4B - Cardiac Cycle & 4C - Control Of Heart Rate

Front 1

Cardiomyocytes

Back 1

Striated muscle cells in the heart.

cardio = heart

myo = muscle

cyte = cell

Front 2

Intercalated Discs

Back 2

Where two cardiomyocytes meet; appear through the microscope as dark transverse lines, heavier than the striations.

Front 3

Desmosomes

Back 3

Help keep the cardiomyocytes from pulling apart when the myocardium contracts.

Front 4

Gap Junctions

Back 4

Allows ions to flow from one cell directly into the cytoplasm of the next, thus enabling electrical excitation to spread rapidly from cell to cell.

Front 5

Autorhythmic

Back 5

Beats at its own rhythm without need of stimuli from the nervous system.

Front 6

Cardiac Conduction System

Back 6

Formed by noncontractile cardiomyocytes and the sinoatrial and atrioventricular nodes.

Front 7

Sinoatrial (SA) Node

Back 7

This is the heart's pacemaker, a patch of cells in the right atrium near the superior vena cava.

Front 8

Internodal Conduction

Back 8

Signals from the SA node spread through both atria causing them to contract before the ventricles.

Front 9

Atrioventricular (AV) Node

Back 9

A patch of cells similar to the SA node but located in the interatrial septum just above the tricuspid valve. It acts as the gateway for all electrical signals headed for the ventricles.

Front 10

Atrioventricular (AV) Bundle

Back 10

Also called the bundle of His; this is a cord of modified cells that leaves the AV node and travels to the interventricular septum. In the septum, if forks into the right and left bundle branches.

Front 11

Right and Left Branches

Back 11

Originate from the AV bundle; they descend toward the apex of the heart.

Front 12

Purkinje Fibers

Back 12

Are large cells that arise from the bundle branches. They distribute excitation through ventricular myocardium.

Front 13

Electrocardiogram (ECG or EKG)

Back 13

A device that reads electrical currents generated by the depolarization and repolarization of the atrial and ventricular myocardium from electrodes on the skin.

electro = electricity

cardio = heart

gram = record of

Front 14

P Wave

Back 14

Reflects depolarization of the atria.

Front 15

QRS Complex

Back 15

Represents depolarization of the ventricles. It is the largest wave of the ECG.

Front 16

T Wave

Back 16

Represents ventricular repolarization.

Front 17

Cardiac Arrhythmia

Back 17

Any deviation from the normal heart rhythm.

Front 18

Atrial Flutter

Back 18

The most common form of cardiac arrhythmia. The atrial chambers show weak chaotic contractions at about 250 to 350 bpm.

Front 19

Ventricular Fibrillation (VF or V-Fib)

Back 19

The most serious ventricular arrhythmia. Uncoordinated squirming contraction of the ventricles often brought on by myocardial infarction (tissue death) or abusing drugs such as amphetamines.

Front 20

Defibrillator

Back 20

A device that sends a strong electrical shock to the heart to stop v-fib.

Front 21

Cardiac Cycle

Back 21

Consists of one complete contraction and relaxation of all four heart chambers, encompassing events from the beginning of one heartbeat to the beginning of the next.

Front 22

Systole

Back 22

Any chamber is said to be _______ when it is contracting.

Front 23

Diastole

Back 23

Any chamber is said to be _______ when it is relaxed.

Front 24

First Heart Sound (S1)

Back 24

When the blood surges against the AV valves and forces them shut; the surge against this obstacle creates a vibration heard with a stethoscope as the ________. (three words)

Front 25

Stroke Volume (SV)

Back 25

The volume of blood ejected by one ventricle of the heart in one contraction.

Front 26

Second Heart Sound (S2)

Back 26

The surge of aortic and pulmonary blood against the closed valves creates another bump, heard as the _______. (three words)

Front 27

Auscultation

Back 27

Listening to the sounds the body makes.

Front 28

Heart Murmurs

Back 28

Whooshing or swishing sounds that are not part of the "lubb-dubb" sounds.

Front 29

Cardiac Output

Back 29

The volume of blood ejected by each ventricle per minute (mL/min.).

Stroke Volume (mL/beat) x Heart Rate (beats/min.) = _______