Transcript Cardiovascular System

Cardiovascular System
Basic Overview of Blood
Vessels
MAIN FUNCTION: Transport O2, CO2, and
nutrients around the body
• Arteries and arterioles (carry blood away
from the heart)
• Veins and venules (carry blood towards the
heart)
• Capillaries (where nutrients and O2 diffuse
into your body tissues and cells)
The Chambers of the Heart
• Consists of 4 chambers
• Pumping chambers are the
ventricles:
- Right ventricle
pumps blood to lungs
- Left vent. pumps
blood to rest of body
• Receiving chambers are the atria
-right atrium receives O2
poor blood from the body
- left atrium receives O2 rich
blood from lungs
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The Valves of the Heart
• Consists of 4 main valves to prevent
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the backflow of blood
Semi-lunar valves are where blood is
pumped out of the heart into major
arteries
- Pulmonary semilunar valve
(right side)
- Aortic semilunar valve (left
side)
AV valves between atria and
ventricles (tricuspid on right, mitral
(aka bicuspid) on the left)
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Coronary Blood Vessels
• Coronary arteries
•
supply myocardium
(heart muscle) with
oxygen and nutrients
Heart attacks occur
when a blockage
occurs in a coronary
artery
Anatomy of Blood Vessels
Contain three layers (tunics):
• Tunica interna (intima) - inner layer
in contact with blood which contains
the endothelium that lines the interior
of all vessels
• Tunica media - muscular layer
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• Tunica externa (adventitia) - mostly
collagen (also elastin) to reinforce
vessel (nerves and lymphatic vessels
also invade this layer)
Blood Pressure
Definition: The force exerted on a vessel wall
by the bloodstream.
• Usually refers to pressure in arteries closest to
the heart
• Pressure is higher during systole (contraction of
ventricles) and lower during diastole (relexation
of ventricles)
• Typical pressure 120/80 (systolic/diastolic)
Some Factors Affecting Blood
Pressure
• Cardiac Output: amount of blood pumped from the
ventricles per minute
• Peripheral Resistance: opposition to blood flow in
blood vessels away from the heart (blood viscosity, blood
vessel length and diameter affect resistance)
• Blood volume: amount of fluid in the blood stream at
any given time
*Baroreceptors (sensory neurons) in arterial walls monitor
blood pressure and send signals to the vasomotor
centers in the medulla to regulate changes in BP (see
figure 19.8 on pg. 727)
Hypertension
(high blood pressure)
Why is it dangerous?
• Heart must work harder to
pump against a greater
resistance (can lead to heart
failure - weakening of the left
ventricle)
• More peripheral resistance
damages endothelium (inner
walls) of arteries and can
damage small blood vessels
in many organs (kidneys,
eyes for ex.)
• Chronic HBP: 140/90 or
greater
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Atherosclerosis
• Disease of the arterial
•
•
wall caused by the
formation of plaques
Cholesterol is deposited
by LDL particles in areas
of damaged endothelium
(1st step in plaque
formation)
When plaques rupture,
blood clots form leading
to blockage of small
arteries
Lipoproteins and Cholesterol
• Lipoproteins are molecules that
carry cholesterol to and from
tissues (are produced in the liver)
• LDL (low density - BAD) particles
carry cholesterol to the tissues
(excess cholesterol ends up in
arterial walls forming plaque)
• HDL (high density - GOOD)
particles take cholesterol from
tissues and blood vessels and
bring it to the liver for disposal
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Conduction System of Heart
• SA node (pacemaker of heart)
in right atrium
• Sends signals to AV node (also
in right atrial wall)
• Signals travel down septum of
heart via Bundle of His
• Signal then travels to
ventricular walls via Purkinje
fibers
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ECG (electrocardiogram)
a.k.a EKG
• Shows electrical
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excitation of cardiac
conduction system
P wave - atrial
depolarization
QRS wave ventricular
depolarization
T wave - ventricular
repolarization
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The Blood
Blood Composition
• Blood consists of:
1) Plasma - mostly
2)
3)
water, soluble
proteins
Erythrocytes (red
blood cells)
Buffy coat
(Leukocytes (white
blood cells),
platelets)
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The Three Formed Elements
• Erythrocytes (Red Blood Cells) transports O2 and CO2 in the blood
• Leukocytes (White Blood Cells) - help
to defend the body against foreign
invaders and cancer cells
• Platelets - function in hemostasis
(coagulation or clotting of blood)
* All are produced during hematopoiesis
in red bone marrow
Erythrocytes (RBC)
• Carry respiratory gases (oxygen and CO2) in
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the blood
Hemoglobin protein binds O2 (see figure 17.4)
Live about 120 days - old RBCs are broken
down in liver, spleen and bone marrow
Contribute to blood viscosity (more RBC
means “thicker” blood)
Erythropoietin (hormone released by
kidneys) stimulates RBC production or
erythropoiesis (see figure 17.6 in book)
Blood antigens and antibodies
• Antigens (also called agglutinogens) are
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proteins on cell membranes that identify the
cell as belonging to that person
Antibodies, or agglutinins (proteins that can
attach to antigens) also circulate in the blood
A, B, and Rh antigens are used in blood
typing and transfusions
Transfusion of the wrong blood type results in
agglutination (clumping of blood cells as they
are attacked by antibodies) and hemolysis
(destruction of erythrocytes)
Table 17.4 pg 668
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Universal
recipient
Universal
donor