Cell injury and adaptation Flashcards
Regarding dystrophic calcification, which of the following statements is correct?
A. It may be caused by multiple myeloma
B. It is associated with hypercalcaemia
C. Calcuim deposition occurs in viable tissues
D. It causes organ dysfunction
D
Explanation
Dystrophic calcification occurs in nonviable (damaged) or dying tissues. It occurs despite normal serum levels of calcium and in the absence of derangements in calcium metabolism. Although dystrophic calcification may be a simple sign of a previous cell injury, it is often a cause of organ dysfunction.
Myeloma causes destruction of bone and an increase calcium level and thus is associated with metastatic calcification
In relation to atrophy, which of the following statements is false?
A. Decreased autophagic vacuoles
B. Decreased smooth endoplasmic reticulum
C. Persistence of residual bodies
D. Decreased myofilaments
A
Explanation
There is an increase of autophagic vacuoles in atrophy
Atrophy is characterized by shrinkage and loss of structural elements of cell (like myofilaments, ER). There is an increase in autophagic vacuoles, into which lysosomes discharge their hydrolytic contents. Some cell debris resists digestion, and they persist as membrane bound residual bodies in cytoplasm (eg Lipofuscin granules).
“Atrophy: A decrease in mass of each cell by loss of cell substance.
- physiologic (Example: embryologic development)
- pathologic (Examples: Disuse, denervation,
ischaemic, nutritive, endocrine-mediated, senile, and pressure atrophies).
- Effected by a change in balance between protein synthesis and degradation, largely in proteasomes.”
Which of the following is an example of hypertrophy?
A. Increased respiratory epithelium in response to vitamin A deficiency
B. Increase in size of female uterus during pregnancy
C. Increase in liver size after partial hepatectomy
D. Increased size of female breast during puberty
B
Explanation
Hypertrophy refers to an increase in mass/ size of each cells and, with such change, an increase in the size of the organ. The hypertrophied organ has no new cells, just larger ones. The increased size of the cells is not due to cellular swelling but to the synthesis of more structural components.
It can be physiological (eg increased demand on striated muscle in body-builders) and pathological (eg diseases causing volume overload & cardiac hypertrophy, BPH) and can occur together with hyperplasia (eg in the pregnant uterus).
The breast hypertrophies during lactation, but during puberty and pregnancy the breast will undergo hyperplasia. Following a partial hepatectomy, the liver undergoes compensatory hyperplasia.
Note: Vit A deficiency induces respiratory epithelium metaplasia.
Which of the following is an example of hypertrophy?
A. the breast at puberty
B. the liver post hepatectomy
C. the pregnant uterus
D. tissue with a high capillary to myocyte ratio
C
Explanation
Hypertrophy refers to an increase in the size of the cells and, with such change, an increase in the size of the organ. The hypertrophied organ has no new cells, just larger ones. The increased size of the cells is due not to cellular swelling but to the synthesis of more structural components. It can be physiological and pathological and can occur together with hyperplasia for example in the pregnant uterus. The breast hypertrophies during lactation, but during puberty and pregnancy the breast will undergo hyperplasia. Following a partial hepatectomy the liver undergoes compensatory hyperplasia.
Note: in muscular hypertrophy, capillary growth is not able to match myocyte growth, hence Capillary to Myocyte ratio decreases in hypertrophy
In relation to hypertrophy, which of the following statements is correct?
A. It is triggered by specific hormonal stimulation
B. It is usually pathological
C. It occurs after partial hepatectomy
D. It increases the function of an organ exponentionally
A
Explanation
Hypertrophy refers to an increase in the size of the cells and, with such change, an increase in the size of the organ. The hypertrophied organ has no new cells, just larger ones. The increased size of the cells is due not to cellular swelling but to the synthesis of more structural components. It can be physiological and pathological and can occur together with hyperplasia, for example, in the pregnant uterus. The breast with hypertrophies during lactation, but during puberty and pregnancy the breast will undergo hyperplasia. Following a partial hepatectomy the liver undergoes compensatory hyperplasia.
Hypertrophy is caused by increased functional demand or by growth factor or hormonal stimulation.
Mechanical triggers, such as stretch and soluble mediators that stimulate cell growth, such as growth factors and adrenergic hormones. These stimuli turn on signal transduction pathways that lead to the induction of a number of genes, which in turn stimulate synthesis of many cellular proteins, including growth factors and structural proteins. The result is the synthesis of more proteins and myofilaments per cell, which increases the force generated with each contraction, enabling the cell to meet increased work demands.
