Cell Adaptations and Growth Disturbances Flashcards
Adaptations due to chronic sublethal injury
- Hypertrophy
- Hyperplasia
- Metaplasia
- Dysplasia
- Atrophy
- Intracellular accumulations (ex: hyaline droplets, hydropic degeneration, etc.)
Cell injury during fetal development
- Agenesis/aplasia
- Hypoplasia
- Stenosis/atresia
Abnormal development
- Dysplasia (usually applied at the organ level)
- Abiotrophy
Cell adaptations that change cell size, number, or appearance
- Hypertrophy
- Hyperplasia
- Metaplasia
- Dysplasia
- Atrophy
Growth disturbances of development
- Hypoplasia
- Aplasia and agenesis
- Atresia
- Abiotrophy
One-time temporary injury
- -> Acute cell swelling
- May recover OR
- Cell death
Repetitive or chronic injury
-Cell death
- Cell survival mechanisms
- -Autophagy
- -Senescence
- Adaptations of surviving cells
- -Positive - increased productivity/efficiency
- -Negative - decreased productivity/efficiency or leads to cancer
Autophagy
- Cells consuming own organelles
- -Non-functional organelles (housekeeping)
- -Proteins and carbohydrates (nutrient source)
Result of autophagy
- Single membrane-bound autophagolysosome
- -Lysosomal enzymes
- -Portion of the cytosol with dysfunctional organelles
Alternative to cell death
Even if the cell dies, the autophagic cell secretes lysophosphatidylcholine and expresses phosphatidylserine on the cell surface to mark cells for heterophagy, and decrease bystander inflammation
Hypertrophy
- Increased size of a tissue or organ due to an increase in the size of individual cells (due to increased number or volume of organelles)
- Term also used to indicate gross enlargement of an organ or tissue
- NOT due to cell swelling
- Often accompanied by hyperplasia in capable tissues
- -Only hypertrophy in heart and skeletal muscle
Hyperplasia
- An increase in organ size or tissue mass de to increased number of cells
- Only if the cells can replicate
- Can cause striking increase in tissue or organ size (macroscopically larger)
- Restrictive process
- Distinct from neoplastic proliferation
- -Long-standing hyperplasia –> benign neoplasia
- -Hyperplasia –> dysplasia –> malignant neoplasia
- -Not a restrictive process
- -Includes DNA mutations
- -Out of control
Metaplasia
- Transformation of a differentiated tissue type into a related type of tissue
- -Typically a reparative process
- -Underlying negative consequences
- Ex:
- -Respiratory epithelium –> stratified squamous epithelium
- -Fibrous connective tissue –> cartilage or bone
Dysplasia
- Abnormal formation of tissue
- Can occur during development or in fully developed tissue organs
- Increase in number of atypical or poorly differentiated cells
- Possible precursor to neoplasia
Atrophy
- Decrease in the amount of tissue after normal growth has been attained; reduced tissue mass due to decreased numbers of cells, and/or reduced cell size (also referred to as “simple atrophy”)
- Involution
- Generalized atrophy - nutritional or chronic diseases
- Localized atrophy - ischemic, pressure, disuse, neurogenic (know some examples of this)
Atrophy morphology
- Gross appearance
- -Can be hard to tell size difference
- -Easier to ID in paired organs
- -Gray and wrinkled surface if tissue has a capsule
- Microscopic features
- -Loss of cells
- -Looks hypercellular
When cells are injured during fetal development
- Agenesis/aplasia
- Hypoplasia
- Stenosis/atresia
When abnormal development
- Dysplasia (usually applied at the organ level)
- Abiotrophy
Hypoplasia
- Failure of organ to reach normal size
- Incomplete growth (was never big)
- All the right structures are present, just not the right size
- Ex:
- -Intestine: distension of intestine proximal to hypoplastic segment
- -Cerebellum:
- –Kittens - in utero infection with panleukopenia virus
- –Calves - in utero infection with BVDV at gestation day 90-130
- -Enamel:
- –Fluoride toxicosis in ruminants
- –Canine distemper virus in dogs
Aplasia
-Reduction in organ growth manifested as markedly reduced or rudimentary organ size
Agenesis
- Complete failure of a tissue or organ to develop
- Ex: amelia, adactyly, anencephaly
Atresia
- Absence of a normal opening
- Ex: atresia coli or atresia ani
Abiotrophy
- Progressive degeneration of cells resulting from an intrinsic defect in cell metabolism, cells develop normally then degenerate
- Most common in degenerative diseases of the CNS
- Ex: cerebellar abiotrophy
Abiotrophy v. atrophy
- Atrophy - cell response to exogenous stimuli
- Abiotrophy - cell response to an inborn error in metabolism (endogenous stimuli)
