What is Physiology?

Christina Keathley, Michael Matott, Christianlly Cena
  • Author
    Christina Keathley

    Christina graduated with a Master's in biology from the University of Louisiana at Lafayette. She is a current PhD student in biology at Wake Forest University, and has been teaching undergraduate students anatomy and physiology for the last two years.

  • Instructor
    Michael Matott
  • Expert Contributor
    Christianlly Cena

    Christianlly has taught college Physics, Natural science, Earth science, and facilitated laboratory courses. He has a master's degree in Physics and is currently pursuing his doctorate degree.

Learn what physiology is. Study the history of physiology, discover the fields of animal and human physiology, and examine physiology systems and functions. Updated: 02/28/2022

Table of Contents


What is Physiology?

Many college programs focused on biology or human health require physiology courses. But what is physiology? Physiology is the study of functions within the body. It is largely focused on "how" questions, such as:

  • How do reproductive cycles work?
  • How does the body digest proteins?
  • How is gas transported from the lungs to tissue?

Physiology is a broad field that produces important findings for human health. It would be incredibly difficult to understand all aspects of the body's physiology. Because of this, it's broken into smaller, more specific fields. For instance, respiratory physiology is interested in the functions involved in breathing, while cardiac physiology is interested in the functions pertinent to the heart and circulatory system. This lesson investigates physiology in more detail to understand how it differs from similar fields, and how it is applied to systems and education.

Anatomy vs. Physiology Definitions

A common topic in biological curriculum is often called "A and P," or "Anatomy and Physiology." While these terms are often seen together, they are not the same. Anatomy is the study of how parts of the body are shaped. For instance, it may be concerned with the shape of a joint or anomalies in the curvature of the skull. Anatomy is part of a larger field of study called morphology, which is interested in the shape and structure of bones and organs (their anatomy) as well as variations in numbers and organization of those structures.

Anatomy focuses on the shape of structures.

A photograph of femur bones.

Form gives rise to function. This means that the shape of a structure often coincides with its use. For instance, human hands are shaped for grasping and holding. Cat paws, while containing homologous (like) structures, are better suited for jumping, climbing, and tearing. Because the relationship between shape and function is so important, anatomy and physiology are often taught in conjunction with one another. The physiology definition may be concerned with how a joint moves, but the anatomy of a joint allows it to do so.

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History of Physiology

Physiology as a science can be traced back to ancient civilizations. In fact, evidence of physiological practices exists from ancient Egyptian societies and the Greek philosopher Hippocrates studied human systems prior to 400 BC. Despite its early origins, the term "physiology" wasn't officially coined until the early 1500's. Jean Fernal was the first to describe physiology as a proper field during his work on the human spinal canal.

Since it's description, famous physiologists have contributed key ideas to the field that act as central themes. In 1865, Claude Bernard introduced the idea of homeostasis. Homeostasis is the concept that life attempts to keep the internal environment (referred to as "milieu intérieur" by Bernard) as consistent as possible.

What is the study of physiology in ancient times compared to today? Modern physiology has expanded to answer more specific questions in ethical ways. Early investigations attempted on people were often viewed as unethical and dangerous. Because of this, physiology often implements model systems. Model systems are those that represent an aspect of human health for examination or experimentation without the need to potentially harm living individuals. Common models include mice, cadavers, and even (in today's world) computational models. These methods are also useful because they can be used to examine specific parts of physiology without having to consider the entire patient. For instance, a model can simulate a specific process in the lungs regardless of a potential issue in the kidneys that may somehow skew results. While animal model systems may offer important implications for human health, scientists must consider the differences between a specific animal's physiology and human physiology before making broad comparisons.

Physiological Functions

Physiological functions occur when specific organs and their subsequent systems engage in specific actions. Physiological functions include a structure and a process. Structures may include single organs, whole organ systems, or even specific tissues. Processes can include breaking down substances, creating substances, or transporting them. Thus, they depend on form and function. Below, investigate how different physiological systems engage in different functions.

Physiology aims to understand how structures function.

An illustration of how the thyroid works.

Physiological Systems

There are numerous physiological systems within the body, and they can be broken down into even smaller, more specific pathways when observing a specific process or action. Some of the most common physiologically defined systems in the body (and their descriptions) are highlighted in the table below.

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Additional Activities

Physiology Word Search Activity

This activity will help you assess your knowledge of the definition and history of physiology.


For this activity, you'll need a printer to reproduce the following page. Search for and circle or highlight the words that will complete each of the given clues. Afterwards, neatly write them in the appropriate blank spaces in the clues.


  1. _____ is the ability of a living organism, such as a cell, to adjust its internal environment to maintain itself within a range of normal function.
  2. Tissues may bundle up to form _____ that have the ability to contract, producing movement in, or maintaining the position of the parts of, the body.
  3. _____ is the branch of biology that deals with the functions and activities of living matter and of the physical and chemical phenomena involved.
  4. Model systems are non-_____ systems or species that are extensively studied to understand particular biological phenomena.
  5. _____ was one of the proponents of cell theory, one of the unifying principles of biology.
  6. The history of physiology was greatly influenced by the works of classical _____ philosophers.
  7. The organ that constitutes the digestive system is known as the _____.
  8. The cell theory states that all biological organisms are composed of cells, which are the basic _____ unit of life.
  9. The idea that cells maintain themselves through supportive and nutritive extra-cellular fluids was first described by _____.
  10. The large parts of an organism that are dedicated to performing certain functions are called _____.

Answer Key

  1. Homeostasis
  2. Muscles
  3. Physiology
  4. Human
  5. Schwann
  6. Greek
  7. Stomach
  8. Structural
  9. Bernard
  10. Organs

Frequently Asked Questions

What is the meaning and definition of physiology?

Physiology is the study of the function of living systems. It aims to answer questions surrounding how processes within living organisms work.

What are the types of physiology?

There are many types of physiology. Physiology can be broken into systems (such as renal physiology or respiratory physiology) or into fields of study (such as cell physiology or defense physiology).

What is an example of physiology?

An example of physiology is exercise physiology. Exercise physiology is interested in investigating how movement of the body correlates with muscle growth and energy expenditure.

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