Other triggers of hypertrophy include mechanical and trophic triggers. Eventually the hypertrophied organ reaches a limit when it is no longer able to compensate for the increased demand, and failure ensues.
Extra: When describing stimuli for hypertrophy: - the most common stimulus for muscular hypertrophy is increased workload.
All the following are features of apoptosis, with the exception of?
A. Formation of cytoplasmic blebs
B. Phagocytosis of apoptotic bodies
C. Cell swelling
D. Chromatin condensation
C
Explanation
Cell shrinkage occurs during apoptosis, which is a form of cell death whereby no harmful substances are released into the surrounding tissue. It is the body’s natural process for removing old, diseased or unnecessary cells.
Apoptotic cells usually exhibit a distinctive constellation of biochemical alterations that underline structural changes. These include:
Activation of caspases: the presence of cleaved, active caspases is a marker for cells undergoing apoptosis.
DNA breakdown
Membrane alterations and recognition by phagocytes
Which of the following statements is correct in relation to dystrophic calcification?
A. It rarely causes dysfunction
B. It is formed by crystalline calcium phosphate
C. It is specific to coagulative necrosis
D. It does not occur on heart valves
B
Explanation
Dystrophic calcification occurs in nonviable or dying tissues. It occurs despite normal serum levels of calcium, and in the absence of derangements in calcium metabolism. Although dystrophic calcification may be a simple sign of a previous cell injury, it is often a cause of organ dysfunction. Myeloma causes destruction of bone and an increase calcium level and is thus associated with metastatic calcification. Dystrophic calcification occurs in all area of necrosis including coagulative, caseous and liquifactive.
In dystrophic calcification, Calcium deposition ultimately involves precipitation of a crystalline calcium phosphate similar to bone hydroxyapatite.
Reversible cell injury is characterised by all of the following, except?
A. Detachment of ribosomes
B. Cellular swelling
C. Lysosomal rupture
D. Nuclear chromatin clumping
C
Explanation
In reversible injury, there is cellular swelling, organelle swelling, blebbing of the plasma membrane, detachment of ribosomes from the ER and nuclear chromatin clumping. It also includes decreased ATP generation, loss of cell membrane integrity, and defects in protein synthesis, cytoskeletal and DNA damage. For a cell to enter the “point of no return”-irreversible injury, it goes through the stages of reversible injury-so features will overlap. However, nucleus destruction in irreversible injury includes pyknosis-karyorrhexis and karolysis. Other features of irreversible cell injury include: lysosomal rupture and disruption/defects of the cellular membranes and depletion of ATP
With regard to metaplasia, which of the following statements is correct?
A. It is typically an irreversible process
B. It is the process that occurs in Barrett’s oesophagus
C. It can be caused by vitamin B12 deficiency
D. It preserves mucus secretion in the respiratory tract
B
Explanation
Metaplasia is a reversible change in which one adult cell type is replaced by another adult cell type. It is an adaptive substitution of cells, which are sensitive to stress, by cell types better able to withstand the adverse environment. The most common metaplasia is columnar to squamous occurring in the bronchial tree due to smoking. Metaplasia of squamous to columnar type occurs in Barrett’s oesophagus. Vitamin A deficiency induces squamous metaplasia in the respiratory epithelium which is a reversible process. However, if the stimulus which has predisposed to such a metaplasia persists, it may induce cancer transformation.
Note:
Vit B12 deficiency is associated with a number of disorders, but most commonly it is associated with penicious anaemia. In pernicious anaemia, the most characteristic alteration is atrophy of the fundic glands, affecting both chief and parietal cells, the latter being virtually absent. The glandular lining epithelium is replaced by mucous-secreting goblet cells that resemble those lining the large intestine, a form of metaplasia referred to as intestinalisation. Pernicious anaemia is believed to result from an autoimmune attack on the gastric mucosa. The gastric atrophy and metaplastic changes are due to autoimmunity and not vitamin B12 deficiency; hence while parenteral administration of B12 corrects the megaloblastic changes in the marrow and the epithelial cells of the alimentary tract, gastric atrophy and achlorhydria will persist).
“Metaplasia: A reversible change when one cell type is replaced by another cell type (Examples: Columnar to squamous metaplasia in trachea and bronchi of smokers; squamous to columnar in Barrett’s oesophagus).
