Anatomy and Physiology Basics

Objectives

• Define anatomy and describe the levels at which it can be studied.
• Explain the importance of the relationship between structure and function.

Anatomy and Physiology

• Anatomy is the study of the structures of the body.
• Physiology is the study of the processes and functions of the body.
• Systemic anatomy studies the body by organ systems.
• Regional anatomy studies the body by areas.
• Surface anatomy uses superficial structures to locate deeper structures.

Structural and Functional Organization

• There are six levels of organization:
  • Chemical level: atoms combine to form molecules.
  • Cell level: molecules form organelles, which make up cells.
  • Tissue level: similar cells and surrounding materials make up tissues.
  • Organ level: different tissues combine to form organs.
  • Organ system level: organs make up an organ system.
  • Organism level: organ systems make up an organism.

Characteristics of Life

• Organization: all parts of an organism interact to perform specific functions.
• Metabolism: the chemical and physical changes taking place in an organism.
• Responsiveness: adjustments that maintain the internal environment.
• Growth: increase in size of all or part of the organism.
• Development: changes an organism undergoes through time.
• Reproduction: formation of new cells or new organisms.

Homeostasis

• Maintenance of a relatively constant internal environment.
• Set point is the ideal normal value (e.g., body temperature).
• Normal range is the fluctuation around set point.
• Homeostasis is maintained by negative and positive feedback mechanisms.
• Negative feedback turns off the original stimulus.
• Positive feedback enhances and up-regulates the initial stimulus.

Terminology and Body Plan

• Body positions:
  • Anatomical position: human standing erect with face directed forward.
  • Supine: person laying face up.
  • Prone: person laying face down.
• Directional terms:
  • Always refer to anatomical position.
  • Right, ventral, left, dorsal, superior, proximal, inferior, distal, cephalic, lateral, medial, anterior, posterior, superficial, and deep.

Body Parts and Regions

• Body planes:
  • Sagittal plane: divides the body into left and right parts.
  • Transverse plane: divides the body into superior and inferior parts.
  • Frontal (coronal) plane: divides the body into anterior and posterior parts.

Organ Planes

• Longitudinal section: along the long axis.
• Cross (transverse) section: right angle to the long axis.
• Oblique section: across the long axis at an angle other than a right angle.

Body Cavities

• Thoracic cavity: bounded by the ribs and the diaphragm.
• Abdominal cavity: bounded by the diaphragm and the abdominal muscles.
• Pelvic cavity: surrounded by the pelvic bones.

Serous Membranes

• Parietal membrane: lines the wall of the cavity.
• Visceral membrane: is in contact with the internal organs.
• Serous fluid: secreted by the serous membrane and protects organs against friction.
• Pericardial cavity: surrounds the heart.
• Pleural cavities: surround the lungs.
• Peritoneal cavity: surrounds certain abdominal and pelvic organs.
• Mesenteries: hold the abdominal organs in place and provide a passageway for blood vessels and nerves to organs.
• Retroperitoneal organs: located “behind” the parietal peritoneum.