Lecture 1 - Cell and Tissue Adaptations

Question 1

In microenvironment, cells interact with:

Answer 1

• adjacent cells
• extracellular matrix
• vascular elements / blood / fluid

cell/hormone, cell/cell, cell/ECM

Question 2

List some physical signals cells respond to:

Answer 2

stretch, cold, heat, electricity

Question 3

Name some labile cells (divide continuously)

Answer 3

skin, hair, mucosa, stem cells (bone marrow)

Question 4

What are quiescent or stable cells?

Answer 4

Divide only in stress or repair

- liver, glands, stroma, smooth muscle cells, endothelial cells, renal tubular epithelium

Question 5

Non-dividing cells?

Answer 5

Cardiac muscle, skeletal muscle, nerve cells

Question 6

Adaptive responses are _______; cell death is not.

Answer 6

REVERSIBLE

Question 7

List some adaptive responses.

Answer 7

Hyperplasia, hypertrophy, regeneration, atrophy, metaplasia, dysplasia (sometimes)

Question 8

Hyperplasia:

Answer 8

Increase in cell NUMBER
- labile and stable cell populations

Physiologic: hormonal control
Pathologic: aberrant hormone, HPV (warts)

Question 9

What is neoplasia?

Answer 9

Irreversible and unregulated cell proliferation; no external signal

Question 10

Hypertrophy:

Answer 10

Increase in size of cells
- can occur in most all cells

More proteins, organelles, cytoskeletal elements synthesized to support new size

Question 11

What is scar tissue?

Answer 11

Fibroblasts and collagen

Question 12

Atrophy:

Answer 12

Loss of cell size OR loss of cells

- cell shrinkage, cell injury, necrosis, apoptosis

Question 13

List two modes for atrophy; decreasing synthesis and increasing degradation of cellular components.

Answer 13

• Ubiquitin proteosome pathway - mark for destruction

- Increase in autophagic vacuoles (lipofuschin granules / brown atrophy)

Question 14

Causes of atrophy (6):

Answer 14

• Disuse
• Decreased nutrients/oxygen (ischemia)
• Loss of innervation
• Loss of endocrine stimulation
• Aging
• Pressure

Question 15

Aplasia / aplastic:

Answer 15

No division

- aplastic anemia: loss of stem cells in marrow

Question 16

Hypoplasia / hypoplastic:

Answer 16

lack of development

• congenital abnormalities
• marrow that makes some cells, but not enough

Question 17

Metaplasia:

Answer 17

One adult cell type replaced by another
- usually adaptive in response to chronic infection, irritation, injury

Stratified squamous best at resisting injury
ONLY in dividing tissues

Question 18

Examples of metaplasia:

Answer 18

• Cigarette smoking: columnar bronchial epithelium to squamous epithelial
• Vitamin A deficiency
• Squamous epithelium to columnar epithelium in Barret’s esophagus (GERD)
• Transitional epithelium to squamous epithelium in Schistosoma haematobium

Question 19

Dysplasia:

Answer 19

Abnormality of cell morphology and alterations in tissue architecture; often pre-cancerous

Further damage –> neoplasia

Question 20

In metaplasia, tissue is ___________.

In dysplasia, tissue development is ________.

Answer 20

normal and well-differentiated; NOT normal - altered cell development via genetic alterations