- Effected by reprogramming of stem cells to differentiate along an alternate pathway
- Is an adaptation that allows the new cells to better deal with altered environment, and occurs in response to a
chemical or physical stressor”
With regards to dysplasia, which of the following features is correct?
A. It is characterised by cellular pleomorphism
B. It is not associated with architectural abnormalities
C. It is a feature of mesenchymal cells
D. It inevitably progresses to cancer
A
Explanation
Dysplasia means disordered growth and is encountered principally in the epithelia. It is characterised by a constellation of changes which include a loss in the uniformity of the individual cells, as well as a loss in their architectural orientation. Dysplastic cells exhibit considerable pleomorphism (variation in shape and size). Dysplasia does not necessarily progress to cancer and only if the entire thickness of the epithelium becomes dysplastic is it likely to progress to a carcinoma in situ. If not the process is usually reversible.
“Dysplasia (disordered growth):
- Alteration in the size, shape and organization of the cellular components of a tissue
- Often reversible
- May result from an environmental insult
- Necessary stage in cancerous transformation
Eg: Epithelial changes in skin (bronchus or cervix) in response to noxious stimuli”
Which of the following statements is correct regarding metastases?
A. They are proven by the finding of lymph node enlargement adjacent to a tumour
B. The breast usually metastasises to supraclavicular nodes
C. They unequivocally prove malignancy
D. They are the most common presentation of melanoma
C
Explanation
Metastases are tumour implants that are discontinuous with the primary tumour. Metastases unequivocally mark a tumour as malignant, because benign tumours do not metastasis. Breast cancers usually metastasis to the axillary lymph nodes. The tumour following, the natural lymphatic drainage route. Lymph node enlargement adjacent to a tumour may be reactive or inflammatory in nature
Metastatic calcification may occurs in which of the following situations?
A. Atherosclerotic vessels
B. Damaged heart valves
C. Tuberculous lymph nodes
D. Gastric mucosa
D
Explanation
Metastatic calcification occurs in normal tissues and is associated with a raised serum calcium
There are 4 principal causes of hypercalcaemia;
- Increased serum parathyroid hormone (PTH)
- Destruction of bony tissue
- Vit D related disorders
- Renal failure
Metastatic calcification may occur widely throughout the body but mainly affects the interstitial tissues of the gastric mucosa, kidneys, lungs systemic arteries and pulmonary veins. These tissues excrete acid and therefore have an internal alkaline medium that predisposes them to metastatic calcification.
Note: atherosclerotic vessels have dystrophic calcium deposits
Which of the following cell organelles is found in the greatest number in growing cells and synthesise ribosomes?
A. Mitochondria
B. Golgi bodies
C. Nucleoli
D. Endoplasmic reticulum
C
Explanation
This question can be an EMQ
Potential stems: ER, golgi, nucleus, peroxisomes, lysosomes, mitochondria and nucleoi
The nucleus of most cells contains a nucleolus, a patchwork of granules rich in RNA. In some cells, the nucleus contains several of these structures. Nucleoli are most prominent and numerous ingrowing cells. They are the site of ribosome synthesis, the structure in the cytoplasm in which proteins are synthesised.
Gangrene of the great toe is associated with what type of necrosis?
A. Coagulative
B. Fibrinoid
C. Liquefactive
D. Caseous
A
Explanation
Gangrenous necrosis is not a distinctive pattern of cell death; however the term is still used in surgical clinical practice. It usually applies to a limb, generally the lower leg which has lost its blood supply and has undergone COAGULATIVE NECROSIS. When bacterial infection is superimposed, coagulative necrosis is modified by the liquefactive action of the bacteria and the attracted leukocytes. (wet gangrene)
In which type of tissue pH is metastatic calcification most likely to deposit?
A. Neutral
B. None of the above
C. Acidic
D. Alkaline
D
Explanation
Metastatic calcification (MC) may occur in normal tissues whenever there is hypercalcaemia. It can occur widely throughout the body but principally affects interstitial tissues of gastric mucosa, kidneys, lungs, systemic arteries and pulmonary veins. All of these tissues excrete acid, and therefore have an internal alkaline compartment that predisposes them to metastatic calcification. Usually, metastatic calcification causes no clinical dysfunction.
Note: another question on metastatic calcification MC occurs in tissues that excrete which type of substance? The correct answer is: Acid
