The Cardiovascular
System
Overview
► The
cardiovascular
system includes the
heart, which is the
pump that circulates
blood, and the blood
vessels, the highways
that carry blood up
and down the body.
The anatomy of the heart
► The
heart is hollow,
about the size of your
fist, and divided into
four main parts: Left
atrium, right atrium,
left ventricle, and right
ventricle.
► The heart is located in
the thoracic cavity.
Friction
► As
any two objects rub against each other,
they cause friction. To help solve that
problem we have the pericardium.
► The
pericardium is a serous sac that covers
the heart. This sac allows the heart to
pump with little resistance.
The heart itself
► The
heart contains three different layers of
tissue: the endocardium, the myocardium,
and the epicardium.
Epicardium
► The
epicardium is the
outermost layer of the
heart. It is a serous
membrane that acts to
reduce friction. There
is adipose tissue found
around the coronary
artery and the cardiac
veins.
The myocardium
► Thick
middle layer of
the heart.
► Rough and tough, has
a large supply of
capillaries that carry
blood and other
nutrients to this tissue.
endocardium
► Consists
of epithelial
tissue and connective
tissue.
► Contains blood vessels
and specialized
purkinje fibers (detects
cardiac impulses in the
A-V bundle).
The chambers and valves of the
heart
► The
upper two chambers of the heart are
called the atria.
► The lower two chambers of the heart are
called the ventricles.
► Separating the left atrium and ventricle from
the right ones is a solid mass of tissue
called the septum. It prevents blood on the
left side of the heart from mixing with blood
from the right side.
Septum
Atrium/ventricle separation
The tricuspid
► On
the right side of
the heart lies the
tricuspid, a three sided
valve that prevents the
blood that is pumped
from the right atrium
to the right ventricle
from coming back into
the right atrium.
Mitral valve
► Like
the tricuspid, the mitral valve prevents
blood from flowing backwards after the
atrium contracts.
► The mitral valve, also called the bicuspid, is
located between the left atrium and left
ventricle.
► The mitral valve contains two flaps instead
of three.
Pulmonary Valve
► Another
tricuspid shaped valve that is
located at the base of the pulmonary artery.
► Just like the other valves, it prevents the
blood from “backwashing” into the heart.
AORTA!
► The
aorta is the largest
artery in the entire
body. At around one
inch in diameter, it can
pump a massive
amount of blood.
► The first two arteries
that branch from the
aorta are the left and
right coronary arteries.
Path of blood through the heart
► 1.
Blood enters the right atrium through the
vena cava.
► 2. Right atrial wall contracts forcing blood
through the tricuspid valve and into the
right ventricle.
► 3. As the right ventricle contracts, blood is
forced through the pulmonary valve into the
pulmonary arteries.
► 4.
Blood exits pulmonary arteries and enters
the capillaries in the alveoli of the lungs.
Gas exchange occurs, and the blood now is
rich in oxygen.
► 5. Blood leaves the capillaries and enters in
the pulmonary veins.
► 6. After passing down the pulmonary vein,
blood reaches the left atrium.
► 7.
When the left atrial wall contracts, it
forces blood through the mitral valve and
into the left ventricle.
► 8. As the left ventricle contracts, the blood
is forced through the aortic valve into the
aorta where it travels throughout the body.
Listening to the heart
► When
hearing the heart beat in a
stethoscope, the louder first noise that is
heard is called ventricular contraction. That
is when the ventricles force the blood inside
them out through their respective arteries.
► The second noise is ventricular relaxation.
At this point the blood in the atrium is
forced into the relaxed ventricle during that
atrium’s contraction.
When to beat
► In
the heart, there are specialized tissues
that are designed to let certain parts of the
heart know when to contract. These tissues
comprise what is known as the cardiac
conduction system.
► The sinoatrial node is a bundle of such
tissue found at the top of the right atrium
by the superior vena cava.
► The
S-A node fires
regularly 70 to 80
times per minute.
► Another name for the
S-A node is the
pacemaker.
► The
impulse does not go directly through
the heart. It travels down specialized
cardiac muscle to the atrioventricular node.
► That signal that is received by the A-V node
and spread throughout the heart by the
purkinje fibers.
Blood Vessels
► The
blood vessels act
as the highway that
blood travels. The
arteries act as one
lane, the veins as the
other, and the
capillaries as their off
ramps.
Arteries
► Strong
and very
elastic.
► Arteries are designed
to take the force of the
blood pushing through
them.
► As they get smaller
and smaller, they are
referred to as
arterioles.
Inside the artery
► The
inner layer of the artery is called the
tunica interna, which is composed of simple
squamous cells. (single layer of flat cells)
► Surrounding the tunica interna is a layer of
connective tissue. On top of that is tunica
media which is the thickest part of the
artery.
► On top of that is the tunica extera which is
another thin layer of connective tissue.
Vasoconstriction and vasodilation
► Vasoconstriction-
When the muscle fibers in
the artery contract, lessening the blood
flow. (Good when cold)
► Vasodilation- When the muscle fibers relax,
increasing blood flow. (Good during a heart
attack)
Veins
►
►
►
►
Carry blood back to the
atria.
The vein is built similar to
the artery, however the
tunica media is very under
developed.
Less tissue means a
greater lumen (opening
where the blood flows)
Smaller veins are called
veinules.
Preventing backwash
► Most
veins contain these valve-like flaps on
them that once blood is forced through
them, they collapse and prevent blood from
flowing backwards.
Capillaries
► Smallest
blood vessels of all.
► Consists only of endothelium tissue.
► There are very tiny slits in the capillaries
that allow for gas and nutrient exchange
between the endothelial cells.
► Oxygen and nutrient rich blood cells will
give away their nutrients and oxygen while
picking up NH3 and CO2.
Blood Pressure
► Systolic
BP- The first number in a blood
pressure reading is the systolic blood
pressure. This measures the amount of
force that is thrust against the arteries
during ventricular contraction.
► Diastolic BP- the second number in a blood
pressure reading is the diastolic BP. This
measures the amount of pressure in the
arteries after the ventricular contraction.
► Normal
Systole- 110-120
 Normal high- 139-149
 High- 150 +
► Normal
diastole- 70-80
 Normal high- 90-109
 High- 110+
► Normal
Reading = 120/80
► High BP= 150/120
Paths of blood circulation
► Pulmonary
circuitblood circulation from
the heart to the lungs.
► Systemic circuit- blood
circulation from the
heart to every where
else in the body.
Major arteries
► Coronary
arteries- first arteries to branch off of the
aorta.
► Femoral arteries- runs down inside of thighs.
► Carotid artery- runs up the neck.
► Renal arteries- runs to the kidneys.
► Axillary arteries- runs to the arms.
► Illiac arteries- runs to the legs.
► Aorta- largest artery, takes blood from heart.
Major veins
► Axillary
veins- leads back from arms
► Femoral veins- leads back from the legs
► Renal veins- leads back from kidneys
► Superior vena cava- draws blood back from
upper half of body.
► Inferior vena cava- draws blood back from
lower half of the body.
Questions?