch clamp recording?

Answer 15

most advanced, measure channel dynamics and currents using a micropipette with electrodes in electrolyte solution; current or voltage clamp

Question 16

what are the four types of patch clamp recording?

Answer 16

cell attached recording, whole cell recording, inside-out recording, and outside-out recording

Question 17

what is cell attached recording?

Answer 17

uses mild suction to surround individual channel and record current and channel dynamics from that small patch of membrane

Question 18

what is whole cell recording?

Answer 18

uses strong suction to create a hole in the membrane that allows you to measure potentials/currents in the whole cell and inject chemicals

Question 19

what is inside-out recording?

Answer 19

uses suction to remove a channel from the membrane, allowing the cytoplasmic side to be manipulated, currents are then recorded from that channel to investigate how the manipulation can altered that channel

Question 20

what is outside-out recording?

Answer 20

suction is used to grab either side of the membrane surrounding a channel and flip the channel, allowing the external side of the channel to be manipulated, currents are then recorded from that channel to investigate how the manipulation has altered that channel

Question 21

what is in vivo microendoscopy?

Answer 21

a camera that films the inside of the brain in order to detect color changes that are caused when calcium is present (indicating the presence of an action potential)

Question 22

what is fiber photometry?

Answer 22

less sophisticated version of in vivo microendoscopy, a fiber is used to detect fluorescence by recording the amount of brightness emitted