Medical Sciences 3999A/B/Y Lecture Notes - Lecture 8: Stratified Squamous Epithelium, Renal Calyx, Renal Corpuscle
2 Feb 2020
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Shapes of the cells a. b. c. d. Squamous - allows for rapid movement of substances. Cuboidal - secretion or absorption; may or may not be ciliated. Columnar - specialized for secretion and absorption; often have cilia or microvilli. Transitional - able to change from cuboidal to flat and reverse (i. e. bladder) Arrangement of cells in layers a. b. c. Composed of a single layer of flattened cells. Cells fit closely together --> thin and smooth membrane. Heart, blood vessels and lymph vessels = endothelium. Epithelium lining the pleural, pericardial and peritoneal cavities is called mesothelium. Composed of a number of layers of cells of different shapes, representing newly formed mature cells. In deeper layers, cells are mainly columnar and grow towards the surface, then become flattened and shed. Surface layer: dead epithelial cells with keratin --> shed --> replaced from below. Tough, relatively waterproof --> prevents drying of the live cells underneath.
