Chapter 04_Tissue Level_ Basic Body Tissues lecture_mod 1.21 23(1) 2
Tissue Overview
Tissues: specialized cells and products performing specific functions; combined to form organs (e.g., heart, liver).
Histology: study of tissues.
Learning Outcomes
Key Objectives
4-1: Identify four major types of tissues (Epithelial, Connective, Muscle, Nervous).
4-2: Discuss types and functions of epithelial tissue.
4-3: Describe structure-function relationship of epithelium types.
4-4: List functions and categories of connective tissue.
4-5: Compare structures/functions of connective tissue proper types.
4-6: Describe fluid connective tissues (blood and lymph).
4-7: Describe cartilage and bone as supporting tissues.
4-8: Explain muscle tissue types and structural features.
4-9: Discuss basic structure and role of nervous tissue.
4-10: Describe tissue effects of injuries and aging.
Types of Tissue
4.1 Four Major Tissue Types
Epithelial Tissue
Covers surfaces, lines passages, and forms glands.
Connective Tissue
Fills internal spaces, supports, transports materials, and stores energy.
Muscle Tissue
Specialized for contraction (skeletal, cardiac, smooth).
Nervous Tissue
Carries electrical signals throughout the body.
Epithelial Tissue Classification
Shape: Squamous, Cuboidal, Columnar.
Layers: Simple (one layer), Stratified (multiple layers).
Glandular: Exocrine (with ducts) and Endocrine (ductless, hormone release).
Epithelial Functions and Characteristics
Functions of Epithelial Tissue
Provides protection, controls permeability, provides sensation, and produces specialized secretions.
Characteristics of Epithelia
Polarity: Apical and basal surfaces.
Cellularity: High cell junctions.
Attachment: Basement membrane.
Avascularity: Lacks blood vessels; nourished by diffusion.
Regeneration: Ability to regenerate;
Connective Tissue
General Characteristics
Composed of specialized cells, extracellular protein fibers, and ground substance (matrix).
Functions include structural support, fluid transport, organ protection, energy storage, and defense against pathogens.
Main Types of Connective Tissue
Connective Tissue Proper: Connects and protects (subtypes: loose, dense).
Supporting Connective Tissue: Provides structural support (cartilage, bone).
Fluid Connective Tissue: Transports (blood, lymph).
Connective Tissue Proper
Loose Connective Tissue: More ground substance (e.g., areolar, adipose, reticular).
Dense Connective Tissue: More fibers; includes dense regular, dense irregular, and elastic tissue.
Key Cells in Connective Tissue Proper
Fibroblasts: Main cell type, secrete proteins and ground substance.
Adipocytes: Fat cells, store energy.
Macrophages: Immune cells, involved in phagocytosis.
Mast Cells: Release chemicals in inflammation.
Lymphocytes: Immune response.
Supporting Connective Tissues
Cartilage Types
Hyaline Cartilage: Reduces friction; found in joints.
Elastic Cartilage: Flexible, returns to shape (e.g., ear).
Fibrocartilage: Durable, limits movement (e.g., intervertebral discs).
Bone Tissue
Offers structural support; calcified matrix for rigidity.
Contains osteocytes; vascularized.
Muscle Tissue
Types of Muscle Tissue
Skeletal Muscle: Voluntary, striated, multi-nucleated.
Cardiac Muscle: Involuntary, striated, connected by intercalated discs.
Smooth Muscle: Involuntary, non-striated, spindle-shaped.
Nervous Tissue
Structure and Function
Neurons: Conduct impulses.
Neuroglia: Support and protect neurons.
Tissue Repair and Aging
Repair Process
Inflammation Stage: Initiates tissue repair; signals from injured cells attract immune cells.
Regeneration Stage: Restoration of tissue function; varies between tissue types.
Aging Effects
Decreased regeneration ability, structural and chemical tissue changes (thinning epithelia, fragile connective tissue).
Cancer Incidence
Increasing with age; risk factors include environmental influences like smoking.