Electrical Signals of Nerve Cells

Question 1

Key objective of excitable tissues

Answer 1

transmit information over distances, for nerves, it is transmitting information over long distances

Question 2

Resting membrane potential

Answer 2

• occurs when an excitable cell like a neuron is not transmitting AP or any type of electrical signal
• membrane is said to be at rest
• this is also known as equilibrium (Nernst) potential

Question 3

Active transporters

Answer 3

• transmembrane proteins responsible for creating ion concentration gradient
• gradient is created using ATP

Question 4

Ion channels

Answer 4

• selectively permeable membrane protein channels that allow certain ions to diffuse down their concentration gradients

Question 5

Voltmeter

Answer 5

measured electrical potential

units are in volts (V)

Question 6

Electrochemical equilibrium potential

Answer 6

the point at which the electrical potential directly opposes and balances the concentration gradient, which prevents flux of ions between ICF and ECF

Question 7

What are the two ways to calculate membrane potential?

Answer 7

Nernst Equation and Goldman-Hodgkin-Katz (GHK) Equation

Question 8

Nernst Equation

Answer 8

allows one to predict the electrical membrane potential at equilibrium for systems with one permeant ion

Question 9

Goldman-Hodgkin-Katz (GHK) Equation

Answer 9

used to find the equilibrium potential when more than one ion is present

Question 10

Permeability

Answer 10

how easily an ion can cross the plasma membrane

Question 11

Depolarization

Answer 11

• positive changes in the resting membrane potential depolarize the neuron
• occurs due to the opening of certain ion channels (e.g., Na+)
• rising phase

Question 12

Threshold potential

Answer 12

level in which electrical signals must pass in order to generate an AP

Question 13

Overshoot phase

Answer 13

• peak potential
• permeability of sodium&raquo_space; permeability of potassium
• sodium channels open and close really quickly

Question 14

Repolarization

Answer 14

• sodium channels are closing
• permeability of sodium is decreasing and the permeability of potassium is increasing
• falling phase

Question 15

Hyperpolarization

Answer 15

• undershoot phase
• happens when neuron becomes slightly more negative than resting potential
• leaky channels are open at rest

Question 16

what are the three types of electrical signals

Answer 16

receptor potential, synaptic potential, and action potential

Question 17

Receptor potential

Answer 17

• occurs due to activation of sensory neurons by external stimuli
• input signal for sensory neurons
• are graded potentials
• magnitude of response is dependent on the number of responses activated

Question 18

Synaptic potential

Answer 18

• input signal for interneuron communication at synapses
• are graded potentials
• summation of postsynaptic potentials and previous synaptic activity determine the strength of the signal

Question 19

Action potential

Answer 19

• output signal for interneuron communication at synapses
• all-or-nothing principle
• stimulus intensity is therefore encoded in the frequency of AP

Question 20

Chemical force

Answer 20

determine the direction of the flow of ions based on concentrations of ions

Question 21

Electrical force

Answer 21

determine the direction of the flow of ions based on the direction of positively charged ions flowing down their electrical gradient