University:
Texas A&M University
Course:
BIOL 319 | Integrated Human Anatomy and Physiology I
Academic year:

2024
Views:

58

Pages:

48
Author:

Apolenajz

EPITHELIUM AND GLANDS Objectives • Identify every epithelium present in any tissue section. • Differentiate between mucus and serous secreting epithelia. • Identify single-celled glands, endocrine glands and the various types of exocrine glands. • Detail the structure of the sebaceous gland. • Identify the different types of sweat glands and distinguish the duct from the secretory region. • Identify myoepithelial cells and know their function. ORIGIN AND DISTRIBUTION OF EPITHELIUM ECTODERM - EPIDERMIS OF SKIN AND EPITHELIUM OF CORNEA TOGETHER COVERS THE ENTIRE SURFACE OF THE BODY; SEBACEOUS AND MAMMARY GLANDS ECTODERM ENDODERM - ALIMENTARY TRACT, LIVER, PANCREAS, GASTRIC GLANDS, INTESTINAL GLANDS • ENDOCRINE GLANDS - LOSE CONNECTION WITH SURFACE MESODERM MESODERM • ENDOTHELIUM - LINING OF BLOOD VESSELS • MESOTHELIUM - LINING SEROUS CAVITIES ENDODERM Characteristics of epithelium • Classification by # of layers • Simple = single layer • Stratified = multiple, stacked layers • Pseudostratified = appears to be multiple layers, but all cells touch basement membrane (all cells do not necessarily reach lumen) • Classification by shape • Squamous = flat • Cuboidal = square • Columnar = column Laboratory Experience • Identify and characterize various types of epithelia • Recognize various glands and modes of secretion • Recognize gland associated structures/cells and differentiate glands from their ducts • Understand significance of cytological expression of epithelial cells with regard to function 053 Slide 93 Slide 35 Kidney (PAS/ hematoxylin) Periodic acid – Schiff • Used to visualize: glycogen, glycoproteins, and glycosaminoglycans • Steps in PAS staining 1. 2. Periodic acid oxidizes 1,2-glycols to aldehydes Schiff’s reagent colors the aldehyde groups (pink to magenta) Brush border Basement membrane The brush border is composed of numerous microvilli which function to increase surface area for absorption of nutrient material and fluid. The structure on the brush border that stains with periodic-acid Schiff (PAS) stain is the glycocalyx. EM 1 & 7 glycocalyx PAS staining Lipid in SER Observe various brush border - microvilli The brush border is composed of numerous microvilli of a uniform size projecting into a lumen. Each microvillus is composed of microfilaments (actin) surrounded by the cell membrane. EM 2 Stereocilia of the epididymis - long thin microvilli Stereocilia are very long, branched, non-motile microvilli of differing lengths that function in absorption from the lumen. EM 5 & 6 Observe cell junctions characteristic of epithelium SPECIALIZATION OF EPITHELIA MAINTAIN EXTENSIVE CONTACTS AMONG CELLS STRUCTURALLY AND FUNCTIONALLY POLARIZED JUNCTIONS ZONULA OCCLUDENS - TIGHT JUNCTION (BELT) ZONULA ADHERENS – ADHERING BELT DESMOSOME (MACULA ADHERENS) - SPOT ATTACHMENT GAP JUNCTIONS - COMMUNICATION Terminal bars Kidney (H&E) Simple squamous Simple squamous Simple cuboidal Simple cuboidal Thyroid gland (endocrine) Simple cuboidal epithelium Basement membrane SUMMARY OF TISSUE FEATURES OF EPITHELIUM • AVASCULAR • EXTRANEOUS CELLS • REGENERATION • MIGRATION SUMMARY OF TISSUE FEATURES OF EPITHELIUM • AVASCULAR • EXTRANEOUS CELLS • REGENERATION • MIGRATION • METAPLASIA • BASEMENT MEMBRANE SECRETION – ACTIVE PROCESS CONSUMING ENERGY EXOCRINE GLANDS - DELIVER THEIR SECRETION INTO DUCTS OPENING INTO EXTERNAL OR INTERNAL SURFACE ENDOCRINE GLANDS DUCTLESS, DELIVER THEIR SECRETIONS INTO THE LYMPH OR BLOOD STREAM PANCREAS PANCREAS has exocrine has endocrine EXOCRINE GLANDS DUCT • SIMPLE - UNBRANCHED DUCT • COMPOUND - BRANCHED DUCT SECRETORY PORTION • TUBULAR • COILED TUBULAR • BRANCHED TUBULAR • ALVEOLAR • BRANCHED ACINAR • TUBULOACINAR • TUBULOALVEOLAR MUCUS VS SEROUS TUBULAR COILED TUBULAR BRANCHED TUBULAR ALVEOLAR BRANCHED ACINAR TUBULOACINAR TUBULOALVEOLAR ACINUS = FUNCTIONAL UNIT SEROUS MUCOUS Mucous - Light staining Cytoplasm and dark, flattened nucleus at base of cell Serous – dark red staining cytoplasm and lighter, spherical nucleus Submandibular gland Simple columnar epithelia Stratified columnar epithelia Submandibular gland Serous cells Mucous cells Serous demilune The submandibular gland is a mixed (seromucous) gland whose mode of secretion is merocrine secretion = exocytosis without loss of cellular components MECHANISM FOR RELEASE OF SECRETORY PRODUCTS MEROCRINE