Cell Adaptations, Injury, and Death Flashcards
An increase in stress leads to an increase in organ size. This occurs by one of two mechanisms.
______ is an increase in cell size.
______ is an increase in number of cells.
Hypertrophy
Hyperplasia
Of hyperplasia and hypertrophy, _______ involves gene activation, protein synthesis, and production of organelles
Hypertrophy
Of hyperplasia and hypertrophy, _____ involves production of new cells from stem cells
Hyperplasia
T/F: Hyperplasia and hypertrophy generally occur together
True; example: uterus in pregnancy
What type of tissue does not have the ability to undergo hyperplasia?
Permanent tissues — cardiac myocytes, skeletal muscle, and nerve tissue
THESE UNDERGO HYPERTROPHY ONLY
Pathologic hyperplasia can progress to ____ and ____
Dysplasia; cancer
[examples: endometrial hyperplasia progessing to endometrial carcinoma]
Pathologic hyperplasia can progress to dysplasia and cancer…with the exception of _________
Benign prostatic hyperplasia
A decrease in stress on an organ leads to a decrease in size — a process called _____ in which there is a decrease in cell size and cell number. The decrease in cell number occurs via _______.
The decrease in cell size occurs via ____________ and _________________
Atrophy; apoptosis
Ubiquitin-proteosome degradation of cytoskeleton; autophagy of cell components
A change in stress on an organ leads to a change in cell type, called _______
Metaplasia
Metaplasia most commonly involves _______ epithelium Metaplastic cells are better able to handle new stress
Surface
Barrett esophagus is a classic example of what growth adaptation? What change has taken place?
Metaplasia
Squamous epithelium —> columnar epithelium
Mechanism of metaplasia and its reversal
Metaplasia occurs by a reprogramming of stem cells
Typically reversible with removal of driving stressor (ex: treatment of GERD)
Like hyperplasia, metaplasia can progress to dysplasia and cancer. An example of this is Barrett esophagus progressing to adenocarcinoma of the esophagus. An exception to this process is ______ metaplasia, which is seen with fibrocystic change of the breast and is not associated with increased risk of cancer
Apocrine
________ deficiency can result in metaplasia (i.e., keratomalacia)
Vitamin A
Myositis ossificans is an example of ______ of mesenchymal tissue
Metaplasia
[bone being produced in the place of muscle tissue; important to distinguish from osteosarcoma in that imaging of adjacent bone will be normal with myositis ossificans]
______ = disordered cellular growth referring to proliferation of precancerous cells (e.g., CIN); arises from longstanding pathologic hyperplasia or metaplasia
Dysplasia
T/F: dysplasia is irreversible
False — Dysplasia is reversible with alleviation of inciting stress. If stress persists, dysplasia progresses to carcinoma which is irreversible
_____ = failure of cell production during embryogenesis
Aplasia (classic example is unilateral renal agenesis)
______ = decrease in cell production during embryogenesis resulting in a relatively small organ
Hypoplasia
Streak ovary in turners syndrome is an example of
A. Metaplasia B. Dysplasia C. Hypertrophy D. Hyperplasia E. Hypoplasia
E. Hypoplasia
Common causes of cell injury include inflammation, nutritional deficiency or excess, hypoxia, trauma, genetic mutations, etc.
Hypoxia occurs when there is low oxygen delivery to tissue. What are the 3 major causes of hypoxia?
Ischemia
Hypoxemia
Decreased O2 carrying capacity of the blood
_______ = decreased blood flow through an organ
Ischemia
Define hypoxemia
Low partial pressure of O2 in the blood (PaO2 < 60 mm Hg, SaO2 < 90%)
[Remember FiO2 is partial pressure of O2 in the atmosphere. PAO2 is partial pressure of oxygen in alveolar air sacs, while PaO2 is partial pressure of oxygen in the arterioles. SaO2 is the partial pressure of oxygen associated with Hb. So the sequence is FiO2 —> PAO2 —> PaO2 —> SaO2]
Anemia is a decrease in RBC mass. This is associated with a _____ PaO2 and a ______ SaO2
Normal; normal
[PaO2 reflects the ability of oxygen to cross from alveolar air sacs into capillaries. SaO2 reflects the percentage of Hb is bound by oxygen. Neither of these is altered by anemia]
Carbon monoxide binds Hb more avidly than O2, resulting in CO poisoning. CO poisoning is associated with a ____ PaO2 and a ______ SaO2. Exposures include smoke from fires and exhaust from cars or gas heaters
Normal; decreased
[Hb can’t hold as much oxygen bc some spaces are now taken up by CO]
Classic finding is cherry red appearance of the skin
Early sign of exposure is headache; significant exposure can lead to coma and death
CO poisoning
_______ refers to the situation in which iron in heme is oxidized to Fe3+, which cannot bind O2
Methemoglobinemia
[REMEMBER Fe2+ binds O2]
Methemoglobinemia refers to the situation in which iron in heme is oxidized to Fe3+, which cannot bind O2. This is associated with a ______ PaO2 and a ______ SaO2.
Normal; decreased
In what conditions might you see methemoglobinemia?
Methemoglobinemia is associated with oxidant stress (e.g., sulfa and nitrate drugs) or in newborns
Classic findings are cyanosis with chocolate-colored blood
Methemoglobinemia
Treatment for Methemoglobinemia
IV methylene blue — helps reduce Fe3+ back to Fe2+ state
Hypoxia impairs ______ _____ —> decreased ATP
Oxidative phosphorylation
[O2 is final acceptor in electron transport chain]
Low ATP resulting from hypoxia disrupts what 3 key cell functions?
Na/K pump — lack of ATP results in buildup of Na in cell, water follows, cell swelling
Ca2+ pump — usually keeps intracellular Ca low; increased Ca activates enzymes in the cell that you don’t want activated
Aerobic glycolysis — leads to lactic acid buildup
Initial phase of cell injury due to hypoxia is cellular ______ which leads to loss of microvilli, membrane blebbing, and swelling of RER
Swelling
[remember that consequence of swelling of RER is that ribosomes will disassociate and protein can no longer be synthesized]
