Chapter 04 APR Enhanced Lecture Slides See separate PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes and animations. 1-1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 4 Histology: The Study of Tissues 4-2 4.1 Tissues and Histology • Tissue classification based on structure of cells, composition of noncellular extracellular matrix, and cell function – Epithelial – Connective – Muscle – Nervous • Histology: Microscopic Study of Tissues – Biopsy: removal of tissues for diagnostic purposes – Autopsy: examination of organs of a dead body to determine cause of death 4-3 Epithelial Tissue Connective Tissue Muscular Tissue Nervous Tissue 4-4 4.2 Embryonic Tissue • Germ layers – Endoderm • Inner layer • Forms lining of digestive tract and derivatives – Mesoderm • Middle layer • Forms tissues as such muscle, bone, blood vessels – Ectoderm • Outer layer • Forms skin and neuroectoderm 4-5 4.3 Epithelial Tissue • Consists almost entirely of Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. cells Free surface • Covers body surfaces and Lung Pleura Epithelial cells with little extracellular forms glands matrix – Outside surface of the body LM 640x Surface view – Lining of digestive, respiratory Nucleus and urogenital systems Basement membrane – Heart and blood vessels Connective tissue Capillary – Linings of many body cavities • Has free, basal, and lateral LM 640x Cross-sectional view surfaces b: © Victor Eroschenko; c: © Ed Reschke • Basement membrane • Specialized cell contacts • Avascular • Regenerate 4-6 Basement Membrane • Extracellular: formed by secretions of both epithelium and connective tissue. Acellular “glue” – Attachment to C.T. – Guides cell migration during tissue repair – Acts as a filter in the nephron of the kidney – Not every epithelium has a basement membrane associated with it 4-7 Functions of Epithelial Tissue • Protecting underlying structures; e.g., epithelium lining the mouth • Acting as barriers; e.g., skin • Permitting the passage of substances; e.g., nephrons in kidney • Secreting substances; e.g., pancreas • Absorbing substances; e.g., lining of small intestine 4-8 Classification of Epithelium • Number of layers of cells – Simple- one layer of cells. Each extends from basement membrane to the free surface – Stratified- more than one layer. Shape of cells of the apical layer used to name the tissue. Includes transitional epithelium where the apical cell layers change shape depending upon distention of the organ which the tissue lines – Pseudostratified- tissue appears to be stratified, but all cells contact basement membrane so it is in fact simple • Shape of cells – Squamous- flat, scale-like – Cuboidal- about equal in height and width – Columnar- taller than wide 4-9 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. TABLE 4.1 Classification of Epithelium Number of Layers or Category Shape of Cells Simple (single layer of cells) Squamous Cuboidal Columnar Stratified (more than one layer of cells) Squamous Nonkeratinized (moist) Keratinized Cuboidal (very rare) Columnar (very rare) Pseudostratified (modification of Columnar simple epithelium) Transitional (modification of Roughly cuboidal to columnar stratified epithelium) when not stretched and squamouslike when stretched 4-10 Functional Characteristics • Simple: allows diffusion of gases, filtration of blood, secretion, absorption • Stratified: protection, particularly against abrasion • Squamous: allows diffusion or acts as filter • Cuboidal and columnar: secretion or absorption. May include goblet cells that produce and secrete mucus. 4-11 Free Surfaces Free surfaces of epithelium • Smooth: reduce friction • Microvilli: increase surface area for absorption or secretion – Stereocilia: elongated microvilli for sensation and absorption • Cilia: move materials across the surface • Folds: in transitional epithelium where organ must be able to change shape. Urinary system. 4-12 Simple Squamous Epithelium • Structure: single layer of flat cells • Location: simple squamous- lining of blood and lymphatic vessels (endothelium) and small ducts, alveoli of the lungs, loop of Henle in kidney tubules, lining of serous membranes (mesothelium) and inner surface of the eardrum. • Functions: diffusion, filtration, some protection against friction, secretion, absorption. