Exam 1: Cellular Adaptations & Accumulations I

Question 1

What is adaptation?

Answer 1

State between the normal unstressed cell & the injured over-stressed cell; the new but altered steady state

Question 2

List some reversible changes that are seen in response to cellular damage.

Answer 2

• Changes in size
• Changes in number
• Phenotype
• Metabolic activity

Question 3

What is physiologic adaptation?

Answer 3

Responses of cells to normal stimulation by hormones or endogenous chemical mediations

Question 4

What is patholgoic adaptation?

Answer 4

Underlying disease mechanisms that allows cells to modulate their environment and escape injury

Question 5

What is hypertrophy?

Answer 5

Increase in cell size & consequent increase in the size of the organ

• No new cells
• Increased synthesis of structural proteins & organelles
• Opposite of atrophy

*Note that this can coexist with hyperplasia (increase in #) and physiologic or pathologic

Question 6

What is hyperplasia?

Answer 6

Increase in number of cells in response to a stimulus or persistent cell injury, which usually results in increased size & weight of an organ or tissue

• Frequently occurs in conjunction with hypertrophy
• Can be physiologic or pathologic

*Cells must be capable of replication

Question 7

What is atrophy?

Answer 7

Decrease in size of a tissue or organ due to a decrease in cell size & organelles

Question 8

What is metaplasia?

Answer 8

A reversible change in cell type i.e. change in which on differentiated cell type is replaced by another cell type
- Cells sensitive to a particular stress are replaced by cells better able to withstand the stress

*Through to arise through “reprogramming”

Question 9

How does the hypertrophy of weight lifting and pregnancy differ?

Answer 9

• Weight lifting= hypertropy without hyperplasia

- Pregnancy= uterus hypertrophies and undergoes hyperplasia

Question 10

Describe an example of pathologic hypertrophy.

Answer 10

• Cardiac enlargement that occurs with HTN or aortic valve disease
• Enlargement of individual cardiac fibers following a MI

*Note that cardiac cells DO NOT enter the cell cycle; thus, they can only get larger

Question 11

What is the difference between concentric hypertrophy & dilated hypertrophy seen in CHF?

Answer 11

• Concentric hypertrophy

Limited ability to enlarge, then degeneration

Question 12

What happens structurally in cardiac hypertrophy? What are the microscope indications of hypertrophy?

Answer 12

• Increased nucleus to make more proteins (“boxcar” nuclei)
• Increased cytoplasm

Question 13

What are the mechanisms that induce hypertrophy?

Answer 13

1) Mechanical stress
2) Vasoactive agents (alpha-adrenergic)
3) Growth factors (TGF-B)

*****There is a limit in the enlargement that can occur and you reach a point where the muscle can no longer compensate, which leads to cardiac failure

Question 14

What changes in expression of genes and proteins occurs in hypertrophy? Are these changes reversible?

Answer 14

• Early embryonic genes are turned on
• Increased synthesis of contractile proteins (actin & myosin filaments)
• Increased production of growth factors that have an autocrine effect

*Yes, these changes are reversible

Question 15

What are the types of physiologic hyperplasia?

Answer 15

• Homronal hyperplasia= increase in functional capacity of a tissue when needed e.g female breast tissue during puberty and pregnancy, and proliferation of the endometrium that is induced by estrogen
• Compensatory hyperplasia= increased tissue mass after damage or resection e.g. liver begins to regenerate in as little as 12 hours

Question 16

What causes most forms of pathologic hyperplasia? List common examples of pathologic hyperplasia.

Answer 16

Most forms of pathologic hyperplasia are due to excessive hormones or growth factors acting on target cells

• E.g. Endometrial hyperplasia due to estrogen/progesterone imbalance
• BPH due to an increase in androgens

Grave’s disease (antibody stimulation, NOT hormonal)

Question 17

What is the mechanism of hyperplasia?

Answer 17

Result of growth factor-driven proliferation of mature cells, & in some cases by increased output of new cells from tissue stem cells

Question 18

What causes atrophy?

Answer 18

• Decreased workload (disuse atrophy)
• Loss of innervation (denervation atrophy)
• Decreased blood supply, called “senile” atrophy
• Inadequate nutrition
• Loss of endocrine stimulation
• Pressure (tissue compression)

Question 19

What are the mechanisms of atrophy?

Answer 19

1) Decreased protein synthesis & increased protein degradation in cells
2) Degradation occurs mainly by ubiquitinaton
3) Autophagy
4) May see increased number of autophagic vacuoles & membrane-bound residual bodies (lipofuscin)

Question 20

What is lipofuscin an indication of?

Answer 20

Age

- Residual bodies that result from being unable to completely digest the phospholipid membrane

Question 21

How is metaplasia seen in smokers?

Answer 21

Replacement of pseudostratified ciliated columnar epithelial cells with stratified squamous epithelial cells

*This is to try and increase the number of cells for the mucociliary escalator & referred to as “squamous metaplasia”

Question 22

Why is metaplasia considered a “double-edged sword?”

Answer 22

Important protective mechanisms are lost; it is more likely that metaplastic cells will transition to dysplastic

Question 23

What happens in Barrett’s esophagus?

Answer 23

Metaplasia of normal squamous mucosa in esophagus to columar mucosa in esophagus

*This is an attempt to deal with the acid in the esophagus

Question 24

What is the typical cause of metaplasia in the connective tissue?

Answer 24

Necrosis leads to formation of cartilage, bone, or adipose tissue in tissue that does NOT normally contain these elements

• E.g.
• Bone formation in muscle after intramuscular hemorrhage
• **Note that this may be result of tissue injury & healing rather than true metaplasia

Question 25

Describe the mechanism of metaplasia.

Answer 25

Metaplasia is the result of reprogramming stem cells that exist in normal tissues

Question 26

What is dysplasia?

Answer 26

Disordered growth

- Farther “down the road” to neoplasia than metaplasia

Question 27

What are the morphological changes that are seen in dysplasia?

Answer 27

• Variations in size & shape of the cell
• Disroderly arrangement within the epithelium
• Nuclear changes, consisting of enlargement, irregular borders, hyperchromasia, or individual cell nuclei