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Cardiovas
cular
System
DAY 1 – C H A P T E R 1 5
General Information
General
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Size: approximately the size of two clasped
fists
Location: in the mediastinum - the cavity in
the center of the chest
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Lies slightly to the left of the midline
Fun Facts
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The first heart cell starts to beat as early as 4-6
weeks
The blue whale has the largest heart – 1500
lbs.
Roughly 1.5 gallons of blood get pumped
every minute
Your heart beats about 100,000 times a day
Surrounding Layers of the Heart
Pericardium
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Double layered sac
Contains roughly half an ounce of pericardial fluid which works to
reduce the friction of the beating heart; lubrication
Fibrous layer: outer layer made of dense connective tissue
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Protects and anchors heart to surrounding structures
Serous layer: creates the pericardial cavity where pericardial fluid is
held; two layers
 Outer: parietal pericardium
 Inner: visceral pericardium
(epicardium)
Surrounding Layers of the
Heart
 Myocardium: cardiac
muscle; thicker on left
side of the heart
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Contractions allow for
movement of blood
 Endocardium: lining
of heart chambers;
squamous epithelial
tissue continuous with
the lining of the blood
vessels
Chambers of the Heart
Atria
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2 upper chambers of heart; thin
walls, smooth inner surface
Responsible for receiving blood
Right atrium receives
deoxygenated (oxygen poor)
blood from the body through
the superior and inferior vena
cava
Left atrium receives oxygenated
(oxygen rich) blood from the
lungs through the pulmonary
veins
Chambers of the Heart
Ventricles
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2 lower chambers of the heart;
thicker walls, irregular inner
surface
Responsible for pumping blood
away from the heart
Left wall 3x as thick as right wall;
forms apex of heart
Right ventricle sends
deoxygenated blood to the lungs
via the pulmonary arteries
Left ventricle sends oxygenated
blood to all parts of the body via
the aorta
Heart Valves
 Tough fibrous tissue between the heart chambers and major
blood vessels of the heart
 Gate-like structures to keep the blood flowing in one
direction and to prevent regurgitation or backflow of blood
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Atrioventricular (AV) valves:
Tricuspid valve: between the right atrium and the right ventricle (right
heart)
 Bicuspid/mitral valve: between the left atrium and the left ventricle (left
heart)
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Semilunar Valves: 3 half moon pockets that catch blood and balloon
out to close the opening
Pulmonary semilunar valve: between the right ventricle and the
pulmonary arteries (right heart)
 Aortic semilunar valve: between the left ventricle and the aortic
arch/aorta (left heart)
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Accessory Structures of the Heart
 Septum: muscular wall dividing
the heart into right and left
halves
 Papillary muscles: located in the
ventricles; attach to the cusps of
the atrioventricular valves
(mitral/tricuspid valves) via the
chordae tendineae and contract to
prevent inversion or prolapse of
these valves
 Ligamentum Arteriosum: cord
of tissue that connects the
pulmonary trunk and the aorta
and that is the remnants of the
ductus arteriosus
Blood Vessels
 3 major types of blood vessels:
 Arteries
 Veins
 Capillaries
 There are over 60,000 miles
of blood vessels in the
human body.
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There are approximately 300 million
capillaries in the human body
Anatomy of Blood Vessels
Three coats (tunics):
1. Tunica intima: endothelium
lines the interior of vessels;
decreases friction as blood
flows
2. Tunica media: smooth muscle
& elastic tissue (dilates &
constricts vessels)
3. Tunica externa: fibrous
connective tissue (collagen) on
outside supports and protects
vessels
Arteries
 Carry blood AWAY from the heart
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Overall, smaller in diameter, have thicker walls in
proportion to their lumen (opening) and carry
blood under higher pressure than veins
 All BUT pulmonary arteries carry
oxygenated blood
 Aorta: largest artery; 1 inch in diameter
 Arterioles: connect arteries to capillaries
 Coronary arteries: very important; supply
blood to the heart muscle
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Left and right main coronary artery
Left coronary artery - left anterior descending, left
circumflex branch
 Right coronary artery - right atrium and right
ventricle
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Veins
 Carry blood TOWARD the heart
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Generally larger in diameter, carry more
blood volume and have thinner walls in
proportion to their lumen.
