Introduction to Anatomy & Physiology

Definitions and Scope

• Anatomy: The study of the structure of body parts and their relationships to one another.

• Physiology: The study of the function of the body’s structural machinery—how the body parts work and carry out their life-sustaining activities.

• Gross Anatomy: Study of large, visible structures (e.g., organs, muscles).

• Microscopic Anatomy: Study of structures too small to be seen with the naked eye (e.g., cells, tissues).

• Histology: Study of tissues.

• Cytology: Study of cells.

• Difference: Histology examines groups of cells (tissues), while cytology focuses on individual cells.

Organ Systems Overview

• There are eleven organ systems in the human body, each with specific functions:

• Integumentary: Protection, temperature regulation, vitamin D synthesis.

• Skeletal: Support, protection, movement, blood cell production.

• Muscular: Movement, posture, heat production.

• Nervous: Fast-acting control system, responds to stimuli.

• Endocrine: Hormone production, long-term regulation.

• Cardiovascular: Transport of nutrients, gases, wastes.

• Lymphatic: Immunity, fluid balance.

• Respiratory: Gas exchange (O2/CO2).

• Digestive: Breakdown and absorption of nutrients.

• Urinary: Waste elimination, water/electrolyte balance.

• Reproductive: Production of offspring.

Serous Membranes

• Structure: Double-layered membranes with a thin layer of serous fluid between them.

• Location: Line body cavities (thoracic, abdominal) and cover organs.

• Purpose: Reduce friction between organs and cavity walls.

• Examples: Pleura (lungs), pericardium (heart), peritoneum (abdominal organs).

Body Cavities and Major Organs

• Thoracic cavity: Contains heart (cardiovascular), lungs (respiratory).

• Abdominal cavity: Contains stomach, intestines (digestive), liver, spleen.

• Pelvic cavity: Contains bladder (urinary), reproductive organs.

Homeostasis

• Definition: Maintenance of a stable internal environment despite external changes.

• Components: Receptor (detects change), control center (processes information), effector (carries out response).

• Feedback Mechanisms:

  • Negative feedback: Reverses a change to maintain balance (e.g., body temperature regulation).

  • Positive feedback: Enhances the original stimulus (e.g., blood clotting, labor contractions).

• Example: The endocrine system uses negative feedback to regulate blood glucose levels.

Characteristics of Life and Levels of Organization

• All living things: Metabolize, respond to stimuli, grow, reproduce, maintain boundaries, move, and excrete wastes.

• Cell: Smallest unit of life.

• Levels of Organization: Chemical → Cellular → Tissue → Organ → Organ System → Organism.

Anatomical Position and Terminology

• Anatomical position: Body erect, feet slightly apart, palms facing forward, thumbs pointing away from body.

• Importance: Provides a standard reference for describing body parts and positions.

Principle of Complementarity

• Structure and function are interrelated; the form of a structure suits its function.

• Examples:

  • Left ventricle has thicker myocardium for stronger contractions.

  • Capillary endothelium and lung alveoli are simple squamous epithelium for efficient diffusion.

Histology: Tissues

Introduction to Histology

• Histology: Study of tissues—groups of similar cells performing a common function.

Epithelial Tissue (ET)

• Types: Covering/lining epithelia and glandular epithelia.

• Functions: Protection, absorption, filtration, excretion, secretion, sensory reception.

• Characteristics: Polarity, specialized contacts, supported by connective tissue, avascular but innervated, high regenerative capacity.

• Basal Lamina: Two parts—lamina lucida and lamina densa.

• Classification Criteria: Number of layers (simple vs. stratified) and cell shape (squamous, cuboidal, columnar).

Specialized Contacts in ET

• Tight junctions: Prevent passage of molecules between cells.

• Gap junctions: Allow communication between cells.

• Desmosomes: Provide mechanical strength by anchoring cells together.

• Hemidesmosomes: Anchor cells to the basement membrane.

Locations and Functions of ET Types

• Simple squamous: Diffusion/filtration; found in alveoli, endothelium, mesothelium.

• Simple cuboidal: Secretion/absorption; found in kidney tubules, glands.

• Simple columnar: Absorption/secretion; found in digestive tract lining.

• Stratified squamous: Protection; found in skin, mouth, esophagus.

• Pseudostratified columnar: Secretion/movement of mucus; found in respiratory tract.

Glands

• Endocrine glands: Ductless, secrete hormones into blood (e.g., thyroid gland).

• Exocrine glands: Secrete products into ducts (e.g., sweat, salivary glands).

• Unicellular exocrine gland: Goblet cell (secretes mucus).

• Multicellular exocrine gland: Sweat gland.

• Merocrine secretion: Products released by exocytosis (e.g., eccrine sweat glands).

• Holocrine secretion: Entire cell ruptures to release product (e.g., sebaceous glands).

Membranes

• Definition: Thin sheets of tissue covering surfaces or lining cavities.

• Types:

  • Mucous: Line body cavities open to exterior (digestive, respiratory tracts).

  • Cutaneous: Skin; covers body surface.

  • Serous: Line closed cavities; secrete serous fluid.

  • Synovial: Line joint cavities; secrete synovial fluid.

Connective Tissue (CT)

• Main Components: Cells, fibers, ground substance (extracellular matrix).

• -blast vs. -cyte: "-blast" cells are immature, actively secrete matrix; "-cyte" cells are mature, maintain tissue.

• Major Types (see summary tables in textbook): Loose CT, dense CT, cartilage, bone, blood.

