absolute refractory period
the early phase of repolarization in which the cell contains such a large concentration of ions that it cannot be stimulated to depolarize.
the pressure in the aorta against which the left ventricle must pump blood.
leukocytes that lack granules.
stimulation of alpha receptors that results in vasoconstriction.
a decrease in the number of red blood cells, for any reason.
anterior descending coronary artery
one of the two branches of the left main coronary artery.
proteins within plasma that react with antigens.
substances on the surface of erythrocytes that are recognized by the immune system.
the largest artery in the body, which carries oxygenated blood from the left ventricle to the entire body.
one of the three described portions of the aorta; the section of the aorta between the ascending and descending portions that gives rise to the right brachiocephalic (innominate), left common caotid, and left subclavian arteries.
the semilunar valve that regulates blood flow from the left ventricle to the aorta.
the blood vessels that carry blood away form the heart.
the deposition of calcium in the arterial walls that results in a loss of elasticity and concomitant reduction in blood flow.
the first of three portions of the aorta; originates from the left ventricle and gives rise to two branches, the right and left coronary arteries.
a disorder characterized by the formation of plaques of material, mostly lipids and cholesterol, on the inner arterial walls.
atrioventricular (AV) node
the site located in the right atrium adjacent to the septum that is responsible for transsiently slowing electrical conduction.
the two valves through which blood flows from the atria to the ventricles.
one of the two chambers in the heart that receives blood back from the body.
the ability of cardiac cells to generate an impulse to contract even when there is no external nervous stimulus.
the vein that is formed from the combination of the basilic and cephalic veins; it drains into the subclavian vein.
receptors in the blood vessels, kidneys, brain, and heart that respond to changes in pressure in the heart or main arteries to help maintain homeostasis.
the artery that is formed when the left and right vertebral arteries unite after entering the brain though the foramen magnum.
one of the two major veins of the arm, it combines with the cephalic vein to form the axillary vein.
the least common of all granulocytes; they are important in both allergic and inflammatory reactions.
stimulation of beta receptors that results in increased inotropic, dromotropic, and chronotropic states.
a waste product of red blood cell destruction that undergoes further metabolism in the liver.
the fluid tissue that is pumped by the heart through the arteries, veins, and capillaries and consists of plasma and formed elements or cells, such as red blood cells, white blood cells, and platelets.
an abnormal "whooshing-like" sound indicating chaotic blood flow within a blood vessel.
bundle of His
part of the conduction system of the heart; a continuation of the atrioventricular node.
thin-walled vessels that allow oxygen and nutrients to pass out into the cells and allow carbon dioxide and waste products to pass from the cells into the capillaries.
the pumping process begins with the onset of myocardial contraction and ends with the beginning of the next contraction.
expressed as liters per minute, the amount of blood pumped through the circulatory system in 1 minute.
a life-threatening state of shock that develops as a result of a large pericardial effusion.
the point of division at which the common carotid artery branches at the angle of the mandible into the internal and external carotid arteries.
an opening in the cranial vault through which the carotid arteries enter.
a slight dilation in the carotid bifurcation that contains structures that are important in the regulation of blood pressure.
one of the two major veins of the arm that combine to form the axillary vein.
the part of the brain that is located dorsal to the pons and is responsible for coordination and balance.
the arteries that supply blood to large portions of the cerebral cortex of the brain.
receptors in the blood vessels, kidneys, brain, and heart that respond to changes in chemical composition of the blood to help maintain homeostasis.
chordae tendineae cordis
small muscular strands that attach the ventricles and the valves, preventing regurgitation of blood through the valves from the ventricles to the atria.
related to the control of the heart's rate of contraction.
circle of Willis
an interconnection of the anterior cerebral arteries and the anterior communicating artery, which forms an important source of collateral circulation to the brain.
circumflex coronary artery
one of the two branches of the left main coronary artery.
a group of complex electrical tissues within the heart that initiate and transmit stimuli that result in contractions of myocardial tissue.
the ability of cardiac cells to conduct electrical impulses.
the strength of heart muscle contraction.
arteries that arise from the aorta shortly after it leaves the left ventricle and supply the heart with oxygen and nutrients.
coronary artery disease (CAD)
the condition that results when either atherosclerosis or arteriosclerosis is present in the arterial walls.
veins that collect blood that is returning from the walls of the heart.
the flaps that comprise the heart valves.
the process of electrical discharge and flow of electrical activity from a cell.
one of the three portions of the aorta, it is the longest portion and extends through the thorax and abdomen into the pelvis.
