Chapter 21
THE CARDIOVASCULAR SYSTEM: BLOOD VESSELS AND HEMODYNAMICS
I. INTRODUCTION
A. One main focus of this chapter considers hemodynamics, the means by which blood flow is altered
and distributed and by which blood pressure is regulated.
B. The histology of blood vessels and anatomy of the primary routes of arterial and venous systems are
surveyed.
II. ANATOMY OF BLOOD VESSELS
A. Blood vessels form a closed system of tubes that carry blood away from the heart, transport it to the
tissues of the body, and then return it to the heart.
1. Arteries carry blood from the heart to the tissues.
2. Arterioles are small arteries that connect to capillaries.
3. Capillaries are the site of substance exchange between the blood and body tissues.
4. Venules connect capillaries to larger veins.
5. Veins convey blood from the tissues back to the heart.
6. Vasa vasorum are small blood vessels that supply blood to the cells of the walls of the
arteries and veins.
B. Arteries
1. Arteries carry blood away from the heart to the tissues.
a. The wall of an artery consists of a tunica interna, tunica media (which maintains
elasticity and contractility), and a tunic externa.
b. The functional properties of arteries are elasticity and contractility.
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1) Elasticity, due to the elastic tissue in the tunica internal and media, allows
arteries to accept blood under great pressure from the contraction of the
ventricles and to send it on through the system.
2) Contractility, due to the smooth muscle in the tunica media, allows arteries to
increase or decrease lumen size and to limit bleeding from wounds.
2. Elastic Arteries
a. Large arteries with more elastic fibers and less smooth muscle are called elastic
arteries and are able to receive blood under pressure and propel it onward.
b. They are also called conducting arteries because they conduct blood from the heart to
medium sized muscular arteries.
c. They function as a pressure reservoir.
3. Muscular arteries have a large amount of smooth muscle in their walls and distribute blood
to various parts of the body.
C. Arterioles
1. Arterioles are very small, almost microscopic, arteries that deliver blood to capillaries.
2. Through vasoconstriction (decrease in the size of the lumen of a blood vessel) and
vasodilation (increase in the size of the lumen of a blood vessel), arterioles assume a key role
in regulating blood flow from arteries into capillaries and in altering arterial blood pressure.
D. Capillaries are microscopic vessels that usually connect arterioles and venules.
1. The flow of blood through the capillaries is called the microcirculation.
2. Capillaries are found near almost every cell in the body, but their distribution varies with the
metabolic activity of the tissue.
3. The primary function of capillaries is to permit the exchange of nutrients and wastes between
the blood and tissue cells through interstitial fluid.
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4. Capillary walls are composed of only a single layer of cells (endothelium) and a basement
membrane.
5. Capillaries branch to form an extensive capillary network throughout the tissue. This network
increases the surface area, allowing a rapid exchange of large quantities of materials.
a. The flow of blood through capillaries is regulated by vessels with smooth muscle in
their walls.
b. Rings of smooth muscle fibers (cells) called precapillary sphincters regulate blood
flow through true capillaries.
c. Some capillaries are continuous, whereas others are fenestrated.
6. Materials can cross the blood capillary walls through intercellular clefts, via pinocytic
vesicles, directly across the endothelial membrane, and through fenestrations.
•
Two types of capillaries are distinguished by the sizes of gaps between or through endothelial
cells.
•
Continuous capillaries occur in most tissues. Their endothelial cells are held tightly
together by tight junctions, and have narrow intercellular clefts between them through
which small solutes pass.
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Fenestrated capillaries have endothelial cells riddled with holes that are covered by a
thin mucoprotein diaphragm. These holes allow for more rapid passage of small
molecules, which is necessary in the kidneys, small intestine, and endocrine glands, for
example.
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Sinusoids are blood-filled spaces in the liver, bone marrow, spleen, and other organs.
Some are continuous capillaries, while others are fenestrated.
•
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E. Venules
1. Venules are small vessels that are formed from the union of several capillaries; venules
merge to form veins.
