CHAPTER
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23The Cardiovascular
System
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23-2
Learning Outcomes
23.1 Describe the structure of the heart and the function of each part.
23.2 Trace the flow of blood through the heart.
23.3 List the most common heart sounds and what events produce them.
23.4 Explain how heart rate is controlled by the electrical conduction system of the heart.
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Learning Outcomes (cont.)
23.5 List the different types of blood vessels and describe the functions of each.
23.6 Define blood pressure and tell how it is controlled.
23.7 Trace the flow of blood through the pulmonary and systemic circulation.
23.8 List the major arteries and veins of the body and describe their locations.
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Learning Outcomes (cont.)
23.9 List and describe the components of blood.
23.10 Give the functions of red blood cells, the different types of white blood cells, and platelets.
23.11 List the substances normally found in plasma.
23.12 Explain how bleeding is controlled.
23.13 Explain the differences among blood types A, B, AB, and O.
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Learning Outcomes (cont.)
23.14 Explain the difference between Rh-positive blood and Rh-negative blood.
23.15 Explain the importance of blood typing and tell which blood types are compatible.
23.16 Describe the causes, signs and symptoms, and treatments of various diseases and disorders of the cardiovascular system.
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Introduction • The cardiovascular system consists of heart
and blood vessels
• Sends blood to– Lungs for oxygen– Digestive system for nutrients
• Also circulates waste products to certain organ systems for removal from the blood
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Structures of the Heart• Cone-shaped organ
about the size of a loose fist
• In the mediastinum • Extends from the
level of the second rib to about the level of the sixth rib
• Slightly left of the midline
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Structures of the Heart (cont.)
Heart is bordered: Laterally by the lungs Posteriorly by the vertebral
column Anteriorly by the sternum
Rests on the diaphragm inferiorly
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Structures of the Heart (cont.)
• Heart coverings– Pericardium
• Covers the heart and large blood vessels attached to the heart
• Visceral pericardium
– Innermost layer
– Directly on the heart
• Parietal pericardium
– Layer on top of the visceral pericardium
• Heart walls:– Epicardium
• Outermost layer• Fat to cushion heart
– Myocardium • Middle layer • Primarily cardiac muscle
– Endocardium • Innermost layer• Thin and smooth• Stretches as the heart
pumps
Click for Larger View
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Structures of the Heart (cont.)
• Four chambers– Two atria
• Upper chambers• Left and right• Separated by
interatrial septum
– Two ventricles• Lower chambers• Left and right• Separated by
interventricular septum
Click for View of
Heart
Atrioventricular septum separates the atria from the ventricles
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Structures of the Heart (cont.)
• Tricuspid valve – prevents blood from flowing back into the right atrium when the right ventricle contracts
• Bicuspid (mitral) valve – prevents blood from flowing back into the left atrium when the left ventricle contracts
• Pulmonary semilunar valve – prevents blood from flowing back into the right ventricle
• Aortic semilunar valve – prevents blood from flowing back into the left ventricle
Click for View of
Heart
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Blood Flow Through the Heart
Deoxygenated blood in from
bodyOxygenated blood
in lungs
Atria Contract Ventricles Contract
Deoxygenated blood out to lungs
Oxygenated blood out to
body
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Blood Flow Through the Heart (cont.)
Right Atrium
Right Ventricle
PulmonarySemilunar
Valve
Left Atrium
BicuspidValve
Left Ventricle
PulmonaryValve
TricuspidValve
LungsBody
AorticSemilunar
Valve
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Cardiac Cycle
• Right atrium contracts– Tricuspid valve opens – Blood fills right ventricle
• Right ventricle contracts– Tricuspid valve closes– Pulmonary semilunar valve
opens– Blood flows into pulmonary
artery
• Left atrium contracts – Bicuspid valve opens – Blood fills left ventricle
• Left ventricle contracts– Bicuspid valve closes– Aortic semilunar valve
opens– Blood pushed into aorta
One heartbeat = one cardiac cycle Atria contract and relax Ventricles contract and relax
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Cardiac Cycle (cont.)
