Chapter+5+PPT.pptx

Chapter 5 Lecture Outline: Anatomy & Physiology

Introduction to Tissues

• The body contains trillions of cells organized into complex units known as tissues.

• Tissues are groups of similar cells and extracellular material (extracellular matrix) that perform a common function such as protection or movement.

• Four types of tissues:

  • Epithelial tissue

  • Connective tissue

  • Muscle tissue

  • Nervous tissue

5.1 Epithelial Tissue

Characteristics of Epithelial Tissue

• Cellularity: Made up of tightly packed cells with minimal extracellular matrix.

• Locations:

  • Covers body surfaces

  • Lines body cavities

  • Forms glands

• Polarity:

  • Apical surface: exposed to the environment or space.

  • Basal surface: attached to connective tissue.

Functions of Epithelial Tissue

• Physical Protection: Guards against dehydration, abrasion, and destruction.

• Selective Permeability: Controls passage of substances, allowing some to pass while preventing others.

• Secretions: Specialized cells secrete substances.

• Sensations: Provides information to the nervous system.

Classification of Epithelial Tissue

• By Number of Cell Layers:

  • Simple epithelium: Single layer, all cells touch the basement membrane.

  • Stratified epithelium: Multiple layers, offers mechanical stress protection.

  • Pseudostratified epithelium: Appears stratified but is not.

• By Cell Shape:

  • Squamous: Flattened and irregular.

  • Cuboidal: Equal height and width.

  • Columnar: Taller than wide.

  • Transitional: Changes shape based on stretching.

5.1d Glands

• Glands are composed of epithelial tissue that secretes substances.

• Endocrine Glands: Secrete hormones into the bloodstream, no ducts.

• Exocrine Glands: Secrete substances onto epithelial surfaces via ducts.

  • Unicellular: Goblet cells; secrete mucin.

  • Multicellular: Contain cell clusters (acini) connected to ducts.

  • Classified by:

    • Anatomic Form: Simple (single duct) vs Compound (branched ducts).

    • Method of Secretion: Merocrine (exocytosis), Apocrine (pinch off), Holocrine (ruptured cells).

5.2 Connective Tissue

Characteristics of Connective Tissue

• Most diverse tissue type; has three basic components:

  • Cells: Resident and wandering cells.

  • Protein fibers: Collagen, elastic, reticular fibers.

  • Ground substance: Extracellular matrix that varies in consistency.

Functions of Connective Tissue

• Provides physical protection, structural support, binding of structures, storage, transport, and immune protection.

5.2d Classification of Connective Tissue

Connective Tissue Proper

• Loose CT: Fewer cells and fibers; includes areolar, adipose, reticular.

• Dense CT: Fewer ground substance but more fibers; includes dense regular, dense irregular, elastic.

Supporting Connective Tissue

• Cartilage: Firm, semisolid matrix with chondrocytes in lacunae; includes hyaline, fibrocartilage, elastic cartilage.

• Bone: Solid matrix; includes compact and spongy bone with osteocytes.

Fluid Connective Tissue

• Blood: Consists of formed elements (red/white blood cells, platelets) in plasma.

• Lymph: Derived from blood plasma containing no cellular components.

5.3 Muscle Tissue

• Muscle tissues are responsible for movement; three types:

  • Skeletal Muscle: Voluntary, striated, multinucleated.

  • Cardiac Muscle: Involuntary, striated, branched, found in the heart.

  • Smooth Muscle: Involuntary, non-striated, found in walls of hollow organs.

5.4 Nervous Tissue

• Composed of neurons (transmit impulses) and glial cells (supporting cells).

• Neurons receive, process, and transmit nerve impulses.

5.5 Organs

• Composed of two or more tissue types working together.

• Example: The stomach contains all four tissues (epithelium, connective, muscle, nervous).

5.6 Tissue Development and Aging

• Tissues develop from embryonic germ layers (ectoderm, mesoderm, endoderm).

• Aging affects all tissues; results in reduced efficiency and changes in structural properties.