Understanding Ekgs Chapter 3 Basic Electrophysiology

Front 1

myocardial working cells

Back 1

Responsible for generating the physical contraction of the heart muscle. When electrically stimulated they produce myocardial contraction.

Hint 1

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Front 2

What is the primary function of the myocardial working cells?

Back 2

Both contraction and relaxation.

Hint 2

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Front 3

specialized group

Back 3

Also known as specialized pacemaker cells are responsible for controlling the rate and rhythm of the heart by coordinating regular depolarization. These cells are found in the electrical conduction system of the heart.

Hint 3

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Front 4

What is the primary function of the specialized group cells?

Back 4

Conduction of electrical impulses.

Hint 4

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Front 5

Cardiac muscles function as...

Back 5

all-or-none principle.

Hint 5

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Front 6

threshold

Back 6

Refers to the point at which a stimulus will produce a cell response.

Hint 6

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Front 7

List the four primary cell characteristics:

Back 7

Excitability (or irritability), conductivity, contractility (or rhythmicity), and automaticity.

Hint 7

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Front 8

automaticity

Back 8

The ability of the cardiac pacemaker cells to generate their own electrical impulses spontaneously without external (or nervous) stimulation. Location is SA node, AV junction, and purkinje network fibers. Function is electrical.

Hint 8

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Front 9

excitability

Back 9

Or irritability is the ability of the cardiac cells to respond to an electrical stimulus. Location in all cells. Function is electrical.

Hint 9

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Front 10

conductivity

Back 10

The ability of cardiac cells to receive an electrical stimulus and then transmit it to other cardiac cells. Location is in all cardiac cells. Function is electrical.

Hint 10

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Front 11

Contractility

Back 11

Also known as rhythmicity, is the ability of cardiac cells to shorten and cause cardiac muscle contraction in response to an electrical stimulus. Producing regular heartbeat. Location myocardial muscle cells. Funciton is mechanical.

Hint 11

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Front 12

electrolyte

Back 12

A substance or compound whose molecules dissociate into charged components, or ions, when placed in water, producing positively and negatively ions.

Hint 12

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Front 13

An ion with a positive charge is called an _______, while an ion with negative charge is called an ______.

Back 13

cation
anion

Hint 13

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Front 14

What are the three primary cations that affect cardiac function?

Back 14

potassium (K), sodium (Na), and calcium (Ca). Magnesium (Mg) is also an important cation.

Hint 14

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Front 15

Postassium, magnesium, and calcium are _____________ cations whereas sodium is ____________ cation.

Back 15

intracellular
extracellular

Hint 15

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Front 16

Potassium plays major roles in...

Back 16

cardiac depolarization and repolarization.

Hint 16

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Front 17

hyperkalemia
hypokalemia

Back 17

high potassium
low potassium

Hint 17

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Front 18

Sodium plays a vital part in...

Back 18

depolarization of the myocardium.

Hint 18

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Front 19

hypernatremia
hyponatremia

Back 19

high sodium
low sodium

Hint 19

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Front 20

Calcium has an important function in...

Back 20

myocardial depolarization and myocardial contraction.

Hint 20

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Front 21

hypercalcemia
hypocalcemia

Back 21

high calcium
low calcium

Hint 21

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Front 22

movement of ion in a resting cardiac cell

Back 22

Potassium ion concentration is greater inside the cell than outside, sodium ion concentration is greater outside the cell than inside. Potassium ions can diffuse through the membrane more readily than sodium ions can. The inside of the cell is electrically negative in relative to the outside of the cell.

Hint 22

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Front 23

During resting period a ______________________ line is recorded on the EKG strip.

Back 23

baseline or isoelectric line

Hint 23

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Front 24

resting membrane potential

Back 24

State of a cardiac cell in which the inside of the cell membrane is negative compared with the outside of the cell membrane; exist when cardiac cells are in the resting state.

Hint 24

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Front 25

Action potential

Back 25

Change in polarity; a five phase cycle that produces changes in the cell membrane's electrical charge; caused by stimulation of myocardial cells which extends across the myocardium; propagated in an all-or-none fashion.

Hint 25

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Front 26

Syncytium

Back 26

Cardiac muscle cell groups that are connected together and function as a unit.

Hint 26

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Front 27

Polarized state

Back 27

Resting state or a cardiac cell, wherein the inside of the cell is electrically negative to the outside of the cell.

Hint 27

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Front 28

Depolarization

Back 28

Electrical occurrence normally expected to result in myocardial contraction; involves the movement of ions across cardiac cell membranes, resulting in positive polarity inside the cell membrane.

Hint 28

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Front 29

Repolarization

Back 29

Process whereby the depolarized cell is polarized and positive charges are again on the outside and negative charges on the inside of the cell; a return to the resting state.

Hint 29

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Front 30

Cardiac depolarization may be thought of as the period during which...

Back 30

sodium ions rush into the cell, changing the interior charge to positive, after a myocardial cell has been stimulated.

Hint 30

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Front 31

action potential

Back 31

change in polarity

Hint 31

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Front 32

During cardiac repolarization

Back 32

Sodium actively returns to the outside of the cell, and potassium returns to the inside of the cell. Takes place via the sodium and potassium pump.

Hint 32

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Front 33

Repolarization is _______ than depolarization.

Back 33

slower

Hint 33

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Front 34

refractory period

Back 34

Ensures that the muscle is totally relaxed before another action potential or depolarization can be initiated. The refractory of atrial muscle (~0.15 seconds) is much shorter than that of the ventricular muscle (~0.25-0.3 seconds). Thus the rate of atrial contractions can potentially be much faster than that of the ventricles.

Hint 34

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Front 35

absolute refractory period

Back 35

The stage of cell activity in which the cardiac cell cannot spontaneously depolarize. No stimulus can cause depolarization. From beginning of QRS to peak of T wave on EKG strip.

Hint 35

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Front 36

relative refractory period

Back 36

The period when repolarization is almost complete, and the cardiac cell can be stimulated to contract prematurely it the stimulus is much stronger than normal. The downslope of the T wave on EKG strip.
Also known as the vulnerable period of the cardiac cells during repolarization.

Hint 36

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