Organization of the Body
Chapter 10: An Org Chart to Live By: Organization of the Body
Tissues
In the building blocks of body structures, cells of similar characteristics and specific tasks join together to form tissue. The body is made up of four differ- ent types of tissue:
✓ Connective tissue supports and encases body structures. It is the most widespread kind of tissue throughout the body. It holds organs in place and connects body parts to each other. The main types of connective tissue include bone that supports the body; cartilage, firm but bendable;
dense fibrous that makes up the tendons and ligaments; loose that con- nects adjoining structures; and apidose tissue that pads and protects, stores fat, and insulates the body against heat loss.
✓ Epithelial tissue: Found in the skin and in the lining of blood vessels, this makes up the outer covering of external and internal body surfaces (such as skin and mucous membranes) and the lining of the digestive, respiratory, and urinary tracts.
✓ Muscle tissue provides movement. The main function of muscle tissue is to contract.
✓ Nerve tissue conducts impulses to and from the brain and is composed of nerve cells called neurons. Nervous tissue needs more oxygen and more nutrients than any other body tissue.
Organs and Systems
When two or more kinds of tissue work together to perform a specific function, you have an organ. For example, the skin is an organ made up of connective, nerve, and epithelial tissue.
Although organs act as units, they do not function alone. Several organs join together to form a system and perform a body function. Each system has a special function.
Some of the major body systems include the following:
✓ The cardiovascular system includes the heart and blood vessels and carries the blood throughout the body.
✓ The digestive or gastrointestinal system includes the mouth, esopha- gus, stomach, and small and large intestines. This system digests and absorbs food and excretes waste.
✓ The endocrine system is made up of a variety of glands and manufac- tures and distributes hormones.
oil glands.
✓ The lymphatic system works with the cardiovascular system to protect the body against disease-causing organisms.
✓ The musculoskeletal system, composed of bones, muscles, tendons, and ligaments, provides the framework for the body, supports organs, and permits movement in the body.
✓ The reproductive systems, the uterus, ovaries, testes, and prostate, pro- vide for reproduction.
✓ The respiratory system includes the trachea, lungs, and bronchi and provides the exchange of gases, absorbs oxygen, and expels carbon dioxide.
✓ The sensory or special senses system, made up of the eyes, ears, nose, and mouth, along with the nervous system composed of the brain and spinal cord, processes stimuli and allows the body to act and respond.
✓ The urinary system manufactures and excretes urine.
Cavities of the Body
The body is not as solid a structure as it appears on the outside. It has five body cavities. Each cavity contains organs that are organized (no pun intended) in a neat and orderly fashion.
The five body cavities include the following:
✓ The abdominal cavity contains the stomach, intestines, liver, spleen, gallbladder, pancreas, ureters, and kidneys.
✓ The cranial cavity, the cavity inside the skull, or the cranium, contains the brain.
✓ The pelvic cavity contains the urinary bladder, urethra, uterus and vagina in the female, part of the large intestine, and the rectum.
✓ The spinal cavity consists of the spinal column connecting to the cranial cavity.
✓ The thoracic or chest cavity contains the esophagus, trachea, lungs, heart, and aorta. This cavity can be divided into two smaller areas. The pleural cavity surrounds the lungs. (Each pleural cavity is lined with a membrane called pleura. Visceral pleura is closest to the lungs. Parietal pleura is closest to the outer wall of the cavity.) The mediastinum is the area between the lungs. It contains the heart, aorta, trachea, esophagus, and thymus gland.
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Chapter 10: An Org Chart to Live By: Organization of the Body
The cranial and spinal cavities are dorsal body cavities, as they are located on the back part of the body. The thoracic, abdominal, and pelvic cavities are ventral body cavities, as they are on the front or belly-side of the body.
The thoracic and abdominal cavities are separated by a muscular partition called the diaphragm. The abdominal and pelvic cavities are not separated and, to really confuse you, together they are frequently referred to as the abdominopelvic cavity.
Table 10-1 lists some root words related to body structure and organization.
Table 10-1 Roots of Structures
Root What It Means Example Term What It Means
Cyt/o Cell Cytology Study of cells
Epitheli/o Epithelium Epithelioma Tumor of the skin
Fibr/o Fibrous Fibrosis Condition of the fibrous
tissue
Hist/o Tissue Histologist Physician who studies
tissue
Lip/o Fat Liposuction Removal of fat cells by
suction
Myo Muscle Myositis Inflammation of a muscle
Neur/o Nerve Neuropathy Condition of the nerve
Organ/o Organ Organomegaly Enlargement of an organ
Viscer/o Internal organs Viscera Internal organs
Table 10-2 lists some suffixes pertaining to body structure and organization.
