Chapter 4: Tissues Chapter 4 Tissues: The Living Fabric Tissue: A group of cells similar in structure; designed to perform a specialized function Primary Tissue Types: Extracellular Tissue: Cells: Matrix: Function: Aggregated Line surface / body cavities; Miniscule Epithelial polyhedral Glandular secretions cells Variable Connective fixed / wandering Abundant Support and protection cells Elongated Muscle contractile Moderate Movement cells Intertwining Nervous elongated None Transmission of electrical impulses processes Chapter 4: Tissues Chapter 4: Tissues Cell Adhesion Molecules (CAMs) Intracellular Connections: Epithelial Tissue: (transmembrane “sticky” proteins) 1) Epithelia: • Cell layers covering internal / external surfaces • Functions: Provide physical protection (e.g., skin) Control permeability (e.g., blood vessels) Provide sensation (e.g., eye – neuroepithelium) Characteristics: • High degree of cellularity Tight Junction Desmosome Gap Junction • Impermeable junction • Anchoring junction • Communication junction (e.g., bladder) (e.g., skin) (e.g., heart) Marieb & Hoehn – Figure 3.5 Chapter 4: Tissues Chapter 4: Tissues Epithelial Tissue: Epithelial Tissue: 1) Epithelia: 1) Epithelia: • Cell layers covering internal / external surfaces • Cell layers covering internal / external surfaces • Functions: Provide physical protection (e.g., skin) • Classification: (e.g., blood vessels) Control permeability # of cell layers + cell shape = epithelia type Provide sensation (e.g., eye - neuroepithelium) Simple Squamous = Simple squamous Stratified Cuboidal Characteristics: epithelium Columnar • High degree of cellularity • Polarity (apical vs. basal surfaces) • Ciliated epithelium (e.g., trachea) • Attachment (basement membrane) • Epithelia connective tissue • Avascularity (no blood vessels) Simple squamous epithelium Stratified squamous epithelium • Regenerative Absorption / secretion Physical protection • Germinative cells (stem cells) • Lining body cavities (mesothelium) • Surface of skin • Lining blood vessels (endothelium) • Lines external openings 1 Chapter 4: Tissues Chapter 4: Tissues Simple cuboidal epithelium Stratified cuboidal epithelium Secretion / absorption • Glandular tissue Protection / secretion / absorption • Ducts / Kidney tubules • Rare – lining of ducts (e.g., sweat glands) Pseudostratified (ciliated) epithelium Protection / secretion / absorption • All cells connect to basal lamina (not stratified) Transitional epithelium • Respiratory tract / Male reproductive tract Expansion / recoil Simple columnar epithelium • Shape changes depending on stretch Protection / secretion / absorption Stratified columnar epithelium • Bladder / Renal pelvis / Ureters • Basal nuclei; often ciliated / microvilliated Protection • GI tract; Uterine tubes; Collecting duct (kidney) • Rare – lining GI tract / ducts / urethra (male) Marieb & Hoehn – Figure 4.6 Chapter 4: Tissues Chapter 4: Tissues Merocrine Epithelial Tissue: Epithelial Tissue: 2) Glandular epithelia: 2) Glandular: • Specialized epithelial cells for secretion: • Methods for classifying exocrine glands: • Exocrine Glands: Release secretions to external environment (ducted) 1) Mode of Secretion • Endocrine Glands: Release secretions to interstitial fluids (ductless) A) Merocrine Secretion • Product released via exocytosis B) Holocrine Secretion • Product released via destruction of cell Holocrine 2) Types of Secretions: A) Serous Glands (water / enzymes) B) Mucus Glands (mucins) C) Mixed Glands Chapter 4: Tissues Chapter 4: Tissues Epithelial Tissue: Tissue: A group of cells similar in structure; designed to perform a specialized function 2) Glandular: • Methods for classifying exocrine glands: Primary Tissue Types: 3) Gland Structure Extracellular • Unicellular Glands: Composed of individual secretory cells Tissue: Cells: Matrix: Function: • e.g., Goblet cells (secrete mucins – respiratory / digestive system) • Multicellular Glands Aggregated Line surface / body cavities; • Named by: 1) Duct structure (simple vs. compound) Miniscule Epithelial polyhedral Glandular secretions 2) Secretory shape (tubular / alveolar / tubuloalveolar) cells 3) Duct / secretory region relationship (e.g., branched) Variable Connective fixed / wandering Abundant Support and protection cells Elongated Muscle contractile Moderate Movement cells Intertwining Nervous elongated None Transmission of electrical impulses processes Marieb & Hoehn – Figure 4.5 2 Marieb & Hoehn – Figure 4.7 Chapter 4: Tissues Chapter 4: Tissues Reticular Elastic Connective Tissue: Types of Connective Tissue: fiber fiber Collagen (never exposed to outside environment) (Syrupy matrix) fiber • Located throughout body 1) Connective Tissue Proper: • Primary functions: A) Cell types: Macrophage 1) Structural