P3- Disorders of Growth and Neoplasia Flashcards Preview

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Flashcards in P3- Disorders of Growth and Neoplasia Deck (38)
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What is the size of the cell population in adult tissues determined by?

rates of cell proliferation, differentiation and death by apoptosis


What can cell numbers be altered by?

rates of stem cell input, by cell death due to apoptosis or by changes in the rate of proliferation or differentiation


What is the key to regeneration of a cell population?

control of the cell cycle


what is the cell cycle controlled by?

chemical factors in the microenvironment of the cell :
-stimulation and inhibitors


what can growth result from?

– Shortening cell cycle time
– Recruiting cells from resting or quiescent population


What cells are not capable of replicating?

Terminally differentiated cells e.g. myocytes


What happens to cells in the liver/kidney?

differentiated cells are normally quiescent but can proliferate when needed


What happens to epithelia of oral cavity, gut and the skin?

the mature cells are terminally differentiated, short-lived and incapable of replicating but may be replaced by new cells arising from stem cells


Name 3 inhibitors of apoptosis.

– Growth factors
– Cell matrix components
– Viral proteins


Name 3 inducers of apoptosis.

– Withdrawal of growth factors
– Loss of matrix attachment
– Viruses


Name the molecular mediators and regulators of apoptosis.

– Extrinsic pathway
• Death receptors
– Intrinsic pathway
• Increased mitochondrial permeability
• Can induce OR inhibit
– Caspases - cascade
– p53


What is hypertrophy?

• An increase in cell size
• Physiological and pathological
• Muscle:
– Skeletal
– Cardiac


What is hyperplasia?

• An increase in cell number
• Physiological and pathological.
• Hormonally sensitive organs:
– Endometrium
– Breast
– Thyroid


What happens in hyperplasia?

• Enlargement of gingival tissues
• Hyperplastic responses within epithelium and underlying connective tissue
• Various causes including certain drugs


What is atrophy?

• Reduction in cell size by loss of cell substance
• Manycauses
• Physiological (thyroglossal duct)and pathological
– Ageing
– Lack of use / stimulation
• Mechanical
• Functional


What is hypoplasia?

• Reduced size of an organ that never fully developed to normal size
• Adevelopmental defect
• e.g. pulmonary hypoplasia


What is metaplasia?

• REVERSIBLE change in which one adult cell type is replaced by another adult cell type
• Can be part of an adaptive response to stress
• Reprogramming of stem cells
• Barrett’s oesophagus,
• Cervix, Bronchus,
• Salivary ducts (sialometaplasia)


What can metaplasia also effect?

• Can also affect mesenchymal tissues
• Not in itself a neoplastic disorder
• Environmental changes leading to metaplasia may if persistent lead to further changes that can manifest as dysplasia and progress to malignancy (cancer) – e.g. Barrett’s oesophagus


What disorder of growth and neoplasia are reversible?

o Hypertrophy
o Hyperplasia
o Atrophy
o Metaplasia
o Dysplasia
o Neoplasia


What disorder of growth and neoplasia are irreversible?



What does dysplasia mean?

disordered growth


Describe dysplasia.

• A pre-malignant process
• Can be identified in
many tissues
• Epithelia are a good example
– Squamous
– Glandular


What happens to do the epithelium in dysplasia?

Atypical epithelial alterations limited to the surface epithelium

Alterations in:


What are the 3 different degrees of dysplasia?

– Mild
– Moderate
– Severe / carcinoma in situ


what do more severe forms of dysplasia have a significant risk for?

progressing to invasive malignancy


What does neoplasia mean?

New growth


What is neoplasia?

A neoplasm is an abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of the normal tissues, and persists in the same excessive manner after cessation of the stimuli that evoked the change


What does neoplasia result from?

Aberration of the normal mechanisms that control cell number ie
-Cell production by cell division
-Cell loss by apoptosis


What are features of most tumours?

Most tumours are monoclonal ie all the cells in a tumour appear to arise from one parent cell which has undergone a genetic change. This is then passed on to all the progeny


What do tumour cells lack?

the normal control mechanisms thus the clone expands due to uncontrolled proliferation