Introduction to Human Anatomy & Physiology: Orientation and Foundational Concepts

Form (Anatomy) Determines Function (Physiology)

Definitions and Relationship

Understanding the human body requires distinguishing between its structure (anatomy) and its function (physiology). These two disciplines are closely linked, as the form of a body part enables its function.

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

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

• Principle of Complementarity: Function always reflects structure; what a structure can do depends on its specific form.

Reference Standards in Anatomy & Physiology

For consistency, textbooks use standard reference individuals when describing anatomical and physiological values.

• Reference male: Healthy, young male weighing about 155 pounds (70 kg).

• Reference female: Healthy, young female weighing about 125 pounds (57 kg).

Anatomical Variability

While most human anatomical structures match textbook descriptions, some variability exists.

• Over 90% of anatomical structures match standard descriptions.

• Variations may include:

  • Nerves or blood vessels in slightly different locations.

  • Missing small muscles.

• Extreme anatomical variations are rare and usually incompatible with life.

Sex and Gender in Anatomy

• Sex: Set of biological attributes based on chromosomes, gene expression, and hormone action; reflected in reproductive anatomy and physiology (male or female).

• Gender: Psychosocial construct including behaviors, expressions, and identities (e.g., man, woman, transgender, non-binary).

Divisions of Anatomy

Gross (Macroscopic) Anatomy

Gross anatomy studies large body structures visible to the naked eye.

• Regional anatomy: Examines all structures in a specific 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

Microscopic anatomy examines structures too small to be seen without magnification.

• Cytology: Study of cells.

• Histology: Study of tissues.

Developmental Anatomy

Developmental anatomy traces structural changes throughout the lifespan.

• Embryology: Study of developmental changes before birth.

Additional info: These foundational concepts are essential for understanding more advanced topics in anatomy and physiology, such as organ systems, homeostasis, and clinical applications.