Growth Adaptations, Cellular Injury, and Cell Death

Question 1

A decrease in STRESS leads to a decrease in organ size (atrophy)

Atrophy is a decrease in cell size or in the number of cells. How is each accomplished?

Answer 1

decrease in cell size - ubiquitin-proteosome degradation of cytoskeleton (INTERMEDIATE FILAMENTS) and autophagy of cellular components

decrease in cell number - apoptosis

Question 2

Hyperplasia?

Hypertrophy? What cells undergo hypertrophy that cannot undergo hyperplasia

Answer 2

HPlasia - Increase in the number of new cells from stem cells

Htrophy - Increase in the size of the cells by increased protein synthesis (Intermediate filaments) and production of organelles; cardiac muscle, skeletal muscle, neurons

Question 3

Physiologic vs Pathologic Hyperplasia

Answer 3

An example of physiologic hyperplasia is pregnancy

Pathologic hyperplasia can lead to dysplasia and eventually cancer - endometrial hyperplasia –> this happens if you are exposed to estrogen for long periods of time

Benign prostatic hyperplasia does NOT increase risk of cancer

Question 4

Barrett esophagus

Answer 4

A change from non-keratinizing squamous epithelium to non-ciliated, mucin-producing columnar cells as a result of acid reflux

This is a metaplasia that is reversible if the stress is taken away

Question 5

Apocrine metaplasia of the breast

Answer 5

Does not carry an increased risk of cancer

Question 6

Vitamin A deficiency can lead to 4 complications:

Answer 6

1. VA is needed for differentiation of specialized epithelial surfaces in the eye – without it, the goblet cell/columnar epithelium of the conjunctiva undergoes metaplasia into keratinizing squamous epithelium (keratomalacia)
2. dry eyes (xerophthalmia) lead to dry eyes and blindness (Vitamin A is involved in tear production)
3. night blindness
4. Can lead to acute pro-myelocytic leukemia; the 15-17 translocation disrupts the retinoic acid receptor and causes cells to remain in the blast state

Question 7

Myositis Ossificans

Answer 7

The connective tissue in muscle changes to bone during healing after trauma

Not to be confused with osteosarcoma (this will be growing off the bone; MO will not be growing off the bone - there will be a separation)

Question 8

Dysplasia?

Aplasia?

Hypoplasia?

Answer 8

disordered cell growth; often arises from long-standing pathological hyperplasia or metaplasia

failure of cell production during embryogenesis (unilateral renal agenesis)

decrease in cell produce during embryogensis leading to a small organ - streak ovary in Turner’s syndrome