a process whereby leukocytes leave blood vessels to move toward tissue where they are needed most.
dorsalis pedis artery
a continuation of the anterior tibial artery at the foot.
related to the control of the heart's conduction rate.
the portion of the blood ejected from the ventricle during systole.
an electrical charge difference that is created by the difference that is created by the difference in sodium and potassium concentration across the cell membrane at any given instant.
a graphic recording of the electrical activity of the heart.
a piece of clot that travels from one part of the body to another, potentially becoming an obstruction to blood flow.
infection of a heart valve.
granulocytes that contain granules that strain bright red with acidic stain, eosin, and function in the body's allergic responce.
the layer of the serous pericardium that lies closely against the heart; also called the visceral pericardium.
a naturally occuring hormone with a greater stimulatory effect on beta receptors that also may be given as a cardiac drug.
a serious condition that results when a pregnant woman's blood type is incompatible with the fetus' blood type and antibodies from the mother enter the fetal circulation and destroy the fetus' red blood cells.
disk-shaped cells that carry oxygen to the tissues; also known as red blood cells.
the process by which red blood cells are made.
a property of cardiac cells that provides the cells with the ability to respond to electrical impulses.
a continuation of the external iliac artery, it supplies circulation to the thigh, external genetalia, anterior abdominal wall, and knee.
a continuation of the saphenous vein that drains into the external iliac vein
a white insoluble protein formed in the clotting process.
an opening between the two atria that is present in the fetus but closes shortly after birth.
a depression between the right and left atria that indicates where the foramen avale had been located in the fetus.
a type of leukocyte that has large cytoplasmic granules that are easily seen with a simple light microscope.
a muscular, cone-shaped organ whose function is to pump blood throughout the body.
the process of blood cell production in the bone marrow; also called hemopoiesis.
the protein in red blood cells that gives them their reddishcolor, it binds oxygen absorbed in the lungs and transports it to the tissues where it is needed.
control of bleeding by formation of a blood clot.
a substance found in large amounts in basophils that inhibits blood clotting.
hepatic portal system
a specialized part of the venous system that drains blood from the liver, stomach, intestines, and spleen.
the veins to which blood empties after liver cells in the sinusoids of the liver extract nutrients, filter the blood, and metabolize various drugs.
a substance found in large iamounts in basophils that increases tissue inflammation.
inferior vena cava
one of two major veins that return deoxygenated blood to the heart via the right atrium. Blood from the lower body is returned to the heart by the inferior vena cava.
related to the strength of the heart's contraction.
a membrane that separates the right and left atria.
a thick wall that separates the right and left ventricles.
insufficient oxygen at a particular tissue site often associated with obstruction of arterial blood flow to the site.
a yellowing of the skin and sclera of the eyes because of excessive concentrations of bilirubin in the blood.
the two main veins that drain the head and neck.
a cancerous condition in which certain cell lines begin to grow abnormally fast and invade other tissues.
white blood cells that are responsible for fighting infection.
the opening or hollow part of a blood vessel.
the smallest of the agranulicytes, they originate in the bone marrow but migrate through the blood to the lymphatic tissues.
cells that are responsible for protecting the body against infection.
the area in the chest that lies between the lungs and contains the heart and great vessels.
pain caused by partial occlusion of the mesenteric artery from atherosclerosis.
blockage of a mesenteric artery resulting in necrosis of a portion of the bowel.
the valve in the heart that separates the left atrium from the left ventricle.
agarnulocytes that migrate out of the blood and into the tissues in response to an infection.
an abnormal heart sound, heard as a "whooshing-like" sound indicating turbulent blood flow within the heart.
myocardial infarction (MI)
blockage of the arteries that supply oxygen to the heart, resulting in death to a portion of the myocardium.
the heart muscle.
one of the three types of granulocytes; they have multi-lobed nuclei that resemble a string of baseballs held together be a thin strand of thread; they destroy bacteria, antigen-antibody complexes, and foreign matter.
a naturally occuring hormone with a greater stimulatory effect on alpha receptors that also may be given a cardiac drug.
the first positive wave in the normal cardiac conduction pattern, it represents movement of the electrical impulse through the atria, resulting in atrial contraction.
the two arches formed from the radial and ilnar vessels within the hand, creating the superficial and deep palmar arches.
specialized muscles that attach the ventricles to the cusps of the valves by muscular strands called chordae tendineae cordis.
one of two layers of the seous pericardium. It is separated from the visceral pericardium by a small amount of pericardial fluid.
