Histology of Epithelium - Dr Muhammad Ali Rabbani - Medicose Academics
Join Dr. Muhammad Ali Rabbani, Assistant Professor of Anatomy, as he navigates through the intricate world of epithelial tissues in histology. Epithelium, comprised of closely aggregated polyhedral cells, forms cellular sheets that line organ cavities and cover body surfaces. Explore the diverse types of epithelium, their structural characteristics, and physiological functions in this enlightening session. 🔬 Key Topics Covered: - Definition and Classification: Understand the fundamental properties of epithelium and classify its various types based on structure and function. - Microscopic Examination: Learn to identify different types of simple epithelium under the microscope and sketch their histological diagrams. - Physiological Functions: Explore the principal functions of epithelial tissues, including covering, lining, protection, absorption, and secretion. 🎓 Learning Objectives: By the end of this lecture, students will: - Define epithelium and distinguish between its basic types. - Identify the histological features of simple epithelium and provide examples of each type. - Comprehend the structural components and physiological roles of the basement membrane. - Differentiate between surface epithelium and glandular epithelium. - Understand the classification, structure, and mode of secretion of glandular epithelium. 💡 Medical Applications: - Gain insights into the clinical relevance of epithelial tissues in understanding pathological conditions and disease mechanisms. - Appreciate the significance of glandular epithelium in various organ systems and secretory functions. 🔍 Connect with Dr. Muhammad Ali Rabbani to delve deeper into the histology of epithelium!🔍 Learning Resources: For additional educational content and resources, visit our website: [www.medicoseacademics.com](www.medicoseacademics.com). For inquiries, contact us at [info@medicoseacademics.com](mailto:info@medicoseacademics.com) or +92 310 7990649. 🔗 Stay Connected! Explore our content on YouTube: [Medicose Academics YouTube Channel](https://www.youtube.com/@MedicoseAcademics) Follow us on Facebook: [Medicose Academics Facebook Page](https://www.facebook.com/medicoseacademics) Connect on Instagram: [Medicose Academics Instagram](https://www.instagram.com/medicoseacademics) 🔬 Embark on a Journey through Epithelial Histology with Dr. Muhammad Ali Rabbani! 🔬 --- Tags Histology, Epithelium, Dr. Muhammad Ali Rabbani, Anatomy Lecture, Medical Education, Simple Epithelium, Basement Membrane, Glandular Epithelium, Exocrine Glands, Endocrine Glands, Paracrine Glands, Unicellular Gland, Multicellular Gland, Merocrine Gland, Apocrine Gland, Holocrine Gland, Serous Gland, Mucous Gland, Mixed Gland, Medicose Academics.
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Histology of Epithelium - Dr Muhammad Ali Rabbani - Medicose Academics
- 1. info@medicoseacademics.com 0310-7990649 Histology of Epithelium Dr. Muhammad Ali Rabbani Asst. Professor Anatomy MBBS (NMC, Multan) FCPS (Anatomy) CHPE (Certificate in Health Professional Education) DHPE (Diploma in Health Professional Education) MBA (Masters of Business Administration) MPH (Masters of Public Health)
- 2. info@medicoseacademics.com 0310-7990649 Learning Objectives By the end of this session students should be able to • Define epithelium and classify various types of epithelium • Identify various types of simple epitheliums under microscope and draw their histological diagrams • Enumerate the examples of each type of simple epithelium
- 4. info@medicoseacademics.com 0310-7990649 Epithelium Epithelial tissues are composed of closely aggregated polyhedral cells adhering strongly to one another and to a thin layer of ECM, forming cellular sheets that line the cavities of organs and cover the body surface
- 5. info@medicoseacademics.com 0310-7990649 Principle Functions • Covering, lining, and protecting • Absorption • Secretion
- 6. info@medicoseacademics.com 0310-7990649 Characteristics • Shape & dimensions • Shape of nucleus • Number of layers • Adjacent connective tissue • Lamina propria • Papilla • Polarity of Epithelial Cells
- 7. info@medicoseacademics.com 0310-7990649 Basement Membrane • The basal surface of all epithelia rests on a thin extracellular, felt-like sheet of macromolecules referred to as the basement membrane • Semi-permeable
