Heart The & Circulation
Heart pumps
over 1 million
gallons per
year
Over 60,000
miles of blood
vessels
BLOOD VESSELS AND
CIRCULATION
The circulatory system is a series
of blood vessels, or hollow tubes,
that begin and end in the heart.
The circulatory system delivers
blood to all the cells in the body
and then returns it to the heart.
Structure of the Circulatory System
Structure
Two Circulations
1. The pulmonary
circulation carries
blood from the right
ventricle to the lungs
and to the left
atrium. The
pulmonary
circulation
oxygenates the
blood.
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Structure of the Circulatory System
2. The systemic
circulation
supplies blood to
the rest of the body
and then returns
the blood to the
heart.
HEART
The heart pumps blood throughout the blood
vessels
supplies the cells of the body with
oxygen and nutrients
carries away the waste products of
metabolism.
Structure of the Heart: What It Is
Location and Size
1.
The heart is the size of a fist. It is located
within the mediastinum, and lies toward the left
side of the body.
2
Heart Orientation
The Hearts Chambers and Large Vessels
Heart
1.
2.
3.
4.
5.
The heart has four chambers:
two atria and two ventricles.
The atria receive the blood
and the ventricles pump the
blood.
The right atrium receives
blood from the vena cava.
The right ventricle pumps
unoxygenated blood to the
lungs.
The left atrium receives blood
from the lungs (pulmonary
veins).
The left ventricle pumps
blood into the aorta.
Heart Valves
Purpose:
Keeps blood flowing in a forward direction.
1.
Two atrioventricular valves:
the tricuspid valve (right heart)
(mitral) valve (left heart)
2.
The two semilunar valves:
pulmonic valve (right heart)
aortic valve (left heart).
The cusps, or flaps, of the AV valves
are held in place by tough fibrous
bands called chordae tendineae.
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Heart Valves
Heart Valves
Heart Sounds
Auscultation
Stethoscope
Sounds of heartbeat are from
turbulence in blood flow caused by
valve closure
first heart sound (lubb) is created with the
closing of the atrioventricular valves
second heart sound (dupp) is created
with the closing of semilunar valves
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Heart Sounds
Where to listen on chest wall for heart sounds.
2. The heart is supported by a slinglike structure called the pericardium.
Fibrous pericardium
dense irregular CT
protects and anchors the heart, prevents overstretching
Serous pericardium
thin delicate membrane
contains
parietal layer-outer layer
pericardial cavity with pericardial fluid
visceral layer (epicardium)
The Hearts Layers and Coverings
The Heart
The heart is composed of three layers of tissue.
1.
2.
3.
The endocardium
innermost lining of the heart
shiny and smooth surface.
The myocardium
thick middle layer of the heart
composed of muscle tissue.
enables the heart to pump blood.
The epicardium
outermost layer of the heart.
continuous with the inner lining of the pericardium (sling).
forms the pericardial space.
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6
Blood Supply to the Myocardium
Branches off aorta above
aortic semilunar valve
Left coronary artery
circumflex branch
anterior interventricular art.
in coronary sulcus, supplies
left atrium and left ventricle
supplies both ventricles
Right coronary artery
marginal branch
in coronary sulcus, supplies
right ventricle
posterior interventricular
art.
supplies both ventricles
Blood Supply to the Myocardium
Marginal
branch
(anterior interventricular art.)
(posterior interventricular art.)
A Double Pump and Two Circulations
1.
The right heart pumps blood to
the lungs for oxygenation. This
process is the pulmonary
circulation.
2.
The left heart pumps blood
throughout the rest of the body.
This process is the systemic
circulation.
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Pathway: Blood Flow Through the Heart
1.
The right heart receives blood from
the vena cava and pumps it to the
lungs for oxygenation. The left heart
receives oxygenated blood from the
lungs and pumps it to the systemic
circulation.
2.
Blood flows in this sequence
through the following structures:
right atrium tricuspid valve
right ventricle pulmonic valve
pulmonary artery pulmonary
capillaries (lung) pulmonary
veins left atrium bicuspid
(mitral) valve left ventricle
aortic valve aorta capilaries
superior & inferior vena cava /
coronary sinus right atrium
Coronary Veins
Collects wastes from cardiac muscle
Drains into a large sinus on posterior surface of heart
called the coronary sinus
Coronary sinus empties into right atrium
Functions of the Heart: What It Does
A. Conduction System
1.
The heart generates an electrical signal
(cardiac impulse) that moves throughout the heart
the electrical signal causes the myocardium to
contract.
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Functions of the Heart: What It Does
2. The cardiac impulse originates in the sinoatrial node (SA
node). The pathway followed by the cardiac impulse is: SA
node AV node bundle of His right and left bundle
branches (of His) Purkinje fibers.
Functions of the Heart: What It Does
Functions
3.
4.
Cardiac muscle displays automaticity and rhythmicity.
The electrical activity of cardiac muscle is recorded as
an electrocardiogram (ECG). The recordings include a P
wave (atrial depolarization), QRS complex (ventricular
depolarization), and T wave (ventricular of repolarization).
