Cell Adaptations To Stress Flashcards
What are adaptions
Reversible changes in size,number,phenotype metabolic activity or functions of cells in response to changes in their environment
What can cells capable of division do that cells not capable of division cant do
Both inc in size by hypertrophy but cells that can undergo division can also undergo hyperplasia
What is hypertrophy
Inc in size of cells that results in inc of attached organ
Pathogenesis of hypertrophy
Most common stimulus is inc workload on skeletal and cardiac muscle
Muscle cells respond by synthesizing more protein and inc production of growth factors leading to inc in number of myofilaments per cell inc amount of force of each myocyte
Physiologic hypertrophy
Uterine hypertrophy during pregnancy as there is growth in uterus stimulated by estrogenic hormone signaling through estrogen receptors that eventually result in inc synthesis of smooth muscle proteins and inc in size of cell
Bulging of muscles in body builders engaged in pumping iron
Pathologic hypertrophy
Ex: concentric left ventricular hypertrophy of heart in response to pressure overload due to inc peripheral resistance to cardiac pumping of blood and occurs in case of systemic hypertension or aortic valve disease
What is hyperplasia
Inc in number of cells in an organ or tissue in response to a stimulus
Mechanism of hyperplasia
Result of growth factor driven proliferation of mature cells and activation of signaling pathways that stimulate cell proliferation by inc output of new cells from stem cells
When does Physiologic hyperplasia occur
Occurs whenever there is a need to inc functional capacity of hormone sensitive organs or when there is a need for compensatory inc after damage or resection
What are the types of physiologic hyperplasia
1-hormonal hyperplasia: proflieration of the glandular epithelium of female breast at puberty and pregnancy
2-compensatory hyperplasia: liver regeneration in transplant patients
3-bone marrow hyperplasia: in response to deficiency of mature blood cells
What is Pathologic hyperplasia caused by
Excessive or inappropriate actions of hormones or growth factors acting on target cells
What are the types of pathologic hyperplasia
Endometrial and breast hyperplasia: under effect of inc estrogen a common cause of abnormal uterine bleeding or breast mass
Benign prostatic hyperplasia: in response to hormonal stimulation by imbalanced estrogen and androgens in old males
What is atrophy
Reduction in size of an organ or tissue due to dec in cell size and number
What are mechanisms of atrophy
Decreased protein synthesis
Increased protein degradation
Increased autophagy with presence of intracytoplasmic autophagic granules
When does physiologic atrophy occur
During normal development as atrophy of embryonic structures ex: notochord and thyroglossal duct and uterine atrophy after menopause