• Influenced by– Exercise– Parasympathetic nerves– Sympathetic nerves– Cardiac control center– Body temperature– Potassium ions– Calcium ions
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Heart Sounds
• One cardiac cycle – two heart sounds (lubb and dubb) when valves in the heart snap shut– Lubb – first sound
• When the ventricles contract, the tricuspid and bicuspid valves snap shut
– Dubb – second sound • When the atria contract and the pulmonary and
aortic valves snap shut
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Cardiac Conduction System• Group of structures that send electrical impulses through
the heart
• Sinoatrial node (SA node)– Wall of right atrium– Generates impulse– Natural pacemaker– Sends impulse to AV node
• Atrioventricular node (AV node)– Between atria just above ventricles– Atria contract– Sends impulse to the bundle of His
• Bundle of His– Between ventricles– Two branches – Sends impulse to Purkinje
fibers
• Purkinje fibers– Lateral walls of ventricles– Ventricles contract
Click the i below for a Diagram
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Cardiac Conduction
System
Back
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Apply Your Knowledge
Match the following:
__ Tricuspid valve A. Two branches; sends impulse to Purkinje fibers
__ Bicuspid valve B. Covering of the heart and aorta
__ Pericardium C. Between the right atrium and the right ventricle
__ SA node D. In the lateral walls of ventricles
__ Bundle of His E. Natural pacemaker
__ Purkinje fibers F. Between the left atrium and the left ventricle D
A
E
B
F
C
ANSWER:
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Blood Vessels
• Closed pathway that carries blood from the heart to cells and back to the heart
• Types– Arteries– Arterioles– Veins
– Venules– Capillaries
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23-23
Arteries and Arterioles • Strongest of the
blood vessels• Carry blood away
from the heart• Under high pressure
– Vasoconstriction– Vasodilation
• Arterioles– Small branches of
arteries
• Aorta– Takes blood from the
heart to the body
• Coronary arteries– Supply blood to heart
muscle
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23-24
Veins and Venules • Blood under no pressure
in veins
– Does not move very easily
– Skeletal muscle contractions help move blood
– Sympathetic nervous system also influences pressure
• Valves prevent backflow
• Venules
– Small vessels formed when capillaries merge
• Superior and inferior vena cava
– Largest veins
– Carry blood into right atrium
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Capillaries• Branches of arterioles
• Smallest type of blood vessel
• Connect arterioles to venules
• Only about one cell layer thick
• Oxygen and nutrients can pass out of a capillary into a body cell
• Carbon dioxide and other waste products pass out of a body cell into a capillary
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Apply Your Knowledge
How do arteries control blood pressure?
ANSWER: The muscular walls of arteries can constrict to increase blood pressure or dilate to decrease blood pressure.
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Blood Pressure• Force blood exerts on the inner walls of blood vessels
– Highest in arteries – Lowest in veins
• Systolic pressure – Ventricles contract– Blood pressure in arteries is at its greatest
• Diastolic pressure – Ventricles relax– Blood pressure in arteries is at its lowest
• Reported as the systolic number over the diastolic number
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Blood Pressure (cont.)
• Control is based mainly on the amount of blood pumped out of the heart
• The amount of blood entering should equal the amount pumped from the heart
• Starling's law of the heart – Blood entering the left ventricle stretches the wall of the ventricle– The more the wall is stretched
• The harder it will contract and • The more blood it will pump out
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Blood Pressure (cont.)
• Baroreceptors – Also help regulate blood pressure
– Located in the aorta and carotid arteries
– High blood pressure in aorta message to cardiac center in brain decreases heart rate lowers blood pressure
– Low blood pressure in aorta message to cardiac center in the brain increases heart rate increases blood pressure
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Apply Your Knowledge
What is the difference between the systolic pressure and diastolic pressure?
ANSWER: Systolic pressure is the result of the contraction of the ventricles increasing the pressure in the arteries. Diastolic pressure is the result of the relaxation of the ventricles lowering the pressure in the arteries.
