Medical Sciences 3999A/B/Y Lecture 6: (HSTL 1102 - Block-1)
2 Feb 2020
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Lecture 6 - cell injury, adaptations & cell death. Causes: deprivation of physical or chemical agents, exposure to infectious agents, immunologic reactions, genetic or nutritional imbalance. Morphologic alterations: necrosis vs. apoptosis; reversible vs. irreversible. Continuously dividing cells (labile) --> always in cell cycle throughout life; replaces cells that are continuously destroyed; can undergo hyperplasia or hypoplasia. Surface epithelia: stratified squamous in skin, oral cavity, etc. Non-dividing cells (permanent) --> enters g0 and remains that way; only hypertrophy or atrophy. Quiescent cells (stable) --> may enter g0 but can reactivate proliferation; neither cycling or dying. Hormonal: proliferation of glandular epithelium of female breast at puberty and during pregnancy (uterus as well), usually accompanied by hypertrophy. Compensatory: can occur in quiescent cells such as liver regeneration after partial hepatectomy or to accommodate increased enzyme synthesis. Pathologic: occurs in cells capable of replication; due to excess hormones or growth factors; cancer risk increased. Abnormal menstrual bleeding: disturbance between estrogen and progesterone.
