Cell adaptation, injury and death

Question 1

Adaptaions

Answer 1

Atrophy - decrease in cell size and number
Hypertrophy - increase in cell size
Hyperplasia - increase in cell number
Metaplasia - change in cell type

Question 2

Tissue atrophy

Answer 2

• decreased cell size and number
• may be physiologic
  + e.g. post-menopausal changes to reproductive organs
  due to loss of endocrine stimulation
• may be pathologic including
  + decreased workload
  + decreased blood supply
  + inadequate nutrition
  + pressure

Question 3

Hypertrophy

Answer 3

• increase in cell size
• may be physiologic
  + e.g. skeletal/cardiac muscle in athletes, uterus in
  pregnancy
• may be pathologic due to
  + excessive workload
  ~ e.g. cardiac muscle due to hypertension
  + exposure to allergies
  ~ e.g. smooth muscle, mucous glands in bronchi in
  chronic asthma

Question 4

Hyperplasia

Answer 4

• increase in cell number
• may be physiologic
  + e.g. female breast at puberty, liver regeneration
• may be pathologic
  + excess hormones or growth factors
  ~ e.g. benign prostatic hyperplasia

Question 5

Metaplasia

Answer 5

• change from one normal differentiated (mature) cell type
  into another normal mature cell type
• may be physiologic or pathologic
• associated with changes in cellular environment resulting
  in activation/suppression of genes
  + e.g. ciliated epithelium of airways of chronic smokers
  + e.g. oesophegeal epithelium in GORD (Barrett
  Oesophagus)

Question 6

Autophagy

Answer 6

• cell response to stress (reduced nutrients)
• starved cell “eats itself”
• autophagic vacuoles form and combine with lysosomes
• as we age, the cells ability to undergo autophagy
  declines
• defects in autophagy may play a role in degenerative
  disorders and cancer

Question 7

Changes in cell injury

Answer 7

• reversible injury: cellular swelling
  + reversible changes to nucleus, mitochondria ER and
  plasma membrane
• irreversible injury: necrosis
  + unregulated, pathologic cell death
  + damage to cell membranes
  + cell contents leak out causing inflammation in
  surrounding tissue
  + lysosomal enzymes digest the cell (lysis)

Question 8

Infarcts

Answer 8

• due to blockage of arterial supply or venous drainage
  + mostly due to an arterial embolus or thrombus
• myocardial or cerebral infarction is common cause of
  death

Question 9

Cell death occurs in what ways?

Answer 9

• Necrosis

- Apoptosis

Question 10

Apoptosis

Answer 10

• programmed cell death or cell suicide
• cells enzyme degrades DNA and proteins
• cell shrinks
• formation of apoptotic bodies
• no inflammation or scarring