cardiology

which circuit does the right ventricle pump blood to?

the pulmonary circuit

what circuit does the left side of the heart correspond to?

the systemic circuit

what kind of blood does the right atrium receive?

blood returning from systemic circuit

what circuit does the left ventricle pump blood to?

the systemic circuit

through which channel(s) does the right atrium receive blood?

superior vena cava, inferior vena cava, coronary sinus

through which channels does the left atrium receive blood?

four pulmonary veins

between which markers is the heart located in the chest?

in the mediastinum, between the second rib and fifth intercostal space

what is the purpose of the fibrous pericardium?

protects, anchors the heart to surrounding structures, and prevents overfilling

what is the purpose of the fluid-filled pericardial cavity between the parietal layer and the visceral layer (epicardium) of the serous pericardium?

to decrease friction

what is pericarditis, and what does it do to the membrane surface?

inflammation of the pericardium, roughens membrane surface, causes pericardial friction rub (creaking sound) heard with stethoscope

what is cardiac tamponade?

excess fluid compressing heart, causing limited ability to pump

what characterizes the myocardium?

spiral bundles of contractile cardiac muscle cells

what is the cardiac skeleton?

crisscrossing, interlacing layer of connective tissues responsible for anchoring cardiac muscle fibers, supporting great vessels and valves, and limiting spread of action potentials to specific paths

what is the purpose of the endocardium?

continuous with endothelial lining of blood vessels; lines heart chambers, covers cardiac skeleton of valves

what is the purpose of the “water slide-like” structure of cardiac muscle bundles?

reduces turbulent flow of blood, prevents clotting

what is the fossa ovalis?

remnant of foramen ovale of fetal heart

what is the trabeculae carnae?

irregular ridges of muscle on walls

how are valves held shut?

chordae tendineae anchor cusps to papillary muscles to hold the valve flaps in closed position

which chambers of the heart have thicker walls, the atria or ventricles?

the ventricles, because they need the power to pump blood

what channel does the right ventricle pump blood through?

pulmonary trunk

what is the valve between the left atrium and left ventricle?

the bicuspid / mitral valve

what is the valve between the right atrium and right ventricle?

tricuspid valve

what kind of blood does the left atrium receive?

blood returning from pulmonary circuit

what channel does the left ventricle pump blood to?

aorta

what separates the posterior and anterior regions of the right atrium?

crista terminalis

where are pectinate muscles found?

right atrium, auricles of left atrium

what do the heart valves do?

ensure unidirectional flow of blood, prevent backflow

how do the heart valves open and close?

in response to pressure changes

what are the valves between the atria and ventricles called?

atrioventricular (av) valves

when do the av valves open?

when atrial pressure is greater than ventricular pressure

what is the valve between the left ventricle and aorta?

aortic semilunar valve

what is the valve between the right ventricle and pulmonary trunk?

pulmonary semilunar valve

what is vulvular stenosis?

stiff valve flaps constrict the valve openings, forcing the heart to exert more force in order to pump blood

what is the blood flow pathway of the pulmonary circuit?

right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → pulmonary trunk → pulmonary arteries → lungs → pulmonary veins → left atrium

what is the blood flow pathway of the systemic circuit?

left atrium → mitral valve → left ventricle → aortic semilunar valve → aorta → systemic circulation → vena cava → right atrium

which part of the heart receives the most cardiac blood supply?

left ventricle

what two arteries does the left coronary artery branch into?

anterior interventricular artery and circumflex artery

what two arteries does the right coronary artery branch into?

right marginal artery and posterior interventricular artery

how do the cardiac veins collect blood?

from capillary beds

where does the coronary sinus empty?

right atrium

what is angina pectoiris?

thoracic pain caused by fleeting deficiency in blood delivery to myocardium, cells weakened

what is myocardial infarction?

heart attack, caused by prolonged coronary blockage, areas of cell death repaired with noncontractile scar tissue

what are intercalated discs?

junctions between cells which anchor the cells

what do desmosomes do?

prevent cells from separating during contraction

what are gap junctions?

allow ions to pass from cell to cell; allow heart to act as single coordinated unit

do cardiac cells have a long or short absolute refractory period?

long (250 ms) to event tetanic contractions

do cardiac muscle cells or skeletal muscle cells have a longer contractile phase and action potential?

cardiac muscle cells; much longer action potential and contractile phase allow blood ejection from heart

what causes depolarization of cardiac muscle cells action potential?

Na⁺ influx through fast voltage-gated Na⁺ channels

what causes the plateau phase of cardiac muscle cells action potential?

Ca²⁺ influx through slow Ca²⁺ channels; this keeps the cell depolarized because few K⁺ channels are open

what causes repolarization of cardiac muscle cells action potential?

Ca²⁺ channels inactivate and K⁺ channels open, allowing K⁺ efflux, and causes the membrane potential to return back to its resting voltage

why do cardiac muscles have many mitochondria?

great dependence on aerobic respiration

how can cardiac muscle cells undergo aerobic respiration without fuel?

switch fuel source; can even use lactic acid from skeletal muscles

does the heart need nervous system stimulation to depolarize and contract?

no, but the rhythm can be altered by autonomic nervous system

what makes coordinated heartbeats possible?

gap junctions and intrinsic cardiac conduction system (network of autorhythmic cells with coordinated depolarization and contraction)

what are the three parts of the action potential initiation by pacemaker cells?

pacemaker potential, depolarization, and repolarization

what causes the pacemaker potential?

this slow depolarization is caused by both opening of Na⁺ channels and closing of K⁺ channels

what causes depolarization of pacemaker cells?

the action potential begins when the pacemaker potential reaches threshold; depolarization is due to Ca²⁺ influx through Ca²⁺ channels

what causes repolarization of pacemaker cells?

Ca²⁺ channels inactivate and K⁺ channels open; this allows K⁺ efflux, which brings the membrane potential back to its most negative voltage

what is the flow pathway of pacemaker cells impulses?

sinoatrial (SA) node → atrioventricular (AV) node → atrioventricular (AV) bundle → right and left bundle branches → subendocardial conducting network (purkinje fibers)

left off on sequence of excitation