circulatory Flashcards
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.
afterload
the pressure in the aorta against which the left ventricle must pump blood.
agranulocytes
leukocytes that lack granules.
alpha effects
stimulation of alpha receptors that results in vasoconstriction.
anemia
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.
antibodies
proteins within plasma that react with antigens.
antigens
substances on the surface of erythrocytes that are recognized by the immune system.
aorta
the largest artery in the body, which carries oxygenated blood from the left ventricle to the entire body.
aortic arch
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.
aortic valve
the semilunar valve that regulates blood flow from the left ventricle to the aorta.
arteries
the blood vessels that carry blood away form the heart.
arteriosclerosis
the deposition of calcium in the arterial walls that results in a loss of elasticity and concomitant reduction in blood flow.
ascending aorta
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.
atherosclerosis
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.
atrioventricular valves
the two valves through which blood flows from the atria to the ventricles.
atrium
one of the two chambers in the heart that receives blood back from the body.
automaticity
the ability of cardiac cells to generate an impulse to contract even when there is no external nervous stimulus.
axillary vein
the vein that is formed from the combination of the basilic and cephalic veins; it drains into the subclavian vein.
baroreceptors
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.
basilar artery
the artery that is formed when the left and right vertebral arteries unite after entering the brain though the foramen magnum.
basilar vein
one of the two major veins of the arm, it combines with the cephalic vein to form the axillary vein.
basophils
the least common of all granulocytes; they are important in both allergic and inflammatory reactions.
beta effect
stimulation of beta receptors that results in increased inotropic, dromotropic, and chronotropic states.
bilirubin
a waste product of red blood cell destruction that undergoes further metabolism in the liver.
blood
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.
bruit
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.
capillaries
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.
cardiac cycle
the pumping process begins with the onset of myocardial contraction and ends with the beginning of the next contraction.
cardiac output
expressed as liters per minute, the amount of blood pumped through the circulatory system in 1 minute.
cardiac tamponade
a life-threatening state of shock that develops as a result of a large pericardial effusion.
carotid bifurcation
the point of division at which the common carotid artery branches at the angle of the mandible into the internal and external carotid arteries.
carotid canals
an opening in the cranial vault through which the carotid arteries enter.
carotid sinus
a slight dilation in the carotid bifurcation that contains structures that are important in the regulation of blood pressure.
cephalic vein
one of the two major veins of the arm that combine to form the axillary vein.
cerebellum
the part of the brain that is located dorsal to the pons and is responsible for coordination and balance.
cerebral arteries
the arteries that supply blood to large portions of the cerebral cortex of the brain.
chemoreceptors
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.
chronotropic state
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.
conduction system
a group of complex electrical tissues within the heart that initiate and transmit stimuli that result in contractions of myocardial tissue.
conductivity
the ability of cardiac cells to conduct electrical impulses.
contractility
the strength of heart muscle contraction.
coronary arteries
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.
coronary sinus
veins that collect blood that is returning from the walls of the heart.
cusps
the flaps that comprise the heart valves.
depolarization
the process of electrical discharge and flow of electrical activity from a cell.
descending aorta
one of the three portions of the aorta, it is the longest portion and extends through the thorax and abdomen into the pelvis.
diapedesis
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.
dromotropic state
related to the control of the heart’s conduction rate.
ejection fraction
the portion of the blood ejected from the ventricle during systole.
electrical potential
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.
electrocardiogram (ECG)
a graphic recording of the electrical activity of the heart.
embolus
a piece of clot that travels from one part of the body to another, potentially becoming an obstruction to blood flow.
endocarditis
infection of a heart valve.
eosinophils
granulocytes that contain granules that strain bright red with acidic stain, eosin, and function in the body’s allergic responce.