Introduction to Anatomy & Physiology

Major Subfields of Anatomy

Types of Anatomical Study

Anatomy is the study of structures visible to the naked eye and those requiring magnification. Several subfields exist, each with unique approaches and applications.

• Gross Anatomy: Study of structures visible without magnification, often using surface observation or dissection.

• Surface Anatomy: Examination of external body features, crucial for physical exams.

• Systemic Anatomy: Study of one organ system at a time (e.g., cardiovascular, nervous systems).

• Regional Anatomy: Study of multiple organ systems within a specific body region.

• Microscopic Anatomy (Histology): Observation of thinly sliced, stained tissue specimens under a microscope.

• Pathology: Microscopic examination of tissues for signs of disease.

Example: Dissection is a key method in gross anatomy, allowing direct visualization of organs and tissues.

Physiology: The Study of Function

Defining Physiology

Physiology focuses on the functions and processes that occur within living organisms, emphasizing how structures work to maintain life.

• Function: Physiology explains how anatomical structures operate.

• Homeostasis: Physiological processes occur to maintain a stable internal environment.

Relationship between Anatomy and Physiology: Form determines function; the structure of a body part influences its role.

Characteristics of Living Things

Biological Qualities

Living organisms share several defining characteristics that distinguish them from nonliving matter.

• Organization: Living things are highly organized, expending energy to maintain order and homeostasis. Disease and death result from breakdowns in this order.

• Cells: The cell is the smallest functional and structural unit of life. All living things are composed of cells.

• Metabolism: The sum of all internal chemical changes. Living things take in molecules from the environment and chemically change them. There is constant molecular turnover.

• Growth: Occurs through metabolic change; body mass is mostly composed of molecules made by chemically altering food.

• Development: Change in form or function over an organism's lifetime, including differentiation (e.g., mesoderm differentiates into muscle, bone, cartilage, and blood).

• Reproduction: Ability to produce copies of themselves and pass genes to offspring.

• Excitability (Responsiveness): Ability to sense and react to stimuli at all levels, from cells to the whole body.

• Evolution: Genetic change in populations over time, driven by mutations and environmental selection. Evolutionary medicine interprets disease in terms of species' biological history.

Homeostasis and Feedback Loops

Maintaining Internal Stability

Homeostasis is the body's ability to maintain stable internal conditions despite external changes. Feedback loops are mechanisms that help regulate physiological variables.

• Homeostasis: Internal stability (e.g., temperature, blood pressure, blood glucose).

• Loss of homeostatic control: Leads to illness or death.

Example: The body regulates temperature through sweating (to cool down) and shivering (to warm up), maintaining values near a set point.

Feedback Loop Terminology

• Receptor: Structure that senses change (e.g., temperature receptors in skin).

• Integrating (Control) Center: Processes information and makes response decisions (e.g., cardiac control center in brain).

• Effector: Structure that carries out the response to restore homeostasis (e.g., the heart).

• Feedback: The response sensed by the receptor completes the feedback loop.

Types of Feedback

• Negative Feedback: Mechanism that reverses a change to maintain homeostasis. Values fluctuate around a set point, not absolute constancy.

• Positive Feedback: Mechanism that amplifies change, sometimes producing rapid effects (e.g., childbirth, fever). Can be harmful if unchecked.

Example: High fever can trigger a positive feedback loop, raising body temperature to dangerous levels.

Feedback Loop Diagram

The following diagram illustrates a negative feedback loop:

• Stimulus detected by receptor

• Information sent via afferent pathway to integrating center

• Integrating center compares to set point and sends response via efferent pathway to effector

• Effector produces response, restoring homeostasis

Summary Table: Characteristics of Living Things

Key Equations

• Homeostasis (General Principle):

• Feedback Loop (Negative Feedback):

Additional info: These notes expand on the brief points in the slides, providing definitions, examples, and academic context for each concept. The feedback loop diagram and table are reconstructed based on standard textbook knowledge.