Epithelial_and_Connective_Tissues_11th_ed.pdf

Anatomy & Physiology I BIOL 2001 C Ibanez Tissues: Epithelial & Connective pp. 115-142 1. Tissue: a group of cells organized into groups or layers that have specialized...

Anatomy & Physiology I BIOL 2001 C Ibanez Tissues: Epithelial & Connective pp. 115-142 1. Tissue: a group of cells organized into groups or layers that have specialized function(s) a. Types: i. Epithelial ii. Connective iii. Muscular iv. Nervous 2. Epithelial Tissue: Epithelia (cover surfaces) and glands (fluid secretions, are attached to epithelia) a. Characteristics: i. Cellularity: highly cellular with strong junctions 1. Tight junctions – provide a strong bonding between neighboring cells and prevent leakage across tissues 2. Adherens junctions – link the cytoskeleton from two adjusted cells together and transmit mechanical forces 3. Gap junctions – facilitate the movement of ions and molecules across the tissue Anatomy & Physiology I BIOL 2001 C Ibanez ii. Polarity: top and bottom; uneven distribution of organelles 1. Apical surface (top) exposed 2. Basal surface (bottom) attached to basal lamina iii. Attached to basement membrane iv. Avascular and Innervated: 1. Blood vessels don’t grow into the epithelial tissue 2. Epithelial cells receive their nutrients from capillaries in the underlying connective tissues 3. Exchange of chemicals between epithelial and connective tissues is accomplished through diffusion 4. Although blood vessels do not penetrate epithelial tissues, nerve endings do v. Regenerate from the basement membrane and move upward (away from blood supply); generally high rates because they take a lot of abuse Anatomy & Physiology I BIOL 2001 C Ibanez b. Functions of Epithelial Tissues: i. Physical protection ii. Regulate permeability (i.e., fluid loss) iii. Sensitivity: highly innervated (also can form a neuroepithelium- sensitive to smell, taste, sight, equilibrium. & hearing) iv. Secretory: glandular c. Specializations: i. Movement of fluids: over surface (protection, lubrication) or through tissue (control permeability) ii. Production of secretions: physical protection (mucus) or as messengers (hormones) d. Anatomy (apical vs. basolateral) Anatomy & Physiology I BIOL 2001 C Ibanez i. Apical: 1. microvilli: increased surface area therefore increased absorption or secretion (ex. digestive, urinary) 2. cilia: beat in a coordinated fashion-move stuff past the exterior of cell (ex. respiratory) ii. Basolateral: 1. Cellular organelles 2. Intercellular cement: proteoglycans 3. Cell junctions e. Epithelial tissue types are based on shape and number of layers i. Layers: 1. Simple - single layer; protected from environment 2. Stratified - multiple layers; take a lot of abuse 3. Pseudostratified (pseudo = fake) – appears like multiple layers because nuclei all over the place, but only one layer 4. Transitional – i.e., urinary bladder: full bladder looks like simple epithelium, empty bladder, looks like stratified epithelium ii. Shape: 1. Squamous (squam = scale) – flat; more surface area than volume 2. Cuboidal - more volume than surface area 3. Columnar - even more volume compared to surface area iii. Modifications: 1. Microvilli – to increase surface area Anatomy & Physiology I BIOL 2001 C Ibanez 2. Cilia - for coordinated movement of stuff over the cell surface 3. Goblet cells - secrete mucus 4. Keratin – waterproofing f. Epithelial Tissue Types i. Simple squamous - in protected areas; function = diffusion across cell (i.e., kidneys, lungs) or lining body cavities & interior of blood vessels ii. Stratified squamous – (i.e., esophagus & skin) 1. On exterior - keratinized for reduction of water loss 2. On interior - not keratinized, moist 3. Division takes place at basement membrane and move upward- move away from blood supply = cell death iii. Simple cuboidal - absorption or secretion (i.e., kidney) 1. Usually have microvilli iv. Stratified cuboidal – rare; (i.e., ducts of sweat & mammary glands) v. Transitional – rare; changes shape to allow for expansion & recoil after stretching (i.e., urinary bladder) vi. Simple columnar - absorption or secretion 1. usually have microvilli & goblet cells (i.e., digestive tract) vii. Pseudostratified - absorption or secretion 1. May have cilia and usually have goblet cells (i.e., respiratory system & male reproductive system) viii. Stratified columnar - absorption or secretion; rare (i.e. salivary duct) Anatomy & Physiology I BIOL 2001 C Ibanez g. Glandular Epithelium: derived from epithelial tissues; produces a secretion i. Exocrine Glands: empty via ducts 1. Merocrine - secretions exit the cell via exocytosis (i.e., sweat gland) 2. Apocrine - form buds of the membrane which break off into the duct, losing part of the cellular membrane in the process (i.e., mammary glands) 