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A&PII - Ch 18

Cardiovascular System - Heart

chambered muscular organ that pumps blood received from the veins into the arteries, thereby maintaining the flow of blood through the entire circulatory system heart
medial cavity of the thorax containing the heart, great vessels, and trachea mediastinum
posterior surface of heart; about 9cm wide & directed toward right shoulder base
points inferiorly toward left hip apex
btwn 5th & 6th ribs just below left nipple; caused by apex of beating heart contacting chest wall apical impulse
contains film of serous fluid; located btwn parietal & visceral layers; slit-like pericardial cavity
serous membranes lubricated by serous fluid in pericardial cavity allows the layers to __ __ past one another during heart activity; friction free environment glide smoothly
inflammation of pericardium, roughens serous membranes surfaces; as beating heart rubs against its pericardial sac it creates & creaking sound pericarditis
beating heart rubs against its pericardial sac it creates & creaking sound pericardial friction rub
condition in which heart is compressed by fluid; "heart plug" cardiac tamponade
superficial, visceral layer of serous pericardium; often infiltrates with fat epicardium
layer of the heart wall composed of cardiac muscle myocardium
myocardium is the layer that __ contracts
in myocardium, branching cardiac muscles cells are tethered to one another by crisscrossing connective tissue fibers & arranged in __ __ spiral/circular bundles
spiral/circular bundles of myocardium effectively __ all parts of heart together link
connective tissue fibers that form dense network that reinforces myocardium internally; network of collagen & elastic fibers fibrous skeleton of heart
fibrous skeleton of heart also __ cardiac muscle fibers anchors
fibrous skeleton of heart constructs rope-like rings that provide __ __ where great vessels issues from heart & around heart valves additional support
because connective tissue is not __ __ fibrous skeleton of heart limits direct spread of action potentials across heart to specific pathways electrically excitable
glistening white sheet of squamous endothelium resting on thin layer of connective tissue that lines the interior of the heart endocardium
on inner __ __ endocardium lines heart chambers & covers fibrous skeleton of valves myocardial surface
endocardium is __ __ endothelial linings of blood vessels leaving & entering heart continuous with
two superior receiving chambers of the heart atria
paired, inferiorly located heart chambers that function as the major blood pumps ventricles
internal partition that divides heart longitudinally; separates atria interatrial septum
internal partition that divides heart; separates ventricles interventricular septum
forms most of anterior surface of hear right ventricle
dominates inferoposterior aspects of heart & forms heart apex left ventricle
grooves visible on heart surface; indicate boundaries of 4 chambers; carry blood vessels supplying myocardium; encircles junction of atria & ventricles like crown coronary sulcus
cradling anterior interventricular artery; marks anterior position of septum separating right & left ventricles anterior interventricular sulcus
anterior interventricular sulcus continues to provide similar landmark on heart's posteroinferior surface posterior interventricular sulcus
small, wrinkled, protruding appendages that increase atrial volume auricles
right & left atria are free of distinguishing __ __ surface features
anterior portion of right atrium; ridged by bundles of muscle tissue pectinate muscles
posterior & anterior regions of right atrium are separated by C-shaped ridge crista terminalis
left atrium is mostly smooth & pectinate muscles are only found in auricle
shallow depression in interatrial septum that marks spot where foramen ovale (opening) existed in fetal heart fossa ovalis
functionally, atria are __ __ for blood returning to heart from circulation receiving chambers
atria are relatively small, thin-walled chambers because they need contract __ __ to push blood " downstairs" into ventricle only minimally
atria contribute little to __ __ activity of heart propulsive pumping
superior vena cava, inferior vena cava, & coronary sinus are veins in which blood enters right atrium
returns blood from body regions superior to diaphragm superior vena cava
returns blood from body areas below diaphragm inferior vena cava
collects blood draining from myocardium coronary sinus
enter left atrium; transport blood from lungs back to heart; best seen in posterior view pulmonary veins
left atrium makes up most of heart's base
make up most of the volume of heart ventricles
marking internal walls of ventricular chambers; irregular ridges of muscle trabeculae carneae
cone-like; play role in valve function. projection into ventricular activity papillary muscles
when ventricles contract, blood is propelled out of heart & into circulation
blood pumped from right ventricle; routes blood to lungs pulmonary trunk
major systemic artery; arises from the left ventricle of the heart aorta
left ventricle ejects blood into the aorta
heart is actually two side-by-side pumps, each serving separate blood circuit
blood vessels that carry blood to/from lungs; serves gas exchange pulmonary circuit
blood vessels that carry functional blood supply to/from all body tissues systemic circuit
right side of heart __ circuit pump pulmonary
blood returning from body is __ & __ oxygen-poor; carbon dioxide-rich
freshly oxygenated blood is carried by __ __ to left side of heart pulmonary veins
opposite ___ ___ exist in veins & arteries of pulmonary circuit oxygenation conditions
left side of heart is systemic circuit pump
freshly oxygenated blood __ __ is returned to left atrium & passes into left ventricle which pumps into aorta leaving lungs
blood loaded with CO2 & depleted of O2 returned through __ veins to right side of heart, where enters right atrium through superior/inferior venae cavae systemic
pulmonary circuit is a short, low-pressure __ circulation
systemic circuit takes long pathway through entire body & encounters about 5x as much friction
walls of left ventricle are 3x as __ as those of the right thick
left ventricle __ is nearly circular cavity
right ventricular cavity is __ into crescent shape that partially encloses left ventricle flattened
functional blood supply of the heart; shortest circulation in the body coronary circulation
arise from base of aorta & encircle heart in coronary sulcus; arterial supply of coronary circulation is provided by right & left coronary arteries
