Cell Biology Chapter on Stress Responses

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Questions and Answers

What is the primary mechanism by which hypertrophy occurs?

Decreased cell size with increased density

Replacement of existing cells with new cells

Increased synthesis of structural proteins and organelles (correct)

Increased cell division

Which of the following is NOT a pathologic adaptation to cellular stress?

Hyperplasia

Atrophy

Metaplasia

Necrosis (correct)

What is the difference between physiologic and pathologic hyperplasia?

Physiologic hyperplasia involves decreased cell division, while pathologic hyperplasia involves increased cell division.

Physiologic hyperplasia is a reversible change, while pathologic hyperplasia is irreversible.

Physiologic hyperplasia is harmful to the organism, while pathologic hyperplasia is beneficial.

Physiologic hyperplasia occurs due to hormonal stimulation only, while pathologic hyperplasia can be triggered by various factors. (correct)

Which of the following descriptions best reflects the concept of cellular adaptation?

Cells modify their structure and function to cope with environmental changes. (B) Signup and view all the answers

The thickening of the left ventricle in a patient with systemic hypertension is an example of what type of adaptation?

Hypertrophy (D) Signup and view all the answers

Which adaptation involves the replacement of one cell type with another, often in response to chronic irritation?

Metaplasia (B) Signup and view all the answers

Which of the following statements is TRUE regarding atrophy?

It involves a decrease in the size of cells and organs due to reduced workload or nutrient deprivation. (B) Signup and view all the answers

Which of the following is NOT a potential cause of physiologic hyperplasia?

Chronic inflammation (A) Signup and view all the answers

Which of the following scenarios is a likely outcome due to atrophy?

A decrease in the size of a muscle in a limb that has been immobilized. (D) Signup and view all the answers

What is the primary mechanism responsible for the enlargement of the prostate gland in benign prostatic hyperplasia?

Excessive proliferation of glandular epithelial cells. (A) Signup and view all the answers

Which process is exemplified by the conversion of columnar epithelial cells in the respiratory tract of smokers to stratified squamous epithelial cells?

Metaplasia. (A) Signup and view all the answers

What differentiates pathologic hyperplasia from physiologic hyperplasia?

Pathologic hyperplasia is characterized by abnormal cell growth while physiologic hyperplasia occurs within normal cell growth regulation. (C) Signup and view all the answers

Which of the following is NOT a cause of atrophy?

Increased workload. (B) Signup and view all the answers

Hormonal hyperplasia is a specific type of cellular adaptation that is commonly observed in which of the following scenarios?

The thickening of the uterine lining during the menstrual cycle. (C) Signup and view all the answers

What is the main difference between atrophy and metaplasia?

Atrophy involves a decrease in cell size, while metaplasia involves a change in cell type. (B) Signup and view all the answers

Which of the following is NOT a characteristic feature of compensatory hyperplasia?

It is driven by hormonal stimulation. (A) Signup and view all the answers

Study Notes

Cellular Responses to Stress and Noxious Stimuli

Cells actively adjust their structure and function to adapt to changing environmental and extracellular stresses.
Cells adapt to physiological or pathological stimuli, achieving a new steady state and maintaining viability and function.
Adaptive responses include hypertrophy, hyperplasia, atrophy, and metaplasia.
If the adaptive capacity is exceeded or the stress is harmful, cell injury occurs.

Cellular Injury

Cells exhibit reversible or irreversible injury.
Reversible injury is characterized as mild and transient, severe and progressive.
Irreversible injury leads to cell death through necrosis or apoptosis.

Cellular Adaptations to Stress

Adaptations are reversible changes in cell number, size, phenotype, metabolic activity, or function in response to environmental changes.
Physiological adaptations are responses to normal stimulation by hormones or endogenous chemical mediators, such as hormone-induced breast and uterine enlargement during pregnancy.
Pathological adaptations are responses to stress that help cells avoid injury.

Hypertrophy

Hypertrophy increases cell size, leading to an increase in organ size.
Existing cells increase in size, not the number of cells.
Increased functional demand or growth factors/hormones stimulate hypertrophy.
Physiological examples: uterine enlargement during pregnancy.
Pathological examples: cardiac enlargement due to hypertension or aortic valve disease.

Hyperplasia

Hyperplasia involves an increase in cell number due to cell proliferation or replacement by tissue stem cells.
Occurs in tissues with cells capable of replication.
Can occur concurrently with hypertrophy.
Physiological examples: proliferation of female breast glandular epithelium due to hormones during puberty and pregnancy and compensatory hyperplasia after partial liver resection.
Pathological examples: hyperplasia from excessive hormonal or growth factor stimulation (e.g., uterine proliferation after a menstrual period).

Atrophy

Atrophy is a decrease in cell size due to loss of cell substance.
Causes include decreased workload, loss of innervation, diminished blood supply, inadequate nutrition, loss of endocrine stimulation, and aging.
Examples: limb immobilization to permit healing, cerebral atrophy in Alzheimer's disease.

Metaplasia

Metaplasia is a change from one adult cell type (epithelial or mesenchymal) to another adult cell type.
A cell type sensitive to a particular stress is replaced by another cell type better able to tolerate the adverse environment.
Examples: squamous metaplasia of respiratory epithelium in habitual smokers. Often a precursor to neoplasia.

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Description

Explore how cells respond to stress and harmful stimuli through adaptive mechanisms and injury types. This quiz covers concepts from cellular adaptations, reversible and irreversible injuries, and their implications for cell viability. Test your understanding of physiological and pathological responses in cell biology.