Cell Injury Patho

Question 1

What are the 3 things cells can do when presented with a challenge?

Answer 1

1. Withstand and return to normal: hydropic, cellular accumulations (reversible)
2. Adapt: atrophy, hypertrophy, hyperplasia, metaplasia, dysplasia (generally reversible)
3. Die: necrosis, apoptosis (irreversible)

Question 2

What is hydropic (Reversible Cell Injury)?

Answer 2

• Accumulation of water within cell
• First manifestation of most forms of reversible cell injury
• Results from malfunction of Na/K pumps: Na remains in cell and H20 follows
• Cell swells
• Generalized swelling in cells of particular organ with cause (this is called megaly)

Question 3

What are 3 types of intracellular accumulations (Reversible Cell Injury)?

Answer 3

1. Excessive amounts of normal intracellular substances (ex. fatty deposits in liver, lipids, carbs, etc.)
2. Accumulation of abnormal substances produced by cell bc of issues (ex. abnormal proteins as a result of stress)
3. Accumulation of pigments and particles that cell is unable to degrade (ex. hyperbilirubinemia in newborns bc immature liver)

Question 4

What are 3 types of responses to increases or decreases in functional demands (Cellular adaptations)?

Answer 4

1. Atrophy
2. Hypertrophy
3. Hyperplasia

Question 5

What is atrophy?

Answer 5

• Cells shrink and reduce their differentiated function
• Ex. disuse and immobilization from cast
• Ex. ischemia

Question 6

What is hypertrophy?

Answer 6

• Increase in cell size accompanied by augmented functional capacity

Question 7

What is hyperplasia?

Answer 7

• Increase in # of cells by mitotic division

- Also increases overall capacity

Question 8

What are 2 types of responses to persistent injury (Cellular Adaptations)?

Answer 8

1. Metaplasia

2. Dysplasia

Question 9

What is metaplasia?

Answer 9

• Replacement of one differentiated cell type with another
• Ex. chronic smokers’ bronchial mucosal cells
• Ex. cervical cells w/ HPV
• Can lead to cancer development

Question 10

What is dysplasia?

Answer 10

• Disorganized appearance of cells because of abnormal variations in size, shape, and arrangement
• Can lead to cancer development

Question 11

What are 2 types of irreversible cell injury?

Answer 11

1. Necrosis
2. Apoptosis
   - Both processes lead to cell death

Question 12

What is necrosis?

Answer 12

• Consequence of injury or ischemia
• Characterized by cell rupture and contents spill out
• Inflammation
• Disruption of cell membrane

Question 13

What is apoptosis?

Answer 13

• Time for cell to die naturally or receives signal telling it to die
• Membrane doesn’t rupture
• No inflammation
• Clean, organized cell death
• Ex. dementia

Question 14

What are 5 categories of cellular injury?

Answer 14

1. Ischemia and hypoxia
2. Nutritional
3. Infectious and immunologic
4. Chemical
5. Physical and mechanical

Question 15

What are examples of nutritional cellular injuries?

Answer 15

1. Deficiencies: iron, vitamin D, vit B, vit C, malabsorption, food
2. Excess: sodium, fat, glucose

Question 16

What are examples of chemical cellular injuries?

Answer 16

1. Free radical
2. Heavy metals: lead, mercury
3. Toxic gases: CO, ozone, environmental changes

Question 17

What are examples of physical and mechanical cellular injuries?

Answer 17

1. Temperature extremes: heat stroke/cramps, frostbite
2. Abrupt changes in atmospheric pressure: high/low altitude
3. Abrasion: trauma
4. Electrical: burns
5. Radiation: damage directly to DNA, creation of free radicals

Question 18

What causes hypoxia and ischemia?

Answer 18

Lack of oxygen

• Poor oxygenation = hypoxia
• Interruption of blood flow, most common cause = ischemia
• Cell death from damage to plasma, mitochondrial and lysosomal membranes being critically damaged

Question 19

What is the mechanism of hypoxia and ischemia?

Answer 19

• No O2
• ATP production in cell stalls
• ATP dependent pumps fail
• Na+ accumulates and brings water inside cell
• Excess Ca2+ in the mitochondria interferes
• Glycogen stores are depleted
• Lactate is produced
• pH falls: cellular components are more dysfunctional

Question 20

What are 3 causes of reperfusion injury and reactive oxygen species?

Answer 20

1. Calcium overload: trigger apoptosis
2. Formation of reactive oxygen molecules/free radicals: ex. long-term autoimmune disease
3. Inflammation: damage to surrounding cells

Question 21

What are examples of infectious and immunologic cellular injuries?

Answer 21

• Bacteria: endotoxins (toxins inside cell wall of bacteria released when cell dies and wall breaks) and exotoxins (produced and excreted by bacteria as protective mechanism)
• Virus
• Indirect immunologic response