1-13 (cellular org and injury)

1-13 (cellular org and injury) - Cellular Organization,...

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Unformatted text preview: Cellular Organization, Injury Cellular and Adaptation and NURS 216 Spring 2010 Sabra Smith, MS, RN Objectives Discuss four types of body tissues, understand functions Understand cellular responses to stress Differentiate causes of cellular injury Understand steps of cellular injury and death Discuss types of necrosis Epithelial Tissue Covering and glandular epithelium • Covering lines body organs, glandular forms the secreting portions of glands • Cells are closely packed, tight junctions • Arranged in continuous sheets, single or multiple layers • Avascular but has nervous supply Epithelium • Attached to underlying connective tissue by the basement membrane Types of Epithelia Form follows function Simple squamous Simple Cuboidal • minimal barrier to diffusion of gases or electrolytes • Ex. Alveoli, endothelium of capillaries and kidneys • Thicker than squamous, less diffusion • usually for secreting substances in glands and absorption Form follows function Simple Columnar Stratified epithelium • • • May contain microvilli – increase surface area (GI tract) • May contain cilia – tiny hairs (upper respiratory, fallopian tubes • thicker for less passive diffusion for areas where there is a lot of wear and tear mouth, skin Glandular Epithelium Glands may be one cell or a group Exocrine – glands that secrete substance into a duct, which then empties at the surface Endocrine – no ducts, diffuse directly out into the ECF and into the blood Examples? Connective Tissue Consists of cells and extracellular matrix Matrix includes fibers, ground substance, and fluid All types except cartilage have nervous and blood supply Content of the matrix causes differences in types of connective tissue Connective Tissue Connective Tissue Cells Fibroblasts – secrete the matrix Macrophages – destroy bacteria Plasma cells – secrete antibodies Mast cells – alongside blood vessels, secrete histamine Adipocytes White blood cells The Matrix Ground substance – made up of many chemicals that lubricate, support and connect cells Fibers – collagen, elastin Collagen is the most abundant, very strong yet flexible, found in cartilage, tendons, ligaments, and bones Connective Tissue Proper Loose – the fibers are loosely woven, contain all the types of cells. Fills intercellular spaces Reticular –provides support for capillaries, nerves, muscle cells Dense ­irregular: same components as loose connective tissue, but more collagen and fewer cells, elastic ­regular: lots of collagen, forms tendons and ligaments, strong in only one direction Specialized Connective Tissue Cartilage – very strong but flexible, gel­ like. No blood vessels. Bone – compact and dense. Matrix contains inorganic calcium salts. Can absorb heavy metals. Blood – plasma serves as a liquid matrix Adipose tissue – energy storage, cushioning, insulation Muscle Tissue Skeletal – striated and voluntary Cardiac – striated and involuntary Smooth – nonstriated, involuntary • GI, bladder, blood vessels • For propulsion • • • • attached to bones aid in movement Contract the heart connected by intercalated discs Nervous Tissue Transmits electrical impulses Neurons: cell body, dendrites, axon Cellular Stress Cells adapt to internal and external changes Examples of adaptation: ­atrophy ­hypertrophy ­hyperplasia ­metaplasia ­dysplasia Atrophy A decrease in cell size Autophagy occurs Causes of atrophy • • • disuse denervation lack of endocrine stimulation • decreased nutrition • ischemia Hypertrophy Increase in cell size Physiologic causes Pathologic causes • exercise • Thickening of urinary bladder due to long continued obstruction • Myocardial hypertrophy • Enlarged kidney, if one removed – trying to compensate The Plasias Hyperplasia ­ increase in number of cells Metaplasia – change in type of cells Dysplasia – disorganized cell growth, strong predictor of cancer Types of Cellular Injury Deficiency of oxygen or other critical nutrient Physical Infectious agents Chemical agents Hypoxic Injury Hypoxia deprives cells of oxygen Oxidative metabolism is disrupted. ATP production slows and ceases Lactic acid production leads to acidosis Sodium/potassium pump halts Lysosomal membranes rupture Cell membrane ruptures Physical Injuries Blunt force Sharp force