Chapter 20 [ EXAM #3 ] Flashcards
what is systematic circulation
oxygenated blood to body and deoxygenated from body to heart
what is pulmonary circulation
deoxygenated blood to lungs and oxygenated blood from lungs to heart
what is ventricular balance
right and left ventricles pump same amount of blood at same time
intercalated discs contain these two things…
desmosomes and gap junctions
function of desmosomes
prevents cell separation during contraction
function of gap junctions
ions and AP pass cell to cell
is cardiac metabolism aerobic or anaerobic
cardiac metabolism is aerobic
what is ischemia
ischemia is low oxygen levels in cardiac metabolism
cannot pump blood due to low ATP
function of autorhythmic cardiac fibers of conducting system
control and coordinate heartbeat automatically
depolarize on their own
function of contractile muscle fibers
powerful contractions
responsible for heart’s pumping activity
function and location of sinoatrial SA node
pacemaker (generates AP), right atrium
location of atrioventricular AV node
floor of right atrium
three conducting cells
AV bundle
bundle branches
Purkinje fibers
what is prepotential (pacemaker potential)
gradual depolarization towards threshold due to Na+ slowly entering ~-40mV
why does the SA node influence atrial muscle, AV node, and ventricular muscle?
the SA node is the fastest of the four ~100 BPM
what is vagal tone and its effect
continuous parasympathetic stimulation
brings 100BPM from SA node to 75BPM
what is the benefit to the delay caused by smaller AV node fibers in comparison to SA node fibers
atria finishes contraction forcing blood into ventricles before the ventricles contract
where does the impulse go to from the AV node
AV node to AV bundle
what causes rapid depolarization
VGSCs open
what causes the plateau
↑ Ca2+
↓ K+
what causes repolarization
K+ flows out of cell
what is the absolute refractory period
membrane will not respond to second stimulus after AP begins
what is long absolute refractory period
contractile fibers, until relaxation depolarization begins
what is an electrocardiogram ECG/EKG
record of all heart electrical activity reflecting all APs
what are the three waves on EKGs
p wave: atria depolarize
QRS complex: ventricles depolarize
t wave: ventricles repolarize
what happens at the P-Q interval
start of atrial depolarization to start ventricular depolarization