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Questions and Answers
Which condition usually leads to hypertrophy of cardiac muscle?
Which condition usually leads to hypertrophy of cardiac muscle?
What characterizes physiological hypertrophy in smooth muscle during pregnancy?
What characterizes physiological hypertrophy in smooth muscle during pregnancy?
What is a common cause of atrophy?
What is a common cause of atrophy?
What indicates that metaplasia is occurring?
What indicates that metaplasia is occurring?
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Which of the following is a potential consequence of persistent metaplastic change?
Which of the following is a potential consequence of persistent metaplastic change?
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What is a characteristic of hypertrophy in adult muscle cells?
What is a characteristic of hypertrophy in adult muscle cells?
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Which stimulus is primarily associated with squamous metaplasia in the respiratory epithelium?
Which stimulus is primarily associated with squamous metaplasia in the respiratory epithelium?
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Which of the following is NOT typically a cause of atrophy?
Which of the following is NOT typically a cause of atrophy?
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What type of receptor is primarily activated by growth factors during cell proliferation?
What type of receptor is primarily activated by growth factors during cell proliferation?
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Which of the following signaling molecules is a local mediator?
Which of the following signaling molecules is a local mediator?
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What is the main role of G-proteins in cell signaling?
What is the main role of G-proteins in cell signaling?
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During which phase of the cell cycle does the most dramatic event, mitosis, occur?
During which phase of the cell cycle does the most dramatic event, mitosis, occur?
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What is the main function of the Retinoblastoma Protein (pRb) in the cell cycle?
What is the main function of the Retinoblastoma Protein (pRb) in the cell cycle?
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Which type of cell population is characterized by persistent division, such as stem cells?
Which type of cell population is characterized by persistent division, such as stem cells?
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What occurs during interphase of the cell cycle?
What occurs during interphase of the cell cycle?
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What is a characteristic of enzyme-linked receptors?
What is a characteristic of enzyme-linked receptors?
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What is the primary characteristic of stable cell populations?
What is the primary characteristic of stable cell populations?
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Which process describes a change of one differentiated cell type to another?
Which process describes a change of one differentiated cell type to another?
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What typically triggers physiological hyperplasia in the female breast?
What typically triggers physiological hyperplasia in the female breast?
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In which scenario is hypertrophy most likely to occur?
In which scenario is hypertrophy most likely to occur?
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What defines pathological hyperplasia?
What defines pathological hyperplasia?
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What characterizes permanent cell populations like neurones and cardiac myocytes?
What characterizes permanent cell populations like neurones and cardiac myocytes?
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Which statement about atrophy is correct?
Which statement about atrophy is correct?
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What is a common outcome of compensatory hyperplasia?
What is a common outcome of compensatory hyperplasia?
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Study Notes
Cellular Adaptations
- Cellular adaptations are adjustments cells make in response to changes in their environment.
- Objectives include describing cell signaling pathways, introducing the cell cycle, and focusing on adaptive responses in cell growth and differentiation.
Control of Cell Growth
- Cells in multicellular organisms communicate via chemical signals.
- Hormones act over long distances.
- Other local mediators act within the local environment (paracrine/autocrine).
- Some cells communicate directly through cell-cell contact.
Cell Signaling Molecules
- Hormones include insulin and cortisol.
- Local mediators include epidermal growth factor (EGF), platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), TGFβ, cytokines (e.g., interferons, TNF).
Receptors
- Two main receptor types are important for cell growth: G-protein-linked receptors and enzyme-linked receptors.
G-protein-linked receptors
- Activate GTP-binding proteins (G-proteins).
- G-proteins are molecular switches.
- They remain active briefly while bound to GTP.
- They turn off by hydrolyzing GTP to GDP.
Enzyme-linked receptors
- Have intracellular domains with enzyme function.
- Mostly receptor tyrosine kinases.
- Activated by growth factors.
- Important in cell proliferation.
- Some activate small GTP-binding proteins like Ras, important in cancer.
The Cell Cycle
- Eukaryotic cell cycle consists of distinct phases, most dramatically nuclear (mitosis) and cytoplasmic (cytokinesis) division.
- M phase.
- Interphase: DNA replication, gene transcription, protein synthesis, and growth occur deceptively without major events.
Cell Cycle Control
- The restriction point (R point) at the end of G1 is the most critical checkpoint.
- Passage beyond R point depends on phosphorylation of the retinoblastoma protein (pRb).
Cell Populations
- Labile: Stem cells constantly divide to replenish losses (e.g., epithelial, hematopoietic cells). Often rapid proliferation.
- Stable: Cells rest in G0, but can divide when stimulated (e.g., hepatocytes, osteoblasts). Proliferate readily when necessary.
- Permanent: Cannot effectively proliferate in response to cell loss (e.g., neurons, cardiac myocytes).
Growth and Differentiation Responses
- Hyperplasia: Increased cell number in a tissue or organ, often from increased functional demand.
- Hypertrophy: Increased cell size leading to enlarged tissue/organ. Usually occurs when cell division capacity is limited.
- Atrophy: Decreased cell size and/or tissue/organ mass. Caused by reduced workload, loss of innervation, decreased blood supply, inadequate nutrition, or aging.
- Metaplasia: Reversible change where one differentiated cell type is replaced by another (e.g., squamous metaplasia in the respiratory tract of smokers).
Hyperplasia Causes
- Physiological: Hormonal stimuli (e.g., breast development during pregnancy), compensatory growth following tissue loss (e.g., liver regeneration)
- Pathological: Excessive hormones/growth factors, often associated with cancer risk (e.g., prostate, endometrium).
Hypertrophy Causes
- Physiological: Hormonal stimulation, increased functional demand
- Pathological: Increased functional demand (e.g., cardiac hypertrophy due to hypertension).
Aplasia, Hypoplasia, Dysplasia
- Aplasia: Complete failure of tissue/organ development.
- Hypoplasia: Incomplete tissue/organ development.
- Dysplasia: Abnormal cell maturation within a tissue, often precursor to cancer.
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Description
This quiz explores cellular adaptations and the control of cell growth within multicellular organisms. It covers key topics such as cell signaling pathways, types of signaling molecules, and receptor functions essential for cellular communication. Test your understanding of how cells respond to environmental changes and the mechanisms that regulate their growth and differentiation.
