College of Education
junabethpanghulan@gmail.com
The Human
Circulatory System
“Worry affects circulation, the
heart, and the glands, the whole nervous system, and profoundly affects the
heart. I have never known a man who died from overwork, but many who died from
doubt.”
-Charles Horace Mayo- (1865 -
1939)
I. Circulatory System or Cardiovascular System
-in humans
the combined function of the heart,
blood and blood vessels.
-to transport oxygen and nutrients to organs and tissues
throughout the body and carry away
waste products.
-among its vital functions, the circulatory system increases
the flow of blood to meet increased energy demands during exercise and
regulates body temperature.
-in addition, when foreign substances or organisms invade
the body, the circulatory system swiftly conveys disease-fighting elements of
the immune system, such as white blood cells and antibodies, to regions under
attack. Also, in the case of injury or bleeding, the circulatory system sends
clotting cells and proteins to the affected site, which quickly stop bleeding
and promote healing.
Figure
1.1 The Human Circulatory System
II. The functions of the circulatory system are:
-Transport
gases, like oxygen from the lungs to cells around the body and carbon dioxide
from the cells to the lungs.
-Transport
nutrients like glucose.
-Transport
wastes from cells to organs that play the role of eliminating them.
-It contains
cells that fight infections and defend against foreign bodies.
-Maintains the
pH levels and ionic concentration of fluids in the body.
-Helps maintain
the body temperature, this is especially important in warm blooded animals like
humans.
III.
Circulatory System Diseases
Atherosclerosis- Literally, “hardening
of the fatty stuff.” High fat diets can lead to formation of fatty plaques
lining blood vessels. These fatty areas can become calcified and hard leading
to arteriosclerosis, hardening of the arteries. When blood vessels become less
stretchable, blood pressure rises and can result in heart and kidney damage and
strokes. Double cheese bacon burger, anybody?
Myocardial infarction (MI) - You
know we are talking about heart muscle, right, myocardial? An infarction is
blockage of blood flow resulting in death of muscle tissue. Layman’s language
for this is a “heart attack.” The blockage occurs in one of the arteries of the
heart muscle itself, a coronary artery. Depending upon how much tissue dies, a
victim of an MI may survive and undergo cardiac rehabilitation, strengthening
the remaining heart muscle, or may die if too much muscle tissue is destroyed.
Did you exercise at the gym this week?
Mitral prolapse, stenosis, regurgitation- Blood
flows through four chambers in the heart separated by one-way valves. A major
valve is the one separating the upper and lower chambers on the left side of
the heart. The left side is especially important because freshly oxygenated
blood returning from the lungs is circulated out of the heart to the rest of
the body. The left valve, called atrioventricular, for the chambers it
separates, is also called the mitral valve, because it is shaped like an upside
down Bishop’s hat, a miter. If the flaps of this valve tear away due to
disease, the process is called prolapse, “a falling forward.” This results in
leakage and backward flow called “regurgitation” (get the picture?). Sometimes
a valve is abnormally narrow causing partial obstruction constricting flow.
Stenosis means “a narrowing.”
Angina pectoris- Literally, “pain in the
chest.” But, this is a special kind of pain associated with the heart and is
distinctive as “crushing, vise-like”, and often accompanied by shortness of
breath, fatigue and nausea. Anginal pain indicates not enough blood is getting
to the heart muscle, and the heart is protesting and begging for more. People
with a history of angina often take nitroglycerine tablets to relieve the pain
by increasing blood flow to the heart muscle.
Arrhythmia/dysrhythmia-
Abnormal heart rates and rhythms all have special names like ventricular
tachycardia, fibrillation, but generically are termed arrhythmias or
dysrhythmia, meaning “no rhythm” and “abnormal rhythm.” There are fine
distinctions between the two, but they are often used interchangeably.
Ischemia- Sometimes the heart
muscle is not getting enough blood flow, more importantly, the oxygen the blood
carries is insufficient to sustain muscle which has a very high metabolic rate,
and oxygen demand. The term loosely means “not quite enough blood.” Typically,
the patient suffers angina pain (see above) and they may think they are having a
heart attack. And, they may be!
IV. Components of the Circulatory System
a. Heart
b.
