Unit 11
The Heart
Introduction
The heart is the pump that
keeps blood moving around a
closed circuit of blood
vessels. It beats over
100,000 times a day.
The Heart
I. Location, Size, Position
The heart is located between
the lungs in the lower
Mediastinum – a subdivision
of the thoracic cavity
The Heart
I. Location, Size, Position
2/3 of the heart is to the left
of the mediastinum
1/3 of the heart is to the
right of the mediastinum
The Heart
I. Location, Size, Position
The heart is:
- triangular shaped
- size of a closed fist
- Positioned between
sternum and thoracic
vertebrae
The Heart
II. Apical Pulse
Heard at the apex of the
heart.
Landmark – between 5th & 6th
rib on a line even with the
midpoint of left clavicle
Apex of heart
The Heart
III. Heart Chambers
A. Atria – “receiving chambers”
- two upper chambers (right
& left)
- Smaller than ventricles
- Thinner less muscular
walls
The Heart
III. Heart Chambers
B. Ventricles – “discharging
chambers”
- two lower chambers (right
& left)
- Thicker more muscular
walls
The Heart
IV. Structures of the heart
A. Myocardium – cardiac
muscle in walls of each heart
chamber
The Heart
IV. Structures of the heart
B. Septum – tissue between
atria (interatrial septum) or
ventricular (interventricular
septum) chambers
The Heart
IV. Structures of the heart
C. Endocardium – thin inner
lining of each chamber
The Heart
IV. Structures of the heart
D. Pericardium – covering of
the heart; made of two
layers:
Visceral pericardium - inner
Parietal pericardium - outer
The Heart
IV. Structures of the heart
D. Pericardium – pericardial
fluid serves as a lubricant to
prevent friction between
layers
The Heart
V. Heart Action
The heart is a muscular
pumping device
Systole – contraction of heart
Diastole – relaxation of heart
The Heart
V. Heart Action
The atria contract first
pushing blood into the
ventricles. Once ventricles
fill they contract and push
blood out of heart.
The Heart
VI. Heart Valves
The heart has 4 valves. Two
valves separate the atria
from the ventricles
Atrioventricular Valves (AV)
The Heart
VI. Heart Valves
Atrioventricular Valves
1. Bicuspid (Mitral) Valve –
Located between the left
atrium and left ventricle
The Heart
VI. Heart Valves
Atrioventricular Valves
2. Tricuspid Valve –
Located between the right
atrium and right ventricle
The Heart
VI. Heart Valves
Atrioventricular Valves
Function of AV Valves –
Prevent backflow of blood
when ventricles contract
The Heart
VI. Heart Valves
Two valves separate the
ventricles and large arteries.
They open and close at the
same time.
Semilunar Valves
The Heart
VI. Heart Valves
1. Pulmonary Semilunar Valve
located at the beginning of
the pulmonary artery
The Heart
VI. Heart Valves
1. Pulmonary Semilunar Valve
Function – 1. allow blood
going to lungs to flow out of
right ventricle 2. Prevents
backflow of blood in ventricle
The Heart
VI. Heart Valves
2. Aortic Semilunar Valve
located at the beginning of
the aorta
The Heart
VI. Heart Valves
2. Aortic Semilunar Valve
Function – 1. Allows blood to
flow out of left ventricle into
aorta 2. Prevents backflow of
blood in ventricle
The Heart
VI. Heart Valves - Disorders
Incompetent Valves – blood
leaks back into chamber
which it came from due to
faulty or incompetent valve
The Heart
VI. Heart Valves - Disorders
Stenosed Valves – valves are
narrower than normal,
slowing blood flow from heart
chamber
The Heart
VI. Heart Valves - Disorders
Rheumatic Heart Disease –
Streptococcal infection
affecting the heart valves.
Occurs more often in children
and can cause permanent
heart damage.
The Heart
VI. Heart Valves - Disorders
Mitral Valve Prolapse (MVP)–
Usually genetic, but can be
from infection. Valve flap
does not close properly
causing leaking. One of
every 20 people have MVP.
The Heart
VI. Heart Valves - Disorders
Heart Murmurs are abnormal
heart sounds caused by
abnormalities in the heart
valves
The Heart
VI. Heart Valves - Disorders
Most damaged heart valves
can be repaired surgically
and in some cases animal or
artificial valves can be used.
