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What are the two ways that an organ becomes bigger and why?
- Hyperplasia (Number, creates more cells) these new cells come from stem cells
- Hypertrophy (Size, creates bigger cells), requires more energy & organelles, so genes must activate to create more proteins
- Organs can become bigger in response to a stress on an organ (throws off the homeostasis of the organ) and these two usually occur together
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How do permanent tissues become bigger, What are the 3 types of permanent tissues?
- Through hypertrophy only
- Since they have completed their growth and cannot create new cells, the cells can only get bigger
- Cardiac Myocytes, Skeletal Muscle and Nerve
 Left ventricle hypertrophy
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Pathologic Hyperplasia makes a high risk for _____, except in which condition?
- Cancer
- Benign prostatic hyperplasia BHP, is NOT related to cancer EXCEPTION TO THE RULE
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Decrease in stress on an organ and decrease in size results in _____. And it occurs through...
- Atrophy
- Apoptosis (reduction in number)
- Ubiquitin-proteosome degradation pathway (breaking down of the cytoskeleton, reduction in size
- Autophagy (trashing organelles in vacuoles and lysosomes, reduction in size)
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A growth adaptation of a cell that results in a change of the actual cell type?
- Metaplasia - usually occurs in surface epithelium
- These metaplastic cells can respond better to stress
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What are the 3 main types of epithelium?
- Squamous (keratinizing or non-keratinizing)
- Columnar - a lot of gut epithelium
- Transitional - usually lines the urinary tract
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Type of metaplasia where changes occur to the epithelium type of the esophagus because of the acid reflux from the stomach.
- Barretts esophagus - a metaplastic change occurs in the epithelium of the esophagus to better deal with the stress of acid reflux. Epithelium turns from squamous epithelium to columnar-ciliated
- This is a risk factor for adenocarcinoma because metaplasia (like hyperplasia can be precancerous)
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Metaplasia occurs through
Reprogramming of stem cells, and the process is reversible!
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Metaplasa that does not increase the risk of cancer
Apocrine metaplasia - is a particular kind of cellular change associated with a variety of breast cystic disorders. It is a completely benign condition which in itself does not increase risk for subsequent breast cancer.
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Vitamin A deficiency can cause
- Night blindness
- Immune deficiency - example 15-17 translocation (acute promyelocytic leukemia), involved the vitamin A receptor, Treatment is a derivative of vit. A, so cells don't become trapped and stay as blasts.
- Metaplasia - "vit A necessary for specialized epithelium, like the conjunctiva of the eye" requires vit A to remain in its state, deficiency results in metaplasia (thickening of the surface) called Ketatomalacia
- Mysenchymal tissues (connective tissues) can also go through metaplasia "Myositis ossificans" inflammation (becuz of trauma) of skeletal muscle results in ossification (you will see radioopaque in the muscle.
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Growth modification where disordered cellular growth occurs
- Dysplasia, example of this is CIN
- Usually arises from longstanding pathologic hyperplasia (endometrial hyperplasia) or metaplasia (barrets esophagus)
- Dysplasia is REVERSIBLE, Cancer is NOT reversible.
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Failure of cell production during embryogenesis?
- Aplasia
- example: Unilateral renal agenesis (failure to develop a kidney)
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Decrease in cell production during embryogenesis?
- Hypoplasia - results in relatively small organ
- example: streak ovary in Turner syndrome
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