Patho ch4 cell injury and death

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mthompson17
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Patho ch4 cell injury and death
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2013-01-20 21:58:27
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Pathophysiology nursing cells
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Cell Injury, Aging, and Death
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  1. 3 general ways cells respond to environmental changes or injry?
    • 1. withstand and completely return to normal if change is mild or short-lived
    • 2. change structure of function to adapt to a persistent but nonlethal injury
    • 3. death if the injury is too severe or prolonged
  2. What are the 2 processes in which cell death may occur?
    necrosis and apoptosis
  3. Necrosis?
    cell death caused by external injury
  4. Apoptosis?
    triggered by intracellular signaling cascades that result in cell suicide
  5. What occurs within a cell in reversible injuries and the early stages of irreversible injuries?

    What causes this?
    swelling and accumulation of excess substances within the cell

    insufficient cellular energy/ATP or dysfunction of associated metabolic enzymes
  6. What is usually the first manifestation of most forms of reversible cell injury?

    What is it?
    hydropic swelling - cellular swelling due to accumulation of water
  7. Why does hydropic swelling occur?
    malfunction of the Na-K pumps that normally maintain ionic equilibrium of the cell
  8. What are the results of malfunction of the Na-K pump?
    accumulation of Na ions within the cell that creates an osmotic gradient = water into the cell
  9. Why will any injury that result in insufficient energy production cause hydropic swelling?
    because the Na-K pump depends on ATP
  10. The Na-K pump works by _____ transport.
    active
  11. The Na-K pump pumps ___ Na ions out of a cell for every ____ K ions it pumps in.
    • 3
    • 2
  12. The malfunctioning of the Na-K pump changes the resting potential of a cell and can affect the functioning of ____ and _____ cells.
    nerve and muscle
  13. Effect of generalized swelling in the cells of an organ on that organ?

    How is this described?
    organ will increase in size and weight

    -megaly

    EX:  hepatomegaly, splenomegaly
  14. 3 categories of intracellular accumulations
    • 1. normal intracellular substances in excess amounts
    • 2. abnormal substances produced by the cell because of faulty metabolism or synthesis
    • 3. accumulation of substances the cell is unable to degrade
  15. 4 normal substances that tend to accumulate in injured cells?

    Why?
    • 1. lipids
    • 2. carbs
    • 3. glycogen
    • 4. proteins

    cell is unable to metabolize them
  16. A common site of intracellular lipid accumulation is the ____ where many fats are normally stored, metabolized, and synthesized.
    liver
  17. 2 genetic disorders where enzymes needed to metabolize lipids are impaired?

    Where do the lipids accumulate?
    Tay-Sachs disease and Gaucher disease

    neurologic tissue
  18. Mucopolysaccaridoses?
    group of genetic diseases in which the enzymatic degradation of glycosaminoglycans in the cells are impaired and cause them to accumulate in the cell

    mental disabilities and connective tissue disorders may result
  19. Common cause of excessive glycogen storage?
    diabetes mellitus
  20. Cellular stress may lead to accumulation and aggregation of _____ proteins.
    denatured
  21. How are denatured proteins dealt with within a cell?

    What happens if they are allowed to accumulate?
    chaperone proteins bind and refold them

    they form complexes with the protein ubiquitin that assists in having them digested into fragments less harmful to the cell
  22. Endogenous and exogenous?
    endogenous - produced within the body

