Altered Cell - CH. 4 Flashcards
Cellular Adaptation
Reversible
Atrophy
Decrease in cell size
Hypertrophy
Increase in cell size
Metaplasia
Reversible replacement of one mature cell type by another, less mature cell type or a change in cell phenotype.
Dysplasia
Deranged cellular growth, not considered a true cellular adaptation but rather atypical hyperplasia.
Physiologic Atrophy
Occurs with early development and is a normal event.
ex. thymus in childhood
Pathologic Atrophy
Result of decrease in workload, pressure, use, blood supply, nutrition, hormonal stimulation, or neural stimulation.
Disuse Atrophy
Occurs with prolonged bedrest or immobilization.
Also known as pathologic atrophy
Ex. arm in a cast
Atrophic cells contain less
ER, mitochondria, and myofilaments.
Mechanisms of atrophy
Decrease in protein synthesis, increase in protein degradation, or both.
Autophagic Vacuoles
Contain cellular debris and hydrolytic enzymes that degrade substances into simple units.
Vacuoles help ensure no uncontrolled destruction.
Lipofuscin
Yellow-brown pigmented granules; lipid-containing residue that persists after lysosomal destruction.
Become age spots in older adults
How does hypertrophy present clinically?
Muscle enlargement
Physiologic Hypertrophy
Result of increased demand, stimulation by hormones, and growth factors.
Pathologic Hypertrophy
Result of chronic hemodynamic overload (ex. hypertension or heart valve dysfunction)
What is pathologic hypertrophy associated with?
Increased interstitial fibrosis, cell death, and abnormal cardiac function.
Compensatory hyperplasia
Enables organs to regenerate
Callus
Thickening of the skin, considered compensatory hyperplasia
Hormonal Hyperplasia
Occurs in organs that respond to endocrine hormonal stimulation
Pathologic Hormonal Hyperplasia
Abnormal proliferation of normal cells, usually in response to excessive hormonal stimulation or to the action of growth factors on target cells.
Dysplasia is described as “low grade” or “ high grade” based on
The degree of variation from normal.
Why is metaplasia thought to develop?
The new cell type might be better suited to withstand an adverse environment. However, the change is usually not beneficial.
Metaplasia results from
A reprogramming of stem cells present in most epithelia or of undifferentiated mesenchymal (tissue from embryonic mesoderm) cells
Irreversible cell injury
Severe vacuolization of the mitochondria and Ca++ moves into the cell.
Hypoxia
Lack of sufficient oxygen within cells
Most common cause of cell injury
Ischemia
Reduced supply of blood and therefore oxygen
What does hypoxia negatively impact?
Differentiation, angiogenesis, proliferation, erythropoiesis, and overall cell viability.
Reactive Oxygen Species (ROS)
Reactive molecules from molecular oxygen formed as a natural oxidant species in cells during mitochondrial respiration and energy generation.