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Tissues Hierarchy of organization Atoms molecules cells TISSUES organs Organ systems organisms populations communities ecosystems biosphere Study of tissues = Histology Tissue types * Epithelial tissue Cover exposed surfaces (linings) both external and internal * Connective tissue Fills internal spaces Connects, supports, transports * Muscle tissue * Neural tissue movement Transmission of information Epithelial tissue Covering of all exposed surfaces CharacteristicsPolarity (apical and basal surfaces) Attachment (basement membrane) Tightly bound cells Avascular (nutrients via diffusion) Regeneration (actively in 24° cell cycle) Epithelial tissue Functions Physical protection Control permeability Sensation Secretion (glands) Exocrine = secretions onto epithelial surface Endocrine = secretions released to surrounding fluids Cilia and microvilli Epithelial connections Special proteins connect cells to each other at Tight junctions Apical In-between epi cells Keeps fluids from leaking between cells Desmosomes Connect cell to cell Gap junctions Interlock cells Attach to cytoskeleton Provide channels Between cells Basement membrane Holds epithelium to rest of body Proteins and glycoproteins from basal lamina and reticular lamina Epithelium continuously replaced by stem cells near basement layer Epithelium classification Simple epithelial tissue = single layer of cells Stratified epithelial tissue = stacked cells Cell shapes Squamous cuboidal Box shaped Flat Ducts Irregular shape Lining ventral body cavity glands Mouth Kidney tubules Blood vessels Where thin/permeable required columnar Long and narrow (simple only) Secretion absorption Cilia and microvilli Small intestine Nasal cavity Epithelium and glands Endocrine glands = to follow Exocrine glands = secrete into ducts Merocrine = secretion via exocytosis mucous Apocrine = secretion with loss of cytoplasm milk Holocrine = secretion with loss of cell sebum Epithelial secretions Serous secretion = watery with enzymes parotid salivary glands Mucous secretions = watery with glycoproteins for lubrication sublingual salivary glands Mixed secretion = both submandibular salivary glands Connective tissue Connect, support, transport Bone, fat, blood Characteristics With specialized cells With extracellular proteins With ground substance Proteins + ground substance = extracellular matrix Connective tissue Functions Structural framework Transport (fluids) Protection (cushion) Support/connect tissues Store energy Defense Connective tissue classification Connective tissue proper Cellular and matrix content varied Adipose, tendons May be loose or dense Fluid connective tissue Distinct cells in watery matrix Blood, lymph Supporting connective tissue Cartilage, bone Connective tissue PROPER The CELLS Fibroblasts Always present, secrete hyaluronan to make ground substance, viscous Macrophages WBCs that engulf pathogens Adipocytes Fat cells Mesenchymal cells Stem cells that produce macrophages, fibroblasts and other connective tissue cells Melanocytes Synthesize/store pigment Mast cells Release histamine and heparin in response to injury Lymphocytes WBCs involved in immune response Microphages WBCs involved in protection from pathogens Connective tissue PROPER The FIBERS Collagen Long, straight, unbranched tendons, ligaments Reticular fibers Like collagen but branched Stabilize position of cells Elastin fibers Thin, branched Return to original shape The GROUND SUBSTANCE Clear, colorless, viscous Loose connective tissue Adipose, reticular Dense connective tissue Tendons, ligaments, surrounding organs FLUID connective tissue Blood Erythrocytes (RBCs) Hemoglobin ~45% blood volume Lymph Lymphocytes Immune system Leukocytes (WBCs) Immune system Platelets Blood clotting Plasma Watery matrix Interstitial fluid Watery matrix collected from surrounding cells SUPPORTING connective tissue Cartilage Chondrocytes produce matrix Avascular Perichondrium separates cartliage from other tissue Types of cartilage Hyaline Common Tightly packed collagen Ribs, sternum Nasal, end bones Elastic Elastic fibers Epiglottis, Middle ear, Pinna, larynx Fibrocartilage Interwoven collagen Durable Spinal vertabrae Pelvic bones SUPPORTING connective tissue Bone Osseous tissue Osteocytes in matrix with calcium salts Covered by periosteum More to follow with skeletal system Connective tissue Membranes Mucous membranes Line cavities that communicate with exterior Respiratory, digestive, urinary, reproductive Serous membranes Line divisions in ventral body cavity Pleural = pleural cavity Peritoneum = peritoneal cavity Pericardium = pericardial cavity Transudate = fluid on surface of serous membranes Connective tissue Membranes Cutaneous membrane = skin = covers surface of body Synovial membranes Capsule at articulations (joints) Loose collagen, proteoglycans, glycoproteins Full of synovial fluid Connective tissue layers Superficial fascia Subcutaneous/hypodermis Skin/underlying organs Deep fascia Deep connective tissue Organs/muscle Subserous fascia Between serous membrane and deep fascia Muscle tissue For MOVEMENT via contraction 3 types of muscle tissue Skeletal muscle Striated, multi nucleated voluntary movement Cardiac muscle Heart connected at intercalated discs Smooth muscle Nonstriated Involuntary movement MORE TO FOLLOW Muscular system Neural tissue Conduct electrical impulses Neurons = conduct nerve impulses Glial cells = support neurons MORE TO FOLLOW Nervous system Embryology Zygote undergoes cleavage morula BLASTULA (blastocyst) = hollow ball Gastrulation forms 3 germ layers Ectoderm, mesoderm, endoderm Become different tissues organ systems (page 1088-1089)