2. They drain blood from capillaries into veins.
F. Veins
1. Veins consist of the same three tunics as arteries but have a thinner tunica interna and media
and a thicker tunica externa; they have less elastic tissue and smooth muscle and are
therefore thinner-walled than arteries. They contain valves to prevent the backflow of blood.
2. Vascular (venous) sinuses are veins with very thin walls with no smooth muscle to alter their
diameters. Examples are the brain’s superior sagittal sinus and the coronary sinus of the
heart.
3. Weak valves can lead to varicose veins.
G. Anastomoses
1. Anastomoses are the union of the branches of two or more arteries supplying the same region.
2. They provide alternate routes for blood to reach a tissue or organ.
3. The collateral circulation is the alternate flow of blood to a body part through an
anastomosis.
4. Arteries that do not anastomose are known as end arteries. Occlusion of an end artery
interrupts the blood supply to a whole segment of an organ, producing necrosis (death) of
that segment.
5. Anastomoses can also consist of two veins or a vein and an artery.
Anastomoses are places where two veins or arteries merge. They can be arteriovenous shunts or arterial or
venous anastomoses.
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Arterovenous – Fingers, toes, palms, ears.
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Arterial anastomoses – anterior and posterior
interventricular
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Venous anastomoses -
H. Blood Distribution
1. At rest, the largest portion of the blood is in systemic veins and venules, collectively called
blood reservoirs.
a. They store blood and, through venous vasoconstriction, can move blood to other parts
of the body if the need arises.
b. In cases of hemorrhage, when blood pressure and volume decrease, vasoconstriction
of veins in venous reservoirs helps to compensate for the blood loss.
2. The principal reservoirs are the veins of the abdominal organs (liver and spleen) and skin.
III. CAPILLARY EXCHANGE
A. Substances enter and leave capillaries by diffusion, transcytosis, and bulk flow (filtration and
absorption).
B. The most important method of capillary exchange is simple diffusion.
1. Substances such as O2, CO2, glucose, amino acids, hormones, and others diffuse down their
concentration gradients.
2. All plasma solutes, except larger proteins, pass freely across most capillary walls.
3. The prime exception of diffusion of water-soluble materials across capillary walls is in the
brain where the blood-brain barrier exists.
Capillary Exchange
•
Diffusion
•
Capillary exchange refers to the two-way movement of substances between capillaries
and tissue fluid.
•
The most important mechanism of exchange is diffusion. Solutes more concentrated in
tissue fluid diffuse into the blood, and vice versa.
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•
Lipid-soluble substances diffuse through the plasma membrane. Other substances must
pass through clefts, fenestrations, or membrane channels.
C. Some materials cross the capillary membrane by transcytosis, the enclosing of substances within tiny
vesicles that enter cells by endocytosis.
Transcytosis
•
In transcytosis, endothelial cells pick up droplets of fluid on one side of the plasma membrane by
pinocytosis, transport the vesicles across the cell, and discharge the fluid on the other side by
exocytosis.
•
Fatty acids, insulin, and albumin are transported this way, but transcytosis accounts for only a
small fraction of solute exchange.
D. Bulk Flow: Filtration and Reabsorption
1. Whereas diffusion is more important for solute exchange between plasma and interstitial
fluid, bulk flow is more important for regulation of the relative volumes of blood and
interstitial fluid.
2. The movement of water and dissolved substances (except proteins) through capillaries is
dependent upon hydrostatic and osmotic pressures.
3. The near equilibrium at the arterial and venous ends of a capillary by which fluids exit and
enter is called Starling’s law of the capillaries.
4. Occasionally, the balance of filtration and reabsorption between interstitial fluid and plasma
is disrupted, allowing an abnormal increase in interstitial fluid called edema. Edema may be
caused by several factors including increased blood hydrostatic pressure in capillaries due to
an increase in venous pressure, decreased concentration of plasma proteins that lower blood
colloid osmotic pressure, increased permeability of capillaries which allows greater amounts
of plasma proteins to leave the blood and enter tissue fluid, increased extracellular fluid
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volume as a result of fluid retention, and blockage of lymphatic vessels postoperatively or
due to filarial worm infection.
