A&P 2.15 Action Potential or Nerve Impulse

Question 0

Iliopsoas

A, I, O

Answer 0

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

Question 1

Iliopsoas

Answer 1

Two muscles

Iliacus And psoas major

Strongest hip flexor

Question 2

Iliacus

A, I, O

Answer 2

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

Question 3

Psoas major

A, I, O

Answer 3

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

Question 4

Ribs are what to the transverse processes they attach to

Answer 4

Anterior

Question 5

Lesser trochanter

Answer 5

Posterior medial

Inferior to the greater trochanter

Question 7

Ions

Answer 7

Electrically charged atoms or molecules

Positive or negatively charged

Question 8

Ions

Three states

Answer 8

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

Number of protons do not change

Question 9

Most plentiful outside cell ions

Answer 9

NA+ sodium

CL- chlorine

Question 10

Most plentiful ion intercellular

Answer 10

K+ potassium

Question 11

Membrane potential

Answer 11

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

Question 12

Resting membrane potential

Answer 12

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

-70 mV

Question 13

What can generate action potentials?

Answer 13

Only muscle cells and neurons can generate an action potential

Question 14

Action potential

Answer 14

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

Question 15

Sodium-potassium pump

Answer 15

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)

Question 16

Local potentials

Answer 16

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

Question 17

Excitation

Answer 17

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

Called depolarization

Question 18

Inhibition

Answer 18

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

Question 19

Action potential

Answer 19

The membrane potential of an active neuron while conducting an impulse

Question 20

Action potential

Answer 20

Same as spreading wave

Question 21

Refractory period

Answer 21

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)

Question 21

How do anesthetics affect pain?

Answer 21

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

Question 22

Action potential process

6 Steps

Answer 22

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

Question 23

Stimulus

Answer 23

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)

Question 24

Threshold potential reached

Answer 24

Membrane reaches -59 Mv

Voltage gated Na+ channels open

Question 25

Action potential peaks

Answer 25

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

Question 26

Repolarization

Answer 26

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

Question 27

Hyperpolarization

Answer 27

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

Question 28

Resting potential restored

Answer 28

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

Question 29

All or none phenomenon

Answer 29

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

Question 30

How does myelin affect conduction of the action potential

Answer 30

Myelinated greatly increases the speed due to nodes of Ranviea