Chapter 15: Cardiovascular System Flashcards
what supplies blood to tissues of the heart?
right and left coronary arteries
cardiac cycle
- events of a heartbeat (one full)
- heart chambers function in coordinated manner
- heart actions regulated
when atria contract…
ventricles relax
when ventricles contract…
atria relax
atrial systole
atria contract
ventricular diastole
ventricles relax; fill
atrial diastole
atria relax
ventricular systole
ventricles contract
what happens to the pressure in heart chambers during the cardiac cycle?
it rises and falls; pressure changes cause valves to open and close
during atrial systole & ventricular diastole…
- ventricles relaxed
- av valves open, semilunar close
- about 70% of blood flows passively from atria into ventricles
- the remaining 30% is pushed by atrial systole into ventricles, causing ventricular pressure to rise
during ventricular systole & atrial diastole…
- av valves close
- atria relax
- chordae tendineae prevent cusps of valves from bulging too far back into atria
- blood flows into atria from vena cava & pulmonary veins
- ventricular pressure increases & opens semilunar valve
- blood flows into pulmonary trunk & aorta
heart sounds
lubb dupp
lubb sound
- first sound
- occurs during ventricular systole
- associated with closing of av valves
dupp sound
- second sound
- occurs during ventricular diastole
- associated with closing of pulmonary & aortic semilunar valves
murmur
abnormal heart sound derived from incomplete closure of cusps of a valve
auscultation
listening to heart/lungs with stethoscope
functional syncitium
mass of merging cells that function as a unit
2 masses in the heart
- atrial syncitium
- ventricular syncitium
fibrillation
unorganized, out of sync contraction of cardiac muscle cells
atrial fibrillation
unorganized contraction of atria
ventricular fibrillation
unorganized contraction of ventricles; medical emergency
cardiac conduction system
group of clumps & strands of specialized cardiac muscle tissue which initiates & distributes impulses throughout myocardium; coordinates the events of cardiac cycle
cardiac conduction system pathway (8)
- SA node
- atrial syncitium
- junctional fibers
- AV node
- AV bundle (of HIS)
- bundle branches
- purkinje fibers
- ventricular syncitium
the heart is…
self polarizing
pacemaker of the heart
SA node
SA node
sinoatrial node; pacemaker of the heart, right atrium
AV node
atrioventricular node; secondary pacemaker
junctional fibers
conduct impulses from SA to AV node
internodal atrial muscle
conducts impulses from SA to atria
AV bundle
conducts impulses rapidly between SA & bundle branches
left & right bundle branches
split off from AV bundle; conduct impulses to purkinje fibers on both sides of heart
purkinje fibers
large fibers that conduct impulses to ventricular myocardium
the cardiac muscle is…
a whorled network
electrocardiogram (ECG,EKG)
recording of electrical changes that occur in the myocardium during the cardiac cycle; used to asses the heart’s ability to conduct impulses
deflections/waves of EKG
- p wave
- qrs complex
- t wave
p wave
atrial depolarization; occurs just prior to atrial contraction
qrs complex
3 waves; ventricular depolarization; occurs just prior to ventricular contraction
t wave
ventricular depolarization; occurs just prior to ventricular relaxation
what normally controls heart rate?
SA node
what modifies the heart rate in response to changing conditions
sympathetic & parasympathetic fibers
parasympathetic impulses
vagus nerve, decreased heart rate, acts on SA/AV
sympathetic impulses
accelerator nerves, increased heart rate, acts on SA/AV
