ANAPHY-CHAPTER1

Anatomy

The scientific study of body structure; the term means “to cut apart.” A bone is hard and mineralized, so it provides strength and support.

Systemic Anatomy

Study of the body by systems such as cardiovascular or skeletal. This approach is used in most textbooks.

Regional Anatomy

Study of the body by specific areas, considering all systems in that region. Medical and dental schools often use this method.

Surface Anatomy

Study of external features used to locate deeper structures. The sternum is used as a landmark to listen to heart sounds.

Physiology

The study of the body’s functions and processes; structures are seen as active and dynamic.

Goals of Physiology

• To study how the body responds to stimuli.

• To study how the body maintains stable internal conditions.

Chemical Level

Atoms interact to form molecules; a molecule’s structure determines its function. Collagen molecules form strong fibers that give skin flexibility and strength.

Cell Level

Cells are the basic structural and functional units of life. The nucleus stores hereditary information, and mitochondria make ATP for energy.

Tissue Level

A group of similar cells and the materials around them. The four types are epithelial, connective, muscle, and nervous tissue.

Organ Level

A structure made of two or more tissue types that perform shared functions. The stomach is made of muscle, connective, and epithelial tissues that together digest food.

Organ System Level

A group of organs working as a unit for common functions. The urinary system includes kidneys that make urine, ureters that transport urine, a bladder that stores it, and a urethra that eliminates it.

Organism Level

A living being considered as a whole. A human is composed of trillions of interdependent cells and organ systems.

Organization

Specific interrelationships among parts of an organism that allow them to function together.

Metabolism

The use of energy for vital functions, including growth, movement, and reproduction.

Responsiveness

The ability to sense and react to internal or external changes. A person sweats when body temperature rises.

Growth

An increase in cell size, cell number, or the material surrounding cells. A child grows taller as bone cells multiply and become mineralized.

Development

Changes an organism undergoes from fertilization to death, often involving differentiation. After fertilization, immature cells become specialized cells such as nerve or muscle cells.

Reproduction

Formation of new cells or new organisms. A species avoids extinction through reproduction of offspring.

Homeostasis

The maintenance of a relatively constant internal environment.

Variables

Internal body conditions that can change. Body temperature and blood pH are variables that must remain within a narrow range.

Normal Range

The range within which a variable is maintained. Body temperature normally stays close to 98.6°F.

Set Point

The ideal normal value of a variable.

Organ Systems in Homeostasis

Organ systems regulate and balance internal conditions. The cardiovascular, digestive, respiratory, and urinary systems deliver oxygen and nutrients while removing wastes.

Feedback Loop

A cycle in which the outcome of a process regulates its own activity.

Receptor

Monitors and detects changes in a variable.

Control Center

Determines the set point and processes information from the receptor.

Effector

Produces a response that adjusts the variable.

Stimulus

The change in a variable that triggers a homeostatic response.

Negative Feedback

A mechanism that resists deviation from the set point and stops once balance is restored. When body temperature rises, sweat glands cool the body until temperature returns to normal.

Positive Feedback

A mechanism that amplifies change until a process is completed. Blood clotting continues until a clot fully seals a wound.

Anatomical Position

Standing upright, face forward, arms at sides, palms forward. Supine means lying face up, and prone means lying face down.

Directional Terms

Words used to describe the location of body structures relative to one another.

Central Region

Includes the head, neck, and trunk (thorax, abdomen, pelvis).

Upper Limb

Includes arm, forearm, wrist, and hand.

Lower Limb

Includes thigh, leg, ankle, and foot.

Abdominal Quadrants

Right upper, left upper, right lower, and left lower.

Sagittal

divides into right and left.

Median

divides into equal right and left.

Transverse

divides into superior and inferior.

Frontal

divides into anterior and posterior.

Longitudinal

along the length.

Transverse

at a right angle to the length.

Oblique

diagonal cut.

Thoracic cavity

lungs, heart (mediastinum).

Abdominal cavity

stomach, intestines, liver, kidneys, spleen.

Pelvic cavity

bladder, reproductive organs, part of large intestine.

Abdominopelvic cavity

abdominal and pelvic combined.

Pericardial

around the heart.

Pleural

around the lungs.

Peritoneal

in the abdominopelvic cavity.

Mesenteries

Double layers of peritoneum anchoring organs and serving as pathways for blood vessels and nerves.

Serous Membranes

Thin layers that reduce friction between organs and cavity walls.

Superior

Toward the head.

Posterior

Toward the back.

Superficial

Closer to the surface of the body.