Cell Damage
3
- For each of the causes of membrane damage listed on the left select the most
appropriate association from those listed on the right.
a. C. welchii aphlatoxin.
b. Hypoxia.
c. Ouabain.
A. Digestive damage to cell membrane.
B. Failure of oxidative phosphorylation in mitochondria.
C. Mechanical rupture of cell membrane.
D. Poisoning of cell membrane ion pump.
E. Stimulation of cell membrane ion pump.
The answer is A, B, D. Clostridium welchii aphlatoxin is a lecithinase which digests
cell membrane resulting in increased permeability.
Hypoxia results in decreased oxidative phosphorylation in mitochondria with resultant
lack of ATP.
Ouabain is a specific cell membrane ion pump antagonist which competes with K+
for a site on Na+K+ dependent ATP ase. - For each of the features on the left select the most appropriate association from the
list on the right.
a. Differentiation.
b. Heterotopia.
c. Metaplasia.
A. Development of a clone of cells growing independently of normal cellular control.
B. Loss of cellular specialization.
C. Result of error in intercellular communication in developing fetus.
D. Result of gene activation due to environmental change.
E. Structural and functional specialization of cells.
The answer is E, C, D. Differentiation is a structural and functional specialization of
cells. This is a feature of multicellular organisms, and depends on the selection of genes
which each cell type expresses.
Heterotopia is a result of error in intercellular communication in developing fetus.
Groups of cell differentiate in a way which is inappropriate to their anatomical location.
Metaplasia is a result of gene activation due to environmental change. This is the
change of one differentiated cell type into another, and is often seen as a result of
environmental factors, i.e., cigarette smoking.
Loss of cellular specialization is dedifferentiation.
4
Neoplasia comprises the development of a clone of cells growing independently of
normal cellular controls. - For each example of necrosis listed on the left select the most suitable description
from those on the right.
a. Caseous necrosis.
b. Coagulative necrosis.
c. Colliquative necrosis.
A. Cheese-like material.
B. Dull, swollen firm area.
C. Firm yellow/white patches.
D. Green/black discolouration.
E. Soft, liquefying material.
The answer is A, B, E. Caseous necrosis – cheese-like material. This is the typical
appearance of tuberculous necrosis, but a similar appearance may also be seen in necrotic
tumours, particularly squamous carcinoma.
Coagulative necrosis – dull, swollen firm area. This is typical of infarction in solid
organs such as heart, kidney. Histologically ‘ghost’ outlines of the tissue structure are still
present.
Colliquative necrosis – soft, liquefying material. This is typical of necrotic tisssue with- a high content of fluid, i.e., brain tissue. Histologically the tissue structure is lost.
