pathology: cellular growth and differentiation

this pathology lecture covered some basic concepts about normal and abnormal cell growth and differentiation. there are several categories of such processes: first is "acquired benign changes", which includes hyperplasia- the increase in the number of cells in a tissue or organ, as well as hypertrophy, which is an increase in the size of the cells. atrophy is the opposite; the decrease in cellular substance and therefore size, due to aging or decreased workload/innervation/nutrients/blood supply/endocrine stimulation. the next category is "congenital/developmental changes", and includes hypoplasia- the defective formation or incomplete development of a part, and agenesis- the absence or failure of formation of an organ or tissue.

the next categories are acquired pre-malignant and acquired malignant. metaplasia is the abnormal transformation of fully differentiated cells into another type of cell; for example, the transition from columnar to squamous cells in a smoker's larynx, or the transition from squamous to columnar cells in a lower esophagus damaged by acid reflux. dysplasia is a partial "de-differentiation" of cells which causes them to lose their functionality, adhesions to neighboring cells, and causes their nuclei to enlarge. anaplasia is an acquired malignant change which is a complete loss of differentiation of cells, as in oat cell carcinoma.

questions
1. define "differentiation" with respect to cell development.
2. what is hyperplasia?
3. what is hypertrophy?
4. what is atrophy?
5. what can cause cell atrophy?
6. what is hypoplasia?
7. what is agenesis?
8. what is metaplasia?
9. what are some examples of metaplasia?
10. what is dysplasia?
11. what is anaplasia?

answers
1. development of specialized morphology and function in cells.
2. increase in the number of cells in an organ or tissue.
3. increase in size of cells in an organ or tissue.
4. decrease in cell size by loss of cell substance.
5. aging, or decreased workload, blood supply innervation, nutrition, endocrine stimulation.
6. defective formation or incomplete development of a tissue or organ.
7. absence or failure of formation of a tissue or organ.
8. the abnormal transformation of one differentiated tissue into another.
9. columnar cells changing into squamous cells in the smoker's larynx, and chronic acid irritation in the lower esophagus changing squamous to columnar cells.
10. an abnormal de-differentiation of tissue. cells lose adhesions, nucleus grows bigger, becomes like a stem cell.
11. a total loss of differentiation as in oat cell carcinoma.