Pathology I & II - Parsa Flashcards
What is atrophy?
- Decrease in size and function
* Similar to apoptosis
What is hypertrophy?
Increase in size
What is hyperplasia?
Increase in number of cells
What is metaplasia?
- Replacement of one differentiated cell type by another;
- An adaptive, undesirable genetic reprogramming of precursor cells due to environmental stresses to differentiate into cells that can better withstand the new environment
What is adaptation?
- Reversible functional and structural responses to more severe physiologic stresses and some pathologic stimuli;
- New but altered steady states are achieved, allowing the cell to survive and continue to function
What are some pathologic causes of atrophy? (7)
- Disuse
- Loss on innervations
- Diminished blood supply
- Inadequate nutrition
- Loss of endocrine stimulation
- Aging (senility)
- Pressure
What are some physiologic causes of atrophy? (2)
- Uterine atrophy after parturition
- Thymic involutional changes
involution by apoptosis → decrease in number and size
What are the biochemical mechanisms of atrophy?
Increased protein degradation
Decreased protein synthesis
What is cellular atrophy?
When structural proteins and organelles are destroyed to reduce the cell’s metabolic overheads;
Autophagy
What are some physiologic causes of hypertrophy? (2)
- Hormone stimulated - uterus and breast in pregnancy
2. Increase workload (excerise - skeletal muscle)
What are some pathologic causes of hypertrophy? (4)
- Increased workload associated with changes in gene expression
- Atrial/brain natriuretic factors (BNP)
- a-myosin replaced by b-myosin heavy chain
- Growth factors (TGF-b)
What are some physiologic causes of hyperplasia? (2)
- Hormonal - female breast and puberty and during pregnancy
2. Compensatory - liver after partial hepatectomy
What are some pathologic causes of hyperplasia? (3)
- Excessive hormonal stimulation - prostate, endometrium
- Effects of growth factors on target cells - repair: fibrovascular proliferation
- Viruses (HPV) - epithelial/epidermal proliferative lesions
What is selective hyperplasia?
When hyperplasia occurs at a sub cellular level;
Ex: mitochondrial hyperplasia in muscle hypertrophy
What is the mechanism of metaplasia?
Result of reprogramming of stem cells signaled by:
Cytokines, growth factors, & extracellular factors → induce transcription factors → cascade of genes → differentiated metaplastic cell