Good Answer!
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Circulation
• Pulmonary circuit right atrium right ventricle pulmonary artery trunk pulmonary arteries lungs
pulmonary veins heart (left atrium)
• Systemic circuitleft atrium left ventricle aorta arteries
arterioles capillaries venules veins vena cava heart (right atrium)
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Circulation (cont.)
• Arterial system– Carries oxygen-rich
blood away from the heart
– Pulmonary arteries carry oxygen-poor blood
– Paired – left and right artery of the same name
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Circulation (cont.)
• Venous system– Carries oxygen-poor
blood toward the heart
• Except pulmonary veins
– Most large veins have the same names as the arteries they are next to
Hepatic portal system Collection of veins
carrying blood to the liver
Click for Larger View
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Apply Your Knowledge
ARTERIES: Pulmonary arteries carry oxygen-poor blood.
Do pulmonary arteries carry blood with high levels of oxygen or low levels of oxygen?
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Blood
• A type of connective tissue
– Red blood cells (erythrocytes)
– White blood cells (leukocytes)
– Platelets – cell fragments
– Plasma – fluid part of blood
Average-sized adult has 4 to 6 liters of blood
Amount depends on: Size of person Amount of adipose tissue Concentrations of ions Females have less than
males
Average-sized adult has 4 to 6 liters of blood
Amount depends on: Size of person Amount of adipose tissue Concentrations of ions Females have less than
males
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Blood Components
• Hematocrit – The percentage of
red blood cells– Normal is about
45%
• White cells and platelets = 1%
• Plasma = 55% © Cre8tive StudiosAlamy RF
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Red Blood Cells• Erythrocytes • Transport oxygen throughout the body• Small biconcave-shaped cells • Hemoglobin is a pigment in RBCs
– Oxyhemoglobin carries oxygen; bright red – Deoxyhemoglobin does not carry oxygen; darker
red • Carries carbon dioxide, so also called carboxyhemoglobin
– Anemia – low RBC count• Erythropoietin – regulates production of
RBCs
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Red Blood Cells (cont.)
© Cre8tive StudiosAlamy RF
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White Blood Cells • Granulocytes
– Neutrophils (55%) –destroy bacteria, viruses, and toxins in the bloodstream (phagocytes)
– Eosinophils (3%) – get rid of parasitic infections such as worm infections
– Basophils (1%) – control inflammation and allergic reactions
• Agranulocytes– Monocytes (8%) – destroy bacteria, viruses, and
toxins in blood – Lymphocytes (33%) – provide immunity for the body
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White Blood Cells (cont.)
• WBC count normally 5000 to 10,000 cells per cubic millimeter of blood– Leukocytosis
• Elevated WBC count• Usually due to infection
– Leukopenia • Low WBC count• Some viral infections and other conditions
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Platelets
• Fragments of cells found in the bloodstream
• Also called thrombocytes • Important in the clotting process of blood• Normal count
– 130,000 to 360,000 platelets per cubic millimeter of blood
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Plasma• Liquid portion of blood
composed mostly of water
• Proteins– Albumins
• Smallest plasma proteins
• Pull water in to help maintain blood pressure
– Globulins – transport lipids and fat-soluble vitamins
– Fibrinogen – needed for blood clotting
• Nutrients– Amino acids– Glucose– Nucleotides– Lipids from the
digestive tract
• Gases – oxygen, carbon dioxide, and nitrogen
• Electrolytes• Waste products
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Bleeding Control• Hemostasis – the control of bleeding
• Three processes of hemostasis– Blood vessel spasm– Platelet plug formation– Blood coagulation
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Platelet plug formation:
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Blood Types
• Types are distinguished by antigens and antibodies
• Agglutination– Clumping of red blood
cells – Antigens on surface of
RBCs bind to antibodies in plasma
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Blood Types (cont.)
Blood Type Antigen Present
Antibody Present
Blood That Can Be Received
A A B A and O
B B A B and O
AB AB None A, B, AB, and O
O None A and B O
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Blood Types (cont.)