runs toward left side of heart & then divides into major branches left coronary artery
follows anterior interventricular sulcus & supplies blood to interventricular septum & anterior walls of both ventricles anterior interventricular artery
anterior interventricular artery is also known as left anterior descending artery
supplies left atrium & posterior walls of left ventricle circumflex artery
courses to right side of heart where it gives rise to 2 branches right coronary artery
serves myocardium of lateral side of heart right marginal artery
runs to heart apex & supplies posterior ventricular walls posterior interventricular artery
near apex of heart posterior interventricular artery __ with anterior interventricular artery anastomosis
together branches of right coronary artery supply __ atrium & nearly all __ ventricle right; right
__ supply of heart varies considerably arterial
there are __ __ among coronary arterial branches many anastomoses
many anastomoses among coronary arterial branches provide __ __ for blood delivery to heart muscle additional/collateral routes
additional/collateral routes provided by anastomoses among coronary arterial branches are not __ __ to supply adequate nutrition when coronary artery is suddenly occluded robust enough
complete blockage of coronary artery branches leads to tissue death & heart attack
coronary arteries provide __, __ blood flow to myocardium intermittent; pulsating
coronary arteries & main branches lie in __ & send branches inward to nourish __ epicardium; myocardium
coronary arteries & branches deliver blood when heart is __ but are fairly ineffective when ventricles are __ because they are compressed by contracting myocardium relaxed; contracting
heart requires / of body's __ __ blood supply
left ventricle receives the __ __ blood supply most plentiful
after passing through capillary beds of myocardium, venous blood is collected by __ __, whose paths roughly follow those of coronary arteries cardiac veins
cardiac veins join together to form enlarged vessel called __ __, which empties blood into right atrium coronary sinus
coronary sinus is on __ __ of heart posterior aspect
great cardiac vein, middle cardiac vein, & small cardiac vein are all tributaries of coronary sinus
located in anterior interventricular sulcus; part of coronary sinus great cardiac vein
located in posterior interventricular sulcus; part of coronary sinus middle cardiac vein
runs along heart's right inferior margin; part of coronary sinus small cardiac vein
anastomosis is connection of __ __ of a branching system to form a network separate parts
severe suffocating chest pain caused by brief lack of oxygen supply to heart muscle angina pectoris
condition characterized by dead tissue areas in the myocardium; caused by interruption of blood supply to the area myocardial infarction (MI)
MI is commonly called heart attack
because adult cardiac muscle is essentially amitotic, most areas of cell death are repaired with __ __ tissue noncontractile scar
damage to __ __ in MIs, which is the systemic pump, is most serious left ventricle
blood flows in __ __ from atria to ventricles & out great arteries leaving superior aspect of the heart one direction
bundle of specialized fibers that conduct impulses from the AV node to the right and left ventricles atrioventricular (AV) bundle
atrioventricular (AV) bundle is also called bundle of His
right atrioventricular valve tricuspid valve
left atrioventricular valve mitral valve
tiny white collagen cords attached to each AV valve, anchoring cusps to papillary muscles chordae tendinae
when heart is relaxed AV flaps __ __ into ventricular chambers below hang limply
valves that prevent blood return to the ventricles after contraction; aortic and pulmonary valves semilunar valves
when ventricles are contracting & interventricular pressure rises above pressure in aorta & pulmonary trunk __ __ open SL valves
forces heart to repump same blood over & over because valve does not close properly * blood backflows incompetent valve
valve flaps become stiff & constrict opening valvular stenosis
specialized muscle of the heart; striated & contracts by sliding filament mechanism cardiac muscle
cardiac muscle cells are shirt, fat, branched, & interconnected
each cardiac muscle fiber contains one/at most two large, pale, centrally located __ nuclei
intercellular spaces filled with loose connective tissue matrix containing numerous capillaries in cardiac muscle endomysium
plasma membranes of adjacent cardiac cells interlock at dark-staining junctions called intercalated discs
intercalated discs contain anchoring __ & __ __ desmosomes; gap junctions
prevent adjacent cardiac cells from separating during contraction desmosomes
allow ions to pass from cell to cell, transmitting current across entire heart gap junctions
because cardiac cells are electrically coupled by gap junctions, myocardium behaves as a single coordinated unit called functional syncytium
account for 25-35% of volume of cardiac cells & give cardiac cells high resistance to fatigue large mitochondria
have Z discs, A bands, & I bands that reflect arrangement of thick (myosin) & thin (actin)filaments sarcomeres
T tubules are wider & enter the cell once per sarcomere at the Z disc system for delivering Ca2+
cells of heart can initiate their own depolarization, as well as the rest of heart as well in spontaneous & rhythmic way automaticity/autorhythmicity
in cardiac muscle, heart either contracts as unit or not at all because gap junctions electrically tie all cardiac muscle cells together into single contractile unit
depolarization wave travels across heart from cell to cell via __ __ through gap junctions ion passage
in cardiac muscles the __ __ __ lasts approximately 250 ms; this is the inexcitable period when Na+ channels are still open/inactivated absolute refractory period
the long cardiac refractory period normally prevents __ __, which would stop heart's pumping action tetanic contractions
about 1% of cardiac fibers are __, having special ability to depolarize spontaneously and thus pace heart autorhythmic
bulk of heart muscle is composed of __ __ __ responsible for heart's pumping activity contractile muscle fibers
cardiac muscle is adaptable & readily switches __ __ to use whatever nutrient supply is available, including lactic acid metabolic pathways
real danger of an inadequate blood supply to myocardium is __ __ __, not of nutrient fuels lack of O2
Created by: lfrancois



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