2-3. SYSTEMS OF THE BODY
A system is a combination of parts or organs, which, in association, perform some
particular function. The systems of the body are as follows:
a. Integumentary. Covers and protects the body from drying, injury, and
infection, and has functions of sensation, temperature regulation, and excretion.
b. Skeletal. Provides a framework for the body, supports the organs, and
furnishes a place of attachment for muscles.
Muscular. Provides the force for the motion and propulsion of the body.
d. Respiratory. Absorbs oxygen from the air and gives off the carbon dioxide
produced by the body tissues.
Cardiovascular. Functions in the transportation of blood throughout the
f. Lymphatic (System of Vessels and Glands). Returns protein and fluid to
the blood from the various body tissues; also furnishes the body with protective
mechanisms against pathogenic organisms.
g. Gastrointestinal. Digests and absorbs food substances and excretes waste
h. Genitourinary. Excretes and transports urine (urinary), and elaborates and
transports reproductive cells and sex hormones (reproductive).
i. Nervous and Special Senses. Gives the body awareness of its
environment, and enable it to react to that environment.
j. Endocrine. Manufactures hormones, which are active in the control of much
of the body activity and behavior.
Section II. CELLS
Each of the 100 trillion cells in a human being is a living structure that is capable
of surviving indefinitely. In most instances, the cell can reproduce itself provided its
surrounding fluids remain intact. To understand the function of the various organs and
other structures of the human body, it is essential that you first understand the basic
organization of the cell and the functions of its component parts.