Membrane Potential & Action Potential ppt/pdf

Question 1

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Answer 1

RESTING MEMBRANE POTENTIAL

Question 2

Net result intracellular Na+ is maintained in?

Answer 2

CONSTANT AT A LOW LEVEL

Question 3

Na+ and K+ enters the cell by?

Answer 3

PASSIVE TRANSPORT

Question 4

Net result intracellular K+ is maintained in constant at a?

Answer 4

HIGH LEVEL

Question 5

Can cross the membranes of every living cell and each contribute to the RPM

Answer 5

Potassium, sodium and chloride

Question 6

Cell membrane of most living cells are much more permeable to __ than to any other ions

Answer 6

potassium ions

Question 9

It Describes the 💡Relation of Diffusion Potential to the Ion Concentration Difference Across a Membrane

Answer 9

NERNST EQUATION

Question 10

The 💡diffusion potential level across a membrane that exactly opposes the net diffusion of a particular ion through the membrane is called?

Answer 10

Nernst potential

Question 12

The most important 💡ions involved in the 💡development of membrane potentials in nerve and muscle fibers, as well as in the neuronal cells in the nervous system

Answer 12

SODIUM
POTASSIUM
CHLORIDE

Question 14

The quantitative importance of each of the ions in determining the voltage is ___ to the membrane permeability for that particular ion.

Answer 14

Proportional

Question 15

A (1)__ concentration gradient from inside the membrane to the outside causes (2)__ inside the membrane

Answer 15

(1) POSITIVE ION

(2) ELECTRONEGATIVITY

Question 16

The permeability of the (1)__ channels undergoes rapid changes during transmission of a nerve impulse, whereas the permeability of the (2)__ channels does not change greatly during this process

Answer 16

(1) SODIUM & POTASSIUM

(2) CHLORIDE

Question 17

The resting membrane potential of large nerve fibers when they are 💡not transmitting nerve signals is about __.

Answer 17

-90 millivolts

Question 18

If 💡potassium ions were the only factor causing the resting potential, the resting potential inside the fiber would be equal to

Answer 18

−94 millivolts

Question 19

Three conditions in the establishment  of  resting  membrane  potentials  in  nerve fibers:

💡💡
K
Na K
Na K Pump

Answer 19

1. When  the  membrane  potential  is caused  entirely  by  potassium  diffusion  alone
2. When  the  membrane potential  is  caused  by  diffusion  of  both  sodium  and  potassium  ions
3. When  the  membrane  potential  is  caused  by  diffusion  of  both sodium  and  potassium  ions  plus  pumping  of  both  these  ions  by  the Na+-K+  pump. 

Question 20

The  diffusion  potentials  alone  caused  by potassium  and  sodium  diffusion  would  give  a  membrane potential  of  about (1)\_\_,  with  almost  all  of  this being  determined  by  potassium  diffusion.  
An  additional (2)\_\_  is  then  contributed  to  the  membrane  potential  by  the  continuously  acting  electrogenic  Na+-K+  pump, giving  a  net  membrane  potential  of (3)\_\_.

Answer 20

(1) −86 millivolts
(2) −4 millivolts
(3) −90 millivolts

Question 21

When a membrane is permeable to several different ions, the diffusion potential that develops depends on three factors:

💡💡
Polarity
Permeability
Concentration

Answer 21

(1) The polarity of the electrical charge of each ion
(2) The permeability of the membrane (P) to each ion
(3) The concentrations (C) of the respective ions on the inside (i) and outside (o) of the membrane.

Question 22

-

Answer 22

STEADY STATE

Question 23

It is the 💡basis of ion movement across the plasma membrane

Answer 23

ELECTROCHEMICAL POTENTIAL

Question 26

The successive stages of the action potential are:

Answer 26

1. RESTING STAGE
2. DEPOLARIZATION STAGE
3. REPOLARIZATION STAGE

Question 27

It is the 💡value of membrane potential when all the permeable are all accounted

Represents the concentration inside and outside of the membrane

Used to calculate the 💡diffusion potential when the membrane is 💡permeable to different ions

Gives the 💡calculated membrane potential on the inside of the membrane when two univalent 💡positive ions, sodium (Na+) and potassium (K+), and one univalent 💡negative ion, chloride (Cl−), are involved.

Answer 27

GOLDMAN-HODGKIN KATZ EQUATION

Question 32

It is an ionotrophic channel which is necessary actor in 💡causing both depolarization and repolarization of the nerve membrane during the action potential

Answer 32

Voltage-gated sodium channel

Question 33

It is an ionotrophic cannel that plays an important role in 💡increasing the rapidity of repolarization of the membrane.

Answer 33

Voltage-gated potassium channel

Question 39

It is generated by ion gradients not directly by ion pumps

Answer 39

MEMBRANE POTENTIAL

Question 40

💡Transient change in the membrane potential characterized by a gradual 💡depolarization to threshold, a 💡rapid rising phase, an 💡overshoot, and a 💡repolarization followed by after 💡hyperpolarization (undershoot) before the membrane potential reaches resting level.

Nerve signals are transmitted by __, which are 💡rapid changes in the membrane potential that spread rapidly along the nerve fiber membrane.

It begins with a 💡sudden change from the normal resting negative membrane potential to a positive potential and ends with an almost equally rapid change back to the negative potential.

Answer 40

ACTION POTENTIAL

Question 41

If the duration of the stimulus is short, the intensity must be high

If the duration is long, a lower-intensity stimulus can trigger an action potential

Answer 41

STRENGTH DURATION CURVE

Question 42

A 💡second response is 💡not possible regardless of strength or duration of the stimulus

Time from the opening of the Na+ channels until the resetting of the channel

Ensures that each 💡AP is in all or none event

Enforces 💡one-way transmission of nerve impulses

Answer 42

ABSOLUTE REFRACTORY PERIODS

Question 43

Most Na+ channels have returned to their resting state.

Some K+ channels are still open

Repolarization is occurring

Threshold for AP generation is elevated

Exceptionally strong stimulus may generate an AP

Answer 43

RELATIVE REFRACTORY PERIOD

Question 45

It is the resting membrane potential 💡before the action potential begins

The membrane is said to be 💡“polarized” during this stage because of the 💡 −90 millivolts negative membrane potential that is present.

Answer 45

RESTING STAGE

Question 47

The membrane suddenly becomes 💡permeable to sodium ions, allowing tremendous numbers of positively charged sodium ions to diffuse to the interior of the axon.

Answer 47

DEPOLARIZATION

Question 48

After the membrane becomes highly permeable to sodium ions, the sodium channels begin to close and the 💡potassium channels open to a greater degree than normal.
Then, rapid diffusion of potassium ions to the exterior re-establishes the normal negative resting membrane potential.

Answer 48

REPOLARIZATION

Question 49

Na+ channel opens and is activated

Answer 49

THRESHOLD

Question 50

Undershoot

Answer 50

HYPERPOLARIZATION

Question 52

Amplitude:
Small Large

Intensity of stimulus:
Subthreshold Threshold/maximal

Summation:
Intensity dependent Intensity independent

All or none law:
None Present

Type of propagation:
Passive/non-propagated Active propagated

Answer 52

LOCAL POTENTIAL vs.

ACTION POTENTIAL