Introduction to Anatomy & Physiology

Definitions and Scope

Anatomy and Physiology are foundational sciences for understanding the structure and function of the human body. Anatomy focuses on the study of body structure, while Physiology examines how those structures function.

• Anatomy: Study of body structure.

• Physiology: Study of body function.

Examination and Variations in Anatomy

Methods of Examination

Various methods are used to examine the body and its structures, both externally and internally.

• Inspection: Visual examination.

• Palpation: Touching body surfaces.

• Auscultation: Listening to body sounds.

• Percussion: Tapping to assess underlying structures.

Cadaver Dissection: Cutting and separating dead body tissues to reveal relationships and structures.

Comparative Anatomy: Study of multiple species to learn about form, function, and evolution (e.g., comparing monkeys and humans).

Exploratory Surgery: Opening the body to look for signs and symptoms.

Medical Imaging Techniques

Imaging allows for non-invasive visualization of internal structures.

• X-ray (Radiograph): Uses radiation to view bones and dense tissues.

• Sonography: Uses ultrasound waves.

• CT (Computed Tomography) Scan: Cross-sectional images using X-rays.

• MRI (Magnetic Resonance Imaging): Uses magnetic fields for detailed images.

• PET (Positron Emission Tomography): Visualizes metabolic processes.

Microscopy: Used to view structures not visible to the naked eye.

• Histology: Study of tissues.

• Cytology: Study of cells.

• Ultrastructure: Details seen with electron microscopy.

Organization of the Human Body

The Organ Systems

The human body is organized into several organ systems, each with specific functions.

• Integumentary System

• Skeletal System

• Endocrine System

• Cardiovascular System

• Lymphatic System (Immune)

• Respiratory System

• Reproductive System

Examples of organs in the body include:

• Brain

• Tongue

• Larynx

• Thyroid Gland

• Trachea

• Lungs

• Heart

• Diaphragm

• Liver

• Gall Bladder

• Stomach

• Spleen

• Small Intestines

• Large Intestines

• Urinary Bladder

• Kidney

• Esophagus

• Adrenal Gland

• Appendix

Physiology and Its Variations

Experimental Science and Subdisciplines

Physiology is based on experimental science and includes subdisciplines such as neurophysiology, endocrinology, and pathophysiology.

• Comparative Physiology: Study of different species to learn about body functions and develop new drugs/procedures.

• Variations exist due to sex, age, diet, weight, and physical activity.

Hierarchy of Complexity

The body is organized from the simplest to the most complex levels:

• Organism

• Organ System

• Organs

• Tissues

• Cells

• Organelles

• Molecules

• Atoms

Homeostasis

Definition and Mechanisms

Homeostasis is the maintenance of a stable internal environment. It involves feedback mechanisms to regulate physiological variables.

• Sensor/Receptor: Detects changes in the body.

• Integrating Center: Processes sensory information and makes decisions.

• Effector: Carries out the final action.

Pathway: Stimulus → Receptor → Control Center → Effector

Feedback Mechanisms

• Positive Feedback: Amplifies change (e.g., childbirth, blood clotting).

• Negative Feedback: Most common; produces change in the opposite direction to maintain homeostasis (e.g., temperature regulation).

Tissue and Histology

Tissue Types

Tissues are groups of similar cells working together for a specific function. Four primary tissue types differ in cell type, matrix, and function.

• Epithelial Tissue: Sheets of closely adhering cells, active in dividing, avascular, nourished by underlying connective tissue.

• Connective Tissue: Diverse, abundant tissue with cells occupying less space than matrix.

• Nervous Tissue: Specialized for communication via electrical impulses.

• Muscular Tissue: Specialized for contraction and movement.

Epithelial Tissue

• Functions: Protection, secretion, absorption, excretion, filtration, sensation.

• Types by Shape: Squamous, Cuboidal, Columnar.

• Types by Layers: Simple (one layer), Stratified (multiple layers).

Simple Epithelia

• Squamous: Thin, flat cells; rapid diffusion.

• Cuboidal: Square or round cells; absorption and secretion.

• Columnar: Tall, narrow cells; absorption and secretion, microvilli increase surface area.

Stratified Epithelia

• Stratified Squamous: Most widespread; keratinized (skin) and nonkeratinized (oral mucosa, esophagus).

• Stratified Cuboidal: Multiple layers; protection and secretion.

• Transitional Epithelium: Surface cells change from round to flat; found in urinary tract.

Connective Tissue Types

• Loose Connective Tissue: Areolar (elastic and collagen fibers, abundant blood vessels), Reticular (mesh of reticular fibers).

• Dense Connective Tissue: Dense regular (parallel collagen fibers), Dense irregular (random collagen fibers).

• Adipose Tissue: Fat storage, insulation, energy reserve.

• Cartilage: Hyaline (clear, glassy), Elastic (flexible), Fibrocartilage (coarse fibers).

• Bone: Compact (dense), Spongy (porous).

• Blood: Fluid connective tissue; transports cells and dissolved matter.

Nervous and Muscular Tissue

• Nervous Tissue: Excitable, specialized for rapid communication.

• Muscular Tissue: Excitable, specialized for contraction and movement.

Integumentary System

Structure and Functions

The integumentary system includes the skin and its appendages (hair, nails, sweat glands, sebaceous glands). It is the largest organ system, covering about 15% of body weight.

• Protection: Against injury, infection, and UV light.

• Barrier Function: Prevents excessive water loss/absorption and blocks harmful chemicals.

• Regulation: Body temperature via dilation/constriction of blood vessels and sweating.

• Other Functions: Sensation, vitamin D synthesis.

Key Terms and Examples

• Keratin: Protein that strengthens skin cells.

• Desmosomes: Intercellular attachments for strength.

• Melanin: Pigment that protects against UV radiation.

Hierarchy of Complexity Table

Key Equations and Concepts

• Homeostasis Feedback Loop:

• Hierarchy of Complexity:

Additional info:

• Some content was expanded for clarity and completeness, such as definitions and examples of tissue types.

• Table entries and equations were inferred and formatted for academic clarity.