HMB322H1 Lecture Notes - Lecture 1: Stratum Spinosum, Stratified Squamous Epithelium, Basal-Cell Carcinoma
Document Summary
Basal cell carcinoma: most common, from cells of stratum basale and invades dermis: treated by surgical removal/radiation. Squamous cell carcinoma: 2nd most common, from keratinocytes in stratum spinosum: can metastasize to lymph nodes and become lethal if untreated. Integumentary system: skin system: useful for protection, excretion, temperature maintenance, nutrient storage, used for vitamin d3 synthesis, sensory detection, bacteria on skin easier to grow, clone, genotype. Stratum corneum: dead cells with hard protein envelope: contain keratin, surrounded by intercellular lipids, up to 30 layers of dead scaled keratinized cells, surface cells flake off/exfoliate. Stratum lucidum: dead cells containing dispersed keratohyalin, only present in thick skin: thin translucent zone, keratinocytes packed with keratin precursor eleidin related to keratohyalin, doesn"t stain well, cells completely agranular, lack organelles. Melanocytes: vesicles (eumelanosomes/phaeomelanosomes from premelanosome) exit cell: melanin isoforms derived from tyrosine, melanosomes transported by both anterograde (kinesin)/retrograde (dynein, epidermis contains variable quantities of melanin and carotene pigment.
