Exam 1: Cell Injury Flashcards
how can cells be injured?
extrinsic injury and intrinsic injury, or both
How can ATP be produced?
oxidative phosphorylation and anaerobic glycolysis
ATP is essential for what processes
major synthetic and degradative processes
depletion of ATP occurs with what?
hypoxia and toxin exposure
loss of as little as ___ of ATP has widespread effects on many critical cellular systems
5-10%
decreased ATP causes loss of activity of
Na-K ATPase pump
loss off activity of the Na-K ATPase pump results in
Na accumulation in the cell and K loss
what is hyropic degeneration
cell swelling and dysfunction due to water following Na into the cell
decreased ATP causes rate of anaerobic glycolysis to _____
increase
increase in anaerobic glycolysis leads to _____ glycogen stores, _____ lactic acid, ______ pH
reduced; increased; reduced
reduced pH decreases activity of
many cellular enzymes
decreased ATP leads to ____ of the Ca pump
failure
failure of the Ca pump causes Ca _______
accumulation in the cell
increased intracellular Ca does what to mitochondria
damages mitochondria
increased intracellular Ca activates
enzymes that can damage cells
as ATP depletion worsens, ribosomes ____
detach
ribosome detachment results in
decreased protein synthesis
ultimately, there is irreversible damge to ____
mitochondrial and lysosomal membranes
free radicals
have a single unpaired electron in outer orbit
energy created by such an unstable configuration is released through reactions with adjacent molecules such as
proteins, lipids, CHO, and nucleic acids
Reactive oxygen species
free radicals normally produced during mitochondrial respiration; normally degraded and removed by cellular defense mechanisms
what are exampls of ROS
superoxide and hydroxyl
what are examples of enzymes that defend against ROS damage
superoxide dismutase
catalase
glutathione peroxidase
oxidative stress
excess of ROS due to ROS increase or scavenging systems are ineffective
what do antioxidants do
either block the initiation of free radical formation or inactivate free radicals (vitamin A, E, D)
Cell membrane injury results in
increased permeability
what can cause membrane damage
atp depletion and free radicals; bacterial toxins, viral proteins, lytic complement components, chemicals, and physical injury
what are the most important sites of membrane damage
plasma membrane, mitochondrial membrane, and membranes of lysosomes
plasma membrane injury results in
loss of osmotic balance and influx of water and ions such as Na and Ca
mitochondrial membrane damage results in
decreased ATPp production and release of pro-apoptotic proteins
loss of lysosomal membrane integrity results in
leakage of lysosomal enzymes into cytoplasma nd enzymatic degradation of proteins, RNA, DNA, and glycogen
what are the 2 forms of cell death
necrosis and apoptosis
morphologic changes during necrosis include
cell swelling
increased eosinophilia
nuclear changes
increased eosinophilia is caused by
loss of RNA and denaturing of the cytoplasmic proteins that normally bind the red dye eosin
pyknosis
shrinkage
karyorrhexis
fragmentation
karolysis
dissolution
coagulative necrosis
architecture of dead tissues is preserved because lysosomal enzymes are dentatured along with structural proteins, so dad cells persist for days or even weeks
coagulative necrosis often occurs in areas of
ischemia
what is an infarct
necrosis secondary to ischemia
liquefactive necrosis
architecture of the dead tissues is not preserved; dead cells are digested by lysosomal enzymes or enzymes secreted by leukocytes
liquefactive necrosis is often seen in
bacterial and fungal infections
fluid accumulations composed of necrotic neutrophils and tissue debris is called
pus
caseous necrosis
necrotic issue has turned into a friable mass resembling cottage cheese
gangrenous necrosis
ischemic necrosis with superimposed bacterial infection
what is apoptosis
individual cell death that can be either physiologic or pathologic
physiologic apoptosis occurs when
during embryogenesis and immune cell development when unneeded cells are removed
pathologic apoptosis occurs when
viral infection, immunologic damage induced by Tlymphocytes, hypoxia, and some toxins
what can induce apoptosis
direct injury to dna
withdrawal of growth factors or hormones can lead to release of proapoptotic proteins from mitochondria
receptor-ligan interactions (TNF binding to receptors in plasma membranes)
enzymes called _____ activate other enzymes that break down DNA and cytoskeletal proteins
caspases
what are the fragments of cells called that contain intracellular oranelles and other cytosolic components
apoptotic bodies
apoptotic bodies are consumed by
phagocytes (macrophages)
unlike necrotic cells that are often _____, apoptotic cells are ______
swollen, shrunken
apoptotic cells are often ______ like necrotic cells
hypereosinophilic
apoptotic bodies are often visible within
macrophages
extrinsic pathway
TNF produced by leukocytes induces apoptosis by binding to receptors in plasma membranes
intrinsic (mitochondrial) pathway
growth factors or hormones can lead to release of proapoptotic proteins from mitochondria
