cardiovascular physiology 2 Flashcards
what does the ECG look like when patient has premature ventricular contractions?
at some point instead of a P wave a new QRS and T wave appears
what causes for premature ventricular contraction?
abnormal site will dire an AP
the beat produced by the abnormally fired AP is called what?
ectopic beat
what may cause for an abnormal site to produce an AP?
-clot formation in Arterie
what happens if the patients then enters sinus tachycardia and heart beats 5x per second?
o Heart doesn’t have time to fill since time of contraction is too slow thus no blood is being pumped in/out
what is the cardiac output if no blood gets pumped in/out
zero
what happens if the cardiac output and pressure and sroke volume are = 0?
ventricular fibrillation
what do the ventricles look like during v fibrillation and why?
like a bag of worms become APs get fired from anywhere
what happens if treatment is not recieved within 5 minutes of V fibrillation?
death
what is used to treat v fibrillation?
defibrillation of the heart using AED
what portion of the heart gets observed during mapping of cardiac electrical activity?
apex of the heart
what does mapping of cardiac electrical activity involve?
o Insert catheters which open into the heart on the epicardial where electrons are deflected
in patients who have already had a heart attach what is being tested by electrical cardiac mapping? how is it tested?
circular path known as reentry. due to presence of scar tissue. induce of ventricle tachycardia in patient
what can be observed through electrical mapping when a patient goes from VT to Vfib?
refractory period due to difference of speed causes for different afferents to propagate
cardiac cells are full of what type of cells?
actin and myosin
what induces contraction in the heart?
calcium which diffuses from T tubules to the cytosol this allows for transition from electrical signal to contraction
in excitation-contraction coupling, what enters the cardiac cells when an AP is fired?
Ca2+
with the entry of calcium into the heart what is released and what does this cause?
more calcium gets released and this causes contraction of the heart
how is contraction of the heart induced?
binding of calcium to actin and myosin
is contraction evaluted in ECGs?
no
how does the heart cycle function?
cyclic process
what happens during systole
pressure in RA is quite small causing for the ventricles to begin to contract
Pv > Pa causing for AV valves to close and semilunar valves
pressure in ventricles increases until Pv > Paorta
opening of aortic valve and blood enters pulmonary trunk
what happens during diastole?
muscles relax as pressure falls
Paorta > Pav valve
P pulmonary trunk > P RV causes for the semilunar valves to close
pressure falls near 0
during this time the atrium has been filling with deoxigenated blood from SVC/IVC where Patrium > P ventricle
what is the name of the phase when Patrium > P ventricle
ventricular filling phase