Volume 3 Chapter 2 Part 1

Innermost layer of the heart. Lines the chambers.

Heart muscle

• Protective sac surrounding the heart
• Consists of the epicardium (touches the heart) and
• Parietal pericardium (outer layer)
• Containts 25 mL fluid between them

• Control blood flow between atria and ventricles
• Right: tricuspid
• Left: mitral

• Regulate blood flow from ventricles and the arteries
• Aortic: left ventricle to aorta
• Pulmonic: right ventricle to pulmonary artery

Communication between two or more vessels

The period of time from the end of one cardiac contraction to the end of the next

The period of time when the myocardium is realxed and cardiac filling and coronary perfusion occur

The period of the cardiac cycle when the myocardium is contracting

Ratio of blood pumped from the ventricle to the amount remaining at the end of diastole

The amount of blood ejected by the heart in on cardiac contraction

The pressure within the ventricles at the end of diastole; commonly called the end-diastolic volume

Law of physiology stating that the more the myocardum is stretched, up to a certain amount, the more forcefull susbsequent contraction will be

The resistance against which the heart must pump

• Preload
• Cardiac contractility
• Afterload

The amount of blood pumped by the heart in one minute

Pertaining to heart rate

Pertaining to cardiac contractile force

Pertaining to the speed of impulse transmission

Specialized bands of tissue inserted between myocardial cells the increase rate in which the action potential is spread from cell to cell.

Group of cardiac muscle cells that physiologically function as a unit

A reversal of charges at a cell membrane so the the inside of the cell becomes positive relative to the outside; the opposite of the cell's resting state in theich the inside is negative in relation to the outside

The normal electrical state of cardiac cells

The stimulation of myocardial cells, as evidenced by a charge in the membrane electrical charge, that subsequently spreads across the myocardium

Return of a muscle cell to its preexcitation resting state

Ability of the cells to respond to an electrical stimulus

Ability of the cells to propagate the electrical impulse from one cell to another

Pacemaker cells' capability of self-depolarization

Ability of muscle cells to contract or shorten

• Bipolar (limb)
• Augmented (unipolar)
• Precordial

EKG leads applied to the arms and legs that contain two electrodes of opposite (positive and negative) polarity (leads I, II, III)

The triangle around the heart formed by the bipolar limb leads

EKG leads applied to the arms and legs, consisting of one positive electrode and a nonpolarized reference point that is created by the EKG machine combing two additional electrodes (aVR, aVL, aVF)

EKG leads applied to the chest in a pattern that permits a view of the horizontal plane of the heart (V1, V2, V3, V4, V5, V6)

• P wave
• QRS complex
• T wave
• U wave

• PR Interval: 0.12-0.20 seconds (3-5 small boxes)
• QRS Segment: 0.08-0.12 seconds (2-3 small boxes)
• QT Interval: 0.33-0.42 seconds

Period from the beginning of the QRS to the end of the T wave