Download The Circulatory System

The Circulatory
System
Rajat Goyal and Michelle Fater
Table of Contents
Table of Contents
Human Organ Systems
The Circulatory System
Open Circulatory System
Closed Circulatory System
Functions of the System
Heart
Pulse
Chambers of the Heart
Arteries
Veins
Blood
Oxygenation of Blood
Red Blood Cells
White Blood Cells
Antigens
Plasma Cells and Platelets
Circulatory Systems of Other Organisms
Mammals and Birds
Amphibians and Reptiles
Fish
First Aid
Glossary
About the Authors
Illustration Credits
1
1
2
3
4
4
5
6
7
7
8
9
10
11
12
13
14
15
16
16
17
18
19
21
23
24
Human Organ Systems
Humans have several organ systems: the immune system,
the circulatory system, the respiratory system, the lymphatic
System, the digestive system, the skeletal system, the muscular system, the endocrine system, the excretory system, the
reproductive system, the integumentary system, and the
nervous system. Each of these systems are responsible for
carrying out unique functions that are essential for human
life. Humans cannot live if one of these systems malfunctions. This book focuses on the
circulatory system and its components.
2
The Circulatory
System
The circulatory system is made up of the vessels and muscles that help to control the flow of blood throughout the
body. This process is called circulation. The main parts of this
system are the heart, the arteries, the capillaries, and the
veins through which the
blood flows. As blood begins to circulate, it leaves
the heart from the left
ventricle and goes into
the aorta. The aorta is the
largest artery in the body.
The blood leaving the
aorta is full of oxygen.
The oxygen-rich blood
travels throughout the
body and its system of arteries into the smallest arterioles.
3
Open and Closed
Systems
The open circulatory system:
The open circulatory system is common in mollusks and arthropods.
Open circulatory systems, which evolved in crustaceans, insects, mollusks and other invertebrates, pump blood into a hemocoel (a bloodfilled, open body cavity) with the blood diffusing back into the circulatory system between cells. Blood is pumped by the heart into the
body cavities, where tissues are surrounded by the blood.
The closed circulatory system
Vertebrates, and a few invertebrates, have a closed circulatory system. Closed circulatory systems have the blood closed at all times
within vessels of different sizes and wall thickness. In this type of system, blood is pumped by the heart through these vessels and does
not normally fill body cavities.
4
Functions of the
System
The circulatory system has many functions including carrying oxygen from the lungs to tissues and carbon dioxide from
tissues to the lungs, resulting in the
exchange of gases. Blood cells supply the oxygen needed for proper
functioning of the cells. The removal of carbon dioxide is equally
essential because it becomes toxic
to cells when present in high concentrations. This system helps in
fighting against infections by using
its defense cells— the granulocytes
and agranulocytes. It prevents over
-bleeding by forming blood clots using the platelets in the
blood.
5
The Heart
The heart is a muscular organ that pumps blood into the
body through blood vessels known as veins and arteries. The
heart is an organ found in all animals that have a circulatory
system. Humans have a
four chambered heart,
with two superior atria
and two inferior ventricles.
The heart pumps blood
throughout the body by
repeated rhythmic contractions. The heart has
two distinct sides, the
right side and the left side.
The right side collects deoxygenated blood in the right atrium from the body and then
pumps the blood back into the lungs using the right ventricle.
The left side of the heart collects oxygenated blood from the
lungs into the left atrium and then oxygenates the blood
through the process of diffusion.
6
Heart Rate
Heart rate is the number of heart beats per minute
(BPM), which can vary as the body's need for oxygen changes,
such as during exercise or sleep. The measurement of heart
rate is used by medical professionals to assist in the diagnosis
and tracking of various
medical conditions. It is
also used by individuals,
such as athletes, who are
interested in monitoring
their heart rate to gain
maximum efficiency from
their training. The heart
rate is measured by finding the pulse of the body. Pulse rate can be measured at any
point on the body where an movement of blood inside an artery can be felt on the surface of the skin. This usually occurs
as the artery is pressed against skin or bone, by pressing on it
with the index and middle finger. The thumb should not be
used for measuring another person's heart rate because it
has a strong pulse of its own.
