MI is a type of -

NEET PG
#1

MI is a type of -
a) Coagulative necrosis
b) Liquefactive necrosis
c) Caseous necrosis
d) Fat necrosis

Correct Answer - A
Ans. is ‘a’ i.e., Coagulative necrosis
Coagulative necrosis

  • This is most common type of necrosis.
  • This type of necrosis is most frequently caused by sudden
    cessation of blood flow (ischemia) in organs such as heart (MI),
    Kidney (ATN), adrenal gland, and spleen.
    Note : Brain is the only exception, i.e.,. It is the only solid organ in
    which ischemia leads to liquifactive necrosis not coagulative
    necrosis.
  • It is also seen with other types of injury e.g., liver necrosis in viral
    hepatitis, Coagulative necrosis of skin after burns (Thermal injury).
  • Why there is predominant protein denaturation and no enzymatic
    digestion ?
    Hypoxia causes intracellular acidosis (has been explained earlier) —

.t pH results in denaturation ofproteins which includes not only
structural proteins hut also enzymes
So, there is no enzymatic digestion. o The necrotic cells retain their
cellular outline for several days.
Liquefactive necrosis

  • It is the necrotic degradation of tissue that rapidly
    undergo softening and liquefaction because of the action of
    hydrolytic enzymes.
    It occurs after
    1.Infection i.e., suppurative inflammation (most common).
    2.Ischemic necrosis in brain.
    Note : Brain lacks any substantial supportive stroma, so ischemic
    necrosis in brain is liquifactive unlike other organs where it is
    coagulative.
  • Mechanism of liquefactive necrosis —> Microbes stimulates
    accumulation of inflammatory cells and these cells release
    lysosomal enzymes.
    Caseous necrosis
  • It is a variant of coagulative necrosis.
  • It is most commonly encountered when cell death is attributable to
    certain organisms e.g., mycobacterium tuberculosis (TB) and
    fungi (Histoplasma, Coccidioidomycosis).
    Why is it called caseous necrosis, not coagulative necrosis ?
  • In contrast to coagulative necrosis where tissue architecture is
    maintained, in caseous necrosis, the tissue architecture is
    completely obliterated. So, it has been called caseous because of its
    cheesy white appearance of the area of necrosis.