The Heart
VII. Heart Sounds
There are 2 distinct heart
sounds in every heart beat
“Lub-Dub”
The Heart
VII. Heart Sounds
The first sound“Lub” is
caused by the closure of the
AV valves during the systole
phase of the ventricles
The Heart
VII. Heart Sounds
The second sound“Dub” is
caused by the closure of the
semilunar valves during the
diastole phase of the
ventricles
The Heart
VIII. Blood Flow Through Heart
The heart acts as 2 separate
Pumps:
• Right Atria and Ventricle
• Left Atria and Ventricle
The Heart
VIII. Blood Flow Through Heart
1. Venous blood enters right
atrium from superior and
inferior vena cava
The Heart
VIII. Blood Flow Through Heart
2. Passes from right atrium
to right ventricle by way of
the tricuspid valve
The Heart
VIII. Blood Flow Through Heart
3. Leaves right ventricle by
way of semilunar valve
into pulmonary artery
which takes blood to lungs
The Heart
VIII. Blood Flow Through Heart
The Pulmonary Artery is the
only artery in the body that
carries deoxygenated blood
The Heart
VIII. Blood Flow Through Heart
4. Blood returns to left
atrium via pulmonary vein
the blood is oxygenated
The Heart
VIII. Blood Flow Through Heart
The Pulmonary Vein is the
only vein in the body that
carries oxygenated blood
The Heart
VIII. Blood Flow Through Heart
5. Passes from left atrium to
left ventricle by way of the
bicuspid (mitral) valve
The Heart
VIII. Blood Flow Through Heart
6. Leaves left ventricle by
way of aortic semilunar
valve into aorta
The Heart
VIII. Blood Flow Through Heart
7. The aorta distributes blood
to the rest of the body by
way of arteries, arterioles,
capillaries, venules, veins
and back to the heart.
Heart
Blood Circulation
Through
Body
The Heart
IX. Conduction System
There are four structures
that generate impulses
causing the atria and
ventricles to contract
The Heart
IX. Conduction System
1. Sinoatrial Node (also
known as the SA node or
the “pacemaker”)
2. Atrioventricular Node
(AV Node)
The Heart
IX. Conduction System
3. AV Bundle of His
4. Purkinje Fibers
The Heart
IX. Conduction System
Order of Conduction
1. SA Node - (atria)
2. AV node - (atria)
3. Bundle of His (ventricles)
4. Purkinje Fibers (ventricles)
The Heart
X. Diseases
Coronary Heart Disease
Myocardial Infarction –
“Heart Attack” – vessel in
heart is not being
oxygenated normally due
to blockage of coronary
artery
The Heart
X. Diseases
Coronary Heart Disease
Angina Pectoris – chest
pain caused by a lack of
oxygen to the heart
muscle. Treatment Nitroglycerin
The Heart
X. Diseases
Cardiac Arrhythmia
Arrhythmia – a heart beat
without regular rate or
rhythm
The Heart
X. Diseases
Cardiac Arrhythmia
Bradycardia –
Pulse rate less than
60 beats/min
The Heart
X. Diseases
Cardiac Arrhythmia
Tachycardia –
Pulse rate greater than
100 beats/min
The Heart
X. Diseases
Cardiac Arrhythmia
Fibrillation – Heart beating
erratically, without any
rhythm and not fully
contracting, hence blood
flow is not adequate – life
threatening
The Heart
X. Diseases
Heart Failure
Cardiomyopathy –
diseases of the myocardial
tissue
The Heart
X. Diseases
Heart Failure
Cor Pulmonale –
Right-sided heart failure,
usually results from
untreated left-sided heart
failure
The Heart
X. Diseases
Heart Failure
Congestive Heart Failure –
“CHF” Left-sided heart
failure, fluid backs up into
the lungs because the
heart is not able to pump
effectively
The Heart
XII. Tests For Heart
Electrocardiogram – EKG
or ECG. A graphic record
of the heart’s electrical
activity
The Heart
XII. Tests For Heart
Electrocardiogram
Depolarization – Electrical
activity triggers
contraction of heart
muscle
The Heart
XII. Tests For Heart
Electrocardiogram
Repolarization – Begins
before relaxation phase of
cardiac muscle
“recharging” the heart
muscle
The Heart
XII. Tests For Heart
Three normal findings:
1. P-Wave
2. QRS Complex
3. T-Wave
The Heart
XII. Tests For Heart
Three normal findings:
1. P-Wave
depolarization/contraction
of atria
The Heart
XII. Tests For Heart
Three normal findings:
2. QRS Complex
depolarization/contraction
of ventricles
The Heart
XII. Tests For Heart
Three normal findings:
3. T-Wave
repolarization/relaxation
of ventricles
End of Lecture