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Ch. 13 – Cardiovascular/Circulatory System
I.
Introduction
A.
The blood vessels form a closed tube
that carry 7,000 liters of blood away from
the heart, to the cells, and back again
B.
Vessels – 5 types
1.
the heart pumps blood thru
arteries, then to smaller arterioles,
to tiny capillaries
 Arteries are thick vessels
adapted for carrying high-pressure
blood away from the heart
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2.
3.
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capillaries are the sites of nutrient,
electrolyte, gas, & waste exchange
capillaries return blood to small
venules, then onto larger veins
 Veins are thinner than arteries &
return blood to the heart
Pg. 338
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This is what happens when blood is drawn from a
deeper artery, rather than a superficial vein
C.
Two Circuits
1.
Pulmonary Circuit – sends
deoxygenated blood to lungs (to pick
up O2 and drop off CO2)
2.
Systemic Circuit – sends oxygenated
blood and nutrients to all body cells
and removes wastes
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Pg. 324
II.
Structure of the Heart
A.
The heart is a hollow,
muscular pump within
the thoracic cavity
B.
Coverings of the Heart Pg. 325
1.
Pericardial sac encloses the heart
a.
fibrous pericardium - outer,
tough connective tissue
b.
parietal pericardium - lines
fibrous pericardium
2.
visceral pericardium (epicardium) –
surrounds the heart
3.
pericardial cavity – fluid filled space
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b/t sac & v.p. to reduce friction
C.
Wall of the Heart – 3 layers
1.
Epicardium - outermost layer made of
connective tissue; houses capillaries,
coronary arteries, & cardiac veins
2.
Myocardium – thickest, middle layer
that consists of cardiac muscle
3.
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Pg. 326
Endocardium inner layer;
lines inside of
heart
D.
Pg. 331
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Heart Chambers
1.
The heart has 4 chambers –
2 atria & 2 ventricles
a.
Atria receive blood
returning to the heart and
have thin walls & flap-like
auricles projecting from
their exterior
b.
The thick-walled ventricles
pump blood to the body
2.
Each also has an atrioventricular
(A-V) valve to ensure one way flow
of blood
3.
A septum divides the atrium &
ventricle on each side
E.
Path of Blood through the Heart
Deoxygenated Blood
Oxygenated Blood
 Superior & Inferior
vena cava
 Right atrium
 Tricuspid valve
 Right ventricle
 Pulmonary Valve
 Pulmonary trunk
 2 Pulmonary arteries

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Capillaries of LUNGS 
 4 Pulmonary veins
 Left atrium
 Bicuspid/Mitral
valve
 Left ventricle
 Aortic valve
 Aorta

Cells of the Body
1.
A-V valves open & close using chordae
tendinae (heart strings), attached to
papillary muscles
 Valves prevent backflow of blood into atria
Pulmonary & Aortic valves are also known as
Semi-Lunar valves, due to their crescent
shapes
2.
Pg. 328
Pg. 329
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http://goo.gl/ugRY04 (Blood Flow)
Circulatory System rap!
F.
Blood Supply to the Heart Muscle
1.
Coronary arteries feed the heart
muscle (myocardium) with O2, from
the aorta
Pg. 331
2.
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Cardiac veins drain CO2-ridden
blood from the myocardium & carry it
to the superior and inferior vena cavae
III. Heart Actions
A.
Blood pressure is the force of blood against
the inner walls of arteries (120/60)
 systolic pressure over diastolic pressure
B.
The cardiac cycle consists of:
1.
Atria beating in unison (atrial systole)
2.
Contraction of both ventricles
(ventricular systole = systolic pressure)
3.
The entire heart relaxes for a moment
(diastole = diastolic pressure)
C.13 - 11 Pulse - ventricle contraction felt in arteries
D.
Heart Sounds – due to vibrations in heart
tissues as blood rapidly changes velocity
within the heart
1.
Heart sounds can be described as
"lubb-dupp" sounds or “Korotkoff”
sounds
2.
“lubb” occurs as ventricles contract
(Tricuspid & Bicuspid valves close)
3.
“dupp” occurs as ventricles relax
(Pulmonary & Aortic valves close)
LISTEN:
http://goo.gl/ugRY04
http://goo.gl/bv7gDi
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IV. Cardiac Conduction System
A.
A few clumps of cardiac muscle tissue
initiate & distribute impulses through the
myocardium, from 1 intercalated disk of a
cardiac muscle cell to the next disk
B.
Sinoatrial (S-A) Node – a pacemaker
1.
a small, elongated mass of tissue
beneath the epicardium
2.
located in the R-atrium, near the
opening of the superior vena cavae
3.
w/o outside agents, the nodal cells
spread impulses to cause the heart
to contract
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C.
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Path of Stimulation
1.
S-A node sends impulse & the atria
contract simultaneously, sending
blood into the ventricles
2.
The impulse then travels
to the atrioventricular (AV) node & onto the A-V
bundle at the top of the
septum
3.
About halfway down the
septum, the A-V bundle
branches into Purkinje
Pg. 334
fibers
4.
Purkinje fibers spread to papillary
muscles that form whorls in the walls
of the ventricles
5.
Pg. 334
When impulses
reach Purkinje
fibers, the
ventricles contract
with a twisting
motion, forcing
blood into the
aorta and
pulmonary trunk
LOOK & LISTEN:
Cardiac Conduction & Sounds
http://goo.gl/ugRY04
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Arrhythmias http://goo.gl/rsLwlJ
D.
Electrocardiogram (ECG or EKG)
1.
a recording of the electrical changes
that occur in the myocardium during a
cardiac cycle
Pg. 335
2.
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body fluids can conduct electrical
currents, so such changes can be
detected on the surface of the body
3. Patterns
 P wave:
depolarization of atrial
fibers that lead to atrial
contraction
 QRS complex: when
rapid depolarization in
ventricular fibers comes
to an end (at the same
time, atrial fibers
repolarize, but are
immeasurable)
 T wave: repolarization
Time b/t intervals can
signal heart problems of ventricular muscle
fibers
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Pg. 335