Disorders of tissue growth

Question 1

Describe the 3 cells are involved in normal tissue growth?

Answer 1

Labile cells - continuously dividing, proliferate throughout life, replacing those that are lost
Stable cells - cells with low levels of replication, but in response to stimuli undergo rapid division
Permanent cells - non-dividing, have left the cell cycle and cannot undergo mitotic division

Question 2

Give some examples of labile cells

Answer 2

Epithelia, epidermis, intestinal mucosa

Adult stem cells

Question 3

Give some examples of stable cells

Answer 3

Mesenchymal cells (fibroblasts, osteocytes, liver, kidney, pancreas

Question 4

Give some examples of permanent cells

Answer 4

Neurones

Heart muscle cells

Question 5

What are stem cells?

Answer 5

Cells that lack fully differentiated morphological, functional and behavioural characteristics

Question 6

Which cells have the ability to give rise to all tissues of the body?

Answer 6

Totipotent embryonic stem cells

Question 7

Which cells can give rise to a smaller variety of tissue types?

Answer 7

Pluripotent, adult stem cells

Question 8

Compare agenesis and aplasia

Answer 8

Agenesis = absence of an organ or body part (no first tract of this structure)
Aplasia = failure of an organ to develop (usually accompanied by the presence of a rudimentary organ)

Question 9

The terms metaplasia, dysplasia and anaplasia all come under which category?

Answer 9

Abnormal cell growth

Question 10

What is hypoplasia?

Answer 10

Failure of an organ to develop to its full size - growth stops
Causes - unknows, genetic, hormone, infectious agent

Question 11

What is atrophy?

Answer 11

Shrinkage of an organ or tissue after it has reached its normal size, caused by a reduction of cell size or number

Question 12

Compare qualitative and quantitative atrophy

Answer 12

Qualitative - cells shrink = reduction in size

Quantitative - cell death exceeds replacement = reduction in number

Question 13

What are some possible causes for cell atrophy?

Answer 13

• Lack of nutrients
• Lack of blood supply
• Lack of innervation
• Disease
• Loss of hormonal stimulation

Question 14

What are the 3 methods of increased growth?

Answer 14

Hyperplasia
Hypertrophy
Neoplasia

Question 15

Define hyperplasia

Answer 15

An increase in the size of an organ due to an increase in cell number - increases mitotic division
It is a reversible change

Question 16

What triggers hyperplasia and hypertrophy?

Answer 16

Hormones
Growth factors
Cytokines
Transcription factors

Question 17

Give 2 examples of hyperplasia in the body

Answer 17

• Mammary gland hyperplasia in response to increased hormonal stimulation during pregnancy and lactation
• Compensatory liver hyperplasia after a hepatectomy

Question 18

Define hypertrophy

Answer 18

An increase in the size of an organ due to an increase in cell size - more organelles
It is a reversible change

Question 19

What is the only type of morphological change in growth that can happen in permanent cells?

Answer 19

Hypertrophy

Question 20

What is the overall cause of hypertrophy?

Answer 20

Demands for increased function

Question 21

Define metaplasia

Answer 21

A reversible change in which one adult cell type is replaced by another adult cell type

• A highly specialised tissue is replaced by a less specialised but more resistant tissue
• Used for protection

Question 22

If the metaplastic injurious stimulus persists what can it lead to?

Answer 22

Neoplastic transformation

Question 23

How can chronic irritation affect the epithelium?

Answer 23

Transformation from columnar to squamous

Question 24

Define dysplasia

Answer 24

Loss of uniformity of the individual cells as well as loss in their architectural orientation
- Epithelium undergo disordered growth and maturation

Question 25

How is dysplasia characterised grossly and microscopically?

Answer 25

• Loss of uniformity of the individual cells and disorganisation, variation in the size and shape of cells and their nuclei

Question 26

What is the most common cause of dysplasia?

Answer 26

Chronic inflammation