    exogenous - comes from outside the body
  23. 5 common adaptive responses made by cells?
    • 1. atrophy
    • 2. hypertrophy
    • 3. hyperplasia
    • 4. metaplasia
    • 5. dysplasia
  24. Atrophy?
    cells shrink and reduce their differentiated functions
  25. 6 general causes of atrophy?
    • 1. disuse
    • 2. denervation
    • 3. ischemia
    • 4. nutrient starvation
    • 5. interruption of endocrine signals
    • 6. persistent cell injury
  26. What is the purpose of cells' atrophying?
    minimize energy requirements of the cell
  27. A person who is on bed rest is at risk for ____ atrophy.
    disuse
  28. 4 common sites of ischemia?
    heart, brain, kidneys, and lower leg
  29. 3 atrophic changes that may occur with ischemia in the lower leg?
    • 1. thin skin
    • 2. muscle wasting
    • 3. hair loss
  30. Atrophy that results from persistent cell injury is most commonly r/t ____ & ____.
    inflammation and infection
  31. Hypertrophy?
    increase in cell mass acoompanied by an augmented functional capacity
  32. Why do cells hypertrophy?
    in response to increased physiologic or pathophysiologic demands
  33. Cellular enlargement results primarily from a net increase in cellular ____ content.
    protein
  34. Organ enlargement may be a result of both ______ and _______.
    hypertrophy and hyperplasia
  35. Hyperplasia?
    increased number of cells
  36. 3 reasons hyperplasia usually occurs?
    • 1. increased physiologic demands
    • 2. hormonal stimulation
    • 3. persistent cell injury
  37. An increase in RBC number in response to high altitude is an example of cell _____.
    hyperplasia
  38. Increase in skeletal muscle in response to exercise is primarily the result of _____.
    hypertrophy
  39. Metaplasia?
    the replacement of one differentiated cell type with another
  40. What usually causes metaplasia to occur?
    persistent injury causes an adaptation that replaces the more injured cells with those better able to tolerate the stimulation
  41. The replacement of ciliated columnar epi cells with stratified squamous epi cells in the bronchial mucosa of a smoker is an example of _______.
    metaplasia
  42. What may be caused by metaplastic cells?
    cancer
  43. Dysplasia?
    disorganized appearance of cells because of abnormal variations in size, shape, and arrangement
  44. Where is dysplasia most often seen?
    in hyperplastic squamous epi

    may be seen in mucosa of intestine
  45. Dysplastic cells have significant potential to transform into _____ cells and are usually regarded as preneoplastic lesions.
    cancerous
  46. Dysplasia that is severe and involves the entire thickness of the epi is called ___ ___ ___.
    carcinoma in situ
  47. Necrosis usually occurs as a consequence of ____ or ____.
    ischemia or toxic injury
  48. 3 characteristics of necrosis?
    • 1. cell rupture
    • 2. spilling of contents into the ECF
    • 3. inflammation
  49. How does apoptosis occur?
    An injury does not kill the cell but triggers cellular cascades that activate cellular suicide.  Cells usually do not rupture.  They are ingested by neighboring cells with minimal disruption of the tissue and without inflammation
  50. Is apoptosis a pathologic process?
    not always
  51. pyknotic?
    shrunken nucleus
  52. Karyolysis?
    swollen cell volume
  53. 4 typical morphologic changes that occur in necrotic cells?
    • 1. pyknotic - shrunken & degraded nucleus
    • 2. karyolysis - swollen cell volume
    • 3. dispersed ribosomes
    • 4. disrupted plasma and organelle membranes
  54. 5 local and systemic indicators of cell death?
    • 1. inflammation - fever, elevated WBC count, malaise
    • 2. increased heart rate
    • 3. decreased appetite
    • pain
    • 4. elevated serum enzyme levels
    • 5. loss of function
  55. What are 2 ways that may be used to identify the location and extent of cellular death?
    1.  testing for the presence of cellular enzymes in the blood that may have been dumped by the burst cells - different cells contain different enzymes

    2.  location of pain
  56. 4 types of tissue necrosis?

