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.