Heart
The heart pumps blood, which creates
pressure, and circulates oxygen,
nutrients, and other substances.
Heart Information
Cardiology is the study of the heart
 In the embryo, the heart begins to beat
at 4 weeks
 The heart beats 100,000 times a day
 The heart is located in the thoracic
cavity between the lungs, and above the
diaphragm.

Cont.
Is located mediastinally within chest
 The location makes CPR possible
 Is about the size of the person’s closed
fist
 The heart is composed of cardiac
muscle

Pericardial Membranes
The pericardium is a triple layered sac that
surrounds and protects the heart
2 portions
•
Fibrous- (pericardial sac) tough, loose fitting
sac that prevents stretching, provides
protection
•
Serous- delicate membrane that forms
double layers around heart
a. parietal
b. epicardium
Pericardial Membranes
Serous fluid, which prevents friction as
the heart beats, is between the parietal
and epicardium layers of pericardium
 Pericarditis is the inflammation of this
fluid

Layers of the heart
1.
2.
3.
4.
5.
Fibrous
Parietal
Epicardium- outermost
Myocardium- responsible for pumping
(heart muscle)
Endocardium- provides smooth lining
for inside of heart
4 chambers of the heart
1.
2.
3.
4.
Right atrium
Left atrium
Right ventricle
Left ventricle
The two superior chambers are the
left/right atrium
The two inferior chambers are the
left/right ventricle
Cont.
Auricle- are found on each atria and
increase size and volume (ear shaped)
 Coronary sulcus- are external grooves
that separate the atria from the
ventricles, and contain coronary blood
vessels

Myocardium is the muscle of the heart
 The chambers are lined with
endocardium, which is a smooth tissue
that prevents abnormal blood clotting

The interatrial septum is an internal wall
that separates the atria
 The interventricular septum is an
internal wall that separates the
ventricles
 Fossa ovalis- remnant of fetal heart
opening found in right atrium

Right Atrium
Receives blood from the upper body by
way of the superior vena cava and
receives blood from the lower body by
way of the inferior vena cava.
 The tricuspid valve prevents the
backflow of blood into the right atrium

Right ventricle
When the right ventricle contracts, the
tricuspid valve closes, and the blood is
pumped to the lungs through the
pulmonary artery
 The flaps of the pulmonary semilunar
valve close to prevent the backflow of
blood into the right ventricle

Right ventricle
The right ventricle has columns of
myocardium(muscle) called papillary
muscles.
 The chordea tendineae, extend from the
papillary muscle to the flaps of the
tricuspid
 The chordea tendineae prevent the
inversion of the tricuspid valve

Left atrium

The left atrium receives blood from the lungs,
by way of four pulmonary veins.
 This blood then flows into the left ventricle
through the bicuspid valve
 The bicuspid valve prevents backflow of
blood from the left ventricle to the left atrium
when the left ventricle contracts.
 Another function is to produce the hormone
ANH (atrial natriuretic hormone) which lowers
blood pressure
Left ventricle
The walls of the left ventricle are thicker
than those of the right ventricle, which
enables the left ventricle to contract
more forcefully.
 The left ventricle pumps blood to the
body through the aorta, the largest
artery of the body.

Left ventricle
The chordae tendineae anchor the
bicuspid valve of the left ventricle
 At the junction of the aorta and the left
ventricle is the aortic semilunar vavle.
 The aortic semilunar valve closes when
the left ventricle relaxes, to prevent the
backflow of blood from the aorta to the
left ventricle

Heart summary

The heart is really a double, or two sided
pump.
 The right side of the heart receives
deoxygenated blood from the body and
pumps it to the lungs to pick up oxygen and
release carbon dioxide.
 The left side of the heart receives oxygenated
blood from the lungs and pumps it to the
body.
 Both pumps work simultaneously, both atria
contract together, followed by the contraction
of both ventricles.
Coronary circulation
Coronary circulation is the flow of blood
through the vessels of the myocardium
 Coronary arteries supply blood
 Coronary veins drain (greater, middle)
 Ischemia- when part of the myocardium
is deprived of blood

