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absolute refractory period
a time when the cell cannot respond to another stimulus
adenosine triphosphate (ATP)
a nucleotide that collects chemical energy produced by the breakdown of food molecules to provide the energy necessary for all cellular activities
arrhythmia
abnormal heart rate and rhythm
arterial insufficiency
insufficient arterial perfusion (blood flow to tissue) of an extremity or particular location
artery
a blood vessel that carries blood away from the heart
atrial gallop
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”
auscultation
the use of a stethoscope to listen for normal and abnormal sounds (e.g., components of the heartbeat, murmurs, valvular sounds, bruits)
blood-brain barrier
continuous capillaries that prevent toxins from entering into the tissues of the brain
bruit
a swishing sound caused by turbulence in the blood vessel and may be heard because of atherosclerotic changes
calcium ion
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
capacitance
the ability of blood vessels to hold blood at a given pressure
capillary exchange
the transfer of material between capillary blood and body tissues, which is essential for delivery of nutrients and removal of waste products
capillary refill
a rapid test performed on the nail beds, used for assessing the blood flow through peripheral tissues
catecholamines
a hormone neurotransmitter involved in heart rate and blood pressure
clinical edema
the swelling of soft tissues due to increased interstitial fluid that is outside of normal daily accumulation
continuous capillaries
capillaries that are common in muscle, connective, and nervous tissues and have the lowest permeability capabilities of all capillaries
CWMS
an acronym that stands for color-warmth-movement-sensation
cyanosis
a bluish or dusky discoloration of the skin and mucous membranes caused by hypoxia
deep vein thrombosis (DVT)
a blood clot that forms in a vein deep in the body
deoxygenated blood
blood that has delivered oxygen to the tissues and picked up carbon dioxide as waste
diastole
the relaxed phase of the cardiac cycle when the chambers of the heart are refilling with blood
dicrotic notch
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
end-systolic volume
the volume of blood remaining in the left ventricle of the heart at the end of each systolic cardiac contraction
endocardium
the thin, smooth membrane that lines the inside of the chambers of the heart and forms the surface of the valves
endocytosis
the movement of molecules into the cell, allowing for nutrient absorption and hormone regulation as well as maintaining fluid balance
endothelium
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
epicardium
a serous membrane that is part of the innermost layer of the pericardium and is fused to the outer surface of the heart
exocytosis
the movement of molecules out of the cell to be eliminated or moved to another area of the body
fenestrated capillaries
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
fibrillation
uncoordinated beating of the heart
formed elements
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)
functional blockage
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
hydrostatic pressure
the pressure of fluids against the walls of the capillaries that forces molecules, typically water, through the capillary wall
inspection
visual observation of areas of the body to assess for symmetry, color, movement, swelling, and obvious alterations in body function
intermittent claudication
cramp-like muscle pain, burning, or extreme fatigue in the leg that is induced by exercise and relieved by rest
isometric contraction
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
isovolumetric contraction
an event occurring in early systole during which the pressure in the ventricles becomes high enough to push blood out, opening the valves
isovolumetric relaxation
the time interval between aortic valve closure and mitral valve opening when the ventricular pressures fall below the aortic and pulmonary pressures
jugular venous distension (JVD)
a bulge over the jugular vein, making it most visible on the right side of a person’s neck
local signaling molecule
a chemical that is released and acts on a specific area of the body
murmur
a blowing or whooshing sound that signifies turbulent blood flow often caused by a valvular defect
myocardium
muscles in the walls of all four chambers of the heart, though it is thicker in the ventricles and thinner in the atria
occlusive blockage
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
orthopnea
shortness of breath that occurs while lying flat and is relieved by sitting or standing
oxygenated blood
blood that has picked up oxygen in the lungs for delivery to the body
pallor
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
palpation
the use of the fingers or hand to assess size, consistency, texture, location, and tenderness of an organ, body part, or body area
pectus excavatum
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
percussion
the tapping of the chest wall with the fingers to assess sound that may indicate an abnormality or dysfunction
pericardial friction rub
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
pericardium
the membrane or sac that surrounds and protects the heart and maintains its position in the thorax
pitting edema
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
postcapillary venules
the segment of microvasculature that works in conjunction with capillaries to regulate solute exchange and respond to foreign agents (e.g., infection, inflammation)
pulmonary embolism
a sudden blockage in the pulmonary arteries that send blood to the lungs
regurgitation
leakage of blood backward through a valve each time the ventricle contracts
relative refractory period
a time when the cell can respond but needs a stronger stimulus
rubor
redness of the skin caused by inflammation
S1
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
S2
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
sinoatrial (SA) node
an oval-shaped region of special cardiac muscle made up of pacemaker cells in the upper back wall of the right atrium
sinus rhythm
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
sinusoid capillaries
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)
spontaneous depolarization (also, prepotential depolarization)
the mechanism that accounts for the autorhythmic property of cardiac muscle; also called prepotential depolarization
stroke volume (SV)
the volume of blood pumped out of the left ventricle of the heart during each systolic cardiac contraction
systole
contraction of the heart chambers, which pumps blood out into the vessels
transcytosis
a process that allows for larger, lipid-insoluble substances to cross the capillary membrane through endocytosis and exocytosis
vein
a blood vessel that returns blood to the heart
venous insufficiency
a condition in which the veins in the legs do not return blood to the heart and upper body normally
ventricular ejection
the central measure of ventricular systolic function, measured as ejection fraction
ventricular gallop
an S3 sound that occurs after the S2 that sounds like “lub-dub-dah,” or a sound similar to a horse galloping
ventricular systole
the period when the ventricles contract
venules
smallest veins that receive blood from the capillaries
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