Cell adaptation

Question 1

Atrophy

Answer 1

decrease in size &/or # of the cells & their metabolic activity after normal growth has been reached

• cells are not dead
• decrease protein synthesis & increase protein degradation

Question 2

Atrophy causes

Answer 2

• decrease workload
• denervation
• decrease blood supply or oxygen
• inadequate nutrition
• loss of endocrine stimulation
• aging (senescence)

Question 3

Atrophy examples

Answer 3

• muscle disuse in a limb that is in a cast
• sedentary atrophy
• atrophy of adrenal cortex by reduction of ACTH stimulation (steroid therapy)
• atrophy in tissues adjacent to a tumor due to pressure & compromised blood supply
• physiologic atrophy

Question 4

Hypoplasia

Answer 4

incomplete development or underdevelopment of an organ or tissue; it is less severe in degree than aplasia

Question 5

Hypoplasia Vs atrophy

Answer 5

never achieved full size Vs decreased size due to decrease in cell number

Question 6

Hypertrophy

Answer 6

• increase SIZE of cells & their functions
• synthesis of more organelles & structural proteins: bigger cells
• more common in cells w/ little replication
• stable or permanent cells: cardiomyocytes, neurons

Question 7

Cardiac hypertrophy

Answer 7

• limit beyond which enlargement of muscle mass is no longer able to cope w/ the increased burden
• several regressive changes occur in the myocardial fibers
• extreme cases–> myocyte death

Question 8

Hyperplasia

Answer 8

• increase in the # of cells of an organ

- cells capable of replication

Question 9

Physiologic Hyperplasia examples

Answer 9

• hormonal: ex. mammary gland during pregnancy

- compensatory: ex. hepactectomy

Question 10

Pathologic Hyperplasia most commonly caused by

Answer 10

excessive hormonal or growth factor stimulation

Question 11

Pathologic Hyperplasia examples

Answer 11

• epidermal thickening (repeated irritation)

- respiratory mucosa (in viral infections)

Question 12

What is the difference b/t atrophy, hyperplasia & hypertrophy?

Answer 12

atrophy (decrease size)
hyperplasia (increase #)
hypertrophy (size increase)

Question 13

Metaplasia

Answer 13

• change in phenotype of a differentiated cell
• response to chronic irritation -> cell withstand stress
• may result in decrease functions or increase propensity for malignant transformation (neoplasia)
• reversible if cause is removed
• most often in epithelial cells

Question 14

Metaplasia examples

Answer 14

• chronic irritation in lungs
• vit-A deficiency
• estrogen toxicity
• in mammary tumors

Question 15

Dysplasia

Answer 15

• refers to abnormal development
• mostly epithelial cells
• term mostly used in neoplastic processes