SECRETION – EXOCYTOSIS W/O LOSS OF SURFACE MEMBRANE APOCRINE SECRETION – LOSS OF PART OF APICAL CYTOPLASM AND SOME PLASMA MEMBRANE HOLOCRINE SECRETION – RELEASE OF WHOLE cell CYTOCRINE SECRETION – MELANIN GRANULES TRANSFERRED FROM MELANOCYTE TO KERATINOCYTES MEROCRINE APOCRINE CYTOCRINE SECRETION - PASS MELANIN GRANULES FROM MELANOCYTES TO KERATINOCYTES Terminal Ileum Brush border composed of microvilli Microvilli are fingerlike projections that greatly increase the surface area of certain cells to help increase absorption. Microvilli are non-motile and are composed of a core of thin microfilaments called actin. Goblet cell releasing contents Simple columnar epithelium Trachea Goblet cell releasing contents Ciliated pseudostratified columnar epithelium with goblet cells Note the thick basement membrane of the respiratory pseudostratified columnar epithelium. The main function of cilia is to sweep or move fluids, cells, or particulate matter across cell surface in the lumen as to remove dust in the lungs. Microtubules of the axoneme are at the core of cilia and make them motile. Epididymis Pseudostratified columnar epithelium with stereocilia Microvilli: small, non-motile projections composed of thin microfilaments Stereocilia: long, non-motile projections (branched microvilli) composed of thin microfilaments Cilia: larger, long, motile projections composed of thick microtubules Urinary bladder Transitional epithelium Specialized “dome-shaped” cells Basal cells Ureter Transitional epithelium Stratified squamous epithelium: the protection epithelium • Keratinized stratified squamous (thick or thin) • Prevent dessication • Protect against abrasion • Prevent foreign invasion • Ex. Slide 29: Thick skin (ventral surface of finger) • Non-keratinized stratified squamous • Moist lubricated surface • Ex. Slide 52: Tongue Tongue Non-keratinized stratified squamous epithelium Mucous acini Serous acini Mucous cells stain light and serous cells stain dark. Esophagus Non-keratinized stratified squamous epithelium Thick skin (ventral surface of finger) Epidermis with keratinized stratified squamous epithelium Dermis Hypodermis The major function of this type of epithelium (thick skin) is for protection from mechanical stress, but it also prevents dehydration. Thick skin (ventral surface of finger) Keratinized stratified squamous epithelium Polyhedral cells Cuboidal cells of the stratum basale The cells in the stratum basale serve as stem cells for the epidermis, and their progeny differentiate as they move away from the base. Thick skin (ventral surface of finger) Duct of eccrine sweat gland with stratified cuboidal epithelium Eccrine sweat gland Myoepithelial cells Myoepithelial cells are eosinophilic because of the presence of a high density of contractile protein. These cells surround the gland like a net and expel glandular secretions upon contraction. Thin skin (scalp) Sebaceous glands The mode of secretion used by sebaceous glands is holocrine secretion Keratinized, stratified squamous epithelium Recto-anal junction Anus – stratified squamous Rectum - simple columnar epithelium Recto -anal junction Sebaceous glands Apocrine sweat gland Eccrine sweat gland GLANDS OF EPIDERMAL ORIGIN SWEAT GLANDS • ECCRINE - COMMON SWEAT GLAND LOCAL COOLING • APOCRINE AXILLARY REGION - FUNCTION IN ANIMALS, discharge in hair follicle Epithelial tissues of the body • Use table as guide • Generalizations • Entire GI system from gastro- esophageal junction to rectoanal junction is lined by simple columnar epithelium • Cilia is present in most respiratory passages EPITHELIA ARE SPECIALIZED FOR FUNCTIONS ABSORPTION - INTESTINE SECRETION - PANCREAS TRANSPORT - EYE, ENDOTHELIUM IN VESSELS EXCRETION - KIDNEY PROTECTION – AGAINST MECHANICAL DAMAGE AND DEHYDRATION SENSORY RECEPTION – PAIN TO AVOID INJURY, TASTE BUDS, OLFACTORY, ETC. CONTRACTION – MYOEPITHELIUM SURFACE SPECIALIZATIONS OF EPITHELIA MICROVILLI - INTESTINE ABSORPTIVE CELL CILIA - RESPIRATORY EPITHELIUM BASAL LAMINA – ALL EPITHELIUM INTERCELLULAR CANALICULUS – HEPATOCYTE SECRETORY CANALICULUS – GASTRIC PARIETAL CELL FLAGELLA SURFACE SPECIALIZATIONS OF EPITHELIA INTERCELLULAR CANALICULUS – HEPATOCYTE SURFACE SPECIALIZATIONS OF EPITHELIA SECRETORY CANALICULUS – GASTRIC PARIETAL CELL Clinical Correlation Normal larynx with ciliated pseudostratified columnar epithelium Abnormal larynx with stratified squamous epithelium

Epithelium and Glands

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