Cellular Adaption and Cell Death Flashcards
Cell injury: reversible and irreversible / Cellular adaptions
Cellular Adaption and Cell Death
Cell’s two responses to stress/stimulus = ?
Two responses:
Adaptation:
- Extent to which cell is able to alter mechanism and able to regain homeostasis in the altered environment.
- Allows cell to function in altered environment and avoids injury.
Cell injury/death: When the cells are unable to adapt.
- Reversible injury: cell is able to recover homeostasis after the removal of stress.
- Irreversible injury.
Cellular Adaption and Cell Death
Cell adaptation may lead to = ?
DAHHM
Adaptation may lead to:
- Atrophy:
- Hypertrophy:
- Hyperplasia:
- Metaplasia:
- Dysplasia:
Cellular Adaption and Cell Death
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Atrophy:
- Decreased cell size.
- Reduce oxygen consumption, cellular function is reduced.
Causes:
- Disuse, immobilized in a cast
- Denervation
- Loss of endocrine stimulation
- Inadequate nutrition
- Ischemia or decreased blood flow
Physiologic atrophy:
- Ageing
Pathologic:
- Muscle wasting due to spinal cord in injury
Cellular Adaption and Cell Death
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Hypertrophy:
- Increased cell size, and also increase in the amount of functioning tissue mass.
- Seen in cardiac and skeletal muscle tissue; cannot divide and form more cells
Cause:
- Most common = increase in workload- to achieve equilibrium between demand and functional capacity
- increase in growth/trophic signals
- Increased hormonal output
- Result of normal physiologic or abnormal pathologic condition.
Physiologic:
- Breast cells during pregnancy; strength building exercises result in increase in muscle cell size
Pathologic:
- Left ventricular hypertrophy
Cellular Adaption and Cell Death
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Hyperplasia: increased cell number
Caused by hormonal signaling and an increase in work load.
Hypertrophy and hyperplasia often seen together.
Occurs in tissue that are capable of mitotic division such as epidermis, intestinal epithelium.
Examples:
Physiologic: breast enlargement during puberty; prolonged pressure on skin causes callus.
Non physiologic: endometrial hyperplasia
Cellular Adaption and Cell Death
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Metaplasia:
- Conversion of one cell type to another.
Cause:
- Chronic irritation/ inflammation = Substitution of cells that can better survive
Example:
- Substitution of stratified squamous epithelial cells for ciliated columnar epithelial cells in trachea and larger airways of a habitual cigarette smoker; causes thickening of respiratory epithelium and loss of functional clearance of mucus and debris.
- GERD: Cells of esophagus are exposed to acidic contents of stomach, cells changes from squamous epithelium to columnar type.
- Chronic inflammation during GERD is a risk factor of Barrett esophagus and esophageal carcinogenesis
Cellular Adaption and Cell Death
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Dysplasia: disorderly growth
- Deranged cell growth of a specific tissue that results in cell that vary in size, shape, and organization.
- Strongly implicated as a precursor of cancer
- Preterm babies who are ventilated for long periods of time and term babies who require intubation during first month of life - can develop bronchopulmonary dysplasia.
Cellular Adaption and Cell Death
Causes of Cerebral Atrophy = ?
Cerebral Atrophy: Reduction of size of cells in the cerebrum of the brain.
Reduction of size of neurons – lack of stimulation- leads to reduction in size of the brain itself.
Causes:
- TBI - ischemia
- Infections / toxins
Clinical Manifestations:
- Focal (deficit in specific functions)
- Global
Cellular Adaption and Cell Death
Swelling, membrane blebs = Reversible or Irreversible ?
Swelling, membrane blebs = Reversible
Cellular Adaption and Cell Death
Alterations in cell nucleus, mitochondria and lysosomes = Reversible or Irreversible ?
Irreversible cell injury:
- Alterations in cell nucleus, mitochondria and lysosomes
- Rupture of cell membrane
- After cell death lysosomes release digestive enzymes to initiate degradation of cellular components.
Dead cells release contents into the ECF
Lactate dehydrogenase.
Creatinine kinase:
- CK-MM, found mostly in skeletal muscles
- CK-MB, found mostly in the heart muscle
- CK-BB, found mostly in brain tissue
Cellular Adaption and Cell Death
Necrosis = ?
Necrosis:
- Occurs in irreversibly damaged cells.
- Initiate inflammation
Cellular Adaption and Cell Death
Apoptosis = ?
Apoptosis:
- Programmed cell death.
- Does not initiate inflammation