Edema
•
Edema is the accumulation of excess fluid in a tissue.
•
Edema has four main causes.
•
Poor venous return causes pressure to back up into the capillaries, resulting in increased
capillary filtration.
•
Reduced capillary reabsorption can be caused by an albumin deficiency.
•
Obstructed lymphatic drainage can lead to the accumulation of tissue fluid.
•
Increased capillary blood pressure.
IV. HEMODAYNAMICS: PHYSIOLOGY OF CIRCULATION
A. The distribution of cardiac output to various tissues depends on the interplay of the pressure
difference that drives the blood flow and the resistance to blood flow.
B. Velocity of Blood Flow
1. The volume that flows through any tissue in a given period of time is blood flow.
2. The velocity of blood flow is inversely related to the cross-sectional area of blood vessels;
blood flows most slowly where cross-sectional area is greatest.
3. Blood flow decreases from the aorta to arteries to capillaries and increases as it returns to the
heart.
C. Volume of Blood Flow
1. Blood flow is determined by blood pressure and resistance.
2. Blood flows from regions of higher to lower pressure; the higher the resistance the lower the
blood flow.
D. Blood pressure (BP) is the pressure exerted on the walls of a blood vessel; in clinical use, BP refers
to pressure in arteries.
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1. Cardiac output (CO) equals mean aortic blood pressure (MABP) divided by total resistance
(R).
2. Factors that affect blood pressure include cardiac output, blood volume, viscosity, resistance,
and elasticity of arteries.
3. As blood leaves the aorta and flows through systemic circulation, its pressure progressively
falls to 0 mm Hg by the time it reaches the right atrium.
E. Resistance refers to the opposition to blood flow as a result of friction between blood and the walls
of the blood vessels.
1. Resistance depends on blood viscosity, blood vessel length, and blood vessel radium.
2. Systemic vascular resistance (also known as total peripheral resistance) refers to all of the
vascular resistances offered by systemic blood vessels; most resistance is in arterioles,
capillaries, and venules due to their small diameters.
F. Venous Return
1. A number of factors aid venous return (the volume of blood flowing back to the heart from
the systemic veins) by increasing the magnitude of the pressure gradient between the venules
and the right atrium.
2. Blood return to the heart is maintained by several factors, including skeletal muscular
contractions, valves in veins (especially in the extremities), and pressure changes associated
with breathing.
G. Syncope, or faint, refers to a sudden, temporary loss of consciousness followed by spontaneous
recovery. It is most commonly due to cerebral ischemia.
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Hypotension is chronic low resting BP. It may be due to blood loss, dehydration, or anemia.
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Blood flow in arteries is pulsatile, and when measured at points farther away from the heart,
systolic and diastolic pressures are lower, with less difference between them.
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•
Blood pressure is determined mainly by (1)cardiac output, (2)blood volume, and
(3)peripheral resistance, and it rises with age.
Cardiac Output
See previous chapter
Blood Volume and Viscosity.
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Blood viscosity is mostly due to erythrocytes and albumin. A deficiency of either decreases
peripheral resistance and increases blood flow; an excess increases peripheral resistance and
reduces flow.
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Polycythemia
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Anemia
Resistance
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Peripheral resistance is the resistance that the blood encounters in the vessels as it travels
away from the heart. It results from the friction of blood against the walls of the vessels and
is proportional to three variables: blood viscosity, vessel length, and vessel radius.
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Blood viscosity is mostly due to erythrocytes and albumin. A deficiency of either decreases
peripheral resistance and increases blood flow; an excess increases peripheral resistance
and reduces flow.
•
Pressure and flow decline with increasing vessel length. If perfusion is good at a great
distance from the heart, it is likely to be good elsewhere in the systemic circulation. For
every pound of adipose tissue added 200 miles of blood vessels are added.