• Elastic CT (in aorta): Allows stretch and recoil.

• Cell Types:

  • Fibroblasts: Produce fibers and ground substance.

  • Macrophages: Phagocytosis of debris and pathogens.

  • Mast cells: Release histamine and heparin during inflammation.

• Fiber Types:

  • Collagen: Strong, resist tension.

  • Elastic: Stretch and recoil.

  • Reticular: Supportive networks.

• Ground Substance: Supports cells, binds water, medium for exchange.

• Tendons, ligaments, aponeuroses: Connect muscle to bone, bone to bone, muscle to muscle; all rich in collagen fibers.

Muscle and Nervous Tissue

• Fascia: Sheets of connective tissue supporting and separating muscles.

• Types of Fascia: Superficial, deep, visceral/parietal; located under skin, around muscles, and around organs.

• Muscle Tissue:

  • Major property: Contractility.

  • Muscle cell: Also called muscle fiber.

  • Types:

    • Skeletal: Voluntary, striated, multinucleate.

    • Cardiac: Involuntary, striated, intercalated disks (contain gap junctions and desmosomes).

    • Smooth: Involuntary, non-striated.

• Nervous Tissue:

  • Cell types: Neurons (transmit impulses), neuroglia (support cells).

  • Function of neurons: Receive, process, and transmit information.

Inflammation

• Cardinal signs: Redness, heat, swelling, pain.

• Major cell: Mast cell (releases histamine and heparin).

• Histamine: Increases blood vessel permeability (swelling, redness).

• Heparin: Anticoagulant, prevents clotting.

• Role in homeostasis: Inflammation isolates injury, brings immune cells, initiates repair.

Integumentary System

Functions of the Integument

• Protection, temperature regulation, sensation, metabolic functions (vitamin D synthesis), blood reservoir, excretion.

Skin Structure

• Two main layers: Epidermis (superficial), dermis (deep).

• Order of layers (superficial to deep): Epidermis → Dermis → Hypodermis (subcutaneous layer).

• Thin skin: 4 layers (stratum basale, spinosum, granulosum, corneum).

• Thick skin: 5 layers (includes stratum lucidum between granulosum and corneum).

Cells of the Skin

• Epidermis:

  • Keratinocytes: Most abundant; produce keratin for protection.

  • Melanocytes: Produce melanin pigment.

  • Langerhans cells: Immune defense.

  • Merkel cells: Sensory receptors for touch.

• Dermis:

  • Fibroblasts: Produce fibers and ground substance.

  • Macrophages: Immune defense.

  • Mast cells: Inflammation mediators.

Skin Color

• Determined by: Melanin, carotene, hemoglobin.

• Melanocytes: Produce melanin; protects against UV radiation.

• Skin color differences: Due to amount and type of melanin produced, not number of melanocytes.

• Blood flow terms:

  • Erythema: Redness (increased blood flow).

  • Pallor: Paleness (decreased blood flow).

  • Cyanosis: Bluish color (low oxygen).

Integument and Homeostasis

• Keratin: Waterproofs and protects skin.

• Vitamin D:

  • Skin synthesizes vitamin D precursor when exposed to UV light.

  • Vitamin D is essential for calcium absorption and bone health.

Dermis and Subcutaneous Layer

• Dermis layers: Papillary (superficial, areolar CT), reticular (deep, dense irregular CT).

• Subcutaneous layer (hypodermis, superficial fascia): Anchors skin, stores fat, insulates, shock absorber.

Accessory Organs of the Skin

• Hair:

  • Parts: Root (in skin), shaft (above skin), follicle (surrounds root), papilla (nourishes hair), arrector pili muscle (causes hair to stand).

  • Types: Lanugo (fetal), vellus (fine, body hair), terminal (scalp, eyebrows, after puberty).

• Glands:

  • Sebaceous glands: Secrete sebum (oil); lubricates skin/hair; found everywhere except palms/soles.

  • Sweat glands:

    • Eccrine: Most numerous; thermoregulation.

    • Apocrine: Axillary/genital areas; active at puberty; odor from bacterial action.

    • Diaphoresis: Visible sweating.

Thermoregulation

• Hyperthermia: Elevated body temperature; signs include hot, dry skin, confusion.

• Hypothermia: Low body temperature; signs include shivering, confusion, slow breathing.

• Mechanisms: Sweating, vasodilation (cooling); shivering, vasoconstriction (warming).

Wound Healing

• Regeneration: Replacement with same tissue type; restores function.

• Fibrosis: Replacement with scar tissue; function may be lost.

• Role in homeostasis: Restores tissue integrity after injury.

Skin Cancer

• Types:

  • Basal cell carcinoma: Most common, least likely to metastasize.

  • Squamous cell carcinoma: May metastasize.

  • Melanoma: Most dangerous, metastasizes quickly.

• ABCDE rule: Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolving.

Burns

• Types:

  • First-degree: Epidermis only; redness, pain.

  • Second-degree: Epidermis and part of dermis; blisters.

  • Third-degree: Full thickness; destroys all skin layers; most serious.

• Treatment: Fluid replacement, infection prevention, skin grafts for severe burns.

• Effects: Loss of barrier, dehydration, infection risk, impaired temperature regulation.

• Classification: Based on depth and extent (rule of nines for body surface area).

Summary Table: Types of Membranes

Key Equations

• Exam Score Calculation:

Where X is your score out of 70 points.

Additional info: Some details (e.g., specific connective tissue summary tables, detailed cell percentages) are inferred from standard Anatomy & Physiology textbooks to ensure completeness.