Coronary vessels

Prolonged ischemia will create an infarct, and
an area of necrotic (dead) tissue. Commonly
known as a heart attack.
Cardiac OutPut
Cardiac Output is the amount of blood
pumped by a ventricle in 1 minute
 Stroke Volume is the amount of blood
pumped per beat
 Starling’s Law of the Heart states that
the more cardiac muscles are stretched,
the more forcefully they contract

Cardiac cycle



Cardiac cycle is the simultaneous
contraction of the two atria, followed
.20 second later by the simultaneous
contraction of the ventricles.
1% of cardiac muscle fibers become
autorhythmic cells (generate action
potentials)
These cells form the conduction
system for the heart
Cardiac Conduction pathway
1.
2.
3.
4.
SA node- found in right atria
AV node- found in atria septum
Bundle of His- found between atria
and ventricles
Purkinje fibers- found in apex of
ventricles
Cardiac cycle
Systole is another term for contraction.
 Diastole is another term for relaxation.

Heart sounds
Each heartbeat produces four sounds,
two are heard lubb-dupp
 The first sound lub, the loudest and
longest, is caused by the closing of the
AV valves.
 The second sound dup, is caused by
the closure of the aortic and pulmonary
semilunar valves.

Heart sounds

If any valves do not close properly, an
extra sound called a heart murmur may
be heard.
Heart rate
A healthy adult has a resting heart rate
(pulse) of 60 to 80 beats per minute,
which is the rate of depolarization of the
SA node.
 A rate of less than 60 (except for
athletes) is called bradycardia; a rate
greater than 100 beats is called
tachycardia.

Heart rate
A child’s normal heart rate may be as
high as 100, that of a infant may be as
high as 120, and that of a near term
fetus as high of a 140 beats per minute.
 These higher rates are not related to
age, but to rather to size; the smaller
the individual the faster the rate.

Regulation of heart rate
The medulla of the brain regulates the
heart rate; it contains the two cardiac
centers, the accelerator, and the
inhibitory center.
 Pressoreceptors in the aortic sinus
detect changes in blood pressure.
 Chemoreceptors in the aortic body
detect changes in the oxygen content of
the blood.

Electrocardiogram


1.
2.
A ECG is a recording of action potentials
produced by the myocardium during each
heart beat
A ECG consist of three waves
P wave-small upward wave, that represents
atrial depolarization
QRS complex- represents the
depolarization of the ventricles
- large Q indicate myocardial infarction
- enlarged R indicates enlarged ventricles
- flatter T indicates insufficient O2 to heart
muscle
ECG
3. T wave- represents the repolarization of the
ventricles.
Risk Factors in Heart Disease
Smoking- Nicotine enters blood stream
and constricts small blood vessels,
which elevates pressure
 Obesity- have extra capillaries in
adipose tissue (200 mi), more work
 High blood pressure- causes the left
ventricle to enlarge

Treatments
Hypothermia- slows metabolism and
reduces needs of tissue
 Heart transplant- 50 to 1
 Cardiac assist
- Cardiomyoplasty- wrapping heart in
muscle
- LVAD- implanted in abdomen
- Hemopump- propeller like pump

Aging and the heart
Heart muscle becomes less efficient
with age.
 Atherosclerosis, hypertension, and
arrhythmias become more common.

Astherosclerosis
Areas where there are a build up
cholesterol plaques in the coronary
artery. These areas narrow the artery
and increase the risk of clot formation,
reducing the flow of oxygen.
 Predisposing risk are cigarette smoking,
diabetes mellitus, and high blood
pressure (genetics).
 Can be treated with angioplasty or
bypass

Arrhythmias

Are irregular heartbeats caused by damage
to part of the conduction pathway.
 Palpitations are non-serious irregular
heartbeats, and may result from too much
caffeine, nicotine, or alcohol.
 Flutter is a very rapid but fairly regular
heartbeat.
 Fibrillation is a very rapid and uncoordinated
ventricular beat that is totally ineffective for
pumping blood (V-fib)
Rheumatic Fever

An infection caused by Streptococcus
bacteria that inflames the heart
damaging the valves by stretching