Cell injury, apoptosis and death II

Question 1

what are some early functional changes as a result of cell injury

Answer 1

• dec ATP gen
• loss of MEMBRANE integrity
• PROTEIN SYNTHESIS defects
• cytoskeletal samage and DNA damage

Question 2

what are some morphological changes as a result of reversible cell injury

Answer 2

• cellular swelling
• plasma membrane alterations (blebbing, blunting and microvilli distortion)
• mitochondrial swelling
• dilation of ER
• nuclear alterations (disaggregation of granular and fibrillar elements)

Question 3

when a cell is in necrosis what happens

Answer 3

• extensive damage to ALL CELLULAR MEMBRANES
• swelling of LYSOSOMES and VACUOLIZATION of mitochondria
• extracellular calcium enters cell
• intracellular calcium (from stores) is released
• activation of enzymes (membrane catabolism, protein, ATP and nucleic acids)
• continued loss of PROTEINS, COENZYMES, RNA from the hyperpermeable plasma membrane
• nuclear changes: PYNKNOSIS (shrink), KARYORRHEXIS (fragmentation) and KARYOLYSIS (disintegration)

Question 4

what is necrosis

Answer 4

pathological cellular or tissue death in a living organism, irrespective of cause
- there are MORPHOLOGICAL CHANGES that follow cell death, resulting from the PROGRESSIVE DEGRADATIVE ACTION OF ENZYMES on lethally injured cells

Question 5

what are the different types of necrosis

Answer 5

• coagulative necrosis
• liquefactive necrosis
• caseous necrosis
• fat necrosis

Question 6

describe coagulative necrosis

Answer 6

• most common form of necrosis
• characterised by HYPOXIC death
• cell MAINTAINS ARCHITECTURE having lost
• cytoplasm looks COAGULATED and stains pink with EOSIN

Question 7

describe liquefactive/colliquative necrosis

Answer 7

• characteristic of FOCAL BACTERIAL INF (accumulation of inflammatory cells)
• HYPOXIC death of cells in CNS
• complete digestion of dead cells causes tissue to become LIQUID VISCOUS MASS
• material= creamy yellow dead cells due to dead WBC (pus)

Question 8

describe caseous necrosis

Answer 8

• most commonly in foci of TB inf
• cheesy white gross appearance
• obliterated tissue architecture

Question 9

describe fat necrosis

Answer 9

• often in ACUTE PANCREATITIS as a result of release of activated pancreatic lipases into substance of pancreas and the peritoneal cavity

Question 10

what is apoptosis

Answer 10

programmed cell death

• individual cell deletion
• in physiological growth control and in disease
• activated/prevented by a variety of stimuli
• reduced apop causes CELL ACCUMULATION
• inc apop causes EXCESSIVE CELL LOSS

Question 11

what regulates apoptosis

Answer 11

• tightly regulated by INTRACELLULAR program in which PRO-APOPTOTIC cells activate enzymes that degrade the cells own DNA and proteins
  NORMAL: eliminate unwanted/harmful cells
  PATHOLOGY (radiation, viral inf): eliminate irreversibly damaged cells esp when damage affects cell DNA

Question 12

what are characteristics of apoptotic cells

Answer 12

• degradataion of cytoskeletal framework
• DNA fragmentation
• loss of mitochondrial function
• nucleus shrinkage (PYKNOSIS) and fragmentation (KARYORRHEXIS)
• cell shrinks, retains INTACT PLASMA membrane, which rapidly induces PHAGOCYTOSIS
• APOPTOTIC BODIES

Question 13

what are some differences between apoptosis and necrosis

Answer 13

Necrosis:

• has ENZYMATIC DIGESTION
• has LEAKAGE OF CELLULAR CONTENTS

Apoptosis:

• chromatin condensation and fragmentation
• cytoplasm budding
• APOPTOTIC bodies
• phagocytosis of apoptotic bodies