Histology L1

• Histology: form and function of the four basic tissues: Epithelia and glands, Connective tissue, Nervous tissue, Muscle tissue.
• Intracellular adhesion and other junctions: Tight junctions, Adherens junction, Desmosomes, Gap junctions, Hemidesmosomes.
• All epithelia rest on a basement membrane: E = epithelial cells, BL = basal lamina (part of) basement membrane, C = collagen (from connective tissues).
• Basement membrane: attachment / structural support, filtration, regulation cell division and differentiation of epithelial cells.
• Categorization of epithelia, based on layers: Single layered, Pseudostratified epithelium, Stratified (multi-layered), Keratinized, Non-keratinized.
• Simple squamous epithelium may vary with function of the organ they are found in.
• Glands: Unicellular, Multicellular, Where secretion is released: Exocrine, Endocrine.
• Exocrine vs endocrine development: multicellular exocrine glands morphology:
• Mechanisms: Merocrine secretion, Apocrine secretion, Holocrine secretion.
• Sweat glands: eccrine and ‘apocrine’: cooling down and signaling.
• Pancreas: heterocrine gland: exo- and endocrine gland.
• Exocrine pancreas: acinus cells secrete inactive zymogens, restricting protease activity to the duodenum.
• Endocrine pancreas: islets of Langerhans.
• Follicle cells: exocrine cells, absorbing cells, endocrine cells.
• Thyroid hormones: increase metabolic rate, regulate growth, regulate development and differentiation, stimulate metamorphosis.