Chapter 4 1 Introduction a General cellular responses to environmental changes injury i Reversible cell injury change back to original function state 1 mild short lived change 2 Cell returns to normal afterwards 3 Results in swelling or intracellular accumulations ii Cellular adaptation not considered irreversible 1 Sub lethal but persistent insult causes cell to adapt in structure function 2 Generally reversible 3 Results in atrophy hypertrophy hyperplasia metaplasia or dysplasia iii Irreversible cell injury Injury prolonged and severe 1 2 Overwhelms cell defenses 3 Results in apoptosis or necrosis 2 Reversible Cell Injury Hydropic Swelling doesn t work due to lack of energy a Usually first manifestation of reversible injury b Malfunction in Na K ATPase pump causes influx of Na into cell creating osmotic gradient that leads to excess water entry into the cell resulting in cell swelling Injuries causing energy loss will cause malfunction of ATPase pump c d Extracellular fluid 140 Na 4 or 5 K i Too much Na going into the cell too much H2O going into the cell 3 Reversible Cell Injury Hydropic Swelling a Microscopic large and pale cytoplasm dilated E R and mitochondria water filled vacuoles if severe b Macroscopic tissue swelling organ enlargement megaly i A Normal kidney cuboidal cells ii B Early renal ischemia surface blebs and cell swelling 4 Reversible Cell Injury Intracellular Accumulations a Cell injury from excess accumulations in cell due to toxicity immune response occupy space needed for other cell functions Inclusions classified as b i Normal substances fat glycogen proteins etc does not mean normal accumulation normal substance abnormally accumulating ii Abnormal substances byproducts of defective metabolism synthesis iii Pigments and non degradable products 1 Lipofuscin pigment normal substance accumulates to skin cells 5 Reversible Cell Injury Intracellular Accumulations to make color change damaging a Fatty liver intracellular lipid vacuoles Fat is normal substance Ex Binge drinking result stop drinking and liver returns to normal b Liver is common site of abnormal cell inclusions 6 Reversible Cell Injury Intracellular Accumulations a Lung silicosis silicon dust accumulation gray in the picture is the cellular 7 Cellular Adaptation Atrophy a without trophy size so atrophy means decreased a Decreased cell size and decrease in differentiated cell functions in order to minimize the cell s energy and nutrient consumption accumulations growth b General causes i Disuse immobilization ii Denervation heart brain kidneys lower leg iii iv Nutrient starvation v Ischemia blood flow perfusion hypoxia is oxygen flow Interruption of endocrine signals adrenals thyroid gonads dependent on trophic hormones vi Persistent cell injury vii Aging viii The picture shows atrophy the cells look the same as in same order and organization but the size is smaller 8 Cellular Adaptation Hypertrophy Increased cell mass and functional capacity in response to excess stimulation a b Can occur as i Physiological response skeletal muscle tissue exercise reproductive organs trophic hormones ii Pathophysiological response heart high blood pressure liver toxins iii Puberty pregnancy iv megaly enlarged organ 9 Cellular Adaptation Hypertrophy a A Left ventricular hypertrophy B Normal heart b You can tell its left ventricular hypertrophy because the RIGHT side of the heart is on the LEFT side of the picture the muscle around the ventricle is smaller and pumps blood to the lung the other sides muscle is larger and pumps to the rest of the body 10 Cellular Adaptation Hyperplasia production Increased cell number causing an increase in functional capacity a b General causes i ii Hormonal stimulation iii Persistent cell injury calus Increased physiological demand pregnancy 11 Cellular Adaptation Metaplasia metamorphosis a Conversion of one differentiated cell type to another in order to better tolerate an injurious stimulus b Metaplastic cells usually remain well differentiated and of the same tissue type but neoplastic transformation can occur c Fully reversible when stimulus removed d Barretts Esophagus normal columnar cells in the wrong location 12 Cellular Adaptation Dysplasia growth is dysfunctional a Disorderly cell growth abnormal variations in size shape arrangement b Due to a defective adaptive effort c High potential for neoplastic transformation i Referred to as preneoplastic lesions precancerous ii Carcinoma in situ severe dysplasia spanning the entire thickness of the epithelium not full blown cancer but close iii To reverse dysplastic cells die off once stimulus is removed and new cells will grow 13 Cellular Adaptation Summary 14 Irreversible Cell Injury Necrosis a Characterized by i Shrunken pyknotic nucleus that is later degraded karyolysis ii Swollen cell volume iii Disrupted plasma and organelle membranes iv Spilling of contents into ECF b Results in a generalized inflammatory process c General causes i Ischemia ii Toxic injury not just poison its anything that can damage cells 15 Irreversible Cell Injury Necrosis a Four Types of Tissue Necrosis i Coagulative A ii Liquefactive B 1 Most common type 2 Process triggered by ischemia and resulting in plasma membrane and nuclear structure degradation 3 Maintains the shape of original tissue Ex Still having your 5 toes 4 Diabetes 5 Bueger s Disease vasculitis damage to the blood vessels due to smoking usually one foot is amputated and eventually the other is too 1 Rapid dissolution of dead cells forms a liquefied area composed of lysosomal enzymes and dissolved tissue resulting in an abscess or cyst 2 All fluid often in the brain 3 Ex Recently died say 5 hours ago the brain loses shape gooey and turns to liquid 4 Ischemic stroke ischemia in the brain and liquefies 5 Cyst fluid filled any type ovarian cyst sterile fluid 6 Abscess form of cyst with pus bacterial infection antibiotics needed iii Fat Necrosis C 1 Release of excess digestive enzymes triggers a process resulting in the death of adipose tissue 2 General causes trauma pancreatitis most often 3 Macroscopic chalky white area saponification soap iv Gaseous Necrosis D 1 Partially degraded dead cells walled off from surrounding tissue by inflammatory white blood cells 2 General causes tuberculosis 3 Macroscopic white soft friable cottage cheese 4 Most often lungs 5 Tb cavity that undergoes gaseous necrosis 16 Irreversible Cell Injury Necrosis a Gangrene cellular necrosis affecting a large area due