Basic body Structure

Introduction
This chapter starts by introducing you to some basic concepts related to the
study of the human body. It will prepare you to learn the roots you need to know
for this and the following chapters on suffixes and prefixes.
The roots in this chapter are grouped according to body systems. You will
find it much easier to remember each root if you associate it with a mental
picture of the organ it refers to. The roots you encounter in this chapter will give
you a foundation for building medical terms.
Anatomy and Physiology
Two terms often used in this text are anatomy (ah-NAT-oh-mee) and physiology
(
fiz-ee-OL-oh-jee). Anatomy is the study of the structure or parts of the body. Physiology
is the study of how a body part functions. For example, the biceps brachii (BYE-seps
BRAY-kee-eye) muscle is located on top of the upper arm (Figure 2-1). It is made up of
cells that are long and slender. These cells are called muscle fibers. The function of the
biceps brachii is to flex the lower arm by pulling on the bones of the forearm.
2.2 Levels of Organization
All life consists of microscopic living structures called cells. They perform various functions
throughout the body. All cells are similar in structure, but not identical. Each cell
has a cell membrane, which acts as a barrier separating the inside of the cell from its
surroundings. The inside of the cell is called the cytoplasm (SIGH-toh-plaz-um). The
cytoplasm contains small organs called organelles. These organelles carry on life’s functions
as mentioned below.
The central portion of the cell is the nucleus (NOO-klee-us). The nucleus contains
DNA. Human DNA contains thousands of genes, which are responsible for transmitting
hereditary characteristics such as the shape of the body and color of the hair.
Chromosomes (KROH-moh-zohms) are structures in the nucleus that carry the DNA
individuals
and to prove genetic relationships.
The body’s cells carry on all of the functions of life such as:
• Taking in food and oxygen
• Producing heat and energy
• Eliminating wastes
• Responding to changes in the environment
• Reproducing
Trillions of cells make up the cellular level, which is the first level of organization of
the body.
The next level is called tissues. Similar cells working together to perform a specific
function combine to make up tissues. For example, muscle cells form muscle tissue.
Nerve cells form nervous tissue. A histologist (hiss-TOL-oh-jist) is someone who specializes
in the study of tissues. The major tissue types are:
• Epithelial (ep-ih-THEE-lee-al) tissue: Epithelial tissue covers external surfaces
of the body, lines body structures, and forms glands. The skin is an example of
an organ that is made up of epithelial tissue. Mucous membrane is also made up
of epithelial tissue. It is found lining the digestive, respiratory, reproductive, and
urinary tracts.
• Connective tissue: Connective tissue functions to support and shape the body
structures and keeps them in place. Tendons and ligaments, blood, bone, cartilage,
and fat are examples of connective tissue.
• Muscle tissue: Muscle tissue takes its name from its location in the body; for
example, in the heart it is called cardiac muscle tissue. Within organs, such as
the stomach and intestines, it is called visceral (VIS-er-al) muscle tissue. Muscle
associated with bones is called skeletal muscle tissue. All muscles, no matter
where their location, create movement of some kind. Muscle cells are not round,
but long and slender. For this reason, muscle cells are often referred to as fibers.
See Figure 2-1.
• Nervous tissue: This tissue makes up nerves that conduct electrical impulses
throughout the body. The brain, spinal cord, and nerves are made up of nervous
tissue.