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18 Cards in this Set

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action potential
The conduction system is specialized nerve tissue responsible for creating and transporting the electrical impulse, or action potential. This impulse initiates depolarization and subsequently cardiac contraction (Fig. 32-4, A). The electrical impulse is initiated by the sinoatrial (SA) node (the pacemaker of the heart). Each impulse generated at the SA node travels through intraatrial pathways to depolarize the atria resulting in a contraction.
afterload
Afterload is the peripheral resistance against which the left ventricle must pump. Afterload is affected by the size of the ventricle, wall tension, and arterial blood pressure.2 If the arterial blood pressure is elevated, the ventricles will meet increased resistance to ejection of blood, increasing the work demand. Eventually this results in ventricular hypertrophy, an enlargement of the cardiac muscle tissue without an increase in CO or the size of chambers.
arterial blood pressure
The arterial blood pressure (BP) is a measure of the pressure exerted by blood against the walls of the arterial system.
cardiac index
a measure of the cardiac output of a patient per square meter of body surface area
Cardiac index (CI) is the CO divided by the body surface area (BSA). The CI adjusts the CO to the body size. The normal CI is 2.8 to 4.2 L per minute per meter squared (L/min/m2).
cardiac output
the amount of blood pumped by each ventricle in 1 minute
Cardiac output (CO) is the amount of blood pumped by each ventricle in 1 minute. It is calculated by multiplying the amount of blood ejected from the ventricle with each heartbeat, the stroke volume (SV), by the heart rate (HR) per minute:

CO = SV × HR

For the normal adult at rest, CO is maintained in the range of 4 to 8 L/min.
cardiac reserve
the ability to respond to demands (exercise, stress, hypovolemia) by altering cardiac output threefold or fourfold
The cardiovascular system must respond to numerous situations in health and illness (e.g., exercise, stress, hypovolemia). The ability to respond to these demands by altering CO threefold or fourfold is termed cardiac reserve.
diastole
the period between contractions of the atria or the ventricles during which blood enters the relaxed chambers from the systemic circulation and the lungs. Ventricular diastole begins with the onset of the second heart sound and ends with the first heart sound.
diastolic blood pressure
The diastolic blood pressure (DBP) is the residual pressure in the arterial system during ventricular relaxation (or filling). BP is usually expressed as the ratio of systolic to diastolic pressure.
the residual pressure of the arterial system during ventricular relaxation.
ejection fraction
The ejection fraction (EF) or the percentage of end-diastolic blood volume that is ejected during systole can also be measured. The EF provides information about the function of the left ventricle during systole.
percentage of end-diastolic blood volume that is ejected during systole
heaves
a chronic pulmonary disease, similar to human pulmonary emphysema, characterized by wheezing, coughing, and dyspnea on exertion. The cause of the condition is unknown.

2. informal. vomiting and retching.
Korotkoff sounds
sounds heard during the taking of a blood pressure reading using a sphygmomanometer and stethoscope
mean arterial pressure
Another measurement related to BP is mean arterial pressure (MAP). The MAP refers to the average pressure within the arterial system that is felt by organs in the body. It is not the average of the diastolic and systolic pressures because the duration of diastole exceeds that of systole at normal HRs.2 MAP is calculated as follows:

MAP=(SBP+2DBP)÷3

A person with a BP of 120/60 mm Hg has an estimated MAP of 80 mm Hg. In patients with invasive BP monitoring, this value is automatically calculated and takes the patient's HR into consideration (see Chapter 66).

An MAP greater than 60 mm Hg is needed to adequately perfuse and sustain the vital organs of an average person under most conditions. If the MAP falls significantly below this number for an appreciable time, vital organs will be underperfused and will become ischemic.
murmur
a gentle blowing, fluttering, or humming sound heard on auscultation and produced by turbulent blood flow through the heart or the walls of large arteries.
point of maximal impulse
the site on the chest wall where the thrust or pulsation of the left ventricle is most prominent
preload
the volume of blood in the ventricles at the end of diastole before the next contraction
pulse pressure
Pulse pressure is the difference between the SBP and DBP. It is normally about one third of the SBP. If the BP is 120/80 mm Hg, the pulse pressure is 40 mm Hg. An increased pulse pressure may occur during exercise or in individuals with atherosclerosis of the larger arteries due to increased SBP. A decreased pulse pressure may be found in heart failure or hypovolemia.
systole
contraction of the myocardium, results in ejection of blood from the ventricles.
systolic blood pressure
the peak pressure exerted against the arteries when the heart contracts.