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Introduction to Human Anatomy & Physiology and Tissues

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Introduction to Human Anatomy & Physiology

Definitions

Human anatomy and physiology are foundational sciences for understanding the structure and function of the human body. Anatomy focuses on the body's structures, while physiology explores how those structures work.

  • Human anatomy: The study of the structure of the human body.

  • Gross anatomy: Study of structures visible to the naked eye.

  • Microscopic anatomy: Study of structures requiring magnification, including histology (study of tissues).

  • Human physiology: The study of the functions and processes of the human body.

Organization of the Human Body

The human body is organized into hierarchical levels, each with increasing complexity.

  1. Chemical level:

    • Atom: Smallest particle of an element exhibiting its qualities.

    • Molecule: Particle consisting of two or more atoms joined by chemical bonds.

  2. Cellular level: Made of molecules; basic unit of life.

  3. Tissue level: Aggregation of similar cells performing a common function.

  4. Organ level: Aggregation of two or more tissue types integrated for a specific function.

  5. Organ system level: Consists of various organs with similar or related functions.

    • Integumentary system: Protection, location of sensory receptors.

    • Skeletal system: Support, levers for movement, mineral storage.

    • Muscular system: Movement, regulation of organ volume.

    • Nervous system: Fast-acting control system.

    • Endocrine system: Hormone production and regulation.

    • Cardiovascular system: Transport of nutrients, gases, and wastes.

    • Lymphatic system: Returns leaked particles to cardiovascular system, immune response.

    • Respiratory system: Gas exchange (oxygen and carbon dioxide).

    • Urinary system: Elimination of waste.

    • Male reproductive system: Production and transfer of sperm.

    • Female reproductive system: Production of eggs, sites for fertilization and fetal development, delivery, milk production for newborn.

  6. Organismal level: Group of systems forming an individual.

Maintaining Life

Life processes are essential functions carried out to maintain life.

  • Maintain boundaries: Separation between internal and external environments.

  • Movement: Locomotion and movement of substances.

  • Responsiveness: Ability to sense and respond to stimuli.

  • Metabolism: All chemical reactions in the body.

    • Anabolism: Building up molecules.

    • Catabolism: Breaking down molecules.

  • Excretion: Removal of wastes.

  • Reproduction: Production of offspring.

  • Growth: Increase in size and number of cells.

Survival Needs

Certain factors must be present for survival and proper functioning.

  • Nutrients:

    • Energy source

    • Vital for cell structure and function

    • Protection and cushioning

  • Vitamins & minerals: Necessary for chemical reactions, often acting as cofactors.

  • Oxygen: Required for chemical reactions that release energy.

  • Water: Makes up 60-80% of body weight; necessary for chemical reactions and environment.

  • Normal body temperature: (); required for optimal chemical reaction rates.

  • Atmospheric pressure: Vital for breathing and gas exchange in lungs.

Homeostasis

Homeostasis is the ability to maintain a stable internal environment despite external changes.

  • Maintaining body fluids:

    • Intracellular fluid

    • Extracellular fluid

  • Feedback systems:

    • Components: Variable, receptor, control center, effector

    • Types: Negative feedback (response reverses stimulus), Positive feedback (response enhances stimulus)

  • Homeostatic imbalance: Disruption leads to disease or dysfunction.

Medical Terminology

Standardized terms describe anatomical positions, directions, and regions.

  • Anatomical position: Body upright, feet together, arms at sides, palms forward.

  • Directional terms:

    • Cranial, caudal, medial, lateral, proximal, distal, superior, inferior, posterior/dorsal, anterior/ventral, superficial/external, deep/internal, palmar, plantar

  • Body planes & sections:

    • Sagittal (midsagittal), frontal (coronal), transverse (horizontal), oblique

  • Body cavities: Confined spaces within the axial region.

    • Dorsal body cavity: Cranial and spinal cavities

    • Ventral body cavity: Thoracic (pleural, mediastinum, pericardial) and abdominopelvic (stomach, intestines, spleen, pancreas, kidneys, liver, urinary bladder, reproductive organs, rectum)

    • Serous membranes: Parietal serosa (lines cavity walls), visceral serosa (covers organs), serous cavity (space between)

Chapter 4: Tissues

Definition and Study of Tissues

Tissues are groups of cells similar in structure and function. The study of tissues is called histology.