7
Arteries
An artery is a blood vessel that sends blood from the heart to any
part of the body. The heart pumps blood the through the main artery
called the dorsal aorta. The
main artery then divides
and branches out into
many smaller arteries so
that each region of the
body has its own system of
arteries supplying it with
fresh, oxygen-rich blood.
Arteries are tough on the
outside and smooth on the
inside. An artery wall actually has three layers: an
outer layer of tissue, a muscular middle layer, and an inner layer of
epithelial cells. The muscle in the middle is elastic and very strong.
The inner layer is very smooth so that the blood can flow easily with
no obstacles in its path. The muscular wall of the artery helps the
heart pump the blood. When the heart beats, the artery expands as
it fills with blood. When the heart relaxes arteries contract, which in
turn exerts a force that is strong enough to push the blood along
through the body. This rhythm between the heart and the arteries results in an efficient circulation system.
8
Veins
Veins are similar to arteries but, because they transport
blood at a lower pressure, they are not as strong as arteries.
Like arteries, veins have
three layers: an outer layer
of tissue, muscle in the
middle layer, and a smooth
inner layer of epithelial
cells. However, the layers
are thinner, containing less
tissue. Veins receive blood
from the capillaries after an
exchange of oxygen and
carbon dioxide has taken
place, and the veins transport deoxygenated blood back to the
lungs and heart. It is important that the deoxygenated blood
keeps moving in the proper direction and not be allowed to
flow backward. This is occurrence is made possible by valves
that are located inside the veins. The valves are like gates that
only allow this particular type of blood to move in one direction.
9
Blood
Without blood, the human body would stop working. Blood is the
considered to be the “fluid of life,” transporting oxygen from the lungs to body tissue and carbon dioxide from body tissue to the
lungs. Blood transports foods, vitamins, and minerals from digestion
and hormones from glands
throughout the body. It also
transports disease fighting
substances to the tissues and
waste to the kidneys. Because
it contains living cells, blood is
considered to be alive. Blood
cells have a definite life cycle,
just as all cells do. Red blood
cells live for about four months before being replaced for new cells.
Approximately 55 percent of blood is plasma, a straw-colored clear
liquid. The plasma carries the solid cells and the platelets which help
blood to clot. Without these blood platelets, humans would bleed to
death.
10
The Oxygenation of
Blood
The blood gets oxygenated this way: Oxygen-poor blood
(blue) blood begins its course at the right atrium of the heart.
It then continues on
to the right ventricle, to the pulmonary arteries and
then to the arterioles (the smaller arteries) in the lungs.
From the arterioles,
the blood travels to
the capillaries, the
smallest blood vessels in the body, where CO2 in the blood is
removed and O2 in the blood is replaced. The newly oxygenated blood (red) then goes into left atrium and left ventricle,
which pumps the oxygen-rich blood throughout the body.
11
Red Blood Cells
Red blood cells are the most common type of blood cells,
and they deliver oxygen to the body tissues through the
blood flow. They take up oxygen in the lungs and release it to
cells in the body. These cells have cytoplasm that is rich in
hemoglobin, an iron-containing molecule that can bind oxygen and is responsible for the blood's red color. Red blood
cells develop in the bone marrow and circulate for about 100
–120 days in the body before
The Discovery of Blood
they are replaced with new cells.
Cells
The first person to describe
red blood cells was a Dutch
biologist, Jan Swammerdam,
who in 1658 used an early
version of the microscope to
study the blood of a frog. Anton van Leeuwenhoek provided another microscopic
description in 1674, which
had a more accurate description of red blood cells and
their size, which he described
as "25,000 times smaller than
a fine grain of sand".
