Epithelial and Connective Tissues PDF

**2A. Epithelia Tissue** Two types of Epithelial Tissue: 1. Covering / Lining Epithelium: forms outer layer of skin and internal structures. 2. Glandular Epithelium: forms glands of body. Functions: 1. Physical protection - Lumen of urinary bladder 2. Absorption - Kidney...

**2A. Epithelia Tissue** Two types of Epithelial Tissue: 1. Covering / Lining Epithelium: forms outer layer of skin and internal structures. 2. Glandular Epithelium: forms glands of body. Functions: 1. Physical protection - Lumen of urinary bladder 2. Absorption - Kidney 3. Sensation - Eyeball 4. Secretion - Occurs in the glands where one or more modified epithelial cells that make or secrete particular substance. - Glands = Exocrine or Endocrine Endocrine - Secrete products directly into bloodstream. - E.g., Thyroid, Pituitary gland Exocrine - Secretes products into ducts. - E.g., Sweat, Earwax, Saliva Structure of Epithelial Tissue - Apical Structure: Free surface exposed to exterior environment or cavity of organ - Often have microvilli or cilia. - Basal Surface: Anchored lower surface. - Basal Lamina: Adhesive sheet beneath *basal surface*; joins epithelial tissue to connective tissue. Classification Classify by... Arrangement of Layers: - Simple - Pseudostratified - Stratified or Cell Shape: - Squamous - Cuboidal - Columnar Epithelial Tissue Rule of Thumb - More layers = more protection - Single layer = easier to permeate - Cilia often helpful in moving substances or involved in sensation. Tissues: - similar in structure - Perform common or related function Histology - A subset of microscopic anatomy Tissue Types: Epithelial Tissue: Protects **2B. Connective Tissue** Epithelial Tissue: Protects Connective Tissue: Supports Muscular Tissue: Moves Nervous Tissue: Controls Connective Tissue - supports body structures - All CT develops from *Mesenchyme* Four types: 1. Connective Proper 2. Cartilage 3. Bone 4. Blood **Connective Tissue** Functions: 1. Support Example: Intervertebral discs containing fibrocartilage. 2. Bind Example: Dense regular connective tissue of a tendon. 3. Storage Example: Adipose tissue showing adipocytes of white fat. 4. Transport Example: RBC, WBC & platelets. 5. Protection Example: Pectoral Girdle: Clavicle and Scapula. 6. Immune Protection Example: Bone Marrow. Types of Connective Tissue (Loose vs. Dense) Loose 1. **Areolar** - Cells found in areolar - Fibroblast, Defense cell, adipose cell - Characteristics: - Strong, flexible, and resistant to stretch - Tough but flexible, branching / lattice - Allows for stretch and recoil - Ground Substance: - Colorless, viscous solution - Support cells - Binds cells together - Provides medium for exchange - Defense Cell: - Breakdown invading pathogens - 2nd line of defense after epithelia - E.g., macrophage, plasma cell, mast cell, eosinophil, neutrophil - Adipose Cells - Mainly lipids - Energy storage - Cushion / protect - Some hormones 2. **Adipose** - primary cell type is lipid 3. **Reticular** - Found in "hollow organs" as supporting framework. Dense 1. Regular - Collagen fibers, running parallel, densely packed, very strong. 2. Irregular - Mostly collagen fibers, irregular / mesh pattern - Provides strength in multiple directions 3. Elastic - Collagen and elastic fibers - Allows for stretch and recoil Tissue Type: Cartilage - Chondrocyte = cartilage cell - Develop from chondroblasts - Collagen + elastic fibers + ground substance - Perichondrium = dense CT, covers cartilage - Makes solid but somewhat pliable - Chondroitin sulfate 1. Hyaline - Most common type, has high concentration of fine collagen fibers - Precursor to skeletal system in fetus - Found at ends of long bones (articular cartilage) - Most hyaline has perichondrium (not articular) 2. Elastic - Composed of both collagen and elastic fibers - more elastic so it is more flexible - Has outer perichondrium 3. Fibrocartilage - Chondrocytes and collagen fibers are arranged in parallel rows - No perichondrium Tissue Type: Bone - Supports, protects, houses blood forming cells - Relatively tough, only had collagen, has calcium Compact vs Spongy Tissue Type: Blood - Has plasma and cells (WBC, RBC, Platelets) - Function is to transport to support tissues (blood carries stuff in it to all over the body) Membranes (Epithelia + Connective Tissue + Basement Membrane) 1. Skin - "Cutaneous membrane" - Two layers - Epidermis - Dermis 2. Mucous - Epithelial + Loose connective tissue + goblet cells 3. Serous - Simple epithelia + areolar connective tissue - Produces thin, watery fluid to allow easy motion over surfaces 4. Synovial - Synovial cells + loose connective tissue - Not technically an epithelial membrane - Lines joint cavities and secrete synovial fluid