a condition, often caused by trauma, in which the pericardial sac fills with too much fluid, hampering the heart's ability to expand and contact properly.
a serous fluid that fills the space between the visceral pericardium and the parietal pericardium and helps to reduce friction.
a thick fibrous membrane that surrounds the heart; also called the pericardium.
a life-saving procedure to correct cardiac tamponade, in which a needle is inserted into the pericardial sac to remove excess fluid that is restricting the heart from expanding and contracting properly.
infection of inflammation of the pericardial membranes, resulting in severe chest pain.
a thick fibrous membrane that surrounds the heart; also called the pericardial sac.
inflammatory condition involving veins; often associated with thrombus formation within the vein.
an enzyme that dissolves the fibrin in blood clots.
small cells in the blood that are essential for clot formation.
the state of the resting cell, which normally has a net negative charge with respect to the outside of the cell.
the mass of nerve fibers at the end of the medulla oblongata.
a continuation of the femoral artery at the lower thigh.
the vein that forms when the anterior and posterior tiial veins unite at the knee.
a flat line or electrical pause that follows the P wave in the normal electrical conduction pattern and represents the time delay that occurs within the atrioventricular node.
the circulatory system in the body that carries blood from the right side of the heart to the lungs, and back to the left side of the heart.
a potentially life-threatening condition that occurs when an embolus travels from one part of the body (typically the legs) to the lungs, blocking blood flow to a portion of the lung.
the semilunar valve that regulates blood flow between the right ventricle and the pulmonary artery.
the second positive waveform that follows the P-R segment in the normal electrical conduction pattern and represents the depolarization of the ventricles. This complex corresponds to ventricular contraction, or systole.
spasms that develop in the digital arteries, particularly following emotional stress or cold exposure, resulting in white and cool fingertips.
relative refractory period
the latter phase of repolarization in which the cells are able to respond to a stronger-than-normal stimulus.
the process of returning to the cardiac cells' resting or polarized state that occurs once the cardiac cells depolarize.
an acute condition that affects children and young adults and may result in permanent damage to the aortic and mitral valves.
the longest vein in the body, it drains the leg, thigh, and dorsum of the foot.
the two valves, the oartic and pulmonic calves, that divide the heart from the aorta and pulmonary artery.
the inner membrane of the pericardium, which contains two layers called the visceral pericardium and parietal pericardium.
sinoatrial (SA) node
the normal site of the origin of electrical impulses; located high in the right atrium, it is the heart's natural pacemaker.
a part of the hepatic portal system in which blood collects within the liver and the liver cells extract nutrients from the blood, filter the blood, and metabolize various drugs.
a molecular (ion-transporting) mechanism whereby sodium is actively moved out of a cell and potassium moved in.
the second pause that occurs in the normal electrical conduction pattern and represents the beginning of reploarization of the heart.
the amount of blood that the left ventricle ejects into the aorta per contraction.
the proximal part of the main artery of the arm, which supplies the brain, neck, anterior chest wall, and shoulder.
the proximal part of the main vein of the arm, which unites with the internal jugular vein.
superior vena cava
one of two major large veins that return deoxygenated blood to the heart via the right atrium. Blood from the upper body is returned to the heart by the superior vena cava.
the circulatory system in the body that is responsible for blood flow in all areas of the body, except for areas covered by the pulmonary circulation.
contraction of the ventricular mass with its concomitant pumping of blood into the system circulation.
the third positive waveform in the normal electrical conduction pattern; it represents the completion of repolarization.
an enzyme that causes the conversion of fibrinogen to fibrin, which binds to the platelet plug, forming the final mature vein.
a continuation of the veins of the feet that unite at the knee to form the popliteal vein, which then drains into the femoral vein.
tissue plasminogen activator (t-PA)
a major component in the fibrinolytic system, in which clots that have already formed are lysed or disrupted, converting plasminogen to plasmin.
the heart calve that separates the right atrium from the right ventricle.
the outer layer of tissue of a blood vessel wallm composed of elastic and fibrous connective tissue.
the smooth, thin, inner lining of a blood vessel.
the middle and thickest layer of tissue of a blood vessel wall, composed of elastic tissue and smooth muscle cells that allow the vessel to expand or contract in response to changes in blood pressure and tissue demand.
the blood vessels that bring blood back to the heart.
spaces between the membranes surrounding the brain that are the primary means of venous drainage from the brain.
one of the two lower chambers of the heart that pumps blood out of the heart.
the layer of the serous pericardium that lies closely against the heart; also called the epicardium.