Download The Circulatory System - missmayerhealthscience20

By Johran, Sydney, and Emily
April 12, 2016
The circulatory system,
sometimes known as the
cardiovascular system,
consists of the heart, arteries,
veins, capillaries, and blood.
The cardiovascular system
actually consists of three
separate systems (circulatory,
systemic, and pulmonary) but
we will be focusing only on
the circulatory system.
Approximately 2000 gallons of
blood travels daily throughout
96 560 km of blood vessels
through the circulatory system
delivering oxygen to all parts
of the body.
The heart is the main component in the circulatory system and it is composed of
cardiac muscle and tissues. The cardiac muscle works constantly to push blood
through the veins and draw it back through the arteries, circulating oxygen and
nutrients throughout the human body. The blood consists of red and white blood
cells, platelets and plasma. The heart is about the size of two adult hands held
together and rests near the center of the chest and slightly to the left. A doublewalled sac called the pericardium goes all around the heart, protecting it. The
human heart has four chambers: two upper chambers (called the atria) and two
lower ones (called the ventricles). The heart's outer wall consists of three layers.
The first layer, (endocardium), is the lining that contacts the blood. The middle
layer, (myocardium), contains the muscle that contracts. The outside layer,
(epicardium), is the inner wall of the pericardium.
Arteries are blood vessels that deliver the
oxygenized blood from the heart to all parts of
the body. Each artery is composed of a muscular
tube lined with smooth tissue. There are three
main layers that form an artery, these are the
intima; the inner layer lined by a smooth tissue
called endothelium, the media; the muscular later
that allows arteries to handle the high pressures
of the heart, and the adventitia which is the
connective tissue that anchors the arteries to the
surrounding tissues. The largest artery in your
body is the aorta artery which runs from your
heart to the neck and down through both legs
then branches into smaller arteries called
arterioles and capillaries. It is the body’s largest
source of blood to the body and an average of 17
liters of blood is pumped per minute through it
which is about 7200 gallons daily.
Veins are blood vessels that transports blood from different areas of the body
back to the heart. Veins are components of the cardiovascular system, which
circulates blood to provide nutrients to the cells of the body. Sometimes vein
problems can occur, most commonly due to either a blood clot or a vein flaw.
There are four main types of veins:
pulmonary, systemic, superficial, and deep
veins.
• Pulmonary veins: carry oxygenated blood
from the lungs to the left side of the heart.
• Systemic veins: return used blood from
the rest of the body to the right side of the
heart.
• Superficial veins: located close to the
surface of skin and are not located near a
similar artery.
• Deep veins: located deep within muscle
tissue and are usually located near a similar
Artery.
Capillaries are the smallest, fine branched blood vessels that carry oxygenated blood from the
arterioles into the small tissues of the body and back again to the arterioles and then to the
veins. Their walls consist of only a single layer of endothelial cells (the inner most layer of
most arteries) and permit only a single file line of red blood cells to pass through them. They
are an essential part of the circulatory system because they make the main connection
between the arteries and the veins and are selectively permeable which means they allow
some substances through, but not others. This helps in the filtration of toxins such as carbon
dioxide and keeps them from reaching the most important parts of the tissues that require
oxygen. Most of the 97 000 kilometers of blood vessels in the body are capillaries. Capillaries
are divided into three main types: fenestrated, continuous and discontinuous. Fenestrated
capillaries allow food molecules from the stomach to be carried into the blood to make
energy for the body, continuous capillaries are the tiniest of capillaries so they don’t allow
anything but the smallest molecule to pass through. Brain capillaries are continues and are so
tiny only water and small ions can pass through. The final type of capillaries are the
discontinuous ones and allow large molecules to pass through and are the most common
capillaries found in the body.
Red blood cells carry oxygen throughout the body. They are produced in the
bone marrow and it usually takes them around 9-10 days to fully develop.
Red blood cells contain hemoglobin which helps them carry oxygen and
carbon dioxide to all the body tissues and to the lungs, where it is excreted.
Hemoglobin is a pigment, it gives the cells their red color. Though red cells
are usually round, a small proportion are oval in the normal person. Some
diseases can change the shape of red blood cells over time.