Blood
c. Blood Vessels
Figure 1.2
Human Heart
Human Heart
- is a
hollow, pear-shaped organ about the size
of a fist.
-the
heart is made of muscle that rhythmically contracts, or beats, pumping blood throughout
the body.
- oxygen-poor
blood from the body enters the heart from two large blood vessels, the inferior
vena cava and the superior vena cava, and collects in the right atrium.
-shaped
like an upside-down pear and is located slightly to the left of center inside
the chest cavity.
-heart
has four chambers.
a. the two upper chambers
b. the two lower chambers
- The upper two
chambers, the right and left atria, are receiving
chambers for blood.
- The atria are sometimes known as auricles. They collect blood that
pours in from veins, blood vessels that return blood to the heart.
-
The
heart’s lower two chambers, the right
and left ventricles, are the powerful pumping chambers.
- The ventricles propel blood into arteries, blood vessels that carry
blood away from the heart.
Function of the
Heart
-
are
much broader than simply pumping blood continuously throughout life.
-
the
heart must also respond to changes in the body’s demand for oxygen. The heart
works very differently during sleep, for example, than in the middle of a 5-km
(3-mi) run.
-
the
heart and the rest of the circulatory system can respond almost instantaneously
to shifting situations—when a person stands up or lies down, for example, or
when a person is faced with a potentially dangerous situation.
Heart Diseases
a. Coronary Heart Disease
b. Congenital Defects
c. Heart Valve Malfunction
d. Arrhythmias
e. Myocarditis
f. Endocarditis
Figure 1.3 BLOOD
Blood
-
is
a vital fluid found in humans and
other animals that provides important nourishment to all body organs and
tissues and carries away waste materials.
-
Referred
to as “the river of life” blood is
pumped from the heart through a network of blood vessels collectively known as
the circulatory system.
Function of the Blood
- Blood carries oxygen from the lungs to all the other
tissues in the body and, in turn, carries waste products, predominantly carbon
dioxide, back to the lungs where they are released into the air.
-
Blood is more than a pipeline for
nutrients and information; it is also responsible for the activities of the
immune system, helping fend off infection and fight disease.
-
Blood carries the means for stopping itself from leaking out of the body after
an injury. The blood does this by carrying special cells and proteins, known as
the coagulation system, that start to form clots within a matter of seconds
after injury.
- Blood is vital to maintaining a
stable body temperature; in humans, body temperature normally fluctuates within
a degree of 37.0° C (98.6° F).
Composition of Blood
-About 55 percent of the blood is composed of
a liquid known as plasma.
-The rest of the
blood is made of three major types of
cells:
a. red
blood cells (also known as erythrocytes)
b. white
blood cells (leukocytes)
c. platelets
(thrombocytes)
Plasma
-
Consists
predominantly of water and salts.
-
usually
yellow in color due to proteins dissolved in it.
-
carries
a large number of important proteins, including albumin, gamma globulin, and
clotting factors.
-
Albumin is the main protein in blood. It helps regulate the water
content of tissues and blood.
-
Gamma
globulin
is composed of tens of thousands of unique antibody molecules. Antibodies
neutralize or help destroy infectious organisms. Each antibody is designed to
target one specific invading organism.
Figure 1.4 Red Blood Cells
Red Blood Cells
-
make up almost 45 percent of the blood
volume.
-
Their
primary function is to carry oxygen from
the lungs to every cell in the body.
-
Composed
predominantly of a protein and iron
compound, called hemoglobin
which captures oxygen molecules as the blood moves through the lungs, giving
blood its red color.
-
Red
blood cells are so packed with hemoglobin that they lack many components,
including a nucleus, found in other cells. Hemoglobin
also takes up and releases nitric oxide, which plays an important role in
regulating blood pressure.
-
The
membrane, or outer layer, of the red blood cell is flexible, like a soap bubble, and is able to bend in many
directions without breaking.
-
Red
blood cells must be able to pass through the tiniest blood vessels, the capillaries, to deliver oxygen wherever
it is needed.
-
The capillaries are so narrow that the red
blood cells, normally shaped like a disk with a concave top and bottom, must
bend and twist to maneuver single file through them.