    How do they differ?
    • 1. coagulative
    • 2. liquifactive
    • 3. fat
    • 4. caseous

    primary by type of tissue affected
  57. ___ necrosis is the most common.
    coagulative
  58. What are the 4 manifestations of coagulative necrosis regardless of the cause of cell death
    (1) ischemic cellular injury, leading to (2) loss of the plasma membrane's ability to maintain electrochemical gradients, which results in (3) an influx of Ca ions and mitochondrial dysfunction (4) and degradation of plasma membranes and nuclear structures
  59. The area of coagulative necrosis is composed of ______ _____ and is relatively solid.
    denatured proteins
  60. How is coagulative tissue preserved for weeks?
    the coagulated area is slowly dissolved by proteolytic enzymes
  61. 2 ways liquefactive occurs?
    • 1.dissolution of dead cells occurs quickly and a liquefied area of lysosomal enzymes and dissolved tissue may result and form an abscess or cyst
    • 2. bacterial infection that triggers a localized collection of WBC's that contain potent degradative enzymes that may cdigest dead cells and result in liquid debris
  62. Liquefactive necrosis may be seen in the ____ because it is rich in degradative enzymes and contains little supportive connective tissue.
    brain
  63. Fat necrosis refers to the death of _____ tissue and usually results from _____ or _____.
    adipose tissue

    trauma or pancreatitis
  64. How does fat necrosis occur?
    Activated digestive enzymes are released from the pancreas or injured tissue.  They attack the cell membranes of fat cells, causing release of their stores of triglycerids.  Pancreatic lipase hydrolyzes the triglycerides to free fatty acids and glycerol which cause the appearance of fat necrosis
  65. What does fat necrosis look like?
    chalky white area of tissue
  66. _____ necrosis is characteristic of lung tissue damaged by tuberculosis.
    caseous
  67. What do areas of caseous necrosis look like?
    white, soft, and fragile resembling clumpy cheese
  68. How does the body isolate caseous necrosis?

    What are cells in the center like?
    dead cells are walled off from the rest of the tissue by inflammatory WBC's

    the dead cells in the center lose their cellular structure but are not totally degraded
  69. What happens to necrotic debris in caseous necrosis?
    may persist indefinitely
  70. Gangrene?
    term used to describe cellular death involving a large area of tissue
  71. What usually causes gangrene?
    interruption of the major blood supply to a particular body part
  72. 3 types of gangrene?
    wet, dry, and gas
  73. Dry gangrene?
    form of coagulative necrosis characterized by black-ended, dry, wrinkled tissue that is separated from adjacent healthy tissue by an obvious line
  74. Dry gangrene typically occurs only in ____.
    extremities
  75. Wet gangrene?
    gangrene that may occur due to liquefactive necrosis
  76. Wet gangrene is typically found in ____ _____, appears _____ & _____, and may have a _____ smell due to the invasion of bacteria.
    internal organs

    black and cold

    foul
  77. 2 reasons wet gangrene is a life-threatening problem?
    1. rapid spread of tissue damage

    2. the release of toxins into the blood
  78. What causes gas gangrene and what indicates it?
    infection of necrotic tissue by anaerobic bacteria of the genus clostridium
  79. How do clostridium bacteria cause gas gangrene?
    produce toxins and degradative enzymes that allow the infection to spread rapidly through the necrotic tissue
  80. What 2 types of gangrene may be rapidly fatal?
    wet and gas
  81. What is the major difference in apoptosis and necrosis?
    apoptosis does causes little tissue damage and does not elicit the inflammatory response
  82. Death of cancer cells in response to radiation or chemotherapy is most likely due to ______.
    apoptosis
  83. ____ cell death is recognized as a primary factor in heart failure and dementia.
    apoptotic
  84. 2 types of environmental or extrinsic signals that may induce apoptosis?
    1. withdrawwal of "survival"signals that normally suppress the apoptotic pathways

