A&P 2.15 Action Potential or Nerve Impulse Flashcards Preview

A&P 2 > A&P 2.15 Action Potential or Nerve Impulse > Flashcards

Flashcards in A&P 2.15 Action Potential or Nerve Impulse Deck (31)
0

Iliopsoas

Two muscles

Iliacus And psoas major

Strongest hip flexor

1

Iliopsoas

A, I, O

A - hip flexion, major postural muscle

I - iliacus muscle and lesser trochanter

O - vertebral bodies, anterior discs of T12-L5 and TP of L1-L5, iliac fossa

2

Iliacus

A, I, O

A - origin fixed: flex the hip
Insertion fixed: flex the trunk toward the thigh

I - lesser trochanter

O - iliac fossa

Named for location: ilium, loin

3

Psoas major

A, I, O

A - origin fixed: flex the hip
Insertion fixed: flex trunk toward the thigh
Unilaterally- assist to laterally flex the lumbar spine

O - bodies of the transverse process of lumbar vertebrae

I - lesser trochanter

4

Ribs are what to the transverse processes they attach to

Anterior

5

Lesser trochanter

Posterior medial

Inferior to the greater trochanter

7

Ions

Electrically charged atoms or molecules

Positive or negatively charged

8

Ions

Three states

Neutral atoms - equal number of protons and electrons
Negative ions - have more electrons
Positive ions - have fewer electrons

Number of protons do not change

9

Most plentiful outside cell ions

NA+ sodium

CL- chlorine

10

Most plentiful ion intercellular

K+ potassium

11

Membrane potential

A difference in electrical charge across the plasma membrane caused by differing concentration of ions across a membrane

Called a potential because it is a type of stored energy called potential energy

Every cell in the body maintains a membrane potential

A membrane that exhibits a membrane potential is said to be polarized

12

Resting membrane potential

When a neuron is not conducting electrical signals is said to be "resting"

-70 mV

13

What can generate action potentials?

Only muscle cells and neurons can generate an action potential

14

Action potential

An impulse results when ions are allowed to move toward each other

15

Sodium-potassium pump



The mechanism in the plasma membrane actively pumps sodium ions (Na+) out of the neuron (cell) and potassium ions (K+) into the neuron at an unequal rate (3:2)

16

Local potentials

In neurons, membrane potentials can fluctuate above or below the resting membrane potential in response to certain stimuli

A slight shift away from resting membrane potential in a specific region of the plasma membrane is often called a local potential

17

Excitation

When any stimulus causes gates or channels to open and causes the RMP to reach -59 MV

Called depolarization

18

Inhibition

Movement of the membrane potential away from zero below usual RMP called hyperpolarization

19

Action potential

The membrane potential of an active neuron while conducting an impulse

20

Action potential

Same as spreading wave

21

Refractory period





A brief period during which a local area of an axon's membrane resists re-stimulation for about 1/2 millisecond after then membrane surpasses the threshold potential, IT WILL NOT RESPOND TO ANY STIMULUS NO MATTER HOW STRONG (absolute) or VERY STRONG (relative)

21

How do anesthetics affect pain?

Block ability of nerve potential to continue by binding to the postsynaptic nerve receptors

22

Action potential process

6 Steps

Stimulus
Threshold potential reached
Action potential peaks
Repolarization
Hyperpolarization
Resting potential restored

23

Stimulus

Anything that changes the resting membranes potential (-70 Mv)
Triggers stimulus gated Na+ channels to open
Allows Na+ inward diffusion

MEMBRANE DEPOLARIZES (Decreases from -70 Mv toward -59 Mv)

24

Threshold potential reached

Membrane reaches -59 Mv
Voltage gated Na+ channels open

25

Action potential peaks

More Na+ enters cell
Depolarization continues until +30 Mv
ACTION POTENTIAL PEAKS AT +30 Mv
Voltage gated Na+ channels close

26


Repolarization

Moving back toward resting membrane potential (-70 Mv)
Begins when voltage gated K+ channels open
Allows outward diffusion of K+

27


Hyperpolarization

K+ exits cell and moves toward resting membrane potential (-70 Mv)
Membrane potential increases beyond resting membrane potential to -100 Mv
HYPERPOLARIZATION ABOVE -70 Mv

28

Resting potential restored

Sodium-potassium pump activates to restore resting membrane potential (-70 Mv)
Decreases membrane potential from -100 Mv (hyperpolarization) to normal (-70 Mv)
Ion channels return to resting state

29

All or none phenomenon

Each action potential is all or nothing

If the threshold (-59 Mv) is surpassed, the full peak action potential is always reached

If threshold potential is not surpassed, no action potential will occur at all

30

How does myelin affect conduction of the action potential

Myelinated greatly increases the speed due to nodes of Ranviea