framework for body Fibroblasts / Fibrocytes: Produce / maintain fibers & ground substance 2) Transport fluids / dissolved materials Connective tissues are classified according to the Adipocytes: 3) Protect delicate organs fluidity of the ground substance Store lipid droplets (fat cells) Fibroblast 4) Insulate body Mast cells: Stimulate inflammation response (fat cells) Macrophages / Microphages: Defense cells; engulf foreign molecules • All contain: Protein Adipocyte Fibers B) Fiber types: 1) Specialized cells Collagen: Mast cell (extracellular) Thick bundles; provide high tensile strength 2) Protein fibers Cell 3) Ground substance (fluid) Elastic: Branched / wavy; allow for stretch (contain elastin) Matrix (most of volume) Reticular: Form fine framework; allow for cell attachment Chapter 4: Tissues Chapter 4: Tissues Types of Connective Tissue: Types of Connective Tissue: 1) Connective Tissue Proper: (Syrupy matrix) 1) Connective Tissue Proper: (Syrupy matrix) A) Mesenchyme: A) Mesenchyme: • Embryonic connective tissue • Embryonic connective tissue • Star-shaped stem cells; fine fibers Gives rise to all • Star-shaped stem cells; fine fibers Gives rise to all other connective other connective B) Loose Connective Tissue: tissues B) Loose Connective Tissue: tissues • “Packing material” of body (fill space / cushion / stabilize / support) • “Packing material” of body (fill space / cushion / stabilize / support) Areolar Tissue Adipose Tissue • Composed primarily of adipocytes • Least specialized CT in adults • Open framework; fiber # • Provides padding, absorbs shock, insulates, “filler” around structures • Absorbs shock • Distort w/o damage; resilient • Metabolically active; incapable of • Fluid reservoir dividing (but mesenchyme cells…) • Highly vascularized • White fat (majority) Attaches epithelia (e.g., skin) to • Brown fat ( blood supply / mitochondria) deeper structures • Thermogenesis (infants) Chapter 4: Tissues Chapter 4: Tissues Types of Connective Tissue: Types of Connective Tissue: 1) Connective Tissue Proper: (Syrupy matrix) 1) Connective Tissue Proper: (Syrupy matrix) A) Mesenchyme: A) Mesenchyme: • Embryonic connective tissue • Embryonic connective tissue • Star-shaped stem cells; fine fibers Gives rise to all • Star-shaped stem cells; fine fibers Gives rise to all other connective other connective B) Loose Connective Tissue: tissues B) Loose Connective Tissue: tissues • “Packing material” of body (fill space / cushion / stabilize / support) • “Packing material” of body (fill space / cushion / stabilize / support) C) Dense Connective Tissue: • Offer strength & support; occupied primarily by collagen fibers Reticular Tissue Dense Regular Connective Tissue • Reticular fibers form complex 3-D • Collagen fibers run parallel to each other structure (stroma) • Packed tightly; align with forces applied • Supports functional cells (parenchyma) of the organ • Tendons – Attach muscle to bone (transfer pull) • Ligaments – Attach bone to bone; stabilize Located in liver / spleen / lymph position of internal organs nodes/ bone marrow • Aponeuroses – Tendon sheet; attaches muscle to bone 3 Chapter 4: Tissues Chapter 4: Tissues Types of Connective Tissue: Types of Connective Tissue: 1) Connective Tissue Proper: (Syrupy matrix) 2) Blood: (Watery matrix) A) Mesenchyme: • Transports materials through body • Embryonic connective tissue 3) Cartilage: (Gel-like matrix) • Star-shaped stem cells; fine fibers Gives rise to all • Provides strong framework for supporting body B) Loose Connective Tissue: other connective tissues • Composition: • “Packing material” of body (fill space / cushion / stabilize / support) • Matrix = firm gel; contain [] chondroitin sulfates (polysaccharide deriviative) C) Dense Connective Tissue: • Complex with proteoglycans in ground substance • Offer strength & support; occupied primarily by collagen fibers Protein cores with glycosaminoglycans Dense Irregular Connective Tissue attached (carbohydrate chains) • Collagen fibers run random to each other Form hydrated gel; resist compression • Support stress from many directions • Chondrocytes: Only cell in mature cartilage; sit in lacunae • Contains variable amounts of elastic fibers • Avascular (release antiangiogenesis factor) • Surrounded by fibrous perichondrium (dense irregular connective tissue) Located underlying skin / around bones (periosteum) / around organs (capsules) Chapter 4: Tissues Chapter 4: Tissues 4) Bone (Chapter 6) Types of Connective Tissue: Tissue: A group of cells similar in structure; designed to perform a specialized function 2) Blood: (Watery matrix) Intervertebral Disks • Transports materials through body Primary Tissue Types: Meniscus 3) Cartilage: (Gel-like matrix) (knee joint) Extracellular Tissue: Cells: Matrix: Function: