Exam 4: Hyperplasia, Hypertrophy Flashcards
What is hypertrophy?
An increase in the size of a cell, or increase in the size of a tissue
What is hyperplasia?
An increase in the number of cells in a tissue
What is the cause of hypertrophy and hyperplasia?
Increased demand, endocrine stimulation, or nutrition
What does increased cell activity cause?
Proliferation of organelles and/or cell division until a new balance is reached
Are hypertrophy and hyperplasia beneficial?
In many cases, yes
However, persistent change in the environment leads to overcompensation and harmful effects may occur
What are causes of physiologic hyperplasia?
Hormonal: maturity/development
Compensatory: liver resection
What are causes of pathologic hyperplasia?
Chronic irritation Endocrine Virus induced Increased bloodflow Nodular hyperplasia
What are causes of hypertrophy?
Increased workload Endocrine stimulation Thyroid- anabolic effects Adrenal- cortisol excess Estroens- uterine and mammary development
What are examples of hypertrophy from increased workload?
Enlarged hearts and muscle mass in athletic animals
Kidney hypertrophy when the other is removed
What does hyperplasia look like histologically?
Definite structures
Increased cells
Well differentiated
What is fibrous osteodystrophy?
Reactive fibroblast hyperplasia and connective tissue production
What can a hematoma be caused by?
Hyperplastic nodule
Hemangiosarcoma
What results due to hypertrophic cardiomyopathy?
Myofiber disarray
Fibrosis
What is compensatory hypertrophy?
When much of the function of one organ (such as a kidney) is lost, hypertrophy occurs in the other
How does a thrombus on the aortic valve cause hypertrophy?
Thrombus on aortic valve interferes with blood leaving left ventricle increases pressure in left ventricle –> increased workload –> myocardial fibers stretch and then increase in size –> hypertrophy of left ventricular myocardium
How does an increase in muscular activity cause hypertrophy?
Increase in muscular activity increased blood and nutrient supply –> increase in muscle fiber size –> hypertrophy of muscle mass
How do pyogenic organisms cause hyperplasia?
Neutrophil chemotaxis –> depletion of bone marrow reserves –> stimulaties granulopoiesis –> hyperplasia of myeloid cells of bone marrow
How does persistent infection cause hypertrophy?
Antigenic stimulation of lymphoid organs –> stimulus for proliferation of lymphocytes –> increase in size of lymph nodes and spleen
How does persistent chronic blood loss cause hyperplasia?
Depletion of erythrocyte reserves –> stimulation of erythroid stem cells in bone marrow –> erythroid hyperplasia
Describe how iodine deficiency causes endocrine stimulation
Iodine deficiency –> overwork of thyroid gland to compensate –> enlargement –> goiter
Describe how chronic renal disease causes endocrine stimulation
Chronic renal disease –> failure of phosphorus excretion and failure of conversion of vitamin D to active form –> failure to absorb calcium from gut and excretion of CaPO4 from gut as P is excreted in gut –> lowered blood calcium levers –> stimulate parathyroids –> parathyroid enlargement
Describe how sexual maturity causes endocrine stimulation
Increased production of sex hormones –> development of secondary sex characteristics
How does excess nutrition cause hyperplasia and hypertrophy?
It leads to an increase in fat tissue and increase of protein synthesis
What is hyperplasia associated with?
Increased workload