Table 10-2 Structural Suffixes
Suffix What It Means Example Term
What It Means
-cyte Cell Erythrocyte Red blood cell
-gen Agent that causes Carcinogen Agent causing cancer
-genic Producing Carcinogenic Has cancer-causing
properties -ologist One who studies/
practices
Cytologist Physician who studies cells
(continued)
Table 10-2 (continued)
Suffix What It Means Example Term
What It Means
-oma Tumor or swelling Myoma Tumor in the muscle
-osis Abnormal condition Cytosis Abnormal condition of cells
-pathy Disease Neuropathy A disease of the nerves
-plasm Growth or formation Neoplasm A new growth -sar-
coma
Malignant tumor Myosarcoma Malignant muscle tumor
Directional Terms and Anatomical Planes
An anatomical plane is an imaginary flat plate or field. Imagine a slice view through the body and you’re on the right track. Anatomic planes provide further division of the body, again to identify a specific location or area.
Visualize dividing the body in half, top from bottom, and then right from left, and finally front from back.
✓ The frontal or coronal plane is a vertical plane dividing the body into anterior (front) and posterior (back) portions.
✓ The midsagittal plane is a horizontal plane that divides the body into right and left halves at the body’s midpoint.
✓ The sagittal plane is a vertical plane that passes from front to back, dividing the body into right and left sides.
✓ The transverse plane is a horizontal (cross-section) plane, parallel to the ground and through the waistline, dividing the body into upper and lower halves.
The anatomical planes of the body are used in radiology when specific body location or direction is necessary.
When thinking about all of these terms, planes, and regions, think of the body as if it is standing, arms at each side, with palms facing forward and the feet side by side. Whether a patient is standing, or lying down face up, the direc- tional terms are always applied in the same manner.
Directional terms are used to pinpoint or specifically locate an area on the body.
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Chapter 10: An Org Chart to Live By: Organization of the Body
When referring to the front of the body, the terms anterior and ventral are used. When referring to the back of the body, it’s posterior and dorsal. With the waistline of the anatomical position as a guideline, above the waistline is referred to as cephalad (“head” or “upward”) or superior (“above”). Below the waistline is referred to as caudal (“tail” or “downward”) or inferior (“below”).
Superior and inferior are also used to describe body parts in relation to one another in general.
The sides of the body are referred to as lateral, and the middle referred to as medial. The term distal refers to “away from the point of origin” (think of distance). Proximal refers to “nearest the point of origin” (close proximity).
Distal and proximal are two directional terms that seem to pose problems.
View the torso of the body as the point of origin. Using the arm as an exam- ple, the proximal portion of the arm is where the arm joins to the shoulder.
The distal, or away-from, portion of the arm, would be the hand. In the leg, the upper thigh would be the proximal portion of the leg, and the foot would be the distal portion of the leg.
Directional terms can be joined together to provide a combined form.
Ipsilateral pertains to one side, whereas mediolateral is a directional term meaning pertaining to the middle and one side (such as right mediolateral pain). It is often used in medical exams and surgical procedures. Here’s one use of mediolateral: A right mediolateral abdominal incision would be an inci- sion beginning at the middle of the abdomen and going toward the right side.
A similar term is lateromedial. A lateromedial incision would be the same as a mediolateral one, but beginning from the side and going towards the middle.
Table 10-3 lists some root words that pertain to directional terms.
Table 10-3 Directional Roots
Root Word What It Means
Anter/o Front
Caud/o Tail or downward
Cephal/o Head or upward
Dist/o Away from (distant) the point of origin
Dors/o Back
Infer/o Below
Later/o Side
Medi/o Middle
Poster/o Back or behind
Proxim/o Near to (proximity) the point of origin
Super/o Above
Ventr/o Front or belly
Regions of the Body
All of these body parts don’t make a whole lot of sense until you can put them in the context of their general location within the body. Your body can be defined in several different ways, from groups and regions to cavities and planes.
Body regions, like the directional terms and anatomical planes we cover later, are used to specifically identify a body area. To illustrate all that’s involved with a body region, take a closer look at two major regions: the abdominal and spinal.
The abdominal area is divided further into anatomic regions to diagnose abdominal problems with greater accuracy.
Starting with the diaphragm, which is the muscle separating the thoracic cavity from the abdominal cavity, down to the level of the pelvis or groin, the abdominal area is divided into nine equal regions.
Visualize the abdomen divided into nine squares: three across the top, three across the middle, and three across the bottom, like a tic-tac-toe board. The center portion is the umbilical region, the region of the navel or the umbili- cus. Directly above this is the epigastric region, or the region of the stomach.
Directly below the umbilical region is the hypogastric region.
On either side of the epigastric region are the right and left hypochondriac regions. To the right and left of the umbilical region are the right and left lumbar regions. To the right and left of the hypogastric region are the right and left iliac regions.