CHAPTER ONE
CARDIOPULMONARY ANATOMY
OBJECTIVES
Describe the function of the respiratory system.
Identify the major organs of the respiratory system.
Describe the function of the major organs in the respiratory system.
Describe the function of the circulatory system.
Identify the major organs of the circulatory system.
Describe the function of the major organs in the circulatory system.
INTRODUCTION
The cardiopulmonary system can be broken into two components, the respiratory
system and the circulatory system. The function of the respiratory system is to
provide oxygen for the metabolic needs of the cells and to remove carbon dioxide,
the cellular waste material. The circulatory system provides the transport
mechanism for oxygen and carbon dioxide.
The Respiratory System
The respiratory system supplies oxygen to support the metabolic needs of the cells,
and removes the cellular waste byproduct, carbon dioxide. The respiratory system
consists of the following organs:
Nose and nasal cavity
Pharynx
Larynx
Trachea
Thorax
Bronchi
Lungs
Alveoli
Nose and Nasal Cavity: The function of the nose is to warm, humidify, and
cleanse the air. As air is inhaled through the nose, it is warmed and humidified as it
comes into contact with the internal surfaces of the nasal passage. Warming
occurs because the walls of the nasal passage contain numerous thin-walled
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capillaries, which radiate heat into the air as it passes over them. Glandular
secretions accomplish humidification. The mucous and serous secretions add as
much as 1,000 ml of water per day to inspired air. The intimate contact between
inspired air molecules and the nasal mucosa assures that the relative humidity of
the inspired gas will be as high as 75 to 85% by the time the air reaches the
nasopharynx. Cleansing is accomplished by particles becoming trapped in the layer
of mucous covering the nasal surface. Ciliated cells then transport the particles to
the throat to be swallowed. The nose and nasal passage are effective filters down
to 4 to 6 microns.
Pharynx: The pharynx, commonly called the throat, is a tube approximately 5
inches long extending from the base of the skull to the esophagus. The pharynx is
divided into three parts; the nasopharynx, the oropharynx and the laryngopharynx.
The nasopharynx is located behind the nose and extends to just above the soft
palate. The oropharynx is located behind the mouth and is defined as the area from
the base of the tongue to the soft palate. The laryngopharynx is located behind the
base of the tongue. The pharynx's function is providing transport for food and air.
When food reaches the
pharynx, the vocal
cords close and the
epigloftis closes over
the trachea, preventing
food from entering the
airway and allowing the
food to enter the
esophagus. When air is
entering the pharynx the
vocal cords and the
epiglottis remain open,
and the air takes the
open path into the
larynx.
Larynx: The larynx, or
"voice box", connects
the pharynx with the
trachea. Its function is
primarily phonation, or
speech. Speech is
accomplished by
regulating the tension of
the vocal cords. As air flows by the vocal cords, the pitch produced is dependent on
the tension and the subsequent size of the opening. Also located in the larynx is
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the epiglotis. Its function is to block the larynx, allowing food to pass into the
esophagus.
Trachea: The trachea, or "windpipe", is a cylindrical tube approximately 4 to 5
inches long and 5/8" to 1" in diameter, consisting of 16 to 20 cartilaginous C-shaped
rings. The function of the trachea is to provide a passageway for air to reach the
lungs.
Bronchi: The trachea branches at the distal end into two main stems, the main
bronchi. The point where the branch begins is called the carina. The right main
stem bronchus further divides into three lobar bronchi and the left main stem
bronchus divides into two lobar bronchi. The bronchi divide further and further to
form bronchioles. These bronchioles will further divide until they terminate into
alveoli. The function of the bronchi is the same as that of the trachea, i.e., to
provide a passageway for air to reach the lungs.
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Thorax: The thorax, or
thoracic cavity, is
separated from the
abdomen by the
diaphragm, a large sheet of
muscle. The center of the
thoracic cavity contains the
heart, aortic arch,
esophagus, trachea, vagus
nerve and numerous blood
vessels in an oblong area
called the mediastinum.
Located on each side of the
mediastinum are the pleural
cavities, which contain the
lungs. Each lung is
contained in a visceral
pleura. Another layer of
serous membrane, the
parietal pleura, is in close
contact with the chest wall
and diaphragm. Between
the two pleura (intrapleural
space) is a small amount of
fluid, whose function is to
provide lubrication to
minimize friction during
respiration.