Layers much thinner, less elastic
 All BUT pulmonary veins carry
deoxygenated blood
 Series of internal valves that work
against the flow of gravity to
prevent reflux
 Superior and inferior vena cava:
largest veins (2 cm diameter)
 Venules: connect veins to
capillaries
Capillaries
 Tiny, microscopic vessels
 Diameter = 5-10
micrometers
 Walls one cell layer thick
 Function: to transport
and diffuse essential
materials to and from the
blood to surrounding
tissues of the body
 Allow for exchanges to
occur between arteries
and veins
Great Vessels
 Superior and inferior vena
cava: receive deoxygenated
blood from all parts of the
body
 Pulmonary arteries: carry
deoxygenated blood to the
lungs from the right ventricle
 Pulmonary veins: carry
oxygenated blood to the left
atrium from the lungs
 Aorta: carries oxygenated
blood to distribute to all parts
of the body
Cardiovascular
System
DAY 2 ~ H OW T H E S Y S T E M W O R K S
Arteries
Capillaries
Veins
• Blood away
from heart
• Oxygenated
blood, except
for pulmonary
arteries
• Thicker walls
• Small lumen
(opening)
• Withstand
higher pressure
• Walls 1-cell
thick
• Diffusion
• Microscopic
• Exchange gases
between blood
and tissue cells
• Blood back to
heart
• Thinner walls
• Deoxygenated
blood, except for
pulmonary veins
• Low pressure
• Large lumen
• Valves: prevent
blood backflow
• Skeletal muscles
enhance venous
return
Auricle
 Auricles: small, cone-shaped,
muscular pouches that are
attached to the anterior, outerwalls of the atria
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Both auricles help their respective
atria hold more blood; essentially
serve as reservoirs
Increase blood volume
Prevents over-filling and increased
size of atria
 The anterior interventricular
sulcus separates the ventricles
of the heart
Cardiovascular Circulations
 Pulmonary circulation: transport of blood from the right
side of the heart to the lungs and then back to the left side
of the heart
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Right atrium  Right ventricle  pulmonary arteries  lungs 
pulmonary veins  left atrium
 Systemic circulation: transport of blood from the left side
of the heart to all parts of the body and then back to the
right side of the heart
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Left atrium  Left ventricle  Aorta  arteries  body tissues 
capillary exchange  veins  inferior/superior vena cava  right
atrium
 Coronary circulation: transport blood from the left side of
the heart to the heart tissues and back to the right side of
the heart
How the Heart Works
Each heartbeat has two phases, systole (sis-tuhl-lee) when the heart pumps
and diastole (dye-as-tuhl-lee) when the heart chambers fill with blood.
1. Blood enters the right atrium from the body via the vena cava.
2. It travels through the tricuspid valve into the right ventricle.
3. A systolic heartbeat sends the blood through the pulmonary valve,
which separates the right ventricle and the pulmonary artery, to the
lung.
4. In the lung, oxygen is delivered to red blood cells and carbon dioxide, a
waste product of metabolism, is removed.
5. The oxygenated blood returns to the left atrium where it travels through
the mitral valve into the left ventricle.
6. The systolic heartbeat also causes the left side of the heart to contract
and send the blood through the aortic valve that separates the left
ventricle and the aorta.
7. Blood passes through the aorta to the body delivering oxygen to the
body's tissues.
Heart Sounds
 When the AV (atrioventricular) and semilunar valves close, they
make the sound heard as “lub-dub”
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First sound (S1): ventricles are contracting and forcing blood to
the lungs and entire body (AV valves closing)
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Duller, longer in duration, and softer than S2
Second sound (S2): atria are contracting
and the semilunar valves are closing
 Abnormal heart sounds = murmur;
valve pathology (M1, M2)
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Regurgitation through the mitral valve is
by far the most commonly heard murmur
Stenosis of the aortic valve is typically the next most common
heart murmur
Vital Signs
 Pulse: expansion & recoil of an
artery with each beat of left
ventricle; equivalent to
measuring heartrate
 A person’s pulse may be taken in
any place that allows an artery to
be compressed against a bone:
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Neck: carotid artery
Elbow: brachial artery
Wrist: radial artery
Groin: femoral artery
Behind the knee: popliteal artery
 Normal resting: 70-76 beats/min
Vital Signs
 Blood pressure:
vessels
pressure of blood on inner walls of blood
 Systolic pressure: measures the pressure in the arteries when the
heart beats (when the heart muscle contracts)
 Diastolic pressure: measures the pressure in the arteries between
heartbeats (when the heart muscle is resting between beats and refilling with
blood)
 Written: Systolic/Diastolic
Homeostatic Imbalances
 Hypertension: high blood pressure
(>140/90)
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Damage to and weakening of blood vessels
Heart damage – thickening of muscle;
enlarged heart
 Hypotension: low blood pressure
(<90/60)
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Heart/brain damage – not enough oxygen to
carry out normal functions
Causes: blood loss, dehydration, lack of
nutrition severe medical issues
 Atherosclerosis: artery walls thicken due
to fatty deposits (plaques)
Veins vs. Arteries
 Veins are easier to access due to their superficial
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location; arteries are located deeper under the skin.
