24.5: Key Terms

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