• Rh antigen – protein on RBCs
• Rh-positive– RBCs contain the
Rh antigen
• Rh-negative – RBCs do not contain
the Rh antigen
• Rh-positive blood is
given to Rh-negative person– Antibodies form
• If Rh-negative person receives more Rh-positive blood– Antibodies bind to the
donor cells – Agglutination occurs
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Apply Your Knowledge
True or False:
__ Hematocrit is the percentage of WBCs in the blood.
__ Neutrophils destroy bacteria, viruses, and toxins in the bloodstream.
__ Platelets are important to the clotting process.
__ Albumin is a small plasma protein that pushes water out of the bloodstream.
__ Hemostasis is the control of bleeding.
__ A person with type AB blood can only receive type AB blood.
__ Blood should be matched for Rh factor.
pulls water into
RBCs
receive any type of blood
T
T
F
T
F
T
F
ANSWER:
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Chest Pain
• Cardiac– Myocardial infarction– Angina– Pericarditis– Coronary spasm
• Non-cardiac– Heartburn– Panic attacks– Pleurisy– Costochondritis – Pulmonary embolism– Sore muscles– Broken ribs
Take all complaints of chest pain seriously!
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Chest Pain (cont.)
• Determine cause– Electrocardiogram– Stress tests– Blood tests– Chest x-ray– Nuclear scan– Coronary
catheterization– Echocardiogram – Endoscopy
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Diseases and Disorders of the Cardiovascular System
Disease Description
Anemia The blood does not have enough red blood cells or hemoglobin to carry an adequate amount of oxygen to the body’s cells
Aneurysm A ballooned, weakened arterial wall
Arrhythmias Abnormal heart rhythms
Carditis Inflammation of the heart
Endocarditis Inflammation of the innermost lining of the heart, including valves
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Diseases and Disorders of the Cardiovascular System (cont.)
Disease Description
Myocarditis Inflammation of the muscular layer of the heart
Pericarditis Inflammation of the membranes that surround the heart (pericardium)
Congestive heart failure
Weakening of the heart over time; heart is unable to pump enough blood to meet body’s needs
Coronary artery disease (CAD)
Atherosclerosis; narrowing of coronary arteries caused by hardening of the fatty plaque deposits within the arteries
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Diseases and Disorders of the Cardiovascular System (cont.)
Disease Description
Hypertension High blood pressure; consistent resting blood pressure equal to or greater than 140/90 mm Hg
Leukemia Bone marrow produces a large number of abnormal WBCs
Murmurs Abnormal heart sounds
Myocardial infarction
Heart attack; damage to cardiac muscle due to a lack of blood supply
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Diseases and Disorders of the Cardiovascular System (cont.)
Disease Description
Sickle cell anemia
Abnormal hemoglobin causes RBCs to change to a sickle shape; abnormal cells stick in capillaries
Thalassemia Inherited form of anemia; defective hemoglobin chain causes, small, pale, and short-lived RBCs
Thrombophlebitis
Blood clots and inflammation develop in a vein
Varicose veins
Twisted, dilated veins
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Apply Your Knowledge
ANSWER: Anemia is a condition in which a person does not have enough red blood cells or hemoglobin in the blood to carry an adequate amount of oxygen to body cells.
The doctor has told your patient she has anemia. How would you explain this to her?
Bravo!
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In Summary
23.1 The structures of the heart include the pericardium, epicardium, myocardium, and endocardium.
– The chambers of the heart consist of the upper atria and the lower ventricles.
– The septums are interatrial, interventricular, and atrioventricular.
– The four valves within the heart are tricuspid, bicuspid, pulmonary semilunar valve, and the aortic semilunar valve.
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In Summary (cont.)
23.2 Superior and inferior vena cavae → right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → pulmonary trunk → right and left pulmonary arteries → the lungs → pulmonary veins → left atrium → bicuspid valve →left ventricle → aortic semilunar valve → aorta → body organs and tissues.
