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:::Index>Profound Human World>Knowledge Acquisition>The Human Body>The
Human Body
The Human Body
The human body is composed of several different kinds of tissues, such as epithelial
tissue, connective tissue, muscular tissue, nervous tissue and etc. The tissues form the
body organs and two or more of organs cooperating together in chemical or physical
interactive ways form the system performing certain function, such as integumentary
system, muscular system, skeletal system, nervous system, endocrine system,
circulatory system, respiratory system, digestive system, urinary system and
reproductive system and so on. First of all, we introduce four kinds of tissues in the
following：
*Epithelial tissue－The cells of epithelial tissue are joined tightly, mainly covering
the surface of body, the lining of body cavities and ducts, also the secretive part of
glands. So the epithelial tissue plays important roles in protection, absorption and
secretion.
*Connective Tissue－This tissue can be classified to four types including connective
tissue proper, cartilage, bone and blood. The connective tissue proper connects two
different tissues and has three main types including dense connective tissue, loose
connective tissue and adipose tissue. The cartilage performs as the cushion of the
body and provides a framework for keeping the shapes of some body areas. The bones
are various in shapes and jointed together with the cartilage to form the joints, so the
bones and cartilages comprise the osseous system and some of the bone marrows even
can produce erythrocytes. The blood cells and plasma are main components of the
blood and their duties are transporting oxygen and nutrients to cells as well as
removing the wastes from cells.
*Muscular Tissuee－This tissue specializes for contraction and has three types
including smooth muscles, skeletal muscles and cardiac muscles. Most of the smooth
muscles exist in the internal organs and contract autonomously without direct body
controlling; the skeletal muscles adherent to the bones by the tendon are responsible
for independent movement, so also called the voluntary muscles; the cardiac muscles
as known as its name are the tissues comprising the heart.
*Nervous Tissue－Neuron is the basic functional unit of this tissue, different types
of them specialize to sense the environmental changes, coordinate the body to
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immediate or long-term responses and transmit the signals to muscles as well as
glands to make responses.
The human body just like a complex and precise factory formed with the basic unit
“cell” which should work separately and cooperatively to maintain a multicellular
organism life. So in the same way, the tissues, organs and systems in our body also
need to cooperate exactly with each other to keep our life, for example, each cell,
tissue and organ all needs energies for action and also creates wastes, so the body
needs circulatory system to carry nutrients and oxygen into the cells and the wastes
away from the cells. Since each organ and system is important to perform certain
functions, the body needs the nervous system be the director coordinating them to
control the whole physiological activities, receive information and make responses, if
it has problems that will result in ache or even worse becoming a good-for-nothing.
The nervous system can be divided into two parts, the central nervous system and
the peripheral nervous system. The central nervous system consists of the cerebrum
and the spinal cord from which the nerves extend outward to each organ and the four
limbs, forming the peripheral nervous system. Besides, the activities of each organ
and tissue are also controlled by a special chemical substance called hormone, which
is secreted by the endocrine glands and then conveyed by the blood to the target tissue
or organ for action.
Reviewed by：Zhang, Yong-Ta、Huang, Mei-Chuan professor
All rights reserved by National Taiwan Science Education Center