Understanding Human Body Structure and Terminology

Cellular level

Smallest structural and functional unit of the body.

Tissue level

Level of organization in the body consisting of groups of cells.

Organ level

Level of organization in the body consisting of groups of tissues.

System level

Level of organization in the body consisting of groups of organs.

Organism level

The highest level of organization in the body, representing a complete living entity.

Directional Terms

Terms that locate position of structures, surfaces, and regions of the body.

Anterior/Posterior

Directional terms referring to the front and back of the body.

Inferior/Superior

Directional terms referring to below and above in relation to the body.

Proximal/Distal

Directional terms referring to closeness or distance from the trunk of the body.

Cephalad/Caudad

Directional terms referring to toward the head and toward the tail.

Ventral/Dorsal

Directional terms referring to the front (belly) and back of the body.

Lateral/Medial

Directional terms referring to the sides of the body and the middle.

Body Planes

Three major planes of reference in anatomy.

Median (midsagittal)

A plane that divides the body into equal right and left halves.

Frontal (coronal)

A plane that divides the body into anterior and posterior sections.

Horizontal (transverse)

A plane that divides the body into superior and inferior sections.

Body Cavities

Spaces that protect, separate, and support internal organs.

Dorsal (posterior) cavity

Contains the cranial and spinal cavities.

Ventral (anterior) cavity

Contains the thoracic, abdominal, and pelvic cavities.

Four Quadrants

Quadrants that locate specific sites of abdominal organs.

RUQ

Right upper quadrant.

LUQ

Left upper quadrant.

RLQ

Right lower quadrant.

LLQ

Left lower quadrant.

Nine Regions

Regions used to locate organs, origin of pain, and pathologies.

Right hypochondriac

Region located under the right rib cage.

Epigastric

Region located above the stomach.

Left hypochondriac

Region located under the left rib cage.

Right lumbar

Region located in the right middle side near the waist.

Umbilical

Region around the navel.

Left lumbar

Region located in the left middle side near the waist.

Right inguinal

Region located in the right lower side near the groin.

Hypogastric

Region located below the stomach.

Left inguinal

Region located in the left lower side near the groin.

Adhesion

Band of scar tissue binding anatomical surfaces that are normally separate from each other.

endoscopy

visual examination of the interior of organs and cavities with a specialized lighted instrument called an endoscope

fluoroscopy

radiographic technique that uses a fluorescent screen to produce a visual image from x-rays resulting in continuous imaging of the motion of internal structures and immediate serial images

inflammation

protective response of body tissues to irritation, infection, or allergy

sepsis

body's inflammatory response to infection, in which there is fever, elevated heart and respiratory rates, and low blood pressure

ultrasonography

imaging technique that uses high-frequency sound waves (ultrasound) that bounce off body tissues and are recorded to produce an image of an internal organ or tissue

Radiograph (x-ray)

Ionizing radiation waves (x-rays) pass through the body onto a photographic film to produce an image of internal structures. Radiopaque dye may be required for radiographs of soft tissue.

Magnetic resonance imaging (MRI)

Radiographic procedure that uses electromagnetic energy to produce multiplanar cross-sectional images of the body. Exceptional detail of soft tissues.

Ultrasound (US)

Ultra-high-frequency sound waves emitted by a transducer or probe to produce an image of a body structure on a computer screen.

Positron emission tomography (PET)

Radioactive chemical (tracer) is introduced into the body. Tracer accumulates in the most rapidly metabolizing tissues.

Positron emission tomography (PET) (continued)

Positively charged particles (positrons) emitted in a body region and detected by a device called a gamma camera to produce an image. Identification of areas of increased and decreased metabolic activity.

anastomosis

Surgical joining of two ducts, vessels, or bowel segments to allow the flow from one to the other.

cauterize

Process of burning abnormal tissue with electricity, freezing, heat, or chemicals (silver nitrate). Usually performed to destroy damaged or diseased tissues or coagulate blood vessels.

visual examination within (an organ)

/scopy

process of recording (images using frequencies) beyond sound

ultra/son/o/graphy

instrument for examining the stomach

gastr/o/scope

instrument to examine within (the body)

endo/scope

process of recording cuts (slices of organs or tissues)

tom/o/graphy

specialist in the study of cells

cyt/o/logist

study of blood

hemat/o/logy

instrument for measuring heat

therm/o/meter

specialist in the study of x-rays

radi/o/logist

study of stomach disorders

gastr/o/logy