12
White Blood Cells
White blood cells are cells of the immune system that defend the body against both infectious diseases and foreign
materials. Five different types of
white blood cells exist, but they are
all produced in the bone marrow
from the same type of cell. White
blood cells are found throughout the
body, including the blood and lymphatic system. The number of white
blood cells in the blood is often a
good indicator of disease. There are
normally between 4×109 and
1.1×1010 white blood cells in a liter
of blood, making up about 1% of blood in a healthy adult. An
increase in the number of these cells is an indication that the
body is producing cells to fight a bacterial or viral infection.
13
Blood Types and
Antigens
Antigens are foreign substances that stimulate the production of antibodies. Antigens include toxins,
bacteria, foreign blood
cells, and the cells of
transplanted organs.
They exist on the surface of red blood cells
and continue their production of antigens
throughout the life span
of the cell. There are three types of antigens: type A, type B,
and type AB. Humans who have type A antigens have blood
type A and anti-B antibodies. Humans who have type B antigens, have blood type B and anti-A antibodies, and humans
who have type A and type B antigens have blood type AB and
no anti-A or anti-B bodies. There are also people with type O
blood. This blood type occurs in a people with no type A or B
antigens on their red blood cells.
14
Plasma Cells and
Platelets
Plasma cells exist on white blood cells that produce many
antibodies. Plasma is the clear, yellowish fluid portion of
blood, lymph, or intramuscular fluid in which cells are suspended. They are also called
plasma B cells, effector B cells, and
plasmocytes. Platelets are cells
that are no longer functional, but
they are essential in the clotting of
blood. They are small, colorless, irregular blood cells that are produced in bone marrow and stored
in the spleen.
15
The Circulatory System
of Other Organisms
The hearts of mammals and birds have four chambers – two
upper chambers called the atria and two lower chambers
called the ventricles. This is
the most efficient system,
as deoxygenated and oxygenated
bloods are not
mixed. The
four-chambered heart means that the tissues of the body are
supplied with oxygen-saturated blood and allows these warm
-blooded organisms to control their body temperature.
16
Circulatory System of
Other Organisms
Amphibians and reptiles have a three-chambered heart,
which consists of two atria and one ventricle. The deoxygenated blood from the right atrium
and oxygenated blood from the left
atrium combine in the single ventricle, so organs of these organisms do
not receive the fully oxygenated
blood. These organisms cannot control their body temperature and are
cold blooded.
17
Circulatory System of
Other Organisms
Fish have the simplest type of heart – a two-chambered organ composed of one atrium and one ventricle. Blood is
pumped from the ventricle to the gills. At the gills, the blood
receives oxygen and loses carbon dioxide. Blood then
moves on to the organs of the body,
where nutrients,
gases, and wastes
are exchanged. The
blood travels from
the heart to the gills and then directly to the body before returning to the atrium to be circulated again.
18
First Aid for the
Circulatory System
Cardiac Arrest
Cardiac arrest occurs when the heart stops beating or beats
too weakly or irregularly to circulate blood effectively to the
bodily organs. Cardiac arrest is life-threatening because vital
organs can only live for a few minutes without receiving oxygen-rich blood.
Causes of Cardiac Arrest
Cardiovascular disease is the most common cause of cardiac
arrest. Drowning, suffocation, and certain drugs can cause
breathing to stop, leading to cardiac arrest as well.
First Aid for Cardiac Arrest
The brain and other vital organs live only for a few minutes
after the heart stops. It is critical
that the patient be given immediate CPR, defibrillation, and advanced emergency medical
care.
19
First Aid
Bleeding
Bleeding causes the blood to escape the circulatory system
and can be life threatening depending on the volume of
blood loss.
First Aid for Severe External Bleeding
External bleeding is usually easy to control. The first aid for
external bleeding includes resting the patient to decrease the
heart rate, elevating the injured area to decrease the blood
flow towards the injury, and applying direct pressure over
the injury.
First Aid for Internal Bleeding
Warning signs of internal bleeding include pain, bruising,
swelling, and blood in vomit, spit, or urine. The first aid for
internal bleeding includes resting the patient, placing an ice
pack over the injury, and contacting Emergency Contact Services (EMS) immediately.
