> The Major Body
Systems
Below
are the major systems of the human body which work together to
help the body function properly:
[Circulatory system]
[Digestive system] [Endocrine
system]
[Immune system] [Lymphatic
system] [Integumentary (Skin)
system] [Muscular system]
[Nervous system] [Reproductive
system]
[Respiratory system] [Skeletal
system] [Urinary system]
Circulatory System
The circulatory system pumps and channels blood
to and from the body and lungs with heart, blood, and blood vessels.
It is made up of a group of organs that transport blood throughout
the body. The heart pumps the blood and the arteries and veins
transport it. Oxygen-rich blood leaves the left side of the heart
and enters the biggest artery, called the aorta. The aorta branches
into smaller arteries, which then branch into even smaller vessels
that travel all over the body. When blood enters the smallest
blood vessels, which are called capillaries, and are found in
body tissue, it gives nutrients and oxygen to the cells and takes
in carbon dioxide, water, and waste. The blood, which no longer
contains oxygen and nutrients, then goes back to the heart through
veins. Veins carry waste products away from cells and bring blood
back to the heart , which pumps it to the lungs to pick up oxygen
and eliminate waste carbon dioxide. >>
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Digestive System
The digestive system coordinates digestion
and processing food with salivary glands, esophagus, stomach,
liver, gallbladder, pancreas, intestines, rectum, and anus. The
digestive organs break down food into protein, vitamins, minerals,
carbohydrates, and fats, which the body needs for energy, growth,
and repair. After food is chewed and swallowed, it goes down the
esophagus and enters the stomach, where it is further broken down
by powerful stomach acids. From the stomach the food travels into
the small intestine. This is where your food is broken down into
nutrients that can enter the bloodstream through tiny hair-like
projections. The excess food that the body doesn't need or can't
digest is turned into waste and is eliminated from the body. >>
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Endocrine System
The endocrine system communicates within the
body producing hormones made by endocrine glands such as the hypothalamus,
pituitary or pituitary gland, pineal body or pineal gland, thyroid,
thymus, parathyroids, adrenals or adrenal glands, pancreas, ovaries,
and testes. Hormones are chemicals that control body functions,
such as metabolism, growth, and sexual development. These endocrine
glands release the hormones directly into the bloodstream, which
transports the hormones to organs and tissues throughout the body.
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Immune System
The immune system defends against disease and
infection-causing agents with leukocytes, tonsils, adenoids, thymus,
and spleen. Organs, tissues, cells, and cell products work together
to respond to dangerous organisms (like viruses or bacteria) and
substances that may enter the body from the environment. There
are three types of response systems in the immune system: the
anatomic response, the inflammatory response, and the immune response.
The anatomic response physically prevents threatening substances
from entering your body. Examples of the anatomic system include
the mucous membranes and the skin. If substances do get by, the
inflammatory response goes on attack.
The inflammatory system works by excreting the invaders from your
body. Sneezing, runny noses, and fever are examples of the inflammatory
system at work. Sometimes, even though you don't feel well while
it's happening, your body is fighting illness.
When the inflammatory response fails, the immune
response goes to work. This is the central part of the immune
system and is made up of white blood cells, which fight infection
by gobbling up antigens. About a quarter of white blood cells,
called the lymphocytes, migrate to the lymph nodes and produce
antibodies, which fight disease. >>
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Lymphatic System
The lymphatic system is also a defense system
for the body. It filters out organisms that cause disease, produces
white blood cells, and generates disease-fighting antibodies.
It also distributes fluids and nutrients in the body and drains
excess fluids and protein so that tissues do not swell. The lymphatic
system is made up of a network of vessels that help circulate
body fluids. These vessels carry excess fluid away from the spaces
between tissues and organs and return it to the bloodstream. >>
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Integumentary (Skin)
System
The integumentary system is made up of the
skin, hair and nails. This system is the body's first line of
defense and its primary purpose is protection: protects the body's
internal living tissues and organs; protects against invasion
by infectious organisms; protects the body from dehydration; protects
the body against abrupt changes in temperature; helps dispose
of waste materials; acts as a receptor for touch, pressure, pain,
heat and cold; and stores water, fat, and vitamin D.
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Muscular System
The muscular system is made up of tissues that
work with the skeletal system to control movement of the body.
Some muscles—like the ones in your arms and legs—are
voluntary, meaning that you decide when to move them. Other muscles,
like the ones in your stomach, heart, intestines and other organs,
are involuntary. This means that they are controlled automatically
by the nervous system and hormones—you often don't even
realize they're at work.
The body is made up of three types of muscle tissue: skeletal,
smooth and cardiac. Each of these has the ability to contract
and expand, which allows the body to move and function. .
Skeletal muscles help the body move.
Smooth muscles, which are involuntary, are located inside organs,
such as the stomach and intestines.
Cardiac muscle is found only in the heart. Its motion is involuntary.
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Nervous System
The organs of the nervous system collect, transfer
and process information via the brain, spinal cord, peripheral
nerves, and the sex organs. The nervous system is your body's
control system. As it sends, receives, and processes nerve impulses
throughout the body, these nerve impulses tell your muscles and
organs what to do and how to respond to the environment.
There are three parts of your nervous system
that work together: the central nervous system, the peripheral
nervous system, and the autonomic nervous system.
The central nervous system consists of the brain and spinal cord.
It sends out nerve impulses and analyzes information from the
sense organs, which tell your brain about things you see, hear,
smell, taste and feel.
The peripheral nervous system includes the craniospinal nerves
that branch off from the brain and the spinal cord. It carries
the nerve impulses from the central nervous system to the muscles
and glands.
The autonomic nervous system regulates involuntary action, such
as heart beat and digestion.
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Reproductive System
The reproductive system allows humans to produce
children.In the male, the organs include the testes, prostate,
vas deferens, seminal vesicles, and penis. In the female, the
organs include the ovaries, fallopian tubes, uterus, vagina, mammary
gland, uterus, and vulva. Sperm from the male fertilizes the female's
egg, or ovum, in the fallopian tube. The fertilized egg travels
from the fallopian tube to the uterus, where the fetus develops
over a period of nine months.
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Respiratory System
The respiratory system is composed of the organs
used for breathing: nose, pharynx, larynx, trachea, bronchi, lungs,
and diaphragm. The respiratory system brings air into the body
and removes carbon dioxide. When you breathe in, air enters your
nose or mouth and goes down a long tube called the trachea. The
trachea branches into two bronchial tubes, or primary bronchi,
which go to the lungs. The primary bronchi branch off into even
smaller bronchial tubes, or bronchioles. The bronchioles end in
the alveoli, or air sacs. Oxygen follows this path and passes
through the walls of the air sacs and blood vessels and enters
the blood stream. At the same time, carbon dioxide passes into
the lungs and is exhaled.
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Skeletal System
The skeletal system provides structural support
and protection with bones, cartilage, ligaments, and tendons.
It shapes the body and protects organs. The skeletal system works
with the muscular system to help the body move. Marrow, which
is soft, fatty tissue that produces red blood cells, many white
blood cells, and other immune system cells, is found inside bones.
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Urinary System
The organs of the urinary system include the
kidneys, ureters, bladder and urethra. This system maintains fluid
balance, electrolyte balance and excretion of urine. The urinary
system eliminates waste from the body, in the form of urine. The
kidneys remove waste from the blood. The waste combines with water
to form urine. From the kidneys, urine travels down two thin tubes
called ureters to the bladder. When the bladder is full, urine
is discharged through the urethra.
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