Veins have thinner walls (less smooth muscle) than
arteries, and have less innervation, so piercing them
with a needle requires less force/doesn't hurt as much
Venous pressure is lower than arterial pressure, less of
a chance of blood seeping back out through the
puncture point before it heals.
Veins tend to be larger than the corresponding artery
in the area, so they hold more blood, making
collection easier
Safer to use veins  blood flow in veins always goes
to larger and larger vessels, so there is very little
chance of a vessel being blocked by the embolism
(bubble in blood) before the bubble reaches the
heart/lungs
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Blood flow in an artery always moves into smaller and smaller
vessels, eventually ending in capillaries
Primary Veins for Medical
Use
 When donating blood or
providing blood for
sampling, various arm
veins are used
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Median Cubital
Cephalic
Basilic
Vericose Veins
 Causes: heredity, obesity,
pregnancy, long periods
of standing/inactivity
 Blood pools in feet and
legs
 Valves weaken  veins
become twisted & dilated
 Treatment: compression
stockings, exercise, laser
treatment, surgery
Congenital Heart Disease
 Defects in the heart that occurred
during embryologic and fetal
development
 Involves defective communication
between the chambers, malformation
of valves, and malformation of septa
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Cyanotic: inability of individual to get
adequate blood oxygenation due to extensive
cardiac abnormalities that cause blood to be
shunted away from lungs
 Approximately 40,000 children are
born with a heart defect each year in
the U.S.
Congestive Heart Failure
 Progressive weakening of heart
 Low heart efficiency 
circulation inadequate to meet
tissue needs
 Caused by:
 Coronary atherosclerosis
 Persistent high blood pressure
 Multiple heart attacks – scar
tissue
Circulation Issues
Stroke
Heart Attack
 Issue with coronary
circulation; blockage, damage
 When the plaque is hard, the
outer shell cracks, platelets
come to the area, and blood
clots form around the plaque
 If a blood clot totally blocks
the artery, the heart muscle
becomes "starved" for oxygen.
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Within a short time, death of
heart muscle cells occurs, causing
permanent damage.
Over 1 million people in the U.S.
suffer from a heart attack
 A stroke occurs when the
blood supply to part of your
brain is interrupted or severely
reduced, depriving brain tissue
of oxygen and nutrients.
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Within minutes, brain cells begin
to die.
 Stroke is the leading cause of
serious, long-term disability in
the U.S.
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Each year, approximately 795,000
people suffer a stroke.
Bypass Surgery
 Common surgery needed
for alleviating blocked
coronary circulation
 During surgery, a blood
vessel is removed or
redirected from one area of
the body and placed
around the area or areas of
narrowing in order to
"bypass" the blockages and
restore blood flow to the
heart muscle.
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This vessel is called a graft.
These substitute blood vessels
can come from your chest,
legs, or arms.
Stent Procedure
 A stent is a wire mesh stainless steel
tube that holds an artery open
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It becomes a permanent part of the artery
 Tiny, flexible plastic tube called a
catheter inserted through an artery
in the groin, leg, or arm.
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A special dye is injected so blood flow
through the arteries is visible on
monitors.
 Balloon catheter, and then a stent, is
moved to the site of the blockage.
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The balloon is inflated and stretched wide
against the artery walls, which opens the
blockage.
Then the balloon is deflated and taken
out, leaving the stent in place.