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Chapter 13 - Cardiovascular
System
heart and blood vessels
Systemic
Circulation –
delivers blood to
all body cells and
carries away
waste
Pulmonary
Circulation –
eliminates
carbon dioxide
and oxygenates
blood (lung
pathway)
Structure of the Heart
Heart Size – about 14
cm x 9 cm (the size of a
fist).
Located in the
mediastinum (space
between lungs,
backbone, sternum),
between the 2nd rib and
the 5th intercostal
space.
The distal end of the
heart is called the apex.
Fibrous Pericardium encloses the heart (like
a bag) and has 2 layers
• visceral pericardium (inner)
• and parietal pericardium (outer, attached
to diaphragm, sternum and vertebrae)
Pericardial cavity – contains fluid for the
heart to float in, reducing friction
Wall of the Heart
Epicardium – outer layer, reduces friction
Myocardium – middle layer, mostly cardiac
muscle
Endocardium – thin inner lining, within chambers
of the heart
Heart Chambers & Valves
• Your heart is a double pump. Circulation
is a double circuit: Pulmonary (lungs
only) and systemic (rest of the body)
• Heart has 4 chambers:
2 Atria – thin upper chambers that receive blood
returning to the heart through veins.. Right and
Left Atrium
o 2 Ventricles – thick, muscular lower chambers.
Receive blood from the atria above them. Force
(pump) blood out of the heart through arteries.
Right and left ventricle.
o
• Septum – separates the right and left sides of
the heart
• Valves of the Heart – allow one-way flow
of blood.
4 total
• (2 Atrioventricular Valves (AV) & 2
Semilunar valves)
Left Atrioventricular valve – also called the
bicuspid valve or mitral valve. Between left atrium
and ventricle
o Right Atrioventricular valve – also called the
tricuspid valve. Between right atrium and ventricle
o
• Aortic Semilunar – or just aortic valve.
Between the left ventricle and the aorta
• Pulmonary Semilunar, or just pulmonary
valve. Between the left ventricle and the
aorta
Mitral = bicuspid (left side)
Tricuspid (right side)
Aortic and Pulmonary are
both semilunar valves
Path of Blood Flow
!
Check your labels!
Name the
valves
(#5 is not a
valve)
1 Pulmonary Valve
2 Tricuspid Valve
3 Mitral (Bicuspid)
Valve
4 Aortic Valve
5 Heart Apex
Heart Actions
• Cardiac Cycle: One complete heartbeat. The
contraction of a heart chamber is called
systole and the relaxation of a chamber is
called diastole.
http://www.youtube.com/watch?v=r32VObKw0gY
The cusps (flaps) of the bicuspid and tricuspid
valves are anchored to the ventricle walls by fibrous
“cords” called chordae tendineae, which attach to
the wall by papillary muscles. This prevents the
valves from being pushed up into the atria during
ventricular systole.
Can you identify
these parts?
1. Right Atrium
2. Right Atrioventricular Valve
(Tricuspid Valve)
3. Right Ventricle
4. Left Atrium
5. Left Atrioventricular Valve
(Mitral Valve)
6. Left Ventricle
7. Papillary Muscle
8. Chordae Tendinae
9. Mitral Valve cusps
Heart Sounds - Opening and Closing of Valves,
"Lub Dub"
Heart Sounds – opening and
closing of the valves, flow of
blood into and out of the
chambers, vibrations in
muscle
Stethoscope - instrument to
listen and measure heart
sounds
• Lub – closing of the A-V valves
• Dub – closing of the semi-lunar valves
Stenosis – not opening all the way
Regurgitation – not closing properly
• http://www.youtube.com/playlist?list=PL83
8882952CEE772E
Cardiac Conduction
Sinoatrial Node (S-A
Node) (Pacemaker)
Atrioventricular Node
(A-V Node)
A-V Bundle
Perkinje Fibers
Can you identify
these parts?
1. Sinoatrial Node
(Pacemaker)
2. Atrioventricular
Node
3. Atrioventricular
Bundle (Bundle
of His)
4. Left and Right
Bundle
branches
5. Purkinje Fibers
What is an EKG?
• How do we get that pattern?
ECG (EKG??)–
electrocardiogram – a recording of the
electrical events (changes) during a cardiac cycle
The instrument used to record an EKG is an
electrocardiograph.
Why do we do this?
•
•
•
•
To determine if:
Conduction pathway is normal
Heart is damaged
Certain regions are damaged
Interpreting ECGs
An ECG is printed on paper covered with a
grid of squares.
