The document includes an overview and in-depth information on the ventricular volume changes, and pressure changes during systole and diastole and the different phases and heart sounds and ECG in the cardiac cycle.
Topic: The Cardiac
Cycle
FLGX 317:
CARDIOLOGY
Questions Notes
Define the following terms: Systole: period of ventricular contraction blood ejection
Systole, diastole, isovolumetric Diastole: period of ventricular relaxation and blood filling
ventricular contraction, Isovolumetric ventricular contraction: First part of systole; ventricles
ventricular ejection, stroke contract but all valves in the heart are closed and so no blood is
volume, ejected
isovolumetric relaxation, Ventricular ejection: increasing pressures in the ventricles exceed that
ventricular filling of in the aorta and pulmonary trunk- and so they valves open blood is
W. p. 380-381. forced out of the ventricles into the aorta and trunk as the ventricular
muscles fibers shorten.
Stroke volume: volume of blood ejected from each ventricle during
systole
Isovolumetric relaxation: First part of diastole; ventricles relax and
aortic and pulmonary valves close, AV valves are also closed; thus no
blood is leaving or entering the ventricles and thus ventricular volume
is unchanged.
Ventricular filling: AV valves open and blood flows from the atria-
atrial contraction at the end of diastole.
What is the relationship ECG show P,Q,R,S,T waves which are electrical voltages generated
between the ECG by the heart and recorded on the ECG.
(electrocardiogram) and the P wave is caused by the spread of depolarization through the atria and
cardiac cycle? G. p. 114. is followed by atrial contraction
QRS wave appear after 0.16 secs which is caused by electrical
depolarization of the ventricles-initiate contraction of the ventricles
and cause ventricular pressure to rise-thus begins slightly after
ventricular systole.
T wave represents stage of repolarization of ventricles- when
ventricular muscle/fibers begin to relax; thus occur before the end of
, ventricular contraction
Discuss the function of the a) Ventricles fill with blood during diastole.
ventricles as a pump under the
following headings:
a) How do the ventricles fill? during ventricular systole; blood accumulates in the atriums as
AV valves are closed
b) What is the period of low diastolic values and increased pressures in the atria cause
isovolumetric contraction? AV valves to open
and blood flows into the ventricles
c) What is the period of lasts first third of diastole
ejection? during middle third, only little blood flows -blood from veins
empty into ventricles
d) What is the period of during last third; atria contract and last bit flows into
isovolumetric relaxation? ventricles.
20% of filling during each heart cycle.
e) What is the end-diastolic
volume, end-systolic volume b) Period of isovolumetric contraction is
and the ejection fraction?
f) What is the function of the after ventricular contraction; ventricular pressure rises abruptly
valves? AV closes
0.02-0.03 sec needed for pressure build-up to push semilunar
g) What is the relationship valves open
between the heart sounds and contraction in ventricles occur, but no emptying
the cardiac cycle? muscle tension is increasing but no muscle fibers are
W. p. 380-384. shortening
G. p. 113-114.
c) Ventricular pressure is when:
pressure in ventricles rise(L=80 mm Hg & R=8 mmHg)
semilunar( aortic and pulmonary) valves open
blood pours out of ventricles
70% flows out during first third
30% in nest two thirds
first third- period of rapid ejection
last two thirds: period of slow ejection
d) Period of Isovolumetric relaxation:
end of systole, ventricles relax
intraventricular pressure decrease rapidly
large arteries are filled with blood from the contracted
ventricles
semilunar valves close shut
0.03-0.06 sec ventricular muscles relax
ventricular volume is unchanged
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