20
Glossary
Antigens: Foreign substances that stimulate the production
of antibodies.
Aorta: The largest artery in the body.
Artery: A blood vessel that sends blood from the heart to any
part of the body.
Capillaries: The smallest blood vessels in the body, where the
nutrients in the blood are exchanged for new blood vessels.
Circulatory system: The system made up of the vessels and
muscles that help to control the flow of blood throughout
the body.
Heart: A muscular organ that pumps blood into the body
through veins and arteries using blood vessels.
Heart rate: The number of heart beats per minute (bpm),
which can vary as the body's need for oxygen changes, such
as during exercise or sleep.
21
Plasma: Clear, yellowish fluid portion of blood, lymph, or intramuscular fluid where cells are suspended.
Platelets: Cells that are no longer functional, but are essential in the clotting of blood.
Red blood cells: The most common type of blood cells and
are one of the principal means of delivering oxygen (O2) to
the body tissues through the blood flow.
Veins: While similar to arteries, they transport blood at a
lower pressure, they are not as strong as arteries.
the body tissues through the blood flow.
White blood cells: Cells of the immune system that defend
the body against both infectious diseases and foreign materials.
22
About the Authors
Rajat Goyal
Rajat Goyal is a junior at the Massachusetts Academy of Mathematics
and Science in Worcester, Massachusetts. Recently he performed an independent research project that analyzed the effect of turmeric (a spice) on
Escherichia coli . He has also recently written a book review on Doctor’s
Diaries (a NOVA documentary) and coauthored an e-book chapter for
Topics in Toxicology. In his spare time, Rajat enjoys skiing, biking, and karate.
Michelle Fater
Michelle Fater is currently a junior at the Massachusetts Academy of
Mathematics and Science in Worcester, Massachusetts. Recently she performed an independent research project as well as published several
pieces of writing, including an e-book chapter for Topics in Toxicology.
In her spare time, Michelle enjoys painting, musical theatre, and ballroom dancing.
23
Illustration Credits
Cover Picture: http://www.nhlbi.nih.gov/health/dci/Diseases/hb/
hb_understanding.html
P.2: http://www.globalneighbourhood.org/k-presentation.php
P.3: http://doctorgrasshopper.wordpress.com/2010/03/11/tools- for-thetoolbox-i-3-the-lub-dubber/
P.4: http://www2.gsu.edu/~bioasx/closeopen.html
P.5: http://www.heartzine.com/anatomy-physiology/the-circulatorysystem.html
P.6: http://www.nytimes.com/imagepages/2007/08/01/health/
adam/19387Circulationofbloodthroughtheheart.html
P.7: http://www.stormgrounds.com/wallpaper/Miscellaneous/
Heart-Rate/
P.8: http://www.kidney-hypertension.com/hypertension.htm
P.9: http://www.landholt.com/3d/arteries_and_veins/
P.10: http://health.nytimes.com/health/guides/specialtopic/
physical-activity/exercise's-effects-on-the-heart.html
P.11: http://en.wikipedia.org/wiki
File:Diagram_of_the_human_heart_(cropped).svg
P.12: http://en.wikipedia.org/wiki/Red_blood_cell
P.13: http://en.wikipedia.org/wiki/White_blood_cell
P.14: http://stemcells.nih.gov/info/scireport/chapter6.asp
P.15: http://repairstemcell.wordpress.com/2009/02/
P.16: http://www.paulnoll.com/Oregon/Birds/Avian-Circulatory.html
P.17:http://www.digitalfrog.com/resources/archives/circ.jpg
P.18:http://www.biology-resources.com/drawing-fish-circulatorysystem.html
P.19:http://kytostat.com/Portals/0/howItWorksGraphic.jpg
http://en.wikipedia.org/wiki/First_aid
P.20:http://www.cbc.ca/22minutes/defibrillator-with-ecg-display-- 4.jpg
http://en.wikipedia.org/wiki/First_aid
24