    2. extracellular signals bind to the cell and trigger the death cascade through activation of "death receptors"
  85. What occurs if a cell loses signals from neighboring cells?
    the cell death cascade is initiated
  86. How may apoptosis be triggered by intrinsic pathways?
    cells monitor their condition and usefulness internally and will trigger their own death if they become too damaged to repair
  87. A large number of cancers are associated with a mutation in the _____ gene which allows cancer cells to escape the intrinsic apoptotic monitoring system.
    p53
  88. ____ is important in preventing the proliferation of cells with damaged DNA and will cause apoptosis if its levels in a cell become high.
    p53
  89. A family of enzymes called _____ is the main component of the proteolytic cascade that degrades key intacellular structures leading to cell death
  90. How are caspases activiated?
    initiator caspases are activated and causes a apid domino effect of caspase activation
  91. When caspases destroy a cell what happens to the contents of the cell?
    the contents are destroyed within the plasma membrane of the cell and the cell remnants are assimilated by neighboring cell
  92. How are apoptotic cells ingested by neighboring cells?
    a phospholipid normally on the cytoplasmic side of a healthy cell flips to the outside of the lipid bilayer and signals neighbors and tissue macrophages to bind and assimilate the cell components and suppresses the inflammatory response that normally accompanies phagocytosis
  93. Heart tissue exhibits ____necrosis, brain tissue exhibits _____necrosis, lung tissue exhibits _______ necrosis, and pancreatic tissue exhibits ______ necrosis.
    coagulative

    liquefactive

    caseous

    fat
  94. 5 common causes of cellular injury?
    • 1. hypoxic injury
    • 2. nutritional injury
    • 3. infectious and immunologic injury
    • 4. chemical injury
    • 5. physical and mechanical injury
  95. 4 causes of tissue hypoxia?
    • 1. interruption of bloodflow to an area
    • 2. heart failure
    • 3. lung disease
    • 4. RBC disorders
  96. _____ is the most common cause of cell injury in clinical medicine and injures cells faster than hypoxia alone.
    ischemia
  97. Why does ischemia injure cells more quickly than hypoxia alone?
    It doesn't just cut off oxygen supply to the area.  It also cuts off waste removal and nutrient supply
  98. What are the results of hypoxia?
    Eecreased oxygen supply to the mitochondria decreases ATP production.  ATP dependent pumps in the cell fail. (Na-K and Ca pumps)  Na builds up in the cell and draws water into the cell by osmosis and causes hydropic swelling.  Excess extracellular Ca builds up in the mitochondria and further inhibits their functioning 
  99. When the mitochondria of a cell is not able to produce enough ATP what occurs?
    Anaerobic glycolytic pathways metabolize cells stores of glycogen.  The pyruvate end products of glycolysis accumulate and are converted to lactate and cause cellular acidification.
  100. Lactic acidosis?
    lactate escapes into the bloodstream as a result of the end products of glycolysis
  101. How does the pH drop due to anerobic glycolysis affect the functioning of the affected cells?
    cellular proteins and enzymes become progressively more dysfunctional as pH falls
  102. When does ischemic injury become irreversible?
    when the plasma, mitochondrial, and lysosomal membranes are critically damaged
  103. How long does it take ischemia to occur?

    When does most ischemia occur?
    many minutes to hours

    most cellular damage occurs after the blood supply to the tissues has been restored
  104. reperfusion injury?
    damage to cells that have the blood flow restored after they have been ischemic
  105. 3 critical components of ischemia - reperfusion?
    • 1. Ca overload
    • 2. formation of reactive oxygen molecules (free radicals)
    • 3. subsequent inflammation
  106. Why does a Ca overload occur during restoration of blood flow to an ischemic area?
    fluids high in Ca bathe the cell which has a non-functioning Ca pump due to lack of ATP production
  107. What can the accumulation of Ca ions in the cytoplasm of a previously ischemic cell cause?
    may trigger apoptosis or activate enzymes that degrade lipids in the membrane
  108. What do reactive oxygen molecules in a cell do?
    they steal hydrogen atoms and form abnormal molecular bonds in a destructive cascade
  109. What are the 4 effects of reactive oxygen molecules in a cell?
    • 1. damage cell membranes
    • 2. denature proteins
    • 3. disrupt cell chromosomes
    • 4. may initiate the inflammatory cascade
  110. What is the result of the inflammatory response that occurs in an ischemic cell when the blood flow is returned?
    may cause ongoing cellular and organ damage for up to weeks following the initial event b/c WBC's release enzymes and other chemicals that further damage the cells in the area
  111. 4 causes of cell nutritional deficiencies?
    • 1. poor intake
    • 2. altered absorption
    • 3. impaired distribution by the circulatory system
    • 4. inefficient cellular uptake
  112. 5 common causes of malnutrition?
    • 1. poverty
    • 2. chronic alcoholism
    • 3. acute and chronic illness
    • 4. self-imposed dietary restrictions
    • 5. malabsorption syndromes
  113. The virulence of a particular biological agent depends on what 2 things?
    its ability to gain access to the cell and its success in altering cellular functions
  114. 2 causes of damage when a biological agent is present?
    1. damage done directly by the agent

