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Homeostasis Exam Review 27/01/2008 14:34:00 Voluntary and Involuntary Homeostatic Mechanisms Voluntary Involuntary Close windows Shivering Turn up heat Vasoconstriction Increased water intake Renal absorption of water Atrophy: shrink in size Common in : o Skeletal muscle o Brain o Heart o Ovaries/testes as hormone production decreases Can be tied to physiologic disuse or decreased stimulation Causes: o Disuse bed rest, immobilization/cast, weightlessness (space travel) o Denervation nerve injury o Lack of endocrine stimulation decreased hormone stimulation Hypertrophy: increase in SIZE of cell Heart and kidneys most commonly affected Can be a normal variance or pathologic Physiologic: o Increased muscle size from exercise o Increased BP from exercise o Breast tissue during pregnancy Pathologic ventricular hypertrophy d/t hypertension Compensatory contralateral kidney size/function post nephrectomy Changes in Cell Number: o Increased # of cells (functional tissue) o Normal Liver regeneration Callus from repeated friction o Hormonal - breast & endometrium during pregnancy o Pathological goiter, abnormal endometrial proliferation Metaplasia: reversible replacement of one mature cell type by a less mature form of cell (closest to normal) Change is adaptive to environmental change Examples : o Bronchus of smoker o Oral mucosa of snuff users o Asbestos With chronic exposure, additional tissue change can occur Dysplasia: abnormal changes in size, shape and organization of normal cell Response to a stimulus NOT cancer but could progress Can regress after removal of stimulus Example Cervical tissue pap smear Anaplasia: cancer More primitive cell form Loss of differentiation Characteristic of malignant cells Autosomal Dominant Inheritance Affects homozygous & heterozygous ***Male and female offspring equally affected*** Each birth and independent event Rarely gene mutations can occur in families with no hx of disease ***NO carriers, if have trait then will show disease*** HUNTINGTONS DISEASE (chromosome 4) ACHONDROPLASIA NEUROFIBROMATOSIS Autosomal Codominant Inheritance Both normal and abnormal genes are expressed A & B blood type alleles can be transmitted as codominant traits SICKLE CELL DISEASE Autosomal Recessive Inheritance Diseases rare Numerous carriers Disease affects ONLY homozygotes 25% from 2 carriers will be affected Males & females equally affected CYSTIC FIBROSIS PHENYLKETONURIA (PKU) TAY-SACHS DISEASE... View Full Document

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