Commonly Used Terms - Cardiac

Question 1

The neurotransmitter released from the parasympathetic nervous system.

Answer 1

ACh

Question 2

A decrease in potassium permeability that occurs when the electrical or chemical driving force on potassium is increased; inherent property of the cardiac cell membrane.

Answer 2

Anomalous (inward) rectification

Question 3

Disturbance in the normal electrical activity of the heart due to either abnormal impulse formation, impulse conduction, or both.

Answer 3

Arrhythmia (dysrhtmia)

Question 4

An intrinsic property of specialized cardiac cells to initiate their own electrical activity, i.e., pacemaker activity

Answer 4

Automaticity

Question 5

Heart rate of <60 beats/minute

Answer 5

Bradycardia

Question 6

Something that affects the pacemaker rate (frequency)

Answer 6

Chronotropic

Question 7

The spread of electrical activity from cell to cell in the heart

Answer 7

Conduction

Question 8

The speed with which conduction occurs; note that it is inversely related to conduction time

Answer 8

Conduction velocity

Question 9

A transient depolarization of the membrane following an AP; an abnromal form of electrical activity caused by abnormally high intracellular calcium

Answer 9

Delayed afterdepolarization (DAD)

Question 10

When the membrane potential becomes more positive than the resting membrane potential

Answer 10

Depolarization

Question 11

A slow depolarization of the membrane potential that is responsible for the automaticity of cardiac pacemaker cells

Answer 11

Diastolic depolarization (phase 4)

Question 12

Any cardiotonic steroid of glycoside that increases the contractile force of the myocardium (heart)

Answer 12

Digitalis

Question 13

A transient depolarization of the membrane during the later portion of the plateau phase or phase 3 repolarization of an action potential; abnormal electrical events that may underlie some types of prolonged Q-T syndrome and other dysrhythmias.

Answer 13

Early afterdepolarization (EAD)

Question 14

The period of time during an action potential when a stimulus (regardless of strength) cannot produce a regenerative action potential.

Answer 14

Effective refractory period (absolute refractory period)

Question 15

The electrical potential and concentration gradient acting on an ion to cross the membrane; these two factors influence the movement of ions across the membrane (ionic current flow).

Answer 15

Electrochemical force

Question 16

A theoretical value at which the concentration gradient and the electrical gradient acting on a single ion are balanced (calculated by the Nernst equation)

Answer 16

Equilibrium potential

Question 17

When the membrane potential becomes more negative than the resting membrane potential

Answer 17

Hyperpolarization

Question 18

Something that affects the contractility of muscular tissue

Answer 18

Inotropic

Question 19

Visualized as pores within the sarcolemma through which ions move into and out of a cell

Answer 19

Ion channels

Question 20

The flow of ions across the sarcolemmal membrane via ion channels; positive ions flowing into the cell represent inward current and positive ions flowing out of the cell represent outward current

Answer 20

Ionic current

Question 21

Reduced blood flow to a region of tissue or an entire organ, usually as a result of an obstruction, such as a narrowed artery (not synonymous with hypoxia - lack of oxygen)

Answer 21

Ischemia

Question 22

NT released from the sympathetic nervous system

Answer 22

NE

Question 23

When a pacemaker cell is electrically stimulated at a rate faster than its own intrinsic rate, stopping the stimulation results in a temporary suppression of pacemaker activity

Answer 23

Overdrive suppression

Question 24

The rate of voltage change during the action potential upstroke (NOT SPONTANEOUS RATE)

Answer 24

Rate of rise (dV/dt)

Question 25

An abnormal form of conduction in which an impulse will re-excite previously excited tissue, resulting in sustained repetitive activity

Answer 25

Re-entry of excitation

Question 26

The period of time during an AP when a stimulus can produce some type of regenerative AP

Answer 26

Relative refractory period

Question 27

When the membrane potential returns to more negative levels following a depolarization

Answer 27

Repolarization

Question 28

The electrical potential difference across a cell membrane; the inside being negative with respect to the outside positive

Answer 28

Resting membrane potential

Question 29

The plasma membrane of a muscle cell

Answer 29

Sarcolemma

Question 30

A protein within the sarcolemma which functions to remove sodium from the inside of the cell and to restore potassium to the inside of the cell; the movements are coupled and ATP is required.

Answer 30

Sodium-potassium pump

Question 31

A protein in the sarcolemma which extrudes intracellular calcium from the cell in exchange for extracellular sodium flowing down its concentration gradient into the cell; does not depend directly on metabolic energy

Answer 31

Sodium-calcium exchange

Question 32

The frequency (beats/minute) of pacemaker activity (NOT RATE OF RISE OR CONDUCTION VELOCITY)

Answer 32

Spontaneous rate

Question 33

Heart rate greater than 100 beats/minute

Answer 33

Tachycardia

Question 34

The membrane potential at which a regenerative action potential is produced; the value depends on the type of AP (slow vs. fast) as well as the ionic environment or presence of drugs

Answer 34

Threshold

Question 35

Abnormal form of pacemaker activity usually lasting a short time, resulting from DADs or EADs

Answer 35

Triggered activity