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absolute refractory period
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a time when the cell cannot respond to another stimulus
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adenosine triphosphate (ATP)
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a nucleotide that collects chemical energy produced by the breakdown of food molecules to provide the energy necessary for all cellular activities
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arrhythmia
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abnormal heart rate and rhythm
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arterial insufficiency
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insufficient arterial perfusion (blood flow to tissue) of an extremity or particular location
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artery
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a blood vessel that carries blood away from the heart
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atrial gallop
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an S4 sound during diastole created by the movement of blood flowing out of the atria against a stiff ventricular wall caused by hypertension, pulmonary hypertension, ventricular outflow obstruction, or ischemic heart disease; occurs immediately before the S1 and sounds like “ta-lub-dub”
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auscultation
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the use of a stethoscope to listen for normal and abnormal sounds (e.g., components of the heartbeat, murmurs, valvular sounds, bruits)
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blood-brain barrier
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continuous capillaries that prevent toxins from entering into the tissues of the brain
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bruit
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a swishing sound caused by turbulence in the blood vessel and may be heard because of atherosclerotic changes
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calcium ion
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the metabolically active portion of calcium; plays a crucial role in several physiological processes including muscle contraction (including the heart), enzyme activation, and synaptic transmission
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capacitance
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the ability of blood vessels to hold blood at a given pressure
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capillary exchange
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the transfer of material between capillary blood and body tissues, which is essential for delivery of nutrients and removal of waste products
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capillary refill
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a rapid test performed on the nail beds, used for assessing the blood flow through peripheral tissues
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catecholamines
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a hormone neurotransmitter involved in heart rate and blood pressure
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clinical edema
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the swelling of soft tissues due to increased interstitial fluid that is outside of normal daily accumulation
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continuous capillaries
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capillaries that are common in muscle, connective, and nervous tissues and have the lowest permeability capabilities of all capillaries
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CWMS
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an acronym that stands for color-warmth-movement-sensation
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cyanosis
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a bluish or dusky discoloration of the skin and mucous membranes caused by hypoxia
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deep vein thrombosis (DVT)
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a blood clot that forms in a vein deep in the body
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deoxygenated blood
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blood that has delivered oxygen to the tissues and picked up carbon dioxide as waste
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diastole
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the relaxed phase of the cardiac cycle when the chambers of the heart are refilling with blood
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dicrotic notch
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a small dip in an arterial waveform when the pressure in the ventricles becomes lower than the pressure in the pulmonary trunk and aorta, causing blood to flow back into the heart
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end-systolic volume
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the volume of blood remaining in the left ventricle of the heart at the end of each systolic cardiac contraction
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endocardium
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the thin, smooth membrane that lines the inside of the chambers of the heart and forms the surface of the valves
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endocytosis
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the movement of molecules into the cell, allowing for nutrient absorption and hormone regulation as well as maintaining fluid balance
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endothelium
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the tissue that forms a single layer of cells lining various organs and cavities of the body, especially the blood vessels, heart, and lymphatic vessels
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epicardium
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a serous membrane that is part of the innermost layer of the pericardium and is fused to the outer surface of the heart
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exocytosis
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the movement of molecules out of the cell to be eliminated or moved to another area of the body
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fenestrated capillaries
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capillaries located in areas that require rapid absorption or filtration (e.g., kidneys, small intestines, brain), which provide no resistance to fluid flow across the membranes
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fibrillation
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uncoordinated beating of the heart
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formed elements
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cells and cell fragments suspended in the plasma. The three classes of formed elements are the erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes (platelets)
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functional blockage
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the widening and narrowing of vessels in response to factors such as brain signals and temperature changes, causing blood flow to be decreased with no physical damage
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hydrostatic pressure
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the pressure of fluids against the walls of the capillaries that forces molecules, typically water, through the capillary wall
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inspection
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visual observation of areas of the body to assess for symmetry, color, movement, swelling, and obvious alterations in body function
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intermittent claudication
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cramp-like muscle pain, burning, or extreme fatigue in the leg that is induced by exercise and relieved by rest
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isometric contraction
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an event occurring early in systole during which the ventricles contract while all the heart valves are closed so blood volume in the heart does not change
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isovolumetric contraction