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In a healthy person, the one real way to influence peripheral resistance is through altering
the diameters of the blood vessels by vasodilation and vasoconstriction.
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•
The arterioles are the most significant point of control over peripheral resistance
because of their
number, their location on the proximal sides of capillaries, and
because they are more muscular for their size compared to other blood vessels.
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Vessel radius exerts a very powerful influence over blood velocity.
V. CONTROL OF BLOOD PRESSURE AND BLOOD FLOW
A. Cardiovascular Center
1. The cardiovascular center (CV) is a group of neurons in the medulla that regulates heart rate,
contractility, and blood vessel diameter.
2. The CV receives input from higher brain regions and sensory receptors (baroreceptors and
chemoreceptors).
3. Output from the CV flows along sympathetic and parasympathetic fibers.
a. Sympathetic impulses along cardioaccelerator nerves increase heart rate and
contractility.
b. Parasympathetic impulses along vagus nerves decrease heart rate.
c. The sympathetic division also continually sends impulses to smooth muscle in blood
vessel walls via vasomotor nerves. The result is a moderate state of tonic contraction
or vasoconstriction, called vasomotor tone.
B. Neural Regulation of Blood Pressure
1. Baroreceptors are important pressure-sensitive sensory neurons that monitor stretching of the
walls of blood vessels and the atria.
a. The cardiac sinus reflex is concerned with maintaining normal blood pressure in the
brain and is initiated by baroreceptors in the wall of the carotid sinus.
b. The aortic reflex is concerned with general systemic blood pressure and is initiated by
baroreceptors in the wall of the arch of the aorta or attached to the arch.
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c. If blood pressure falls, the baroreceptor reflexes accelerate heart rate, increase force
of contraction, and promote vasoconstriction.
d. Carotid sinus massage can slow heart rate in paroxysmal superventricular
tachycardia.
2. Receptors sensitive to chemicals are called chemoreceptors.
a. These receptors are located close to the baroreceptors of the carotid sinus and arch of
the aorta.
b. They monitor blood levels of oxygen, carbon dioxide, and hydrogen ion
concentration.
C. Hormonal Regulation
1. Hormones such as angiotensin II, epinephrine, norepinephrine, antidiuretic hormone, and
atrial natriuretic peptide affect blood pressure and blood flow by altering cardiac output,
changing systemic vascular resistance, or adjusting the total blood volume.
D. Local Regulation of Blood Pressure
1. The ability of a tissue to automatically adjust its own blood flow to match its metabolic
demand for supply of O2 and nutrients and removal of wastes is called autoregulation.
2. In most body tissues, oxygen is the principal, though not direct, stimulus for autoregulation.
3. Researchers have identified two general types of stimuli that cause autoregulatory changes in
blood flow: physical and chemical.
Regulation of Blood Pressure and Flow
•
Local Control
•
Autoregulation is the ability of tissues to regulate their own blood supply.
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If a tissue is inadequately perfused, its metabolites accumulate and stimulate
vasodilation. Vasodilating agents include:
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•
•
K+
•
H+
•
lactic acid
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adenosine
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Nitric oxide (endothelium-derived relaxation factor (EDRF))
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Kinins
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Histamine
As the bloodstream delivers oxygen and carries away wastes, the vessels constrict.
Vasoconstrictors include:
•
thromboxane A2
•
superoxide radicals
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serotonin from platelets
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endothelins
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If blood supply to a tissue is cut off and then restored, the tissue exhibits reactive hyperemia.
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Over time, hypoxic tissue can increase its own perfusion by angiogenesis.
VI. SHOCK AND HOMEOSTASIS
A. Shock is an inadequate cardiac output that results in failure of the cardiovascular system to deliver
adequate amounts of oxygen and nutrients to meet the metabolic needs of body cells. As a result,
cellular membranes dysfunction, cellular metabolism is abnormal, and cellular death may eventually
occur without proper treatment.
