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Questions and Answers
What defines atrophy in cellular adaptation?
What defines atrophy in cellular adaptation?
What is a major mechanism causing atrophy?
What is a major mechanism causing atrophy?
Which of the following statements about autophagy is true?
Which of the following statements about autophagy is true?
In which condition is accelerated proteolysis notably observed?
In which condition is accelerated proteolysis notably observed?
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What is the role of ubiquitin ligases in cellular atrophy?
What is the role of ubiquitin ligases in cellular atrophy?
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What may accumulate in cells during prolonged atrophy and resist digestion?
What may accumulate in cells during prolonged atrophy and resist digestion?
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Which cellular adaptation represents a reversible change in the number and size of cells?
Which cellular adaptation represents a reversible change in the number and size of cells?
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Which factors may trigger atrophy in cells?
Which factors may trigger atrophy in cells?
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What characterizes pure hypertrophy?
What characterizes pure hypertrophy?
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Which type of hypertrophy is characterized by increased functional demand?
Which type of hypertrophy is characterized by increased functional demand?
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Which of the following is NOT a cause of hypertrophy?
Which of the following is NOT a cause of hypertrophy?
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What pathway is involved in physiological hypertrophy?
What pathway is involved in physiological hypertrophy?
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What can excessive cardiac hypertrophy lead to?
What can excessive cardiac hypertrophy lead to?
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Which of these organs primarily undergoes pathological hypertrophy under hormonal influence?
Which of these organs primarily undergoes pathological hypertrophy under hormonal influence?
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Which statement about hypertrophy is true?
Which statement about hypertrophy is true?
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What is an advantage of epithelial metaplasia?
What is an advantage of epithelial metaplasia?
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What is a common indicator of pathological hypertrophy in cardiac tissue?
What is a common indicator of pathological hypertrophy in cardiac tissue?
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What is a disadvantage associated with squamous metaplasia?
What is a disadvantage associated with squamous metaplasia?
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Which type of metaplasia involves fibroblast transformation into chondroblast?
Which type of metaplasia involves fibroblast transformation into chondroblast?
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Which of the following is a cause of cellular aging?
Which of the following is a cause of cellular aging?
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Which condition is characterized by premature aging due to DNA damage?
Which condition is characterized by premature aging due to DNA damage?
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What role do exogenous factors play in cellular aging?
What role do exogenous factors play in cellular aging?
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What process involves the transformation of fibroblasts into osteoblasts?
What process involves the transformation of fibroblasts into osteoblasts?
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How does DNA damage contribute to the aging process?
How does DNA damage contribute to the aging process?
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What condition leads to a brown discoloration of tissue known as brown atrophy?
What condition leads to a brown discoloration of tissue known as brown atrophy?
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Which of the following is NOT a common cause of atrophy?
Which of the following is NOT a common cause of atrophy?
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What type of atrophy occurs naturally as part of normal development or aging?
What type of atrophy occurs naturally as part of normal development or aging?
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Which of the following is an example of generalized atrophy?
Which of the following is an example of generalized atrophy?
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What type of atrophy results from prolonged pressure on tissues?
What type of atrophy results from prolonged pressure on tissues?
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Which condition is an example of neuropathic atrophy?
Which condition is an example of neuropathic atrophy?
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Which type of atrophy may result from loss of hormonal regulation?
Which type of atrophy may result from loss of hormonal regulation?
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What is the primary consequence of hypertrophy?
What is the primary consequence of hypertrophy?
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What is hyperplasia primarily characterized by?
What is hyperplasia primarily characterized by?
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Which type of hyperplasia occurs due to hormonal stimulation?
Which type of hyperplasia occurs due to hormonal stimulation?
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What is an example of compensatory hyperplasia?
What is an example of compensatory hyperplasia?
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Which cells are incapable of undergo hyperplasia?
Which cells are incapable of undergo hyperplasia?
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What hormone is primarily responsible for the hyperplastic changes in the uterine smooth muscle during pregnancy?
What hormone is primarily responsible for the hyperplastic changes in the uterine smooth muscle during pregnancy?
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What is the cause of adenomatous hyperplasia of the endometrium?
What is the cause of adenomatous hyperplasia of the endometrium?
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Which type of hyperplasia is associated with viral infections?
Which type of hyperplasia is associated with viral infections?
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What occurs alongside hyperplasia in the massive enlargement of the uterus during pregnancy?
What occurs alongside hyperplasia in the massive enlargement of the uterus during pregnancy?
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What role do growth factors play in both papillomatous epidermal hyperplasia and prostatic gland hyperplasia?
What role do growth factors play in both papillomatous epidermal hyperplasia and prostatic gland hyperplasia?
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What is a potential consequence of hyperplasia?
What is a potential consequence of hyperplasia?
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What is the primary cause of metaplasia?
What is the primary cause of metaplasia?
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What is an example of squamous metaplasia?
What is an example of squamous metaplasia?
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Which of the following is NOT a type of metaplasia?
Which of the following is NOT a type of metaplasia?
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What specific type of metaplasia is referred to as Barrett esophagus?
What specific type of metaplasia is referred to as Barrett esophagus?
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Which cell type is primarily involved in the wound healing process of connective tissue hyperplasia?
Which cell type is primarily involved in the wound healing process of connective tissue hyperplasia?
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How do intrahepatic stem cells respond to hepatitis-related cell injury?
How do intrahepatic stem cells respond to hepatitis-related cell injury?
