Pathophysiology Exam 1 Study Guide Cellular And Tissue Function

Embryonic Origin of body tissues • A fertilized ovum develops into an embryo • Cells differentiate into 4 basic tissues, which include: the epithelium, muscle, connective and nervous tissue o The ectoderm develops into epithelium o The mesoderm develops into epithelium, muscle and connective tissue o The endoderm develops into nervous tissue • A cell is comprised of a plasma membrane, a nucleus (which contains DNA and RNA), and the cytoplasm which contains organelles such as: ribosomes, the endoplasmic reticulum, the golgi apparatus, mitochondrion, and lysosomes Cell metabolism • Energy metabolism is the process which converts carbohydrates, fats and proteins into energy needed for cell function • ATP is the major source of cellular energy • The 2 types of metabolism include: aerobic or anaerobic metabolism (which occurs in the absence of oxygen and results in lactic acid build up) Membrane transport mechanisms include: • diffusion, facilitated diffusion and active transport (which requires ATP and transport is directed against the concentration gradient) The normal cell responds to physiologic and pathologic stresses by adapting • Atrophy – decrease in cellular size o Ex. As we don’t use muscles, they shrink, including skeletal, cardiac, cerebral and secondary sex organs. Ex. atrophy can result due to prolonged bed use. • Hypertrophy – increase in cell size o Ex. The heart muscle cells when stressed will increase in size and won’t be as effective, commonly seen in ventricular hypertrophy. • Hyperplasia – increase in the number of cells; it is a compensatory mechanism that enables organs to regenerate o Ex. With pregnancy, hormonal hyperplasia enables the uterus to enlarge. Also seen in breastfeeding. • Metaplasia – replacement of one mature cell by another; due to chronic inflammation o Ex. Lung cells of smokers! However, the replaced tissue will not work as effective as normal tissue. Bronchial metaplasia can be reversed if the inducing stimulus, usually cigarette smoking is removed. With prolonged exposure to the inducing stimulus, however, dysplasia and cancerous transformation can occur. • Dysplasia – abnormal changes in the size, shape and organization of a mature cell o Ex. This mechanism is a precursor of cancer and is also due to chronic inflammation. A peptic ulcer for instance, causes cells to change and become cancerous. Benign vs. malignant neoplasms • Neoplasm – is altered cell differentiation and growth; an abnormal growth of tissue, which if it forms a mass, it is referred to as a tumor. A benign neoplasm is localized and does not spread or become cancerous. A malignant neoplasm does become cancerous and metastasizes. Cell injury and death is caused by: physical agents, radiation injury, chemical injury, biological injury or nutritional imbalances. Other mechanisms such as, free radical formation and hypoxia cause cell injury. • Hypoxia, or lack of sufficient oxygen within cells, is the single most common cause of cellular injury. Hypoxia can result from a reduced amount of oxygen in the air, loss of hemoglobin or decreased efficacy of hemoglobin, decreased production of RBCs, diseases of 2 the respiratory and CV systems and poisoning of the oxidative enzymes (cytochromes) within the cells. • If hypoxia becomes prolonged and cells begin to suffer, there is ischemia