3. Holocrine - cellular membrane ruptures to release its product into the duct (i.e., sebaceous glands) 3. Connective Tissue a. Functions: bind structures, transport fluids, framework, support, filler, store fat, produce blood & immune cells b. Cells are farther apart than in epithelial tissue c. Defining characteristic: cells in an extracellular matrix; matrix composed of fibers (collagen, elastic & reticular) and ground substance (solid, gel, or liquid) d. Classification i. Connective Tissue Proper 1. Cell types a. Fibroblasts - always present i. Secrete hyaluronic acid and proteins Anatomy & Physiology I BIOL 2001 C Ibanez ii. Secrete collagen fibers (protein is long, straight, unbranched, wound together like rope → flexible but strong) iii. Secretes reticular fibers (same protein as collagen, but thinner and branched → resist forces from all directions) iv. Secrete elastic fibers (elastin is a protein that is branched and complex → very elastic but not very strong) b. Fibrocytes - derived from fibroblasts; function = maintain fibers c. Macrophages - scavenge pathogens, signal other macrophages to attack; fixed and free populations d. Adipocytes - contain a single large drop of lipid; signet ring = organelles e. Mesenchymal - stem cells; with injury/infection, these guys divide and produce daughter cells that differentiate f. Melanocytes – produce pigment g. Mast cells - release histamine (inflammation) and heparin (increase blood fluidity) after injury/infection h. Lymphocytes - migrate to tissue damage 2. Tissue types a. Loose: packing material; cushion & support; energy storage i. Areolar 1. Loose organization 2. Distorts without damage 3. Very vascular; all cell and fiber types present ii. Adipose 1. Padding, insulation, energy storage 2. White fat: adult; few blood vessels 3. Brown fat: babies/young children; very vascular; lots of mitochondria iii. Reticular 1. Lots of reticular fibers 2. Supports functional cell of organ they are in [liver, kidney, spleen] Anatomy & Physiology I BIOL 2001 C Ibanez b. Dense: mostly fibers i. Regular white 1. Collagen = main fiber type, run parallel-same direction as force applied to them (STRONG) 2. i.e., Tendons, ligaments & aponeuroses (flat sheet) ii. Regular yellow 1. Collagen + elastin fibers; stabilization & cushion (i.e., ligaments between vertebrae) c. Fluid i. Blood 1. Cells: Red blood cells (erythrocytes), White blood cells (leukocytes), platelets (cell fragments) 2. Ground substance: serum + clotting factors = plasma ii. Lymph: recirculates fluid; contains 99% of lymphocytes d. Supporting i. Cartilage (chondro = cartilage) 1. Matrix: firm gel; polysaccharide derivatives chondroitin sulfates + proteins form proteoglycans 2. Cells: chondrocytes live in chambers called lacunae 3. No blood or lymph vessels or nerves; diffusion is used for exchange = slow healing 4. Surrounded by perichondrium - outer layer for strength and inner layer for growth & repair 5. Types of Cartilage: a. Hyaline: most common, lots of collagen; surrounded by dense perichondrium b. Elastic: lots of elastin c. Fibrous: mostly fiber, very little matrix; VERY tough - prevents bone to bone injury; between spinal vertebrae, pubic bones; heals very poorly Anatomy & Physiology I BIOL 2001 C Ibanez ii. Bone (osteo = bone) 1. Matrix: 2/3 = Calcium salts; lots of collagen; little ground substance; rigid and strong 2. Functional unit = osteon 3. Osteocytes: cells in lacunae, surrounded by matrix 4. Matrix laid down in lamellae (concentric circles around central canal with blood vessel = good blood supply = heal fast 5. Lacunae connected by canaliculi 6. Surrounded by periosteum: outer = fibrous; inner = cellular (repair, growth) 7. Osteoblast: cells that BUILD bone 8. Osteoclast: cells that CHEW UP bone 4. Membranes: barriers, composed of several tissue types a. Mucous: open to outside; secrete mucus; made of epithelium with goblet cells and lamina propria (connective tissue) b. Serous: lack outside exposure; act as linings; made of simple squamous and thin connective tissue; secrete serous fluid; double layered with liquid between which allows organs to slide by each other (surrounds heart, lungs, intestines) i. Layer next to organ = visceral ii. Layer next to cavity = parietal (pleura, peritoneum, pericardium) c. Synovial: inner lining of joints, ends of bones; made of fibrous connective tissue over loose connective tissue; secrete synovial fluid d. Cutaneous = skin (integument) Anatomy & Physiology I BIOL 2001 C Ibanez 5. Abnormal tissue growth patterns a. Hyperplasia = too many cells b. Hypoplasia = not enough cells c. Metaplasia = normal tissue, wrong location d. Dysplasia = pre-cancerous e. Neoplasia = new growth of abnormal cells i. Benign = an abnormal but noncancerous collection of cells ii. Malignant = cancerous