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Study Notes
Cellular Adaptation
- Cellular adaptation is a new, steady altered state that allows cells to survive and continue to function in abnormal environments.
- Adaptations are reversible changes in cell number, size, phenotype, metabolic activity, or function in response to environmental changes.
- The process can progress to significant cell injury if the stress isn't relieved.
Atrophy
- Atrophy is a decrease in the size of an organ or tissue due to a decrease in cell size and/or number.
- Atrophic cells shrink due to loss of cell substance.
- Atrophic cells may have diminished function but are not necessarily dead. Continued stress can lead to cell death via apoptosis.
- Mechanisms of atrophy include decreased protein synthesis and increased protein degradation in cells. Protein degradation mainly occurs via the ubiquitin-proteasome pathway.
Atrophy: Mechanisms
- Nutrient deficiency and disuse can trigger the ubiquitin-proteasome pathway.
- This pathway activates ubiquitin ligases that attach ubiquitin to cellular proteins, thus targeting the protein for degradation in proteasomes.
- Atrophy is also accompanied by increased autophagy (cellular "self-eating") in which the cell consumes its own components and may result in increased autophagic vacuoles.
- Some of the remaining debris can persist as residual bodies within the cell (eg., lipofuscin).
Atrophy: Causes
- Reduced workload
- Inadequate nutrition
- Ageing
- Loss of innervation
- Reduced blood supply
- Loss of endocrine stimulation
Atrophy: Types
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Physiological atrophy: Natural reduction in size of organs, tissues (e.g., thymus in adults, ductus arteriosus in infants, gonads in old age).
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Pathologic atrophy: Reduction in organ/tissue size due to disease e.g., starvation, chronic inflammation, cancer, ischemia (reduced blood supply).
- Generalized atrophy: Reduction in the size and function of entire organs or organ systems (e.g., due to starvation).
- Localized atrophy: Reduction in the size of a specific area or organ (e.g., due to ischemia).
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Ischemic atrophy (e.g., kidneys in atherosclerosis)
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Disuse atrophy (e.g., muscles in a cast)
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Neuropathic atrophy (e.g., muscles due to nerve damage)
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Endocrine atrophy (e.g., tissues due to hormonal deficiency)
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Pressure atrophy (e.g., tissue due to prolonged pressure)
Hypertrophy
- Hypertrophy is an increase in the size of cells, leading to an increased size of the organ.
- No new cells are created; existing cells simply enlarge.
- Cells containing more structural proteins and organelles. Increased workload and hormonal stimulation can cause hypertrophy.
- Cells capable of division can respond to stress by hypertrophy and hyperplasia.
- Pure hypertrophy affects mainly striated muscles (e.g. heart, skeletal muscle) as well as some stable cells (e.g., liver, kidney).
Hypertrophy: Causes
- Increased functional demand or hormonal stimulation
- In both cases, it's caused either by increased functional demand or hormonal stimulation.
Hypertrophy: Types
- Physiologic hypertrophy: (e.g., skeletal muscle hypertrophy with exercise). Increased uterine size during pregnancy. Breast tissue enlargement during pregnancy.
- Pathologic hypertrophy: Increase in size of an organ due to disease or abnormal stimulation. Example: enlarged left ventricle in response to high blood pressure.
Hyperplasia
- Hyperplasia is an increase in the number of cells in an organ or tissue.
- It occurs through increased cell proliferation of existing cells, differentiated cells or in instances progenitor cells.
- Hyperplasia often results from either hormonal stimulation or tissue loss.
- Many labile cells and stable cells can undergo hyperplasia, unlike permanent cells.
Hyperplasia: Causes
- Hormonal stimulation: Ex., increased breast and uterine smooth muscle during puberty and pregnancy.
- Tissue loss: Ex., regeneration of liver tissue after surgical removal of parts of it.
Hyperplasia: Types
- Physiologic hyperplasia: (e.g. breast at puberty, pregnancy; uterus during pregnancy; compensatory liver increase after removal)
- Pathologic hyperplasia: (e.g. hormonal imbalance in endometrium potentially leading to abnormal periods and cancer risk; viral infections like HPV).
Metaplasia
- A reversible change where one adult cell type (epithelial or mesenchymal) is replaced by another adult cell type.
- Often due to chronic irritation, chronic inflammation, or vitamin A deficiency.
Metaplasia: Causes
- Chronic irritation (e.g., cigarette smoke, stones)
- Chronic inflammation
- Vitamin A deficiency
Metaplasia: Types
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Epithelial Metaplasia:
- Squamous metaplasia (columnar epithelium replacing squamous epithelium, e.g., in respiratory passages or cervix; Barrett’s esophagus)
- Columnar metaplasia (squamous epithelium replacing columnar epithelium, e.g., in Barrett’s esophagus)
- Mesenchymal metaplasia: (fibroblast transforming into cartilage or bone cells. Eg. Myositis ossificans.)
Cellular Aging
- Cellular aging is a progressive decline in the life span and functional activity of cells.
- It's caused by genetic abnormalities, accumulation of cellular and molecular damage and continuous exposure to exogenous factors.
Cellular Aging: Mechanisms
- Telomere shortening
- DNA damage and mutations
- Defective protein homeostasis
- Persistent inflammation
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Description
Explore the concepts of cellular adaptation and atrophy in this quiz. Understand how cells change in response to environmental stressors and the mechanisms underlying atrophy, including the role of the ubiquitin-proteasome pathway. Test your knowledge on these essential cellular processes.
