Why This Matters

Understanding anatomical terminology and physiological principles is essential for effective communication and practice in the health sciences. This foundational knowledge supports further study and clinical application in Anatomy & Physiology.

Anatomy and Physiology: Definitions and Scope

Anatomy

Anatomy is the study of the structure of body parts and their relationships to one another.

• Gross (macroscopic) anatomy: Study of large, visible structures.

• Regional anatomy: Examines all structures in a particular area of the body.

• Systemic anatomy: Studies organ systems (e.g., cardiovascular, nervous, muscular).

• Surface anatomy: Focuses on internal structures as they relate to the overlying skin (e.g., visible muscle masses or veins).

• Microscopic anatomy: Deals with structures too small to be seen by the naked eye.

  • Cytology: Study of cells.

  • Histology: Study of tissues.

• Developmental anatomy: Studies anatomical and physiological development throughout life.

  • Embryology: Study of developments before birth.

Physiology

Physiology is the study of the function of body parts and how they carry out life-sustaining activities. It often focuses on cellular and molecular levels and examines how the body's abilities depend on chemical reactions within cells.

Complementarity of Structure and Function

Anatomy and physiology are closely related. Function always reflects structure, and what a structure can do depends on its specific form. This is known as the principle of complementarity of structure and function.

Levels of Structural Organization

The human body is organized into several levels, each building on the previous one:

1. Chemical level: Atoms combine to form molecules.

2. Cellular level: Cells are made up of molecules.

3. Tissue level: Tissues consist of similar types of cells.

4. Organ level: Organs are made up of different types of tissues.

5. Organ system level: Organ systems consist of different organs that work closely together.

6. Organismal level: The human organism is made up of many organ systems working together.

The Four Types of Tissues

• Epithelial tissue

• Muscle tissue

• Connective tissue

• Nervous tissue

Note: Students should know the names and functions of each system.

Requirements for Life: Necessary Life Functions

To maintain life, organisms must perform several essential functions:

1. Maintaining boundaries: Separation between internal and external environments (e.g., plasma membranes, skin).

2. Movement: Muscular system allows movement of body parts and substances (e.g., blood, food, urine).

3. Responsiveness: Ability to sense and respond to stimuli (e.g., withdrawal reflex, breathing rate changes).

4. Digestion: Breakdown of ingested foodstuffs, absorption of simple molecules into blood.

5. Metabolism: All chemical reactions in body cells, including catabolism (breakdown) and anabolism (synthesis).

6. Excretion: Removal of wastes from metabolism and digestion (e.g., urea, carbon dioxide, feces).

7. Reproduction: Cellular division for growth or repair; production of offspring.

8. Growth: Increase in size of a body part or organism.

Survival Needs

Humans require several factors for survival, each in appropriate amounts:

1. Nutrients: Chemicals for energy and cell building (carbohydrates, proteins, fats, minerals, vitamins).

2. Water: Most abundant chemical in the body; necessary for chemical reactions and as a fluid base for secretions/excretions.

3. Oxygen: Essential for energy release from foods; the body can only survive a few minutes without it.

Homeostasis

Homeostasis is the maintenance of relatively stable internal conditions despite continuous changes in the environment. It is a dynamic state of equilibrium, always readjusting as needed, and is maintained by contributions of all organ systems.

Homeostatic Controls

The body must constantly monitor and regulate variables to maintain homeostasis. Variables are factors that can change (e.g., blood sugar, body temperature, blood volume).

Components of Homeostatic Control

1. Receptor: Monitors environment, responds to stimuli (changes in controlled variables).

2. Control center: Determines set point at which variable is maintained, receives input from receptor, determines appropriate response.

3. Effector: Receives output from control center, provides means to respond, and either reduces (negative feedback) or enhances (positive feedback) the stimulus.

Feedback Mechanisms

• Negative feedback: Most common; response reduces or shuts off the original stimulus (e.g., regulation of body temperature, blood glucose by insulin).

• Positive feedback: Response enhances or exaggerates the original stimulus (e.g., labor contractions by oxytocin, platelet plug formation in blood clotting).

Homeostatic Imbalance

Disturbance of homeostasis increases risk of disease and contributes to changes associated with aging. If negative feedback mechanisms become overwhelmed, destructive positive feedback mechanisms may take over (e.g., heart failure).

Summary Table: Levels of Organization

Key Equations

• Homeostasis (dynamic equilibrium):

Additional info:

• Students should be able to distinguish between afferent (toward control center) and efferent (away from control center) pathways in homeostatic control.

• Examples of negative feedback: regulation of blood glucose, body temperature.

• Examples of positive feedback: blood clotting, childbirth.