Lungs: The lungs are a
conical shaped, spongy
mass generally blue-gray in color. The lungs are enclosed in the two pleural
cavities of the thorax. The right lung is divided into three lobes, while the left lung is
divided into two lobes. The functional unit of the lung is the alveoli or air sac. Gas
exchange between blood and air occur at this level. The lungs provide a large
surface area for gas exchange to take place. The total surface area of the lungs, in
a normal adult is approximately 8Om2, about the size of a tennis court! Normal life
processes require approximately 1 m2 of lung surface for every kilogram of body
weight.
Alveoli: Distal to the terminal bronchioles are alveolar ducts. The walls of the
alveolar ducts are composed of alveoli separated by septal walls. About one half of
the total lung alveoli are located in the alveolar ducts and are responsible for about
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35% of gas exchange. The last generation of airways is the alveolar sac. The
alveolar sac exist in clusters of 15 to 20 with common walls between them. This
greatly increases the surface area of the lung. The alveolar sacs are responsible
for approximately 65% of gas exchange.
The Circulatory System
The circulatory system is comprised of the heart, the blood vessels, and the fluid
contained in the circulatory system, namely blood. The main function of the
circulatory system is to bring nutrients to cells to satisfy metabolic needs and to
carry cellular waste away. In the context of respiration, the circulatory system
brings oxygen-enriched blood from the lungs to the cells, and carries oxygendepleted, carbon dioxide-enriched blood from the cells to the lungs. The circulatory
system also provides the transport mechanism for various hormones used in the
regulation of the body's metabolism.
Blood: Blood represents 8% of total
body volume. Although blood
appears homogeneous, if placed on a
microscope, blood's heterogeneous
nature becomes apparent. When
centrifuged, blood separates into two
distinct groups. Formed elements
comprise 45% of total blood volume
and plasma comprises 55% of the
remaining blood volume. Formed
elements include erythrocytes,
leukocytes and platelets. Another
name for the formed elements is
hematocrit.
Erythrocytes: Erythrocytes, or red
blood cells, are by far the most
numerous cells in the formed
elements. There are approximately
4.2 to 6.2 million cells/mm3-. The
erythrocyte is shaped like a
biconcave disc. The unique shape of
the red blood cell increases its total
surface area, allowing it to carry more
oxygen. The total surface area of all
the red blood cells represents approximately 32OO m2 or 1500 times the surface
area of the human body. Erythrocytes are produced primarily in the bone marrow
and the life expectancy is 80 to 120 days. Hemoglobin, contained in the red blood
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cells, assumes an essential role in oxygen transport. The most important feature of
hemoglobin is its ability to combine loosely and reversibly with oxygen.
Leukocytes: Leukocytes, or white blood cells, protect the body against disease.
There are approximately 5000 to 6000 cells per cubic millimeter. There are several
different types and they are classified on the basis of size, number, nuclear shape,
and the staining qualities of the cytoplasm.
Platelets: Platelets are essential for the clotting of blood. There are 140,000 to
340,000 cells/mm3.
Plasma: Plasma is a straw-colored liquid composed mainly of water (91%) and
chemical compounds, primarily proteins (9%). The four major plasma proteins are
albumin, globulin, fibrinogen, and prothrombin. Plasma plays an important role in
maintaining homeostasis.
Heart: The primary function of
the heart is to serve as a
muscular pump propelling blood
into and through vessels to and
from all parts of the body. The
heart is a four- chambered,
hollow, muscular organ lying
between the lungs in the middle
mediastinum. Approximately
two thirds of its mass is to the
left of the midline. It is about the
size of a man's fist and weighs
approximately 300 gm. The
heart is shaped like an inverted
cone with its apex pointed
downward. The heart is divided
into right and left halves, with
each half-divided into upper and
lower chambers. The upper
chambers are called the atria
and are separated by the
interatrial septum. The lower
chambers are called the
ventricles and are separated by
the interventricular septum.
The atria serve as receiving chambers for blood from the various parts of the body
and pump blood into the ventricles. The right atrium is a thin walled chamber
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receiving blood from all tissues except the lungs. Three veins empty into the right
atrium; the superior and inferior venae cavae, which brings blood from the upper
and lower portions of the body (respectively), and the coronary sinus, which drains
blood from the heart itself. The right ventricle expels blood out the pulmonary artery
to the lungs. The left atrium receives oxygenated blood returning from the lungs via
the four pulmonary veins. Blood then flows into the left ventricle. Oxygenated
blood is forced out of the left ventricle to all parts of the body via the aorta.