    2. damage incurred due to the body's immune response
  115. Most _____ do not gain entry into the cell and accomplish their injurious effects from the outside.
    bacteria
  116. Why do some bacteria produce and secrete powerful destructive enzymes?
    to digest cellular membranes and connective tissues
  117. exotoxins?
    toxin produced by a bacteria that interferes with specific cellular functions
  118. Exotoxins are generally _______ and are usually susceptible to extremes of heat.
    proteins
  119. Certain gram-negative bacteria have an _____ in their cell wall that is released upon lysis of the bacteria and causes fever, malaise, and even circulatory shock.
    endotoxin
  120. Why does the inflammatory response cause damage to cells?
    WBC's secrete enzymes and chemicals meant to destroy invading organism that can damage normal body cells that are close by
  121. 6 substances that may be secreted by WBC's during the inflammatory response?

    What may WBC's cause to be produced?
    • 1. histamines
    • 2. kinins
    • 3. complement
    • 4. proteases
    • 5. lymphokines
    • 6. protaglandins

    free radicals that attack host cell membranes
  122. What is a virus?
    small piece of genetic material that is ale to gain entry into a cell
  123. What do viruses do within the body?
    invade the cells and use the cell's functioning to survive
  124. How may cells infected with a virus trigger their own destruction?
    express viral proteins on the cell surface that are recognized by the immune system
  125. How does the hepatitis B virus replicate and cause immune mediated cell death?
    It becomes incorporated into the host cell's nucleus where it is transcribed by the normal DNA plymerases.  The viral genes are transported to the cytoplasm and translated into structural proteins and enzymes which are used to make more copies of the virus.
  126. 2 ways that toxic chemicals cause cellular injury?
    1. directly

    2. chemical is metabolized into reactive chemical within the body
  127. What is carbon tetrachloride?

    What can it do within the body?
    chemical that is converted to a highly toxic free radical by liver cells and forms abnormal chemical bonds in the cell

    ultimately destroys cell membranes of liver cells and causes liver failure
  128. What common household drug acts similarly to carbon tetrachloride within the body if taken in high doses?
    acetaminophen
  129. How does carbon monoxide cause damage?
    binds selectively to Hgb and prevents RBC from carrying sufficient O2
  130. 5 injurious physical and mechanical factors?
    • 1. extremes of temp
    • 2. abrupt changes of atm pressure
    • 3. mechanical deformation
    • 4. electricity
    • 5. ionizing radiation
  131. Extremes of cold result in the hypothermic injury known as _____.
    frostbite
  132. What may damage cells that experience frostbite even before they actually freeze?
    ischemia due to extreme vasoconstriction and increased blood viscosity
  133. With continued exposure to cold, a ___ ___ response may occur leading to intense _____ and _____ _____ ____.
    rebound vasodilatory

    swelling and peripheral nerve damage
  134. Frostbit generally affects the ____, ____, and ____ and is often complicated by ______ necrosis.
    extremities, ears, and nose

    gangrenous
  135. What are the effects of high temp?
    microvascular coagulation and may accelerate metabolic processes in the cell
  136. 4 possible effects of abrupt changes in pressure?
    • 1. interference with gas exchange in the lungs
    • 2. formation of gas emboi in the bloodstream
    • 3. collapse the thrax
    • 4. rupture internal organs
  137. Electrical current damages tissues in what 2 ways?
    1. disruption of neural and cardiac impulses