23.3 Heart sounds are described as lubb dubb. Lubb is created when the ventricles contact and the tricuspid and bicuspid valves snap shut. Dubb occurs when the atria contract and the pulmonary and aortic semilunar valves snap shut.
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In Summary (cont.)
23.4 The sinoatrial node generates an impulse to the atrioventricular node. The AV node then sends the impulse to the bundle of His. The bundle splits into the left and right bundle branches and sends the impulse to the Purkinje fibers in the ventricles.
23.5 The arterial system is composed of the aorta, arteries, and arterioles (largest to smallest) bring blood from the heart to the body. The capillaries act as the connectors between the arterioles and venules. From the venules, blood returns to the heart via the veins to the superior and inferior vena cavae.
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In Summary (cont.)
23.6 Blood pressure is the force exerted on the inner wall of blood vessels by blood as it flows through vessels. It is highest in arteries and lowest in veins.
Clinically, BP refers to the force of blood within the arteries.
Blood pressure is largely controlled by the amount of blood pumped out of the heart, but various other events may also raise and lower BP.
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In Summary (cont.)
23.7 Pulmonary circulation: right atrium→ tricuspid valve → right ventricle→pulmonary semilunar valve → pulmonary trunk→pulmonary arteries→lungs→pulmonary veins→left atrium.
Systemic circulation: left atrium→bicuspid valve→left ventricle→aortic semilunar valve → aorta → arteries → arterioles→capillaries→venules→veins→vena cavae→right atrium.
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In Summary (cont.)
23.8 The largest artery in the body is the aorta. Other major arteries include lingual, facial, occipital, maxillary, ophthalmic, axillary, brachial, ulnar, radial, intercostals, lumbar, external iliac, common iliac, femoral, popliteal, and tibial.
The largest veins in the body are the superior and inferior vena cavae. Other major veins are jugular, brachiocephalic, axillary, brachial, ulnar, radial, intercostals, azygos, gastric, splenic, mesenteric, hepatic portal, hepatic, iliac, femoral, popliteal, and saphenous.
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In Summary (cont.)
23.9 The components of blood are red blood cells (RBC), white blood cells (WBC), platelets, and plasma.
23.10Red blood cells carry oxygen and carbon dioxide throughout the body. White blood cells are divided into two types: granulocytes and agranulocytes. Granulocytes include neutrophils, eosinophils, and basophils. Agranulocytes include lymphocytes and monocytes. Platelets are essential in the blood clotting process.
23.11Plasma contains three major proteins: albumins, globulins, and fibrinogen.
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In Summary (cont.)
23.12Hemostasis is bleeding control. When a blood vessel breaks, the vessel wall spasms and reduces blood loss.
Platelets stick to the broken area and to each other, forming a platelet plug.
A blood clot occurs when fibrinogen converts to fibrin, which sticks to the damaged area of the blood vessel, creating a meshwork to trap blood cells and platelets, which will remain while tissues repair themselves.
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In Summary (cont.)
23.13Blood types are named for the antigen present on the cell surfaces. The “opposite” letter is the name of the antibody present. Blood type A has antigen A and antibody B; blood type B has antigen B and antibody A; blood type AB has antigens A and B and 0 (zero) antibodies; Blood type O has no antigens present and both A and B antibodies.
23.14Rh-positive blood contains the Rh antigen on its RBCs. Rh-negative blood carries no such antigen.
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In Summary (cont.)
23.15Due to the antibodies present on different blood types, it is important for blood typing to be done prior to any transfusion.
It is equally important to know if a patient’s blood type is positive or negative for the same reason.
A negative blood type will “fight” the positive antigen found on a positive blood type.
An Rh-negative woman carrying an Rh-positive fetus will develop antibodies against the child’s blood type.
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In Summary (cont.)
23.16Many different types of cardiac and blood diseases are described in this chapter. The signs, symptoms, and treatments are as varied as the diseases themselves. The Pathophysiology section of this chapter outlines the most common of these diseases, their signs and symptoms, as well as the treatments.
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Your work is to discover your world and then with all your heart give yourself to it.
~ Buddha
End of Chapter 23