B. Types of Shock
1. Hypovolemic shock is due to decreased blood volume.
2. Cardiogenic shock is due to poor heart function.
3. Vascular shock is due to inappropriate vasodilation.
4. Obstructive shock is due to obstruction of blood flow.
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Circulatory Shock
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Circulatory shock is a state in which cardiac output is not sufficient to meet the body's needs.
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Cardiogenic shock occurs because the heart is not beating adequately, perhaps from a MI. All
other forms are due to low venous return (LVR) shock.
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There are three principal forms of LVR shock.
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Hypovolemic shock is due to a loss of blood due to hemorrhage, dehydration, burns, or
trauma.
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Obstructed venous return shock occurs with a tumor or aneurysm.
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Venous pooling (vascular) shock occurs when too much blood accumulates in the limbs.
This can be due to prolonged standing, neurogenic shock (brainstem trauma or
emotional shock that results in fainting), septic shock, or anaphylactic shock.
Compensated shock (Nonprogressive) Shock
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Activation of the sympathetic nervous system. (Norepinephrine and epinephrine from the
adrenal medulla.
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Renin-angiotensin pathway.
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Antidiuretic pathway.
Decompensated (Progressive) Shock
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Depression of cardiac activity.
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Depression of vasoconstriction.
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Increased permeability of capillaries.
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Intravascular clotting.
•
Cellular destruction.
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Acidosis.
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Irreversible Shock
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Energy depleted.
•
Electrolyte imbalances.
Homeostatic responses to shock include activation of the renin-angiotensin-aldosterone system, secretion of
ADH, activation of the sympathetic division of the ANS, and release of local vasodilators.
C. Signs and symptoms of shock include clammy, cool, pale skin; tachycardia; weak, rapid pulse;
sweating; hypotension (systemic pressure < 90 mm HG); altered mental status; decreased urinary
output; thirst; and acidosis.
VII. CHECKING CIRCULATION
A. Pulse
1. Pulse is the alternate expansion and elastic recoil of an artery wall with each heartbeat. It
may be felt in any artery that lies near the surface or over a hard tissue and is strongest in the
arteries closest to the heart; the radial artery is most commonly used to feel the pulse (Table
21.2) depicts the most common pulse points.
2. A normal resting pulse (heart) rate is between 70 to 80 beats per minute.
a. Tachycardia means a rapid resting heart or pulse rate (> 100 beats/min).
b. Bradycardia indicates a slow resting heart or pulse rate (< 60 beats/min).
Blood Pressure, Resistance, and Flow
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Blood flow is the amount of blood flowing through an organ, tissue, or vessel in a given
time. Perfusion is the rate of blood flow per given volume or mass of tissue.
•
Blood flow is an important measure of the amount of oxygen and nutrients
delivered to a tissue and the rate of waste removal.
•
Inadequate blood flow can result in necrosis of the tissue or even death of the
individual.
•
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B. Measurement of Blood Pressure
1. Blood pressure is the pressure exerted by blood on the wall of an artery when the left
ventricle undergoes systole and then diastole. It is measured by the use of a
sphygmomanometer, usually in one of the brachial arteries.
a. Systolic blood pressure is the force of blood recorded during ventricular contraction.
b. Diastolic blood pressure is the force of blood recorded during ventricular relaxation.
c. The various sounds that are heard while taking blood pressure are called Korotkoff
sounds.
d. The normal blood pressure of a young adult male is 120/80 mm Hg (8-10 mm Hg less
in a young adult female). The range of average values varies with many factors.
2. Pulse pressure is the difference between systolic and diastolic pressure. It normally is about
40 mm Hg and provides information about the condition of the arteries.
Blood Pressure
•
Blood pressure (BP) can be measured by various means, but most commonly a
sphygmomanometer is employed.
•
Two pressures are recorded: systolic pressure, which indicates the peak arterial pressure during
ventricular systole, and diastolic pressure, which is the minimum arterial pressure between
heartbeats.
•
The difference between systolic and diastolic pressure is called pulse pressure, which is an
important measure of the stress exerted on small arteries by the pressure surges of the heart.
