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
what interval marks the start of atrial depolarization to start ventricular depolarization
what happens a the P-Q interval
what happens at the Q-T interval
time from beginning of vent. depol. to end of vent. repol.
what is bradycardia
too slow heart beat
what is tachycardia
too fast heart beat
what is fibrillation
SA node lost control of heart rhythm
purpose of artificial pacemaker
generate AP
what is cardiac cycle
all the events associated with one heartbeat
what is systole
contraction of atria and ventricles
what is diastole
relaxation of atria and ventricles
what pressure gradient does blood flow by
high to low
what is EDV end diastolic volume
how much blood left in ventricle after rest
what is iso-volumetric contraction
contraction of ventricle with valves closed and no volume change
what is ESV end systolic volume
how much blood left in ventricle after systole
what is iso-volumetric relaxation
ventricles relax, valves close, no volume change
normal EDV in ml
EDV = ~ 130 ml
normal ESV in ml
ESV = ~ 50 ml
what is dicrotic notch
breif drop in aortic pressure with backflow and semilunar valve closes
what is the formula for stroke volume
EDV - ESV = stroke volume
[130] - [50] = [80ml]
what is stroke volume
EDV - ESV = SV
L vent ejects ~ 80 ml blood into aorta
R vent into pulmonary trunk
during one heartbeat/cardiac cycle
what is iso-volumetric relaxation
all valves closed
ventricular myocardium relaxed
ventricular pressure > atrial pressure
when does ventricular filling occur
when atrial pressure > ventricular pressure
what is auscultation
listening to heart with stethoscope
what is heart murmur
valve problems, regurgitation of blood
what is the formula for cardiac output
HR * SV = CO
what is the average cardiac output and the formula
HR * SV = CO
75 * 80 = 6L/min
what is cardiac reserve
[exercise CO] - [resting CO] = cardiac reserve
athletes have higher cardiac reserves
function of autonomic NS
regulates heart rate and strength of contraction
input and output of cardiovascular center in medulla oblongata
input: higher brain centers and sensory receptors
output: cardioacceleratory center (sympathetic) and cardioinhibitory (parasympathetic via vagus)
↑ sympathetic activation results in…
↑ HR and contraction force
faster relaxation
release NE and ↑ Na+ entry → faster depol
what is atrial reflex
if ↑ in venous return, right atrium stretched and cardioaccelatory center stimulated
result of NE, Epi, and thyroid hormone
↑ HR and contractility
what is preload
how much stretch of cardiac muscles before contraction
what is contractility
force of contraction heart muscle fibers
what is afterload
pressure that must be overcome for the ventricles to eject blood
result of ↑ preload and contractility
↑ SV
result of ↑ afterload
↓ SV
what is the Frank-Starling principle
“more in - more out”
↑ EDV = ↑ SV
what are positive inotropic agents
factors that ↑ contractility
what are negative inotropic agents
factors that ↓ contractility
left-side heart failure result…
pulmonary congestion (edema)
right-side heart failure result…
peripheral congestion (edema)
