
A complete heartbeat in which the
heart chambers function in a
coordinated fashion
› Systole – heart chamber walls contract
› Diastole- heart chamber walls relax
Atrial systole (atria contracts) while
ventricles relax called ventricular diastole
 Then the ventricles contract (ventricular
systole) and atria relax (atrial diastole)
 Then the atria and ventricles both relax
for an interval


The cusps (flaps) of the
bicuspid and tricuspid
valves are anchored to
the ventricle walls by
fibrous “cords” called
chordate tendineae,
which attach to the wall
by papillary muscles. This
prevents the valves from
being pushed up into the
atria during ventricular
systole
Blood pressure rises in the ventricles,
forcing the aortic and pulmonary
valves(semilunar valves) open, while
closing the tricuspid and bicuspid valves
(A-V valves)
 This makes a lubb sound

The pulmonary and aortic valves are
closing, while the tricuspid and bicuspid
valves open to let blood flow from the
atria to the ventricles
 This makes a dubb sound


http://highered.mheducation.com/sites/
0072495855/student_view0/chapter22/a
nimation__the_cardiac_cycle__quiz_1_.h
tml
The heart normally makes a lubb dubb
sound.
 A heart murmur is a deviation from this
sound and is usually due to a valve’s
cusp not closing entirely, allowing blood
to backflow from the ventricle into the
atrium
 Ranges from harmless to requiring open
heart surgery

http://depts.washington.edu/physdx/he
art/demo.html
 Stethoscope – instrument to listen and
measure heart sounds


Electrocardiogram- recording of the
electrical charges that occur in the
myocardium during a cardiac cycle
› Electrodes are placed on the skin and
respond to weak electrical changes

P wave- atrial systole (contraction)
› Review: What valves are closed and which
are open?

QRS complex- Ventricle systole
(contraction)
› Review: Which valves are closed and which
are open?

T wave- repolarization of the ventricles
(resting period)
Controlled by the cardiac center in the
medulla oblongata
 Signals the heart to increase or decrease
heart rate depending on various factors

› Body temperature
› Muscle activity
› Blood Ca2+ & K+ levels
Tachycardia = rapid heartbeat ( > 100
BPM)
 Bradycardia = slow heartbeat ( < 60
BPM)
 Fibrillation = rapid, uncoordinated
unsynchronized heart rate. Atria (not
serious. Ventricles (deadly)

Common treatment for lifethreatening cardiac arrhythmia
 The device shocks the heart and allows it
to re-establish its normal rhythm
 The device can also be used to start a
heart that has stopped

Device used to measure blood pressure
 Average normal blood pressure = 120/80
 Average Heart Rate = 72
 http://www.sumanasinc.com/webconte
nt/animations/content/bloodpressure.ht
ml