Temperature extremes Radiation Electricity Blunt and Sharp Forces Blunt – tissue is torn, sheared or crushed ­contusions, hematomas, abrasions, lacerations, fractures Sharp – incised wounds, stab wounds, puncture wounds Low Intensity Heat Injury Examples Sequelae • • • • • • partial thickness burns heat stroke vascular injury accelerated cell metabolism inactivates temperature sensitive enzymes disrupts cell membrane High Intensity Heat Injury Examples Sequelae • electrical burns • full thickness burns • coagulation of blood vessels • coagulation of proteins • Cell regeneration not possible Electrical ­longer duration more damaging, pathway through brain or heart more damaging, may have little surface damage but extensive internal damage Cold Injury Example: Frost bite Sequelae • • • • • • vasoconstriction decreased blood flow hypoxic tissue injury ice crystal formation capillary stasis thrombosis Electrical Burn Radiation Injury Ionizing radiation Nonionizing radiation • radiation energy above the visible ultraviolet range • radiation energy below the visible ultraviolet range Ionizing Radiation Examples Sequelae • • gamma rays X­rays • Ionization of molecules and atoms within cells by direct hit • Ionization of molecules and atoms within cells by free­radical formation • kill cell, cause mutations, or prevent replication Nonionizing Radiation Examples • • • Sequelae infrared light microwaves laser energy • vibrations and rotations of atoms and molecules • thermal injury Types of Tissue Epithelial – covers all body surfaces, lines organs, forms glands Connective – protects, binds, and supports organs, stores fat Muscle – skeletal, smooth, cardiac Nervous – central and peripheral Tissue Calcification Abnormal deposits of calcium and other minerals in tissues Metastatic – no tissue damage, but increased calcium salts in the blood leads to calcium deposits in tissues Dystrophic – injured or dead cells release calcium, which is deposited in surrounding tissue (atherosclerosis, healed TB lesions) Aortic Valve Calcification Normal aortic valve Steps of Cellular Injury Biochemical lesion – metabolic reactions are changed Accumulation of water – most common, cell loses ability to pump out sodium Accumulation of fat – most common in the liver Cell death – complete loss of function = necrosis Ischemia Critical lack of blood supply to an area Tissue is not yet dead Reversible IF blood supply is restored Most common cause of ischemia is atherosclerosis Symptoms • angina pectoris • intermittent claudication Infarction Death of tissue caused by lack of blood supply No going back! • Myocardial infarction (heart attack) Necrosis localized tissue death that occurs in groups of cells in response to disease or injury Types of Necrosis Coagulative – AKA gangrene, due to decreased blood supply, most common (dry, wet, gas) Liquefactive – enzymes liquefy tissue, usually in the brain Caseous – “cheesy” look because some cells remain undigested (TB) Gangrene Gangrene is an area of coagulative necrosis Usually caused by deprivation of blood supply Saprophytic bacteria grow over the dead tissue Dry Gangrene Characteristics Usually due to arterial occlusion with no interference of venous return Occurs in the extremities • tissue becomes dry, shrinks, wrinkles, and changes color to dark brown or black Dry Gangrene Dry Gangrene Wet Gangrene Characteristics • • • • • Usually due to interference with venous return, can occur after severe burns tissue is cold, swollen, and pulseless skin moist, black, and under tension blebs form on the surface liquefaction occurs foul odor (bacteria) Wet Gangrene Gas Gangrene The most deadly form of gangrene Occurs in wounds which are affected by anaerobic bacteria, which release gas and poisons into the body as cells are killed Symptoms: high fever, brown pus, and gas bubbles on the skin, spreads very quickly, and causes a rapid death What types of wounds would be likely to develop gas gangrene?? Gas Gangrene Fate of Necrotic Tissue Demolished and removed by phagocytes New tissue regenerates or scar forms Dead tissue may slough off May be encapsulated with fibrous connective tissue then calcified ...
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This note was uploaded on 02/15/2011 for the course NURS 216 taught by Professor Smith during the Spring '10 term at South Carolina.

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