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an event occurring in early systole during which the pressure in the ventricles becomes high enough to push blood out, opening the valves
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isovolumetric relaxation
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the time interval between aortic valve closure and mitral valve opening when the ventricular pressures fall below the aortic and pulmonary pressures
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jugular venous distension (JVD)
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a bulge over the jugular vein, making it most visible on the right side of a person’s neck
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local signaling molecule
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a chemical that is released and acts on a specific area of the body
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murmur
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a blowing or whooshing sound that signifies turbulent blood flow often caused by a valvular defect
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myocardium
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muscles in the walls of all four chambers of the heart, though it is thicker in the ventricles and thinner in the atria
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occlusive blockage
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a narrowing or blockage of an artery in the extremities, most often the legs, caused by inflammation, plaque buildup, or trauma to tissue, resulting in decreased blood flow
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orthopnea
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shortness of breath that occurs while lying flat and is relieved by sitting or standing
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oxygenated blood
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blood that has picked up oxygen in the lungs for delivery to the body
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pallor
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the loss of color, or paleness of the skin or mucous membranes, which may be caused by reduced blood flow, oxygenation, or decreased number of red blood cells
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palpation
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the use of the fingers or hand to assess size, consistency, texture, location, and tenderness of an organ, body part, or body area
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pectus excavatum
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a structural deformity of the anterior chest wall that causes the sternum to be caved in or sunken into the chest; when severe, pectus excavatum can eventually adversely affect cardiac and respiratory function
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percussion
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the tapping of the chest wall with the fingers to assess sound that may indicate an abnormality or dysfunction
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pericardial friction rub
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a grating, to-and-fro sound or creaky-scratchy noise produced by friction of the heart against the pericardium caused by inflammation of the pericardium
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pericardium
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the membrane or sac that surrounds and protects the heart and maintains its position in the thorax
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pitting edema
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a visible swelling of a specific area caused by fluid buildup in the tissues, seen as indentions or “pits” in the skin when pressure is applied and the indentations remain on the skin after the pressure is released
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postcapillary venules
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the segment of microvasculature that works in conjunction with capillaries to regulate solute exchange and respond to foreign agents (e.g., infection, inflammation)
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pulmonary embolism
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a sudden blockage in the pulmonary arteries that send blood to the lungs
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regurgitation
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leakage of blood backward through a valve each time the ventricle contracts
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relative refractory period
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a time when the cell can respond but needs a stronger stimulus
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rubor
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redness of the skin caused by inflammation
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S1
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the first heart sound (“lub”), which identifies the onset of systole, when the atrioventricular (AV) (mitral and tricuspid) valves close and the ventricles contract and eject the blood out of the heart
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S2
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the second heart sound (“dub”), which identifies the end of systole and the onset of diastole when the semilunar (pulmonic and aortic) valves close, the AV valves open, and the ventricles fill with blood
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sinoatrial (SA) node
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an oval-shaped region of special cardiac muscle made up of pacemaker cells in the upper back wall of the right atrium
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sinus rhythm
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the normal rhythm of the heart in which electrical stimuli are initiated in the SA node, and are then conducted through the AV node, bundle of His, bundle branches, and Purkinje fibers
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sinusoid capillaries
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capillaries found in areas where white blood cells are formed; they have large pores to allow for movement of these cells in and out of the bloodstream (e.g., red bone marrow, liver)
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spontaneous depolarization (also, prepotential depolarization)
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the mechanism that accounts for the autorhythmic property of cardiac muscle; also called prepotential depolarization
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stroke volume (SV)
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the volume of blood pumped out of the left ventricle of the heart during each systolic cardiac contraction
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systole
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contraction of the heart chambers, which pumps blood out into the vessels
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transcytosis
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a process that allows for larger, lipid-insoluble substances to cross the capillary membrane through endocytosis and exocytosis
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vein
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a blood vessel that returns blood to the heart
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venous insufficiency
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a condition in which the veins in the legs do not return blood to the heart and upper body normally
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ventricular ejection
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the central measure of ventricular systolic function, measured as ejection fraction
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ventricular gallop
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an S3 sound that occurs after the S2 that sounds like “lub-dub-dah,” or a sound similar to a horse galloping
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ventricular systole
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the period when the ventricles contract
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venules
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smallest veins that receive blood from the capillaries