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Histology The study of tissues Tissue A group of similar cells working together to perform a common function. 4 Types of Tissues Epithelial Connective Muscle Nervous Epithelial Tissue Covers a body surface or lines a body cavity Characteristics of Epithelial Tissue Composed of closely packed cells with specialized points of attachment Have a free surface and attached to a basement membrane Avascular but innervated Rapid cell division Specialized to form glands Functions of Epithelial Tissue Protection Absorption Secretion Filtration Excretion Sensory Classification of Epithelial Tissue Cell Shape: Squamous – flattened cells Cuboidal- boxes Columnar-tall Cell Arrangement: Simple – single layers Stratified – multiple layers Examples of Epithelial Tissue Simple Squamous Epithelium (Alveoli of lungs & linings of Blood vessels) Simple Cuboidal Epithelium (Kidney tubules) A. B. Cuboidal cells Nucleus of cell Simple Columnar Epithelium (Digestive Tract) A. B. C. Columnar cells Nucleus Cell membrane Pseudostratified Epithelium (Trachea) A. B. C. Basement membrane Cilia Nucleus Stratified Squamous Epithelium (Lining of mouth) A. B. Layers of epithelium Surface cells Stratified Squamous Epithelial (Human Cheek Cells) A. B. C. Nucleus Cytoplasm Cell Membrane Transitional Epithelium (Urinary bladder) A. B. Surface cells Attached cells Specialized for stretching Connective Tissue Connective Tissue Found everywhere in the body; most abundant and widely distributed of all the tissues. Characteristics of Connective Tissue Cells widely separated by an extracellular matrix Varying degrees of vascularization Functions of Connective Tissue Binding and support Protection Insulation Transportation Structural Elements Ground Substance – unstructured material that fills the space between the cells Cells Fibers Collagen fibers Elastic fibers Reticular fibers Examples of Connective Tissue Areolar Connective Tissue (beneath the skin) A. B. C. Fibroblasts Collagen fibers Elastic fibers Reticular Tissue (Spleen, liver, lymph nodes) A. Reticular fibers Adipose Tissue (Fat) A. B. Nucleus of fat cell Fat droplet Dense Fibrous Connective Tissue (Tendons) A. B. Fibroblasts Collagenous fibers Hyaline Cartilage (Ends of bones, trachea, larynx) A. B. C. Chrondrocyte Matrix Lacuna Bone A. B. C. D. Central Canal Lamellae Osteocyte in lacuna Canaliculi Blood Leucocytes (White Blood Cells) Erythrocytes (Red Blood Cells) Sickle Cells Muscle Tissue Responsible for body movements Classification Location Skeletal Cardiac Visceral Appearance Smooth Striated Action Voluntary Involuntary Skeletal Muscle: Attached to bones for movement A. B. AKA: Muscle fibers Long, blunt, cylindrical Multinucleated Striated Voluntary Width of cell Nucleus Cardiac Muscle: Found in heart A. B. Involuntary Mononucleate Branched Striated Intercalated discs Nucleus Visceral/Smooth Muscle: Found in walls of hollow organs Involuntary Spindle-shaped Mononucleate No visible striations B. Nucleus Nervous Tissue Regulates and controls body functions 2 Major Cell Types Neurons Generate and conduct nerve impulses Functional cells of the nervous system Supporting Cells Nonconducting Support, protect and insulate neurons Neuroglia Parts of Neuron Cell Body Dendrite Receives information from sensory receptors Axon Carries impulses away from cell body to target structure Neurons & Neuroglia A. B. C. Cell Body Cell Process (axon or dendrite) Neuroglia (small dark dots) Neuromuscular Junction A. B. C. Axon Motor end plates Skeletal cell