There are two types of valves located in the heart; the atrioventricular (the mitral
and tricuspid) and the semilunar valves (pulmonary and aortic). The tricuspid valve
guards the opening to the right ventricle from the right atrium. The mitral valve
guards the opening to the left ventricle from the left atrium. The pulmonary
semilunar valve guards the opening from right ventricle to the pulmonary artery.
The aortic semilunar valve guards the opening from the left ventricle to the aorta.
The function of these valves is to prevent backflow of blood during the contraction
of a particular chamber.
Blood Vessels: The blood vessels consist of a closed system of tubes functioning
to transport blood to all parts of the body and back to the heart. The blood vessel
structure consists of arteries, arterioles, capillaries, venules and veins. The arteries
and arterioles carry blood away from the heart, while venules and veins carry blood
to the heart. The capillary bed is where the exchange of oxygen, carbon dioxide
and other nutrients between the blood and cells takes place.
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Whole Blood
(Volume)
Leukocytes
Formed Elements
Leukocytes
5,000 - 10,000
Neutrophils
57 - 67%
Formed
Elements
45%
Eosinphils 1 - 3%
Erythrocytes
4.2 - 6.2 Million
Basophils
0 - 0.75%
Lymphocytes
25 - 33%
Platelets
140,000 - 340,000
Monocytes 3 - 7%
Plasma Weight
Proteins
Proteins 7%
Albumin
54%
Plasma
55%
Alpha
14%
Water
91.5%
Globulins
Beta
13%
Fibrinogen 7%
Gamma
11%
Prothrombin < 1%
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Arteries: Arteries transport blood to the various body tissues under high pressure
exerted by the pumping action of the heart. The heart forces blood into these
elastic tubes, which recoil, sending blood on in a pulsating wave. Consequently,
these tubes must possess strong, elastic walls to insure fast, efficient blood flow to
the tissues.
Arterioles: The transition from artery to arteriole is gradual, marked by a thinning
of the vessel wall and a decrease in the size of the passageway. Arterioles act as
control valves through which blood is released into the capillaries. The walls of the
arterioles are capable of completely closing the passageway or dilating to several
times its normal size, thereby vastly altering blood flow to the capillaries.
Capillaries: The focal point of the entire cardiovascular system is the network of
approximately 10 billion microscopic capillaries functioning to provide a method
whereby fluids, nutrients, and waste are exchanged between the blood and the
cells. The largest capillary is approximately 0.2mm in diameter, about the size of
the tip of a pin. The capillary network contains, at any given time, about one-sixth of
the total circulating blood volume. The wall of the capillary is extremely thin (one
cell thickness) and acts as a semipermeable membrane allowing small molecular
substances such as oxygen, carbon dioxide, water, and glucose to be transported
across the membrane. Oxygen and nutritive material pass into the tissues through
the wall at the arterial end of the capillary unit, and carbon dioxide and waste pass
into the bloodstream at the venous end of the capillary unit.
Venules: As the capillaries converge, small venules begin to form. The function of
the venules is to collect blood from the capillary bed.
Veins: Veins function to return blood from the peripheral tissues to the heart.
Blood pressure in these vessels is much lower than the arterial system, and blood
must exit at a much lower pressure. In order to keep the blood moving on its way to
the heart and to keep it from pooling, many veins contain a system of bicuspid
valves that serve to direct the flow of blood to the heart.
Blood Circulation: The circulatory system can be broken down into smaller units;
the systemic system, the pulmonary system, and the portal system. The systemic
circulatory system carries oxygen and nutrients to the entire body except the lungs
and transports wastes away from the cells. All systemic arteries spring from the
aorta. Blood is returned to the heart in the systemic system via the inferior and
superior venae cavae. The pulmonary system carries oxygen-depleted blood from
the right ventricle to the lungs via the pulmonary artery, and oxygen-enriched blood
is returned from the lungs to the left atrium via the pulmonary veins. The portal
circulatory system differs from the systemic system in that the blood from the
spleen; stomach, pancreas and intestine first pass through the liver before going to
the heart. Blood flowing into the liver comes from the hepatic artery and the portal
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vein. Blood leaving the liver passes through the hepatic vein and empties into the
inferior vena cava.
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REVIEW
The cardiopulmonary system can be broken down into two subsystems; the
respiratory system and the circulatory system. The function of the respiratory
system is to provide oxygen for the metabolic needs of the cells and to remove
carbon dioxide from the body. The circulatory system provides the transport
mechanism for the above to occur.
