Anatomy & Physiology Foundations

Definitions and Hierarchy

Anatomy and physiology are core disciplines in understanding the structure and function of the human body. The organization of biological systems follows a hierarchical structure:

• Anatomy: The study of body structure.

• Physiology: The study of body function.

• Hierarchy Levels: Chemical → Cellular → Tissue → Organ → Organ Systems → Organism

Homeostasis

Homeostasis refers to the body's ability to maintain stable internal conditions.

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

• Negative Feedback: Reduces changes to maintain equilibrium (e.g., temperature regulation).

Language of Anatomy

• Anatomical Position: Standard reference posture for describing locations and directions.

• Directional Terms: Used to describe relative positions (e.g., anterior, posterior, medial, lateral).

• Body Planes: Sagittal, frontal (coronal), transverse.

Body Cavities

• Dorsal: Cranial cavity, spinal cavity.

• Ventral: Thoracic cavity, abdominopelvic cavity.

• Diaphragm: Separates thoracic and abdominopelvic cavities.

Serous Membranes

• Layers: Parietal (wall) and visceral (organ).

• Examples:

  • Heart → Pericardium

  • Lungs → Pleura

  • Intestines → Peritoneum

Connective Tissue

Classification and Cell Types

Connective tissue (CT) supports, binds, and protects organs. It is classified by structure, function, and characteristics.

Muscle Tissue Types

• Skeletal

• Cardiac

• Smooth

Epithelium: Cell Shape and Arrangement

• Simple: Squamous, cuboidal, columnar, pseudostratified

• Stratified: Squamous, cuboidal, columnar, transitional

Nervous Tissue

Cell Types

• Neurons: Conduct electrical impulses.

• Neuroglia: Support and protect neurons.

Integumentary System

Structure and Function

The integumentary system includes the skin and its appendages, providing protection, sensation, and thermoregulation.

• Epidermis: Five layers (deep to superficial):

  1. Stratum basale (germinativum)

  2. Stratum spinosum

  3. Stratum granulosum

  4. Stratum lucidum

  5. Stratum corneum

• Keratinocytes: Produce keratin; involved in Vitamin D synthesis ( for bones).

• Melanocytes: Produce melanin for skin color and UV protection.

• Dermis:

  • Papillary layer (20%): Contains dermal papillae.

  • Reticular layer (80%): Dense irregular connective tissue.

• Appendages:

  • Hair (arrector pili)

  • Nails

  • Glands: Sweat (sudoriferous)

• Skin Color: Determined by melanin, carotene, hemoglobin; disorders include albinism.

Bone

Structure and Function

• Functions: Support, protection, movement, mineral storage, hemopoiesis.

• Classification: Long, short, flat, irregular bones.

• Tissue Types: Compact and spongy bone.

• Long Bone Parts:

  • Diaphysis: Hollow shaft, contains yellow marrow.

  • Medullary cavity: Contains yellow marrow.

  • Endosteum: Inner lining.

  • Periosteum: Outer (fibrous), inner (osteogenic).

  • Sharpey's fibers: Anchor periosteum to bone.

  • Epiphysis: Contains red marrow in trabeculae.

  • Articular cartilage: Hyaline cartilage covering joint surfaces.

• Epiphyseal Plate: Growth plate with zones:

  • Reserved cartilage

  • Proliferating cartilage

  • Hypertrophic cartilage

  • Ossification/calcification

  • Resorption

• Compact Bone:

  • Haversian system (osteon)

  • Haversian canal

  • Lacuna

Spongy Bone and Composition

• Spongy Bone: Contains trabeculae.

• Chemical Composition:

  • Organic components: Collagen, cells (structure and function).

  • Inorganic components: Hydroxyapatite (structure and function).

Bone Development

• Intramembranous Ossification: Direct, embryonic fibers.

• Endochondral Ossification: Indirect, hyaline cartilage model.

• Zones: Reserved cartilage, proliferating cartilage, hypertrophic cartilage, calcified matrix.

Hormones and Imbalances

• Growth hormone, thyroid (T3, T4), sex hormones, vitamins and minerals.

• Imbalances: Osteoporosis (adults), osteomalacia/rickets (children).

Articulations (Joints)

Classification and Structure

Articulations secure bones and may permit movement. They are classified by connective tissue type and structure.

Associated Structures

• Ligaments

• Menisci

• Bursae

• Tendons

• Tendon sheaths

• Weeping lubrication

Movement Types

• Nonaxial, uniaxial, biaxial, multiaxial

• Angular movements: Flexion, extension, circumduction, rotation

Homeostatic Imbalances

• Sprain, strain, dislocation, herniated disc

• Arthritis: Osteoarthritis, rheumatoid arthritis, gouty arthritis

Additional info: Academic context and expanded explanations have been added for clarity and completeness.