Basic Types of Tissues

  1. Epithelial tissue

  2. Connective tissue

  3. Muscle tissue

  4. Nervous tissue

Epithelial Tissue

Epithelial tissue covers body surfaces, lines cavities, and forms glands.

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

  • General categories:

    • Lining & covering epithelium

    • Glandular epithelium

  • Characteristics:

    • Almost entirely cells

    • Apical border (free surface), basement membrane

    • Supported by connective tissue

    • Innervated but avascular

    • Highly reproductive

  • Classification: Based on number of cell layers and cell shape

    • Number of cell layers:

      • Simple (one layer)

      • Stratified (multiple layers)

    • Cell shape:

      • Squamous (flat)

      • Cuboidal (cube-shaped)

      • Columnar (tall)

  • Types of epithelium:

    • Simple squamous: Lines capillaries, glomeruli, alveoli

    • Stratified squamous:

      • Nonkeratinized: Lines mouth, esophagus, vagina

      • Keratinized: Skin surface

    • Simple cuboidal: Found in kidney tubules, small gland ducts

    • Simple columnar: May be ciliated, contain goblet cells; lines digestive tract

    • Transitional: Lines ureters, bladder, parts of urethra; can stretch

    • Pseudostratified columnar: Ciliated with goblet cells; found in trachea, bronchi

Connective Tissue

Connective tissue supports, protects, and binds other tissues together.

  • Characteristics:

    • Originates from mesenchyme

  • Structural components:

    • Ground substance: Fills space between cells, contains protein fibers

    • Fibers: Provide support and flexibility

      • Collagen: Strong, resists tension

      • Elastic: Stretch and recoil

      • Reticular: Support soft tissue

    • Cells:

      • Fibroblasts: Produce fibers

      • Chondrocytes: Cartilage cells

      • Osteocytes: Bone cells

      • Hemocytes: Blood cells

      • Adipocytes: Fat cells

  • Types of connective tissue:

    • Connective tissue proper:

      • Loose (areolar, adipose, reticular)

      • Dense (regular, irregular)

    • Cartilage:

      • Hyaline: Most common, supports and cushions

      • Elastic: Flexible, found in ear

      • Fibrocartilage: Alternating rows, resists compression and tension

    • Bone: Hard matrix due to collagen and calcium salts

    • Blood: Functions in transportation and protection

Nervous Tissue

Nervous tissue is specialized for communication via electrical impulses.

  • Neurons: Generate and conduct impulses

  • Neuroglia: Non-conducting cells that support neurons

Muscle Tissue

Muscle tissue is responsible for movement and consists of cells containing contractile protein fibers.

  • Types of muscle tissue:

    • Skeletal muscle: Striated, multinucleated, voluntary, attached to bones

    • Smooth muscle: Non-striated, mononucleated, involuntary, found in hollow organs

    • Cardiac muscle: Striated, mononucleated, branching, involuntary, found only in the heart

Integumentary System and Skin

Functions of the Skin

The skin is the largest organ and serves multiple protective and regulatory functions.

  • Protection via blood vessels and physical barrier

  • Sensation: Touch, pressure, warmth, coolness

  • Excretion: Water and some wastes

  • Absorption: Fat-soluble vitamins, oxygen, carbon dioxide, and some toxins

Layers of the Skin

  • Epidermis: Thinnest and outermost layer; contains specialized cells

    • Keratinocytes: Produce keratin

    • Melanocytes: Produce melanin

    • Langerhans cells: Immune function

    • Merkel cells: Sensory function

  • Distinct layers (strata) depend on location:

    • Stratum basale: Deepest, single cell layer, mitotically active

    • Stratum spinosum: Several cell layers, Langerhans cells

    • Stratum granulosum: 3-5 cell layers, keratinization begins

    • Stratum lucidum: Only in thick skin, thin band of flattened cells

    • Stratum corneum: Outermost, 20-30 cell layers, 3/4 of epidermis thickness

  • Dermis: Thicker than epidermis, contains connective tissue, blood vessels, nerves, and sensory receptors

Additional info:

  • Some content inferred and expanded for completeness, such as the functions of organ systems and tissue types.

  • Tables and diagrams referenced in the notes are described in text for clarity.

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