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. TABLE 4.2 Simple Epithelium (a) Simple Squamous Epithelium Structure: Single layer of flat, often Function: Diffusion, filtration, Location: Lining of blood vessels hexagonal cells; the nuclei appear some secretion, and some and the heart, lymphatic vessels Kidney as bumps when viewed as a cross protection against friction (endothelium) and small ducts, section because the cells are so flat alveoli of the lungs, portions of the kidney tubules, lining of serous membranes (mesothelium) of the body cavities (pleural, pericardial, peritoneal), and inner surface of the tympanic membranes Free surface Nucleus Basement membrane Simple squamous epithelial cell 4-13 LM 640x © Dr. Fred Hossler/Visuals Unlimited Simple Squamous Epithelium Simple Squamous squamous cell epithelium Loose Nucleus of connective squamous cell tissue Simple Cuboidal Epithelium • Locations: Kidney tubules, glands and their ducts, choroid plexus of the brain, lining of terminal bronchioles of the lungs, and surface of the ovaries. • Structure: single layer of cube-shaped cells; some types have microvilli (kidney tubules) or cilia (terminal bronchioles of the lungs) • Functions: – Secretion and absorption in the kidney – Secretion in glands and choroid plexus – Movement of mucus out of the terminal bronchioles by ciliated cells. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. TABLE 4.2 Simple Epithelium (b) Simple Cuboidal Epithelium Structure: Single layer of cube- Function: Secretion and absorption Location: Kidney tubules, glands shaped cells; some cells have by cells of the kidney tubules; and their ducts, choroid plexuses Kidney microvilli (kidney tubules) or cilia secretion by cells of glands and of the brain, lining of terminal (terminal bronchioles of the lungs) choroid plexuses; movement of bronchioles of the lungs, surfaces particles embedded in mucus of the ovaries out of the terminal bronchioles by ciliated cells Free surface Nucleus Simple cuboidal epithelial cell Basement membrane 4-15 LM 640x © Victor Eroschenko Simple Cuboidal Epithelium Simple cuboidal Cuboidal cell epithelium Lumen of Nucleus of cuboidal tubule cell Simple Columnar Epithelium • Location. Glands and some ducts, bronchioles of lungs, auditory tubes, uterus, uterine tubes, stomach, intestines, gallbladder, bile ducts and ventricles of the brain. • Structure: single layer of tall, narrow cells. Some have cilia (bronchioles of lungs, auditory tubes, uterine tubes, and uterus) or microvilli (intestine). • Functions: – Movement of particles out of the bronchioles by ciliated cells – Aids in the movement of oocytes through the uterine tubes by ciliated cells – Secretion by glands of the stomach and the intestine – Absorption by cells of the intestine. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. TABLE 4.2 Simple Epithelium—Continued (c) Simple Columnar Epithelium Structure: Single layer of tall, Function: Movement of particles Location: Glands and some ducts, narrow cells; some cells have cilia out of the bronchioles of the lungs bronchioles of the lungs, auditory Lining of (bronchioles of lungs, auditory by ciliated cells; partially responsible tubes, uterus, uterine tubes, stomach and tubes, uterine tubes, and uterus) for the movement of oocytes through stomach, intestines, gallbladder, intestines or microvilli (intestines) the uterine tubes by ciliated cells; bile ducts, ventricles of the brain secretion by cells of the glands, the stomach, and the intestines; absorption by cells of the small and large intestines Free surface Goblet cell containing mucus Nucleus Simple columnar epithelial cell 4-17 Basement LM 640x membrane © Victor Eroschenko Simple Columnar Epithelium (Ciliated) Simple columnar Basement membrane epithelium (ciliated) Simple columnar Lamina propria cell (ciliated) Lumen of uterine tube Cilia Simple Columnar Epithelium (nonciliated) Simple columnar Goblet cell epithelium Simple columnar cell Lumen of jejenum Microvilli (brush border) Lamina propria Stratified Squamous Epithelium • Locations: – Moist- mouth, throat, larynx, esophagus, anus, vagina, inferior urethra, and cornea – Keratinized- skin • Structure: multiple layers of cells that are cuboidal in the basal layer and progressively flatten toward the surface. In moist, surface cells retain a nucleus and cytoplasm. In keratinized, surface cells are dead. • Functions: protection against abrasion, caustic chemicals, water loss, and infection. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. TABLE 4.3 Stratified Epithelium (a) Stratified Squamous Epithelium Structure: Multiple layers of cells that Function: Protection against Location: Keratinized—primarily In Skin are cube-shaped in the basal layer and abrasion, a barrier against the skin; nonkeratinized—mouth, progressively flattened toward the surface; infection, reduction of water throat, larynx, esophagus, anus, Cornea the epithelium