Electrophysiology

Question 1

Resting membrane potential

Answer 1

The electrical charge that a membrane has because it has separated ions. The outside of the membrane becomes more positive than the inside. Cells use IONS whereas batteries use electrons. Equilibrium, approximately -70 mVolt difference inside the cell than out for neurons

Question 2

Action potential

Answer 2

Traveling signals, rapid change in membrane potential and rapid change back. This rapid change overrides the usual graded potential and sends and electrical signal as a result of the overshoot. All or nothing

Question 3

Hypokalemia

Answer 3

decreased extracellular K+ which leads to more potassium separating from its paired anion and leaving the cell to comply with the concentration gradient. This leaves more anions in the cell and thus a more negative intracellular environment

Question 4

Hypokalemia

Answer 4

decreased extracellular K+ which leads to more potassium separating from its paired anion and leaving the cell to comply with the concentration gradient. This leaves more anions in the cell and thus a more negative intracellular environment

Question 5

cellular components for making electricity

Answer 5

Sodium/potassium pump, K+ leakage channel, gated Na voltage channel, K+ voltage gated channel, and negatively charged proteins

Question 6

electrochemical gradient

Answer 6

K+ ions are pumped into the cell due to the Na/K+ pump. The potassium then leaves the cell through the K+ leakage channel due to the concentration gradient. There is then a more negative charge inside the cell than outside because of negatively charged proteins and because the K+ ion left. This means that a K+ ion will enter the cell through to potassium leakage pump due to an electro-gradient difference. This state of K+ in= K+ out is equilibrium

Question 7

Na+ and K+ voltage-gated channels

Answer 7

Are closed at RMP rest, require excitatory stimuli to open such as touch. When stimuli happens, the external Na+ voltage-gate opens quickly and allows Na+ to rush into the cell. The external K+ voltage-gate opens more slowly and lets out only a few K+ ions. When a certain Na+ threshold is reached inside the cell, the internal Na+ voltage-gate closes while the K+ gate remains open. This allows the K+ to leave and the charges even out and get back to normal

Question 8

Equilibrium

Answer 8

when the pull from the electrostatic charge outweighs the pull from the concentration gradient and both forces become even. Ions may not be equal in concentration, but the forces between them even things out. Resting electrochemical gradient.

Question 9

Excitable cells

Answer 9

tissues that act in a unique and predictable way when stimulated. -50 mVolts to -85 mVolts. Neurons and skeletal muscle

Question 10

Leak channels

Answer 10

protein channels that are open all the time

Question 11

Polorized state

Answer 11

the state that the membrane is in at rest. The term polarized means that there is a charge difference between the intracellular and the extracellular. Otherwise known as the resting membrane potential. Inside of cell will be negative and outside will be positive

Question 12

Depolorization

Answer 12

change is membrane charge toward 0 mVolts. De = away from

Question 13

Repolorization

Answer 13

move back towards resting membrane potential

Question 14

Hyperpolorization

Answer 14

A change away from resting potential but in a more negative direction. Hyper = excessive

Question 15

graded potentials

Answer 15

the magnitude of the response is proportional to the strength of the stimuli. Result from mechanical or ligand gated channels opening. Can be compounded or on levels, thats why it’s graded. The number of channels open influences the speed of the repolarization. Only spreads over short distances. Like ripples in water, sometimes called local potential

Question 16

Refractory period

Answer 16

a time when a cell is incapable to repeating an action potential. The membrane is not ready to respond to the stimulus.

Question 17

Absolute refractory periods

Answer 17

depolarization and repolarization. Time when a second action potential cannot be initiated no matter how strong the stimuli

Question 18

relative refractory periods

Answer 18

hyper-polarization, time when a second action potential can be initiated but it requires a stronger stimulus

Question 19

Myelin

Answer 19

forms a sheath around neurons to protect against waves of depolarization. Depolarization only occurs on the nodes of Ranvier or the bare spots on the neurons. Because of this, action potentials can travel up to 10X faster than on un-myelinated neurons.

Question 20

Saltatory conduction

Answer 20

“jumping” of action potential to one node of Ranvier to the next