What Is Physiology?

Physiology is the study of how the body and its parts function. It explains how organs and systems work to keep the body alive and balanced.

Examples of physiology include:

• How the heart pumps blood

• How the lungs exchange oxygen and carbon dioxide

• How muscles contract and relax

Nurses use physiology to understand how illnesses affect the body and how treatments help restore function.

Levels of Organization in the Human Body

The human body is organized into levels that work together:

1. Cells – the smallest units of life

2. Tissues – groups of similar cells

3. Organs – structures made of different tissues

4. Organ Systems – groups of organs working together

5. The Human Organism – the entire body

Each level depends on the others to maintain health.

Major Body Systems

Some of the major body systems nurses must understand include:

• Cardiovascular system – circulates blood and oxygen

• Respiratory system – supports breathing and oxygen exchange

• Digestive system – breaks down food and absorbs nutrients

• Nervous system – controls communication and responses

• Musculoskeletal system – provides movement and support

• Urinary system – removes waste and balances fluids

Nurses assess these systems to monitor patient health.

Homeostasis

Homeostasis is the body’s ability to maintain a stable internal environment.

Examples include:

• Maintaining normal body temperature

• Keeping blood sugar levels balanced

• Regulating blood pressure

When homeostasis is disrupted, illness can occur. Nurses help patients restore and maintain balance.

Why Anatomy & Physiology Matter in Nursing

Understanding anatomy and physiology allows nurses to:

• Recognize normal vs. abnormal findings

• Understand disease processes

• Provide safe and effective patient care

• Communicate accurately with healthcare teams

This knowledge forms the foundation for all nursing skills and clinical decision-making.