Tissues and Mechanisms of Disease

INTRODUCTION TO TISSUES

  • Definition of Tissues: Groups of cells that form the fabric of the body.
  • Four Main Types of Tissue:
    • Epithelial Tissue: Covers body and lines cavities.
    • Connective Tissue: Provides structural and functional support.
    • Muscle Tissue: Responsible for movement.
    • Nervous Tissue: Conducts and processes information.

MATRIX

  • MATRIX: Fluid material between cells that gives tissues their shape, mainly composed of water and interlocking fibers.
  • Plasma: The watery matrix of blood without fibers, allowing it to flow freely.

EPITHELIAL TISSUE

  • Characteristics:
    • Forms sheets covering the body and linings of organs and duct systems.
    • Cells are tightly packed with little intercellular matrix.
    • Classification by Shape:
    • Squamous: Flat, scalelike.
    • Cuboidal: Cube-shaped.
    • Columnar: Taller than wide.
    • Transitional: Variable shapes that can stretch.
    • Classification by Arrangement:
    • Simple: Single layer of cells.
    • Stratified: Multiple layers of cells; named for the outer layer cell shape.

SIMPLE CUBOIDAL EPITHELIUM

  • Often specialized for secretion:
    • Cuboidal cells group into glands.
    • Secretion examples: saliva, digestive juices, hormones.

SIMPLE VS STRATIFIED EPITHELIUM

  • Simple Columnar Epithelium:

    • Single layer of columnar cells.
    • Lines stomach and intestines; contains goblet cells for mucus.

  • Stratified Transitional Epithelium:

    • Located in the urinary bladder; can stretch.
    • Composed of 10 layers of roughly cuboidal cells that distort to a squamous shape when stretched.

CONNECTIVE TISSUE

  • Definition: Most abundant and widely distributed tissue in the body, few cells in a robust matrix.
  • Types:
    • Areolar: Binds organs together.
    • Adipose (Fat): Stores lipids.
    • Fibrous: Composed of strong collagen fibers (e.g., tendons).
    • Bone: Calcified matrix for support and protection.
    • Cartilage: Gel-like matrix; produced by chondrocytes.
    • Blood: Fluid matrix functioning in transport and protection.

ADIPOSE VS FIBROUS CONNECTIVE TISSUE

  • Adipose: Functions in lipid storage.
  • Fibrous: Contains strong collagen fibers, found in tendons.

BONE AND CARTILAGE

  • Bone:
    • Matrix is calcified, serves support and protection.
  • Cartilage:
    • Gel-like matrix, composed of chondrocytes, flexible support.

BLOOD

  • Blood has a fluid matrix; its primary functions are transport and protection.

TYPES OF MUSCLE TISSUES

  • Skeletal Muscle:

    • Attaches to bones, striated and voluntary control.

  • Cardiac Muscle:

    • Striated, involuntary, forms heart walls.

  • Smooth Muscle:

    • Non-striated/involuntary; found in blood vessels and organs.

NERVOUS TISSUE

  • Function: Rapid communication and control of body functions.
  • Components:
    • Neurons: The conducting cells with a cell body, dendrites, and axon.
    • Glial Cells: Supportive and connecting cells.

TISSUE REPAIR

  • Regeneration: Epithelial and connective tissues regenerate easily.
  • Scar Formation: Large or deep injuries may result in dense fibrous scars.
  • Keloid: Exaggerated scar response, thickened tissue.

STUDYING DISEASE

  • Health: A state of physical, mental, and social well-being.
  • Disease: An abnormality threatening health.
  • Etiology: Study of disease causation.

DISEASE TERMINOLOGY

  • Idiopathic: Unknown cause of the disease.
  • Signs and Symptoms: Objective and subjective abnormalities.
  • Pathogenesis: The development pattern of a disease.

EPIDEMIOLOGY

  • Definition: Study of disease occurrence and transmission.
  • Types of Diseases:
    • Endemic: Native to a particular region.
    • Epidemic: Affects many at once.
    • Pandemic: Global epidemic.

PATHOPHYSIOLOGY

  • Mechanisms of Disease: Genetic, infectious, neoplastic, traumatic, metabolic imbalances.
  • Risk Factors: Genetic, age, lifestyle, stress, environment, preexisting conditions.

PATHOGENIC ORGANISMS

  • Viruses: Microscopic intracellular parasites; invade host cells.
  • Prions: Pathogenic proteins causing degenerative disorders.
  • Bacteria: Tiny nucleated cells, can be classified by wall composition and growth requirements.

FUNGI AND PROTOZOA

  • Fungi: Simple organisms lacking chlorophyll.
  • Protozoa: Large one-celled organisms that may parasitize or destroy cells.

MECHANISMS OF TRANSMISSION

  • Person-to-person contact, environmental contact, opportunistic invasion, and vector transmission.

PREVENTION AND TREATMENT

  • Vaccination, drug therapy (antibiotics, antivirals), and new treatment strategies.

TUMORS AND CANCER

  • Neoplasms: Abnormal cell growths, divided into benign (localized) and malignant (spread).
  • Classification of Tumors: By type and origin.

CAUSES OF CANCER

  • Key Factors: Genetic risk, carcinogens, age, environmental factors, viruses.

METHODS OF DETECTING CANCERS

  • Approaches: Self-exams, imaging, biopsy, blood tests.

STAGING CANCER

  • To classify tumors by size/spread and assess development pattern.

INFLAMMATION

  • Response: A protective mechanism with signs including redness, heat, swelling, pain.
  • Mediators: Histamine, prostaglandins, kinins.
  • Effects: Increases circulation, attracts white blood cells, dilutes irritant, forms edema.

QUESTIONS?

  • Reach out for clarification on any discussed topics.