Functions the Heart: What It Does
Functions
B. Cardiac Cycle
1.
The cardiac cycle is the sequence of events that occur during one
heartbeat.
2.
The cardiac cycle has three stages: atrial systole (contraction),
ventricular systole, and diastole (relaxation).
3.
The heart chambers fill with blood during diastole and empty during
systole.
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Structure of the Circulatory System
Names of Blood Vessels
1. Arteries
carry blood away from
the heart
smallest arteries are the
arterioles.
2. Capillaries
the smallest and most
numerous of the blood
vessels.
There is a capillary close
to every cell in the body.
Structure of the Circulatory System
Structure
3. Veins
carry blood from the
cells back to the
heart.
Small veins are called
venules.
Structure of the Circulatory System
4. The sequence of blood
flow is: heart (left side)
arteries arterioles
capillaries venules
veins heart (right
side).
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Structure of Blood Vessels
Figure 21.2
The Function of Valves in the Venous System
Figure 21.6
Blood Vessels: What They Do
1. Arteries conduct blood
from the heart to the
organs and are called
conductance vessels.
2. The arterioles constrict
and dilate, thereby
determining resistance to
the flow of blood. The
arterioles are called
resistance vessels.
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Blood Vessels: What They Do
3. Capillaries are concerned
with the exchange of water
and dissolved substances
between the blood and tissue
fluid. Capillaries are called
exchange vessels.
4. Veins and venules return
blood to the heart from the
body. The veins also store
blood and are therefore
capacitance vessels.
Functions of the Circulatory System
Functions
The Circulatory System and Blood Pressure
1. The circulatory system maintains a blood
pressure to ensure an adequate flow of blood to
the body.
2. The normal blood pressure is 120/80 mmHg;
120 is the systolic reading
80 is the diastolic reading
Pulse pressure is the difference between the
systolic and diastolic reading (120 minus 80 =
40).
Functions of the Circulatory System
3. Blood pressure varies throughout the circulatory
system
BP highest in the aorta
lowest in the vena cava
normal blood pressure is the blood pressure in
a large artery.
4. Blood pressure determined by the action of the
heart and the blood vessels
Heart affects blood pressure by increasing or
decreasing heart rate or stroke volume
Blood vessels affect blood pressure by
constricting or dilating the arterioles.
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Functions of the Circulatory System
5.
Blood
pressure is
regulated on a
day-to-day
Functions of the Circulatory System
Renin-angiotensinaldosterone system
decrease in BP or
decreased blood flow to
kidney
release of renin / results in
formation angiotensin II
systemic vasoconstriction
causes release aldosterone
(H2O & Na+ reabsorption)
The Circulatory System and the Pulse
1. The pulse is due to the alternating expansion
and recoil of the artery creating a pressure
wave (similar to vibration).
2. The pulse is caused by the pumping of the
heart; pulse rate therefore reflects heart rate
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Pulse Points
An Overview of the Patterns of Circulation
Figure 21.20
The Pulmonary Circuit
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Pulmonary circuit consists of
pulmonary vessels
Arteries which deliver blood to the lungs
Capillaries in the lungs where gas exchange
occurs
Veins which deliver blood to the left atrium
The Pulmonary Circuit
Figure 21.21
Major Arteries of the Systemic Circulation
The major
arteries include
the aorta and the
arteries arising
from the aorta.
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Special Circulations
Circle of Willis
Blood supply to the head and brain.
The head is supplied by two sets of arteries:
the carotid arteries
the vertebral arteries.
The internal carotid arteries and the basilar arteries form the circle
of Willis.
Blood from the head and brain drains into the jugular veins.
Arteries of the Brain
Figure 21.25
Major Veins of the Systemic Circulation
The major
veins include
the venae
cavae and the
veins that
empty into
them.
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Veins of the Systemic Circulation
Drain blood from entire
body & return it to right
side of heart
Deep veins parallel the
arteries in the region
Superficial veins are
found just beneath the
skin
All venous blood drains
to either superior or
inferior vena cava or
coronary sinus
Liver Blood Supply
The blood supply to the
liver is composed of:
portal vein
hepatic artery
hepatic vein.
The hepatic artery brings
oxygen-rich blood to the
liver.
The portal vein carries
blood from the digestive
tract to the liver.
The hepatic vein carries
blood from the liver to the
inferior vena cava.
Arterial Supply and Venous Drainage of Liver
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Fetal Circulation
Fetal circulation has
several unique
features
Fetus uses the
placenta as lungs
Umbilical blood
vessels carry blood
between the placenta
and the fetus
Three special
structures:
ductus venosus
foramen ovale
ductus arteriosus.
Fetal Circulation
Figure 21.35a, b
Age-related changes in blood may include
Age Decreased hematocrit
Constriction or blockage of peripheral veins by a
thrombus
Pooling of blood in the veins of the legs
Vessels are less elastic, prone to Ca2+ deposits
and thrombi formation
The aging heart has reduced output, decreased
activity, and scarring
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