Homeostasis Exam Review - Homeostasis Exam Review...

Homeostasis Exam Review
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Unformatted text preview: 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*** • HUNTINGTON’S 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...
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