White blood cells only account for 1% of your blood, but their impact is significant. The white blood cells
found in human blood are essential for good health because they constantly protect against illness and
disease. They are almost continuously at war battling viruses, bacteria and other foreign intruders. Like
other red blood cells, white blood cells are produced inside the bone marrow and because they only
have a lifespan of one to three days, your bone marrow is constantly producing more healthy cells to
replace the dead ones. There are five types of white blood cells;
Monocytes – these help to break down bacteria
Lymphocytes – these create antibodies to defend against the bacteria, viruses and other harmful things
that enter the body
Neutrophils – these white blood cells kill and digest bacteria and fungi. They are the most common and
the body’s first line of defense when infection strikes
Basophils – these small cells “sound an alarm” when infectious agents (such as pollen) enter the body.
The secret chemicals such as histamine that help control the body’s immune response to something such
as allergies are then released.
Eosinophils – these attack and kill parasites, destroy cancer cells and help with allergic responses.
Platelets are also called thrombocytes. They are made in the bone marrow and are very
essential in the circulatory system. People with low numbers of platelets may bleed or
bruise easily, even after minor injuries. When you have a low platelet count, it increases
the risk of bleeding, especially from the mouth or nose. Platelets are the smallest of our
blood cells and can only be seen under a microscope. A blood vessel sends out a signal
when it becomes damaged. When platelets receive that signal, they will travel to the area
and start to do their job by fixing it. To make contact with the broken blood vessel, they
grow long tentacles that are similar to a octopus or spider.
There are two types of thrombocytosis (a medical term when you have too many
platelets in your system).
Primary or essential thrombocytosis – Abnormal cells in the bone marrow that cause an
increases in platelets, reason is currently unknown.
Secondary thrombocytosis – The same condition as primary thrombocytosis, but may be
caused by different diseases such as anemia, cancer, inflammation, or infection.
Parts of blood can be put into two categories.
First, there are the solid particles. In this
category there are red blood cells, white blood
cells, and platelets. The rest of the blood is
made of blood plasma. Plasma is a yellowish,
watery liquid that works with all other parts of
the blood. It is about 55% volume of our blood.
Plasma itself is made up of 91.5% water.
Plasma is important, as it carries our proteins,
nutrients, electrolytes, gases, white blood
cells, red blood cells and platelets throughout
the liquid in which they travel. Plasma is a
critical treatment of many serious health
problems. This is why there are many blood
drives that encourage people to donate their
blood plasma.
The circulatory system works with other main types of systems in the body in different ways. It works
with the nervous system by the brain sending messages to the heart telling it to beat. The heart then
beats blood throughout the body so nutrients and oxygen can be brought to different cells. It works
with the digestive system by putting the nutrients that are broken down into the blood stream for
cells to use as energy. Along with nutrients, minerals and vitamins also get put into the blood stream
to strengthen the immune system and bones. Since the heart is a muscle, it also works with the
muscular system. The expanding and contracting of the heart is how blood pumps through our body.
Working with the respiratory system, oxygen made from the lungs is sent through blood vessels into
the blood stream for the body to use. The skeletal system helps the circulatory system by producing
red and white blood cells. These blood cells are essential for our body by carrying oxygen and fighting
off diseases. The immune system is made of white blood cells and antibodies. These parts travel inside
the blood so that they can be transported to the site of infection to remove or hopefully destroy
it. This is how you fight off sicknesses.
• Your heart beats about 70 times a minute
• It only takes 20 seconds for a red blood to circle the whole body.
• In your lifetime your heart pumps enough blood to fill 100 Olympic size
swimming pools.
• Red blood cells make approximately 250 000 trips around the body before
returning to the bone marrow, where they were made.
• Human blood is colorless, it is a hemoglobin that makes it red.
• The heart beats about 3 billion times in the average human life.
• About 8 million blood cells in the human body die every second, and the
same number are born each second.
• Red blood cells may live for about 4 months circulating throughout the body,
feeding the 60 trillion other body cells.
• Within a tiny drop of blood, there are 5 million red blood cells.
• An adult human body contains 5 to 6 liters of blood and an infant has about
1 liter of blood.
• The human heart continues to beat even after it is taken out of the human
body or cut into pieces.
• A woman’s heart beats faster then a man’s.
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