Pathology: Tissue and Cell Injury, and Cell Cycle

Question 1

List the ways that cells can adapt

Answer 1

• Hyperplasia
• Hypertrophy
• Atrophy
• Metaplasia

Question 2

How could a tissue adapt to increased demand?

Answer 2

• Hyperplasia

- Hypertrophy

Question 3

How could a tissue adapt to increased demand?

Answer 3

• Atrophy

Question 4

How could a cells adapt to an altered stimulus?

Answer 4

Metaplasia

Question 5

Define hypertrophy

Answer 5

Cells get bigger

Question 6

Define hyperplasia

Answer 6

More cells are produced

Question 7

List the 3 categories of growth receptor

Answer 7

• Receptors with intrinsic tyrosine kinase activity
• 7 transmembrane G protein-coupled receptors
• Receptors without intrinsic tyrosine kinase activity

Question 8

What aspect of the pathways started by the activation of growth receptors make them susceptible to aiding the development of malignancy?

Answer 8

Lots of steps in pathway, so lots of chance for a mutation

The pathways govern cell proliferation so important in malignancy

Question 9

Name the phases of the cell cycle in order (including those of the interphase)

Answer 9

• Gap 1 (G1) phase
• Synthesis (S) phase
• Gap 2 (G2) phase
• Mitotic (M) phase
• Cytokinesis
• Gap 0 (G0) phase

Question 10

Explain the role of CDKs and cyclins at cell cycle checkpoints

Answer 10

• Cyclins accumulate
• Cyclins combine with Cyclin Dependant Kinases (CDKs)
• This activates the CKD
• Activated CDKs
  phosphorylate other proteins
• Stimulating the move to the next phase of the cell cycle

Question 11

Describe the G1 phase

Answer 11

• Cell gets bigger, increased protein synthesis

- Cyclin D accumulates

Question 12

Describe how the G1 progresses to the S phase

Answer 12

• Cyclin D accumulates
• CDK4 activated by cyclin D
• Activated CDK4 phosphorylates (inactivates) retinoblastoma (Rb)
• Usually Rb is bound to E2F, preventing E2F from staring the S phase
• When Rb is phosphorylated E2F is free to start the S phase

Question 13

Describe E2F

Answer 13

• Transcription factor

- When free from Rb it initiates the S phase

Question 14

Describe the S phase

Answer 14

• DNA synthesis to produce 2 copies of the cells genome

Question 15

Which cell cycle phases make up the interphase?

Answer 15

G1, S, G2

Question 16

Describe the G2 phase

Answer 16

• Second growth phase
• Cells get bigger, more protein synthesis
• Main checkpoint occurs at the end of the G2 phase

Question 17

Describe the G2 checkpoint

Answer 17

• p53 is activated if DNA damage s detected
• If there is a mistake then the cell cycle arrests
• Repair is attempted
• If successful then the cell progresses to the M phase, if unsuccessful then apoptosis

Question 18

Describe the M phase

Answer 18

• Prophase, Metaphase, Anaphase, Telophase
  (*The four wonders)
• Ends up with a cell with 2 discrete nuclei

Question 19

Describe cytokinesis

Answer 19

The connecting cytoplasm is severed, leaving 2 identical daughter cells

Question 20

Describe the G0 phase

Answer 20

A resting state where cells can stay if there is no need for cell division

Question 21

Define replicative senescence

Answer 21

When a cell is prevented or is is incapable of dividing

Question 22

Explain the importance of replicative senescence

Answer 22

Cancer suppression:

• Gives all cells max number of divisions
• Cancers have to overcome this

Keeps cells that need to not divide from doing so
e.g. Neurons

Question 23

Describe telomeres

Answer 23

• The “caps” on the end of chromosomes
• Prevent degradation and fusion of the chromosome
• Consist of TTAGGG repeats
• Get smaller every division

Question 24

Describe telomerase

Answer 24

• An enzyme expressed by stem cells

- Regenerates the telomeres

Question 25

Describe physiological hormonal hyperplasia

Answer 25

- Due to hormones | e. g. female breast during puberty, uterine lining during pregnancy

Question 26

Describe compensatory hyperplasia

Answer 26

After tissue loss Not common in most tissues Liver and bone marrow are good examples

Question 27

List the types of physiological hyperplasia

Answer 27

- Hormonal | - Compensatory

Question 28

List the types of pathological hyperplasia

Answer 28

- Hormonal | - Infection

Question 29

Describe pathological hormonal hyperplasia

Answer 29

- Hormonally induced - Will regress on withdrawal of the stimulus e.g. Prostatic hyperplasia

Question 30

Give an example of pathological hyperplasia due to infection

Answer 30

Lymph nodes undergo hyperplasia during infection

Question 31

Describe the cancer risk of hyperplastic tissue

Answer 31

At a higher risk of cancer

Question 32

Describe hyperplasia

Answer 32

More cells are produced - Happens due to specific external signalling - Will regress on withdrawal of stimulus - Can be physiological or pathological

Question 33

Describe hypertrophy

Answer 33

- Cells get bigger - Often occurs along with hyperplasia - Common in non-dividing cells e. g. skeletal muscle, cardiac myocytes - Often in response to mechanical stress

Question 34

Give an example of pathogenic hypertrophy

Answer 34

In response to increased workload cardiac myocytes undergo hypertrophy This becomes pathological when the heart can no longer function as requires more blood than it is provided

Question 35

Give a difference between cancer and hyperplasia

Answer 35

Hyperplasia regresses at stimulus withdrawal Cancer doesn't

Question 36

Define atrophy

Answer 36

A reduction in cell size

Question 37

Give an example of physiological atropy

Answer 37

Cells in many embryological structures

Question 38

List causes of pathological atrophy

Answer 38

- Decreased workload - Loss of function due to loss of innervation - Lack of adequate perfusion - Loss of hormonal stimulation - Inadequate nutrition - Aging - Pressure (endogenous or exogenous)

Question 39

Where are common places to see atrophy due to endogenous pressure?

Answer 39

- Besides tumours | - Besides abscesses

Question 40

Describe the mechanism of atrophy

Answer 40

- Reduced cellular components - Proteins degraded by lysosomes - Often by ubiquitin protease pathway - Some hormones promote atrophy

Question 41

Which hormones promote degradation and atrophy?

Answer 41

- Glucocorticoids | - Thyroid hormone

Question 42

Which hormones oppose atrophy, and support growth?

Answer 42

Insulin

Question 43

A balance of growth and atrophy maintains homeostasis

Answer 43

Yep