Ch. 2 Stress, Injury, and Aging Flashcards
(37 cards)
Atrophy
Decrease in cell size and oxygen consumption in adverse conditions (or decreased demands)
How is atrophy related to insulin/insulin-like growth factor-1?
Muscles are maintained by insulin/IGF-1, so if levels are low then muscle atrophy will occur by the ubiquitin-protease system or apoptosis
5 Causes of atrophy
- Disuse
- Denervation (paralysis)
- Loss of endocrine stimulation (menopause)
- Inadequate nutrition
- Ischemia
Hypertrophy
Increase in cell size and tissue mass from increased workload
When does hypertrophy occur?
Normal (exercise) or pathologic
What is an example of adaptive hypertrophy?
urinary bladder thickens when urinary outflow is obstructed
Myocardial hypertrophy from valvular heart disease or HTN
What is an example of compensatory hypertrophy?
When a remaining organ/tissue becomes larger after part of it is removed or becomes inactive
After a kidney removal, the remaining becomes larger to compensate.
How is hypertrophy initiated?
ATP depletion, stretching of muscle fibers, activation of cell degradation products, and hormones.
Hyperplasia
Increase in number of cells in an organ or tissue capable of mitotic division like the epidermis, intestinal epithelium, and glands
How is hyperplasia initiated?
Genes that control cell proliferation are activated
Intracellular messengers that control cell replication are present
What are the two types of physiologic hyperplasia?
- Hormonal (breast and uterine enlargement during pregnancy from estrogen stimulation)
2.Compensatory (regeneration of liver after partial hepatectomy)
What causes nonphysiologic hyperplasia?
Excess hormone stimulation or growth factors
Example: excessive estrogen production causes endometrial hyperplasia
Benign prostatic hyperplasia may be related to androgens
Skin warts caused by growth factors produced by papillomaviruses
Metaplasia
When an adult cell type is replaced by another cell type
What causes metaplasia?
Response (undifferentiated stem cell reprogramming) to chronic inflammation and is an adaptation for tissue to survive a harsh environment
example: columnar ciliated epi cells are replaced by stratified squamous epi cells in the trachea and bronchi of smokers which can better survive smoke but the protective function of cilia is lost
Dysplasia
Deranged cell growth of a specific tissue resulting in cells of varying size, shape, and organization
What causes dysplasia?
Chronic irritation and inflammation
What are the most common examples of dysplasia?
-metaplastic squamous epithelium of respiratory tract and cervix
How does dysplasia relate to cancer?
It may be a precursor for cancer with incremental cellular changes
BUT it is adaptive and can revert!
(this is what an abnormal pap test detects)
What is fatty liver disease?
Intracellular accumulation of triglycerides (liver cells usually have some fat that is oxidized for energy use or stored as triglycerides. Fat is released from adipose tissue. Delivery of free fatty acids to the liver is increased in diabetes mellitus (enzyme hormone sensitive lipase is usually inactivated with binding of insulin) and starvation, and in alcoholism lipid metabolism is disturbed.
What is jaundice an example of?
Endogenous bile pigment accumulation (bilirubin)
Dystrophic calcification
Calcium salt deposits in injured tissue (heart valve calcifications and advanced atherosclerosis)
Metastatic calcifiation
Calcium salt deposits in normal tissue due to hypercalcemia
What are causes of cell injury?
Physical, radiation, chemical. biologic agents, and nutritional imbalances
How does hypoxia lead to cell injury?
It causes ATP depletion due to lowered ECT activity