- 8. info@medicoseacademics.com 0310-7990649 Basement Membrane Structure • Basal Lamina • Lamina Densa • Lamina rara • Reticular Lamina • Structures forming Basal Lamina • Type IV collagen • Laminin • Nidogen & Perlecan • Structures forming reticular lamina • Type III & Type VII collagen
- 9. info@medicoseacademics.com 0310-7990649 Basement Membrane Functions • Filter • Structural Support • Attach epithelium to underlying connective tissue • Organize integrins → maintain cell polarity • Localize endocytosis, signal transduction etc • Mediate cell-to-cell interactions • Scaffold for repair
- 12. info@medicoseacademics.com 0310-7990649 a) lining the thin renal loops of Henle b) covering the outer wall of the intestine c) lining the inner surface of the cornea 12
- 15. info@medicoseacademics.com 0310-7990649 a) a renal collecting tubule b) a large thyroid follicle c) the thick mesothelium covering an ovary Simple cuboidal epithelium. 15
- 18. info@medicoseacademics.com 0310-7990649 a) renal collecting duct b) the oviduct lining, with both secretory and ciliated cells c) the lining of the gall bladder Simple columnar epithelium 18
- 20. info@medicoseacademics.com 0310-7990649 Pseudo stratified epithelium • Pseudostratified epithelium appears stratified, although some of the cells do not reach the free surface; all rest on the basement membrane • A good example of pseudostratified columnar epithelium is that lining the upper respiratory tract, where the cells are also heavily ciliated. 20
- 27. info@medicoseacademics.com 0310-7990649 Learning objectives • Define glandular epithelium and explain with examples • Differentiate the structure between serous and mucus secreting glands • Identify and draw histological sections of different types of glandular epithelium with eosin and hematoxylin 27
- 28. info@medicoseacademics.com 0310-7990649 A gland is an organ of secretion made of specialized secretory cells derived from surface epithelium on which it opens 28
- 29. info@medicoseacademics.com 0310-7990649 General Features • Glands can be present as discrete organs or in the layers of viscera. • The secretory cells of the glands form functional units called secretory end pieces, which are either flask shaped (acini) or cylindrical in shape (tubules). • It is epithelial in origin. • The fluid secreted by the gland contains enzymes, hormones, mucus or fat 29
- 31. info@medicoseacademics.com 0310-7990649 • The secretory end pieces of some exocrine glands are surrounded by star-shaped contractile cells that lie between the secretory cells and the basement membrane. • They are called myoepithelial cells as they share characteristics of both epithelial and muscle cells 31
- 33. info@medicoseacademics.com 0310-7990649 Classification Based on the site of secretion 1. Exocrine gland: secretes its products onto a surface through ducts, e.g. salivary glands. 2. Endocrine gland: secretes its products into the bloodstream, e.g. thyroid glands. 3. Paracrine gland: secretes its products into the local extracellular space affecting the surrounding cells, e.g enteroendocrine cells of gastrointestinal tract (GIT) 33
- 35. info@medicoseacademics.com 0310-7990649 Based on the number of cells 1. Unicellular gland: composed of a single cell, e.g. goblet cells in the respiratory and intestinal tracts. 2. Multicellular gland : composed of many cells, e.g. all glands other than goblet cells 35
- 37. info@medicoseacademics.com 0310-7990649 Based on the number of ducts and shape of secretory end piece 1. Simple gland: has one duct 2. Compound gland: has minor and major ducts 37
- 40. info@medicoseacademics.com 0310-7990649 Based on the mode of secretion 1. Merocrine gland: Secretory cells release their contents by exocytosis (no loss of cytoplasm), e.g. most of the compound glands. 2. Apocrine gland: Apical part of the cytoplasm of the secretory cells is lost in the process of secretion (partial loss of cytoplasm), e.g. lactating mammary gland, sweat gland in the axilla and external genitalia. 3. Holocrine gland: Secretory cells burst out pouring their contents, resulting in the death of the cells (complete loss of cytoplasm), e.g. sebaceous gland, tarsal gland 40
- 43. info@medicoseacademics.com 0310-7990649 Based on the nature of secretion 1. Serous gland: Parotid salivary gland 2. Mucous gland: sublingual salivary gland 3. Mixed gland (seromucous): submandibular salivary gland 43