Another measure of stress on the blood vessels is mean arterial pressure (MAP).
•
Hypertension is a chronic resting systolic pressure of 140 mmHg or a diastolic pressure
higher than 90 mmHg. Hypertension can weaken small arteries and cause aneurysms.
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VIII. CIRCULATORY ROUTES
A. Introduction
1. The blood vessels are organized into routes that deliver blood throughout the body. Figure
21.17 shows the circulatory routes for blood flow.
2. The largest circulatory route is the systemic circulation.
3. Other routes include pulmonary circulation and fetal circulation .
B. Systemic Circulation
1. The systemic circulation takes oxygenated blood from the left ventricle through the aorta to
all parts of the body, including some lung tissue (but does not supply the air sacs of the
lungs) and returns the deoxygenated blood to the right atrium.
a. The aorta is divided into the ascending aorta, arch of the aorta, and the descending
aorta.
b. Each section gives off arteries that branch to supply the whole body.
2. Blood returns to the heart through the systemic veins. All the veins of the systemic
circulation flow into the superior or inferior venae caveae or the coronary sinus, which in
turn empty into the right atrium.
C. Hepatic Portal Circulation
1. The hepatic portal circulation collects blood from the veins of the pancreas, spleen, stomach,
intestines, and gallbladder and directs it into the hepatic portal vein of the liver before it
returns to the heart.
2. A portal system carries blood between two capillary networks, in this case from capillaries of
the gastrointestinal tract to sinusoids of the liver.
3. This circulation enables nutrient utilization and blood detoxification by the liver.
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D. Pulmonary Circulation
1. The pulmonary circulation takes deoxygenated blood from the right ventricle to the air sacs
of the lungs and returns oxygenated blood from the lungs to the left atrium.
2. The pulmonary and systemic circulations differ from each other in several more ways.
a. Blood in the pulmonary circulation is not pumped so far as in the systemic circulation
and the pulmonary arteries have a larger diameter, thinner walls, and less elastic
tissue. As a result, resistance to blood flow is very low meaning that less pressure is
needed to move blood through the lungs.
b. Because resistance in the pulmonary circulation is low, normal pulmonary capillary
hydrostatic pressure is lower than systemic capillary hydrostatic pressure which tends
to prevent pulmonary edema.
E. Fetal Circulation
1. The fetal circulation involves the exchange of materials between fetus and mother.
2. The fetus derives its oxygen and nutrients and eliminates its carbon dioxide and wastes
through the maternal blood supply by means of a structure called the placenta.
3. Blood passes from the fetus to the placenta via two umbilical arteries and returns from the
placenta via a single umbilical vein.
4. At birth, when pulmonary, digestive, and liver functions are established, the special
structures of fetal circulation are no longer needed.
a. The ductus arteriosus becomes the ligamentum arteriosum shortly after birth.
b. The foramen ovale becomes the fossa ovalis shortly after birth.
c. The ductus venosus becomes the ligamentum venosum shortly after birth.
d. The umbilical arteries become the medial umbilical ligaments.
e. The umbilical vein becomes the ligamentum teres (round ligament).
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IX. DEVELOPMENTAL ANATOMY OF BLOOD VESSELS AND BLOOD
A. Blood vessels develop from isolated masses of mesenchyme in the mesoderm called blood islands.
1. Spaces soon appear in the islands and become the lumens of the blood vessels.
2. Some of the mesenchymal cells immediately around the spaces give rise to the endothelial
lining of the blood vessels.
B. Blood plasma and blood cells are produced by the endothelial cells of blood vessels, a function later
assumed by the liver, spleen, bone marrow, and lymph nodes.
X. AGING AND THE CARDIOVASCULAR SYSTEM
A. General changes associated with aging and the cardiovascular system include loss of compliance
(extensibility) of the aorta, reduction in cardiac muscle fiber size, progressive loss of cardiac
muscular strength, reduced cardiac output, a decline in maximum heart rate, and increased systolic
blood pressure.