Figure
1.5 White Blood Cells
White Blood Cells
-
Make
up about 1 percent of blood, but
their small number belies their immense importance.
-
They
play a vital role in the body’s immune system—the primary defense mechanism against invading bacteria, viruses, fungi,
and parasites.
-
They
often accomplish this goal through direct attack, which usually involves
identifying the invading organism as foreign, attaching to it, and then
destroying it. This process is referred to as phagocytosis.
-
Also
produce antibodies, which are released into the circulating blood to target and
attach to foreign organisms.
-
There
are several varieties of white blood cells, including neutrophils, monocytes, and lymphocytes,
all of which interact with one another and with plasma proteins and other cell
types to form the complex and highly effective immune system.
Figure
1.6 Platelets
Platelets
-
smallest
cells in the blood
-
which
are designed for a single purpose—to begin the process of coagulation, or forming a clot, whenever a blood vessel is broken.
-
The
platelets in the area of the injury begin to clump together and stick to the
edges of the cut.
-
They
also release messengers into the blood that perform a variety of functions: constricting the blood vessels to reduce
bleeding, attracting more platelets to the area to enlarge the platelet plug,
and initiating the work of plasma-based
clotting factors, such as fibrinogen.
-
The
plasma protein fibrinogen is transformed into long, sticky threads of fibrin.
Together, the platelets and the fibrin create an intertwined meshwork that
forms a stable clot. This self-sealing aspect of the blood is crucial to
survival.
Figure 1.7: Blood Vessels
Blood
Vessels
-
It
circulates blood through the body.
-
The
three major types of blood vessels are the arteries,
veins, and capillaries.
a.
Arteries
-
One
of the tubular vessels that conveys blood from the heart to the tissues of the
body.
-
Two
arteries have direct connection with the heart: (1) the aorta, which, with its branches, conveys oxygenated blood
from the left ventricle to every part of the body; and (2) the pulmonary artery, which conveys blood from the right ventricle
to the lungs, whence it is returned bearing oxygen to the left side of the
heart.
-
Arteries in their ultimate minute branching
are connected with the veins by capillaries. They are named usually from the
part of the body where they are found, as the brachial (arm) or the metacarpal
(wrist) artery; or from the organ which they supply, as the hepatic (liver) or the ovarian artery.
-
Carry blood away from the heart.
b. Veins
-
Carry blood toward the heart.
-
blood
vessel that conducts the deoxygenated blood from the capillaries back to the
heart.
-
Three
exceptions to this description exist: (1)
the pulmonary veins return blood from the lungs, where it has been oxygenated,
to the heart; the portal veins receive blood from the pyloric, gastric, cystic,
superior mesenteric, and (2) splenic
veins and, entering the liver, break up into small branches that pass through
all parts of that organ; and (3) the
umbilical veins convey blood from the fetus to the mother's placenta.
-
Enlarge
as they proceed, gathering blood from their tributaries. They finally pour the
blood through the superior and inferior venae cavae into the right atrium of
the heart. Their coats are similar to those of the arteries, but thinner, and
often transparent.
References:
4.
https://www.google.com.ph/search?q=circulatory+system&hl=fil&tbo=u&tbm=isch&source=univ&sa=X&ei=hvsWUYHGL6a5iAecsYCYDA&ved=0CDIQsAQ&biw=1024&bih=630#imgrc=RV5Q3vQuRSylgM%3A%3BR1GI1m0vFH231M%3Bhttp%253A%252F%252F2.bp.blogspot.com%252F-Pi5PGN2RVCE%252FT479oFi4WtI%252FAAAAAAAAFYQ%252Fm3J19rlKGpU%252Fs1600%252Fcirculatory-system-7.jpg%3Bhttp%253A%252F%252Fphotos1-ol.blogspot.com%252F2012%252F04%252Fcirculatory-system.html%3B340%3B450
10. http://www.fit-ed.org/congress2008/contents/ALIGAEN/Circulatory%20system%20and%20its%20functions.htm
Prepared
By:
Junabeth
B. Panghulan
Beed 2a
Prepared
To:
Dr.
Myrna C. Bigueja
Associate
Professor 1
