What are the 3 main causes of hypoxia? Correct Ans-1. ischemia
2. hypoxemia
3. decreased O2 carrying capacity of blood
Ischemia is decreased blood flow through an organ and arises with decreased arterial
perfusion (e.g. _________), decreased venous drainage (e.g. ________), or shock. Correct
Ans-atherosclerosis
Budd-Chiari syndrome (thrombosis of hepatic vein causing infarction of the liver)
Hypoxemia is defined as low partial pressure of O2 in the blood (PaO2 < ______, SaO2
<______) Correct Ans-60 mmHg
90%
If a patient came in after being exposed to excessive smoke from fires, having a cherry-red
appearance of skin and complaining of a headache, what should you suspect? Correct Ans-
carbon monoxide poisoning
What is the difference between anemia and carbon monoxide poisoning in terms of arterial
blood gases? Correct Ans-PaO2 is normal in both anemia and carbon monoxide poisoning.
SaO2 is decreased in CO poisoning and normal in anemia.
, Pathoma (Complete) Exam- Questions and Answers
Which decreased O2-carrying capacity condition is characterized by chocolate colored blood?
What is the treatment? Correct Ans-Methemoglobinemia where iron in heme is oxidized
to Fe3+ (normally Fe2+ binds O2), so it can no longer bind O2. PaO2 is normal while SaO2 is
decreased. Seen with oxidative stress (e.g. sulfa or nitrate drugs) or in newborns.
-treatment with methylene blue, which helps to reduce Fe3+ back to Fe2+ state.
Hypoxia impairs_________, which results in decreased production of _________; this is
necessary for function of ___________ Correct Ans-Oxidative Phosphorylation
ATP -- necessary for Na/K Pump
What is the hallmark of REVERSIBLE cellular injury? Correct Ans-Cellular swelling
-cytosol swelling results in the loss of microvilli and membrane blebbing
-swelling of the RER results in dissociation of ribosomes and decreased protein synthesis.
What is the hallmark of IRREVERSIBLE cellular injury? Correct Ans-Membrane damage
-cytosolic enzymes leak into serum (e.g. cardiac troponin)
-additional Ca2+ enters the cell
-loss of electron transport chain in inner mitochondrial membrane
-cytochrome C leaks into cytosol, activating apoptosis pathway
-lysosomes leak into cytosol
end result of irreversible injury = CELL DEATH
, Pathoma (Complete) Exam- Questions and Answers
What is the morphologic feature of cell death? What are the two mechanisms of cell death?
Correct Ans-LOSS OF NUCLEUS (pyknosis - nucleus shrinks down, karyorrhexis - nucleus
fragmentation, karyolysis - dissolution, nuclear fragments further breakdown)
two mechanisms of cell death are necrosis and apoptosis
Necrosis = murder
Apoptosis = cellular suicide
Necrosis is follow by _____. It is never a physiologic process, it is always ______. Correct
Ans-Acute inflammation
Pathologic
___________ necrosis is seen with ischemic infarction of any organ except for _______.
Correct Ans-coagulative
brain
In coagulative necrosis, the area of infarcted/occluded tissue is often __________ and
_______. Correct Ans-wedge-shaped (pointing to vascular occlusion)
pale
Study the image: Correct Ans-
, Pathoma (Complete) Exam- Questions and Answers
What is the difference between the picture on the L and R? What kind of necrosis is seen
here? Correct Ans-The picture on the right is of normal renal histology. All the nuclei are
within the cells and the structure is maintained. On the left, there is no nuclei seen but all the
membranes are still intact so that you can still tell this is a kidney histology slide. This is an
example of COAGULATIVE necrosis.
Study the image: Correct Ans-
What is shown here? Correct Ans-This is an image of a testicle that has undergone
hemorrhagic/Red infarction. This occurs if blood re-enters loosely organized tissue.
Liquefactive necrosis is characteristic of _____, ____, and ______. Correct Ans-1. brain
infarction (proteolytic enzymes from MICROGLIAL cells liquefy the brain)
2. abscess (proteolytic enzymes from NEUTROPHILS liquefy tissue)
3. pancreatitis (proteolytic enzymes form pancreas liquefy parenchyma)
Study the image: Correct Ans-
What kind of necrosis is seen here? Correct Ans-Gangrenous necrosis (dry gangrene) which
is a type of coagulative necrosis that resembles mummified tissue, characteristic of ischemia
in the lower limb and GI tract.
-if superimposed infection of dead tissue occurs, then liquefactive necrosis ensues (wet
gangrene). You can see some wet gangrene in this image by the toes.
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