B. The incidence of coronary artery disease, congestive heart failure, and arteriosclerosis increases with
age.
XI. DISORDERS: HOMEOSTATIC IMBALANCES
A. Hypertension, or persistently high blood pressure, is defined as systolic blood pressure of 140 mm
Hg or greater and diastolic blood pressure of 90 mm Hg or greater.
1. Primary hypertension (approximately 90-95% of all hypertension cases) is a persistently
elevated blood pressure that cannot be attributed to any particular organic cause.
2. Secondary hypertension (the remaining 5-10% of cases) has a identifiable underlying cause
such as obstruction of renal blood flow or disorders that damage renal tissue, hypersecretion
of aldosterone, or hypersecretion of epinephrine and norepinephrine by pheochromocytoma,
a tumor of the adrenal gland.
B. High blood pressure can cause considerable damage to the blood vessels, heart, brain, and kidneys
before it causes pain or other noticeable symptoms.
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C. Lifestyle changes that can reduce elevated blood pressure include losing weight, limiting alcohol
intake, exercising, reducing sodium intake, maintaining recommended dietary intake of potassium,
calcium, and magnesium, not smoking, and managing stress.
D. Various drugs including diuretics, beta blockers, vasodilators, and calcium channel blockers have
been used to successfully treat hypertension.
Circulatory Disorders
Coronary Artery Disease (CAD) RISK FACTORS
1. Elevated Blood Cholesterol Level
Cholesterol is carried in the blood as HDL, LDL, and VLDL.
1. HDL = High Density Lipoprotein
2. LDL = Low Density Lipoprotein
3. VLDL = Very Low Density Lipoprotein
A total cholesterol level of 200 – 239 mg/dl is borderline elevation, while values of 240 mg/dl and greater
indicate significantly elevated levels.
A LDL value between 130 –159 mg/dl is borderline elevation, while values of 160 mg/dl and above are
considered significantly elevated.
HDL values less than 35 mg/dl are a high-risk indicator for CHD.
Age
Ideal Total Cholesterol Level
Less than 20
less than 150 mg/dl
20 – 29
less than 180 mg/dl
30+
less than 200 mg/dl
The total cholesterol to HDL ratio is a more precise indicator of risk than the total cholesterol level. The higher
the ratio, the greater the risk of CHD.
a. The ideal ratio for men is equal to or less than 4.0.
b. The ideal ratio for women is equal to or less than 3.5.
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LIFESTYLE FACTORS THAT DECREASE LDL CHOLESTEROL
a.
Increased physical activity level.
b.
Decrease dietary saturated fat.
c.
Decreased dietary cholesterol.
d.
Increased dietary soluble fiber.
e.
Decreased percent body fat.
f.
Managing stress effectively.
g.
Controlling diabetes.
LIFESTYLE FACTORS THAT INCREASE HDL CHOLESTEROL
2.
a.
Increased physical activity level.
b.
Decreased percent body fat.
c.
Quitting smoking.
d.
Decreased blood triglyceride levels.
Hypertension
Hypertension in adults is defined as a resting blood pressure of greater than 140/90 mm Hg on 2 separate
occasions, or an individual taking antihypertensive medications.
3.
Cigarette Smoking
a. Smoking damages the lining of artery walls.
b. Smoking causes increased tendency for blood clot formation.
c. Smoking decreases HDL levels.
4.
Diabetes Mellitus
Diagnosed when a fasting blood glucose level is greater than 125 mg/dl on 2 separate occasions.
LIFESTYLE FACTORS THAT IMPROVE BLOOD GLUCOSE/INSULIN LEVELS
a. Increased physical activity levels.
b. Decreased percent body fat (if over fat to begin with).
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c. Emphasis on a prudent diet.
5.
Family History (Genetic Predisposition)
6. Sedentary Lifestyle
7.
Age
a. Men greater than 45 years.
b. Women greater than 55 years.
8. Obesity
9. Elevated Blood Triglyceride Level
Levels greater than 150 mg/dl in the blood are associated with an increased risk.
10. Stress
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