Notice that five small squares on the paper
form a larger square. The width of a single
small square on ECG paper represents 0.04
seconds. (know this number)
A common length of an ECG printout is 6
seconds; this is known as a "six second
strip."
Rules to remember:
• Depolarization precedes contraction
• Repolarization precedes relaxation
P Wave – depolarization of the atria (atrial contraction –
systole)
(spreads from S-A node throughout both atria)
QRS Complex – depolarization of the
ventricles (ventricular contraction, systole)
(spreads throughout ventricles)
T wave - Represents ventricular repolarization –
just before ventricles start to relax
The shape indicates that it is a slow
process.
Does something seem to be
missing?
Analyze an ECG
Each one of the figures represents
an ECG pattern displaying three
types of abnormal rhythms:
Arrhythmia
Tachycardia
Bradycardia
Identify each.
Other Abnormalities
• Enlarged P – enlargement of an atrium
possibly due to mitral stenosis
• Enlarged Q wave – MI
• Enlarged R wave – ventricular hypertrophy
• EKG lab
Regulation of Cardiac Cycle
controlled by the cardiac center within the
medulla oblongata. The cardiac center
signals heart to increase or decrease its rate
according to many factors that the brain
constantly monitors.
Muscle Activity
Body Temperature
Blood ion levels (potassium & calcium)
Cardiac Output
Cardiac Output = Stroke Volume x Heart
Rate
Defibrillator
common treatment for lifethreatening cardiac arrhythmia
The device shocks the heart and
allows it to re-establish its
normal rhythm
The device can also be used to
start a heart that has stopped.
13.4 BLOOD VESSELS
Blood Vessels: arteries, veins, capillaries
ARTERIES : strong elastic vessels which carry blood
moving away from the heart. Smallest ones are arterioles
which connect to capillaries.
VEINS - Thinner, less muscular vessels carrying blood
toward the heart.
Smallest ones are called venules which connect to
capillaries. Contain valves.
Capillaries: Penetrate nearly all tissues. Walls are composed
of a single layer of squamous cells – very thin. Critical function:
allows exchange of materials (oxygen, nutrients) between blood
and tissues.
Control of Blood Flow:
Precapillary sphincters – circular, valve-like muscle at
arteriole-capillary junction
Vasoconstriction – narrowing blood vessel’s lumen
(“passageway”
Vasodilation –
explanding blood
vessel’s lumen
•Blood flow through veins
– not very efficient. Slow,
weak “pushing” by arterial
blood pressure is not
much of a factor at all.
Important factors include:
•Contraction of the
diaphragm.
•Pumping action of the
skeletal muscles
•Valves in the veins
Blood Clots can occur if blood does not flow properly through the
veins - can occur if a person does not move enough
Factors affecting blood pressure:
Average is
120/80 (higher number is the systolic pressure)
1.
Cardiac Output
2.
Blood volume (5 liters for avg adult)
3.
Blood Viscosity
4.
Peripheral Resistance
Cardiac output =
stroke volume x
heart rate
Major Blood Vessels
Aorta - Ascending Aorta, Aortic Arch, Descending Aorta,
Abdominal Aorta. The aorta is the largest artery. (leaves left
ventricle)
Pulmonary Trunk – splits into left and right, both lead to the
lungs (leaves left ventricle)
Pulmonary Veins – return blood from the lungs to the heart
(connects to left atrium)
Superior and Inferior Vena Cava – return blood from the head
and body to the heart (connects to right atrium)
•Disorders of the Circulatory System
•MVP - mitral valve prolapse, the mitral valve does not close
all the way; this creates a clicking sound at the end of a
contraction.
•Heart Murmurs – valves do not close completely, causing an
(often) harmless murmur sound. Sometimes holes can occur
in the septum f the heart which can also cause a murmur
•
•Myocardial Infarction (MI) - a blood clot obstructs a coronary
artery, commonly called a “heart attack”
•Atherosclerosis – deposits of fatty materials such as cholesterol form a
“plaque” in the arteries which reduces blood flow. Advanced forms are
called arteriosclerosis. Treatment: Angioplasty, where a catheter is
inserted into the artery and a balloon is used to stretch the walls open.
A bypass can also treat clogged arteries, a vein is used to replace a
clogged artery. Coronary bypass refers to a procedure where the
coronary artery is bypassed to supply blood to the heart. (The phrase
“quadruple bypass” means that 4 arteries were bypassed.)(Mayo Clinic)
•. Hypertension – high blood pressure, the force within the arteries is
too high. A sphygmomanometer can be used to diagnose hypertensiona
Stent and