Basic Units of Structure - Medical Terminology(Adaptive*)

Cells are the smallest living units of structure and function in the human body. Every tissue and organ in the body is composed of cells. Review the illustration depicting the cellular level in Levels of structural organization of the human body shown from the basic unit of structure, the cellular level, to the most complex, the organism level—a living human being.

The body system illustrated is the digestive system.. Note the darkened area in the center, the nucleus. It is the control center of the cell and is responsible for reproduction. This spherical unit contains genetic codes for maintaining life systems of the organism and for issuing commands for growth and reproduction.

Levels of structural organization of the human body shown from the basic unit of structure, the cellular level, to the most complex, the organism level—a living human being. The body system illustrated is the digestive system.

Any chemical substance, such as a drug that interferes with or destroys the cellular reproductive process in the nucleus, is referred to as a nucle/o/toxic substance. Examples of nucle/o/toxic drugs are those administered to cancer patients during chemotherapy.

A cyt/o/logistis usually a biologist who specializes in the study of cells, especially one who uses cyt/o/log/ic techniques to diagnose neoplasms. At the tissue level, the structural organization of the human body consists of groups of cells working together to carry out a specialized activity.

See Figure (Levels of structural organization of the human body shown from the basic unit of structure, the cellular level, to the most complex, the organism level—a living human being. The body system illustrated is the digestive system.) The medical scientist who specializes in microscopic identification of cells and tissues is called a hist/o/logist.

The human body is capable of being in many different positions, such as standing, kneeling, and lying down. To guarantee consistency in descriptions of location, the anatomic/al position is used as a reference point to describe the location or direction of a body structure. In anatomic/al position, the body is erect and the eyes are looking forward. The arms hang to the sides, with palms facing forward; the legs are parallel with the toes pointing straight ahead.

Review Figure(Body planes) and study the terms to become acquainted with their usage in denoting positions of direction when the body is in the anatomic/al position. When a person is standing upright facing forward, arms at the sides with palms forward, with the legs parallel and the feet slightly apart with the toes pointing forward, he or she is in the standard position called the anatomic/al position

Body planes.

Health care professionals use a common language of special terms when referring to body structures and their functions. However, their descriptions of any region or part of the human body assume that it is in anatomic/al position. In anatomical position, the terms anter/iorand ventr/al refer to the front of the body or the front of any body structure. The terms poster/ior and dors/al refer to the back of the body or the back of any body structure.

Directional terms are commonly used in radi/o/logy to describe the direction of the x-ray beam from its source and its point of exit. In an anter/o/poster/ior projection, the beam enters the body anteriorly and exits posteriorly. A poster/o/anter/ior projection indicates that the beam enters the body on the posterior, anterior side and exits on the back, front side.

The stomach is on the anter/ior side of the body. The shoulder blades are on the poster/iorside of the body. The term inferior in the English language refers to something of little or no importance. However, when used in a medical report, it designates a position or direction meaning lower, below.

The word element later/o means side, to one side. A radiographic projection that enters through the left or right side of the body is referred to as a later/al projection. The term medi/al is used to describe the midline of the body or a structure. The medi/al portion of the face contains the nose.

Anatomists use the term infer/ior to refer to a body structure located below another body structure or the lower part of a structure. For example, your chin is situated infer/ior to your mouth. (See Figure Body planes.)The rectum is the infer/ior portion of the colon.

The legs are infer/ior to the trunk. The eyes are later/al to the nose. Anatomists and health care professionals use the term super/ior to refer to a body structure that is above another body structure or toward the head, because the head is the most superior structure of the body. Cephal/ad is a term that refers to the direction toward the head.

The CF caud/o means tail. In this sense, tail designates a position toward the end of the body, away from the head. In humans, it also refers to an infer/ior position in the body or within a structure. The terms proxim/al and dist/al are used as positional and directional terms. Proxim/al describes a structure as being nearest the point of attachment to the trunk or near the beginning of a structure. Dist/al describes a structure as being far from the point of attachment to the trunk or from the beginning of a structure.

The directional element proxim/o means near or nearest the point of attachment; dist/o means far or farthest from the point of attachment. The knee is proxim/al to the foot; the palm is dist/al to the elbow. (See Figure Body planes.)

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