Introduction to Anatomy & Physiology: Structure, Function, and Organ Systems

Introduction to Anatomy & Physiology

Definition and Scope

Anatomy is the study of the structure of body parts and their relationships to one another. Physiology is the study of the function of the body, or how body parts work and carry out their life-sustaining activities.

• Anatomy focuses on identification and naming of body structures.

• Physiology concerns the function of those structures, often at the cellular or molecular level.

• Example: The heart (anatomy) pumps blood (physiology).

Topics of Anatomy

Macroscopic (Gross) Anatomy and Subdivisions

Gross anatomy examines structures visible to the naked eye.

• Regional Anatomy: All structures in a particular body region (e.g., abdomen, leg).

• Systemic Anatomy: Body structure is studied system by system (e.g., cardiovascular system).

• Surface Anatomy: Study of internal structures as they relate to the overlying skin surface.

Microscopic Anatomy and Subdivisions

Microscopic anatomy examines structures too small to be seen with the naked eye.

• Cytology: Study of cells.

• Histology: Study of tissues.

Developmental Anatomy

• Embryology: Study of developmental changes before birth.

To Study Anatomy

• Use anatomical terminology.

• Observe, manipulate, palpate, and auscultate.

Scope of Physiology

Physiology often focuses on events at the cellular and molecular levels, relying on chemical reactions in individual cells.

• Includes principles of physics (e.g., electrical currents, pressure, movement).

• Basic chemical principles (e.g., biochemistry, osmosis, diffusion).

Complementarity of Structure and Function

Structure and function are inseparable; function always reflects structure. This is known as the principle of complementarity.

• Example: Bones can support and protect body organs because they contain hard mineral deposits.

• Teeth are shaped differently for cutting versus grinding food.

Levels of Structural Organization

The body is organized into several levels:

• Chemical Level: Atoms combine to form molecules.

• Cellular Level: Cells are made up of molecules.

• Tissue Level: Tissues consist of similar types of cells.

• Organ Level: Organs are made up of different types of tissues.

• Organ System Level: Organ systems consist of different organs that work together closely.

• Organismal Level: The human organism is made up of many organ systems.

Organ Systems of the Body

There are 11 organ systems in the human body. Each system has specific components and functions.

System	Main Components	Major Functions
Integumentary	Skin, hair, nails, glands	Protection, temperature regulation, vitamin D synthesis, sensory receptors
Skeletal	Bones, joints, cartilage	Support, protection, movement, mineral storage, blood cell formation
Muscular	Skeletal muscles	Movement, posture, heat production, facial expression
Nervous	Brain, spinal cord, nerves, sensory organs	Control system, response to stimuli, memory, learning, balance
Endocrine	Glands (pituitary, thyroid, etc.)	Hormone production, regulation of growth, metabolism, reproduction
Cardiovascular	Heart, blood vessels	Transport of oxygen, nutrients, wastes, hormones
Lymphatic/Immune	Lymph nodes, lymphatic vessels, spleen, thymus	Defense against infection, return of tissue fluid to blood
Respiratory	Lungs, trachea, bronchi, nasal cavity	Gas exchange (oxygen and carbon dioxide)
Digestive	Mouth, esophagus, stomach, intestines, liver, pancreas	Breakdown and absorption of nutrients, elimination of waste
Urinary	Kidneys, ureters, bladder, urethra	Elimination of nitrogenous wastes, regulation of water and electrolytes
Reproductive	Male: testes, penis; Female: ovaries, uterus, vagina	Production of offspring

Key Concepts and Examples

• Homeostasis: The maintenance of a stable internal environment.

• Feedback Mechanisms: Negative feedback reduces the effect of the original stimulus; positive feedback enhances it.

• Example: Regulation of body temperature (negative feedback); blood clotting (positive feedback).

Summary

• Anatomy and physiology are closely related fields essential for understanding the human body.

• Structure and function are interdependent at all levels of organization.

• The human body is organized into 11 major organ systems, each with specific roles.