    2. hyperthermic destruction of tissues
  138. Where does an electrical current usually go in the body?
    follows path of least resistance through neurons and body fluids
  139. 3 manifestations of electrical cell damage?
    • 1. violent muscle contractions
    • 2. thermal injury
    • 3. coagulation in BV's
  140. 2 ways radiation can injure cells?
    1. directly by breaking chemical bonds

    2. indirectly by generating free radicals
  141. How does radiation damage DNA?
    breaks apart DNA bonds
  142. Ionization?
    the ability of the radiant energy to split water molecules by knocking off orbital electrons
  143. What is the result of ionization?
    free radicals are created that steal electrons from other molecules and disrupt chemical bonds
  144. 2 primary effects of radiation at the cellular level?
    • 1. genetic damage
    • 2 acute cell destruction
  145. The vulnerability of a tissue to radiation-induced genetic damage depends on its rate of _____.

    Which cells are the most vulnerable?
    proliferation

    cells that divide slowly will have time to repair the DNA damage done by radiation, but rapidly dividing cells may pass the damaged DNA info from cell to cell
  146. What is radiation-induced cell death most attributed to?
    radiolysis of water with resulting free radical damage to the plasma membrane
  147. How is radiation therapy used?
    kills cancer cells in an area by b/c it induces death in rapidly proliferating cells
  148. What damage to normal cells can occur due to radiation therapy and where does it occur?
    usually localized to the irradiated area

    small arteries and arterioles may be damaged and cause blood clotting and fibrous deposits that compromise tissue perfusion
  149. What is cellular aging?
    cumulative result of a progressive decline in the proliferative and reparative capacity of cells coupled with exposure to environmental factors that cause accumulation of cellular and molecular damage
  150. 3 mechanisms believed to be responsible for cellular aging?
    • 1. DNA damage
    • 2. reduced proliferative capacity of stem cells
    • 3. accumulation of metabolic damage
  151. How is DNA caused in aging?
    damage to DNA occurs due to various factors and is corrected by repair mechanisms in the cell which work less efficiently with age resulting in inhibited cell replication or apoptosis initiated due to DNA damage
  152. Programmed senescence theory?
    aging is the result of an intrinsic genetic program in which cells are programed to replicate a certain number of times and then stop
  153. In programmed senescence theory why is it believed cells stop dividing at some point?
    when telomeres get short enough the cell stops dividing
  154. Progressive loss of _____ gene expression with aging may contribute to reduced proliferative capacity because telomeres are not repaired when they are shortened.
    telomerase
  155. Free radical theory of aging?
    accumulated metablic cell damage over time
  156. In free radical theory what determines the life span?
    rate of metabolism
  157. 2 factors that may cause cells to age more quickly?
    • 1. DNA repair mechanisms are faulty
    • 2. reduced antioxidant activity
  158. Somatic death?
    death of the entire organism
  159. Characteristics of somatic death that occur immediately? (3)
    • 1. body temp falls
    • 2. skin becomes pale
    • 3. blood and body fluids collect in dependent areas
  160. When does rigor mortis begin in somatic death?
    within 6 hours
  161. What causes rigor mortis?
    accumulation of Ca and depletion of ATP result in actin-myosin cross-bridge formation in muscle cells
  162. When does rigor mortis progress to limpness as tissues of the body begin to deteriorate?
    24 to 48 hours after death
  163. Postmortem autolysis?
    release of lytic enzymes in tissues throughout the body that causes putrefaction
  164. 6 criteria for determining brain death?
    • 1. unresponsiveness
    • 2. flaccidity
    • 3. absence of brainstem reflexes (swallowing, gagging, pupil and eye movements)
    • 4. absence of respirtory effort when the subject is removed from the ventilator
    • 5. absence of electrical brain waves
    • 6. lack of cerebral blood flow

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