The respiratory system is comprised of the following organs; the nose and nasal
cavity, pharynx, larynx, trachea, thorax, bronchi, lungs and alveoli. The nose and
nasal cavity function to warm, humidify, and cleanse the inspired air. The pharynx,
larynx, trachea, and bronchi provide a passageway for air to enter the lungs.
Additionally, the larynx assists in speech formation. The bronchi divide further and
further until a terminal bronchiole is reached. At this point, alveolar ducts develop.
The last generation of airways is the alveolar sac. The alveoli is the functional unit
where gas exchange takes place. The lungs are a conical, spongy mass comprised
of many alveoli. The total surface area of the lung in a normal adult is
approximately 8Om2- The lungs are located in the thoracic cavity. Each lung is
contained in a visceral pleura. Another layer of serous membrane, the parietal
pleura, is in close contact with the chest wall and diaphragm. Located in the
intrapleural space is a small amount of fluid, whose function is to provide lubrication
to minimize friction during respiration.
The circulatory system is composed of the heart, blood vessels, and the blood.
Blood consists of 45% formed elements and 55% plasma. The formed elements are
called hematocrit. Erythrocytes, leukocytes and platelets compose the formed
elements. Erythrocytes are the oxygen/carbon dioxide carriers of the blood.
Hemoglobin gives the erythrocytes its ability to combine with oxygen. Leukocytes
protect the body against disease. Platelets are important in blood clotting. Plasma
is composed mainly of water, and the remaining substances are proteins.
The heart is a four-chambered pump whose main function is to propel blood into
and through vessels to and from all parts of the body. The upper chambers of the
heart are called the right and left atria. The lower chamber-s of the heart are called
the right and left ventricles. There are four valves in the heart designed to prevent
the backflow of blood during a chamber contraction.
Blood vessels are divided into arteries and veins. Arteries carry blood away from
the heart and veins carry blood back to the heart. Arteries progressively become
smaller to become arterioles. Arterioles act as control valves, through which blood
is released into the capillary bed. Capillaries are the functional unit where the
exchange of fluids, oxygen, and waste between the blood and the cells takes place.
The capillary wall is one cell thick and acts as a semipermeable membrane.
Venules collect blood from the capillary bed. Veins contain a system of bicuspid
valves and serve to direct the flow of blood back to the heart.
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The circulatory system can be broken down into three smaller systems; the systemic
circulatory system, the pulmonary system, and the portal system. The systemic
system functions to provide the entire body, except the lungs, with oxygen and
nutrients, and to carry wastes away from the cells. The pulmonary system is
responsible for the transport of blood to and from the lungs.
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CHAPTER QUIZ
1. The _________________ and the __________________comprise the
cardiopulmonary system.
2. The function of the respiratory system is to provide ________________ for the
metabolic needs of the cells and to remove __________________, the cellular
waste material.
3. The respiratory system contains the__________________ and
_______________________, the ______________________,
_______________________, ________________________,
_______________________, and _____________________________.
4. The organ that warms, humidifies, and cleanses inspired air is the
___________________ and __________________.
5. The ____________________is commonly called the throat.
6. The function of the pharynx is providing transport for ____________________
and _____________________.
7. This organ assists in speech, and connects the pharynx with the trachea; it is
called the ________________.
8. The ________________________ is approximately 5 inches long and consists
of 16 to 20 cartilaginous rings.
9. As the trachea branches to become this organ, it is called
___________________________.
10. The _________________________ are the functional unit where gas exchange
takes place.
11. This organ has a total surface of approximately 8O m2 and it is called the
____________________________.
12. The lungs, heart, aortic arch, esophagus, trachea, vagus nerve and numerous
blood vessels are located in the
_______________________________________.
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13. The ___________________________________________ system is responsible
for bringing nutrients to the cells and carrying waste away from the cells.
14. The ____________________________ and
_____________________________ comprise the circulatory system.
15. _____________________________ represents 8% of total body volume.
16. The ________________________ are responsible for oxygen transport.
17. The ____________________ is a four-chambered pump.
18. The __________________________ are the receiving chambers of the heart.
19. The _____________________________ function to expel blood to various parts
of the body and lungs.
20. The ________________________________________ carry blood away from
the heart.
21. The __________________________________ carry blood to the heart.
22. The focal point of the entire cardiovascular system is the
__________________________.
23. The _______________________ system is responsible for carrying blood to and
from the lungs.
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