A Guide to Anatomy and Physiology

The study of the human body is a core pillar of biomedical science, fundamentally divided into two interconnected disciplines: Anatomy and Physiology. To truly understand health and disease, one must grasp both the structure of the body and how those structures function.

As the physician and philosopher Galen once observed, structure (anatomy) always dictates function (physiology).

What is Anatomy? (The Study of Structure)

Anatomy is the science dedicated to the study of body structures. This includes examining the size, shape, composition, coloration, and precise location of various parts of the body.

The study of human anatomy requires examining individual parts and understanding their complex relationships and interactions within an organ system.

Subdivisions of Anatomy

Anatomy is typically studied through several specialized lenses:

Type of Anatomy	Focus of Study	Example
Gross Anatomy	Structures visible to the naked eye.	Studying the heart, bones, and muscles via dissection.
Microscopic Anatomy	Structures only visible with a microscope.	Cytology (study of cells) and Histology (study of tissues).
Systemic Anatomy	The structure of specific body systems (organs with similar functions).	Studying the cardiovascular system, nervous system, or muscular system.
Regional Anatomy	The structure of a specific region of the body.	Studying the arm, head, or thorax, including all systems within that area.
Developmental Anatomy	The growth and development of the body from conception through adulthood.	Studying embryology and fetal development.
Pathological Anatomy	The examination of diseased body parts or entire bodies to understand the effects of illness.	Post-mortem examination or biopsy analysis.

Clinical Methods for Studying Anatomy

In clinical practice, anatomy is often explored non-invasively:

Palpation: Examining a body part by feeling it with the hands (e.g., checking a pulse, assessing swollen areas).
Auscultation: Listening to the natural sounds of the body, often using a stethoscope (e.g., heartbeats, lung sounds).
Percussion: Tapping fingers, hands, or instruments on body parts to evaluate the resonance or echo sounds. Used to check for abnormal air or fluid pockets.

🧠 What is Physiology? (The Study of Function)

Physiology is the biomedical science that investigates the normal functioning of various organs and organ systems in the body. It is the study of how the body works.

Physiology examines:

The functions of individual cells, tissues, and organs.
How the actions of these parts affect the whole body.
How these functions are integrated and coordinated to synchronize all body activities.

For instance, studying the physiology of liver cells involves understanding what functions they perform (e.g., detoxification, protein synthesis) and how those functions contribute to overall body homeostasis.

Subdivisions of Physiology

Physiology is divided based on organism type, organizational level, or specific system:

By Organism: Plant Physiology, Human Physiology.
By Organizational Level: Molecular Physiology, Cellular Physiology.
By System: Respiratory Physiology, Neurophysiology (study of the nervous system), Cardiovascular Physiology.

📍 Anatomical Position and Directional Terms

To ensure clarity and precision when describing the body, scientists use the Anatomical Position—a standardized reference point for describing movement, posture, and the relationship between different parts. In this position, the body is standing upright, facing forward, with arms at the sides, palms facing forward, and feet parallel.

Key directional terms are used relative to this position:

Directional Term	Meaning	Example
Anterior (Ventral)	The front side of the body.	Your kneecaps are located in the anterior position.
Posterior (Dorsal)	The back side of the body.	Your shoulder blades are located in the posterior position.
Superior	Toward the upward position (towards the head).	Your hands are superior to your feet.
Inferior	Toward the downward position (towards the feet).	Your feet are inferior to your hands.

The Interrelation: Anatomy and Physiology

Anatomy and Physiology are inextricably linked. You cannot fully comprehend one without the other:

The Anatomy of the lungs is their structure (lobes, bronchi, alveoli).
The Physiology of the lungs is their function (gas exchange, moving oxygen into the blood).

A branch of science called Pathophysiology combines these studies to examine diseased cells and tissues, utilizing an understanding of normal human physiology to easily diagnose and understand bodily disorders.