Chapter 1: The Human Body – An Orientation (Anatomy & Physiology Study Notes)

The Human Body: An Orientation

Introduction to Anatomy & Physiology

Anatomy and physiology are foundational sciences that provide a framework for understanding the structure and function of the human body. Mastery of these subjects is essential for careers in health and biological sciences.

• 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.

Key Principle: Form (anatomy) determines function (physiology). The structure of a body part enables its function.

Reference Standards in Anatomy & Physiology

For consistency, textbooks use standard reference individuals:

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

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

• Average weights (US, ages 20-29): Men: 188.6 lb (85.54 kg); Women: 165 lb (74.9 kg).

Anatomical Variability

While most anatomical structures match textbook descriptions, some variability exists:

• Nerves or blood vessels may be in slightly different locations.

• Some small muscles may be absent.

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

Sex and Gender in Anatomy

• Sex: 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

Anatomy is divided into several subfields:

• Gross (macroscopic) anatomy: Study of 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).

• Surface anatomy: Studies internal structures as they relate to the overlying skin (e.g., visible muscles, veins).

Example: Studying the heart's structure (anatomy) and how it pumps blood (physiology).

*Additional info: Further divisions of anatomy include microscopic anatomy (cytology and histology) and developmental anatomy (embryology), which are covered in later sections.*