Form Determines Function

Introduction to Anatomy and Physiology

The study of the human body is divided into two closely related fields: anatomy and physiology. These disciplines are inseparable, as the structure of a body part (anatomy) directly influences its function (physiology). This relationship is known as the principle of complementarity of structure and function.

• Anatomy: The study of the structure of body parts and their relationships to one another.

• Physiology: The study of the function of body parts; how they work to carry out life-sustaining activities.

• Principle of Complementarity: What a structure can do depends on its specific form.

Topics of Anatomy

Subdivisions of Anatomy

Anatomy is divided into several subfields based on the scale and focus of study.

• Gross (Macroscopic) Anatomy: Study of large, visible structures.

  • Regional Anatomy: Examines all structures in a particular area of the body.

  • System Anatomy: Focuses on one organ system (e.g., cardiovascular, nervous, muscular).

  • Surface Anatomy: Studies internal structures as they relate to the overlying skin (e.g., visible muscle masses or veins).

• Microscopic Anatomy: Deals with structures too small to be seen by the naked eye.

  • Cytology: Study of cells.

  • Histology: Study of tissues.

• Developmental Anatomy: Studies anatomical and physiological development throughout life.

  • Embryology: Study of developments before birth.

To study anatomy, one must know anatomical terminology and be able to observe, manipulate, palpate, and auscultate (listen to) body structures.

Topics of Physiology

Subdivisions of Physiology

Physiology is typically organized by organ systems and often focuses on cellular and molecular levels.

• Organ System Physiology: Examples include renal physiology (kidneys) and cardiovascular physiology (heart and blood vessels).

• Cellular and Molecular Physiology: Examines how the body's abilities depend on chemical reactions in individual cells.

• Understanding physiology requires knowledge of basic physical and chemical principles.

Structural Organization of the Human Body

Levels of Organization

The human body is organized in a hierarchical manner, from the smallest chemical components to the entire organism.

• Chemical Level: Atoms and molecules.

• Cellular Level: Organelles and a single cell.

• Tissue Level: Groups of similar cells working together to perform a specific function.

• Organ Level: Contains two or more types of tissues working together.

• Organ System Level: Organs that work closely together to accomplish a common purpose.

• Organismal Level: All organ systems combined to make the whole organism.

Example: The heart (organ level) is made of muscle tissue, connective tissue, and nervous tissue, and is part of the cardiovascular system (organ system level).