Anatomy and physiology form the foundation of all nursing care. Anatomy studies the physical structure and form of body parts, while physiology examines how those parts function to keep the person alive. Understanding normal structure allows nurses to spot abnormal physical findings during a head-to-toe assessment. Physiological knowledge helps predict how a disease process disrupts normal body functions. Gross anatomy looks at large structures visible to the naked eye, such as organs and limbs. Microscopic anatomy requires tools like a microscope to study tiny structures like cells and tissues.
The human body builds itself in a step-by-step hierarchy from the smallest chemical building blocks up to the entire organism.
Every living human body performs several vital life processes to maintain existence. Metabolism covers all the chemical reactions happening inside the body, breaking down nutrients or building new cellular structures. Responsiveness is the ability to sense changes in the external or internal environment and react to them. Movement involves not just walking, but also the internal transport of blood, food, and substances across cell membranes. Growth increases body size through an increase in cell numbers or cell size. Reproduction creates new cells for repair and growth, or a brand new human being. Digestion and excretion break down food and get rid of unwanted metabolic waste products.
Medical professionals use precise language to describe body locations accurately. The standard anatomical position requires the patient to stand upright, face forward, with arms at the sides and palms facing forward.
Directional terms like superior, inferior, anterior, posterior, medial, lateral, proximal, and distal help nurses document wound locations and physical assessment findings clearly without confusion.
The human body contains internal spaces called cavities that protect delicate organs and allow them to change shape. The two main divisions are the dorsal cavity, which houses the brain and spinal cord, and the ventral cavity, which holds visceral organs in the chest and abdomen. A muscular wall called the diaphragm separates the thoracic cavity from the abdominopelvic cavity.
Thin sheets of tissue called serous membranes line the ventral cavities and cover the organs inside. The parietal layer lines the cavity wall, while the visceral layer hugs the organ surface directly. A lubricating fluid sits between these layers to reduce friction as the heart beats and lungs expand.
Homeostasis is the body's ability to maintain a stable internal environment despite constant changes in the outside world. Control mechanisms regulate this balance using three core components. The receptor monitors the environment and detects changes called stimuli. The control center, usually the brain or spinal cord, analyzes the incoming signal and determines the proper response. The effector carries out the command from the control center to restore normal balance.
Most body systems rely on negative feedback loops to reverse a harmful directional change, such as lowering a high body temperature through sweating. Conversely, positive feedback loops amplify the original change to push a process through to completion, such as uterine contractions during childbirth.