necrosis, gangrene, and cellular aging

types of tissue necrosis

coagulative necrosis

liquefaction necrosis

fat necrosis

caseous necrosis

what is coagulative necrosis?

most common form of necrosis

general tissue structure remains intact while slowly dissolved by proteolytic enzymes (may take weeks)

what happens to the injured cell during coagulative necrosis?

becomes encapsulated by denatured proteins due to a lack of lysosomal enzymes

what does coagulative necrosis attack?

attacks solid tissue and organs

what is liquefaction necrosis?

digestive enzymes rapidly dissolve affected cells into a liquid, viscous mass

where does liquefaction necrosis typically occur?

tissue lacking strong connective structure; often a localized infection resulting in an abscess or cyst

ex: brain

what is fat necrosis?

injury to fat tissue

what is fat necrosis often associated with?

release of pancreatic enzymes due to pancreatitis

also seen in breast trauma or surgical cases

what is caseous necrosis?

a unique type of cell death seen in lung tissue infected with tuberculosis

incomplete proteolytic digestion of necrotic tissue

what is gangrene?

cellular death in a large area of tissue

results from interruption of blood supply to a particular part of the body

3 primary types of gangrene

dry gangrene

wet gangrene

gas gangrene

what is dry gangrene?

a form of coagulative necrosis

what is dry gangrene characterized by?

blackened, dry, wrinkled tissue separated by a line of demarcation from healthy tissue and high sensitivity in places near

nursing considerations for dry gangrene?

DO NOT apply moisture or dressings to dry gangrene

keep the area dry

monitor for drainage, odor, erythema at the edges, or increased pain

what is wet gangrene?

a form of liquefactive necrosis

losing structural integrity

where is wet gangrene typically found?

in internal organs

is wet gangrene fatal?

yes! it can spread fast

what is gas gangrene?

results from infection of necrotic tissue by anaerobic bacteria (Clostridium)

what is gas gangrene characterized by?

formation of gas bubbles in the damaged muscle tissue → byproducts of the organism’s metabolism

what can gas gangrene also present with?

crepitus (crunchy)

• palpable crepitus → gas in the subcutaneous spaces we can palpate

treatments for gangrene

removal of dead tissue

antimicrobial agents

revascularization

hyperbaric oxygen therapy

examples of removal of dead tissue

debridement

maggots

amputation

purpose of antimicrobial agents

treats the underlying infection

examples of revascularization

angioplasty/stenting

surgical transposition

leeches

purpose of revascularization

need good perfusion/circulation to deliver oxygen to the damaged tissue

purpose of hyperbaric oxygen therapy

used for gas gangrene

🍌what is cellular aging?

cumulative result of factors that cause cellular and molecular damage

🍌cellular aging is a progressive decline in what?

the proliferation and reparative capacity of cells, from exposure to environmental factors

🍌responsible mechanism of cellular aging

DNA damage

reduced proliferative capacity of stem cells

accumulation of metabolic damage

🍌physiological changes of cellular aging

age-related decrease in functional reserve

inability to adapt to environment demand

🍌triggers of apoptosis

extrinsic and intrinsic

not usually associated with systemic manifestations of inflammation

🍌impact of apoptosis

rate of apoptosis > rate of cell replacement = impaired tissue/organ function

🍌what is the programmed senescence theory?

an intrinsic genetic program

decline in telomerase production over time results in shortened telomeres with each cell division

cell dies once a critical low is reached

what is somatic death?

death of the entire organism

general features of somatic death: inflammation

no inflammation or immunologic response occurs prior to death

general features of somatic death: vital signs

cessation of respirations and heartbeat

temperature drops

general features of somatic death: pallor

pallor from blood and body fluid pooling in dependent areas

general features of somatic death: tissues

rigor mortis, later becoming flaccid as tissues deteriorate

general features of somatic death: postmortem autolysis

release of lytic enzymes in body tissues

determining “brain death”

the accepted proof of somatic death

absence of brainstem reflexes

absence of electrical brain waves

absence of cerebral blood flow