Cell Injury Patho Flashcards
What are the 3 things cells can do when presented with a challenge?
- Withstand and return to normal: hydropic, cellular accumulations (reversible)
- Adapt: atrophy, hypertrophy, hyperplasia, metaplasia, dysplasia (generally reversible)
- Die: necrosis, apoptosis (irreversible)
What is hydropic (Reversible Cell Injury)?
- 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)
What are 3 types of intracellular accumulations (Reversible Cell Injury)?
- Excessive amounts of normal intracellular substances (ex. fatty deposits in liver, lipids, carbs, etc.)
- Accumulation of abnormal substances produced by cell bc of issues (ex. abnormal proteins as a result of stress)
- Accumulation of pigments and particles that cell is unable to degrade (ex. hyperbilirubinemia in newborns bc immature liver)
What are 3 types of responses to increases or decreases in functional demands (Cellular adaptations)?
- Atrophy
- Hypertrophy
- Hyperplasia
What is atrophy?
- Cells shrink and reduce their differentiated function
- Ex. disuse and immobilization from cast
- Ex. ischemia
What is hypertrophy?
- Increase in cell size accompanied by augmented functional capacity
What is hyperplasia?
- Increase in # of cells by mitotic division
- Also increases overall capacity
What are 2 types of responses to persistent injury (Cellular Adaptations)?
- Metaplasia
2. Dysplasia
What is metaplasia?
- Replacement of one differentiated cell type with another
- Ex. chronic smokers’ bronchial mucosal cells
- Ex. cervical cells w/ HPV
- Can lead to cancer development
What is dysplasia?
- Disorganized appearance of cells because of abnormal variations in size, shape, and arrangement
- Can lead to cancer development
What are 2 types of irreversible cell injury?
- Necrosis
- Apoptosis
- Both processes lead to cell death
What is necrosis?
- Consequence of injury or ischemia
- Characterized by cell rupture and contents spill out
- Inflammation
- Disruption of cell membrane
What is apoptosis?
- 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
What are 5 categories of cellular injury?
- Ischemia and hypoxia
- Nutritional
- Infectious and immunologic
- Chemical
- Physical and mechanical
What are examples of nutritional cellular injuries?
- Deficiencies: iron, vitamin D, vit B, vit C, malabsorption, food
- Excess: sodium, fat, glucose
What are examples of chemical cellular injuries?
- Free radical
- Heavy metals: lead, mercury
- Toxic gases: CO, ozone, environmental changes
What are examples of physical and mechanical cellular injuries?
- Temperature extremes: heat stroke/cramps, frostbite
- Abrupt changes in atmospheric pressure: high/low altitude
- Abrasion: trauma
- Electrical: burns
- Radiation: damage directly to DNA, creation of free radicals
What causes hypoxia and ischemia?
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
What is the mechanism of hypoxia and ischemia?
- 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
What are 3 causes of reperfusion injury and reactive oxygen species?
- Calcium overload: trigger apoptosis
- Formation of reactive oxygen molecules/free radicals: ex. long-term autoimmune disease
- Inflammation: damage to surrounding cells
What are examples of infectious and immunologic cellular injuries?
- 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
