Pathology: Adaptation, Injury, Death (Part 2) Flashcards
Describe hydropic degeneration
Injured cells tend to swell with water, which follows sodium that the injured cell is unable to pump out fast enough. Also called ballooning degeneration.
If ischemia goes on too long, the result is beyond injury; it is the death of the tissue or the organ, termed _________.
Infarction.
The earliest gross pathologic change in ischemic organs is often a __________ of ________.
darkening of color
Define and distinguish hypoxia from ischemia.
Hypoxia is deprivation of oxygen, such as low oxygen concentration in blood (hypoxemia) that is still adequately perfused unlike in ischemia when blood is simply not reaching an organ. Hypoxia IS a component of ischemia but ischemia is not always the cause of hypoxia.
Hypoxia induces the transcription factor:
hypoxia-inducible-factor-1 (HIF-1)
HIF-1 does what to counteract hypoxia?
enhances anaerobic glycolysis, stimulates cell survival pathways and promotes new blood vessel formation.
What causes the sodium pumps needed to keep potassium in and sodium out of cells to shut down, leading to further problems? (This also lets excess calcium in)
Depletion of ATP. ‘cause Na ATPase pumps, yo!
Lack of ATP shuts down protein synthesis, leading to the accumulation of misfolded ________, which can progress to the ________ _________ response.
Proteins; unfolded protein response
Injury to a mitochondrion leads to formation of a high-conductance channel in its membrane referred to as the ____ ______ ________ _____, which wrecks 3 things. Name the three things.
mitochondrial permeability transition pore
- membrane potential
- oxidative phosphorylation
- ATP production capacity
Deranged oxidative phosphorylation secondary to mitochondrial injury generates excess:
reactive oxygen species
Name the reactive oxygen species.
superoxide, hydrogen peroxide, and hydroxyl ion
Superoxide and hydroxyl ions are free radicals that react in pathologic ways by:
attacking the double bonds on unsaturated fatty acids in membrane lipids (peroxidation), by oxidizing the amino acid side chains in proteins (sometimes forming abnormal cross-links with other proteins), and by breaking and cross-linking DNA.
The highly reactive peroxynitrite (ONOO) is derived from what molecule found in the blood stream?
Nitric Oxide (NO)
What are responsible for donating or accepting free electrons during intracellular reactions and catalyzing free radical formation?
metals like iron and copper
Describe the condition of oxidative stress.
Derives from the presence of reactive oxygen species and free radicals. Such an important mechanism of injury that some liken oxygen to a low grade slow poison.
This compound is responsible for a cell’s normal disposal of the free radical hydrogen peroxide
catalase
This compound is responsible for a cell’s normal disposal of the free radical superoxide.
superoxide dismutase
This compound is responsible for a cell’s normal disposal of the free radicals hydroxyl ion and hydrogen peroxide
Glutathione peroxidase
NAPQI, a toxic product of Tylenol (acetaminophen) metabolism when accumulated in hepatocytes, can be detoxified by:
conjugation to glutathione
How does alcohol impair the liver’s natural defenses to NAPQI, leading to acetaminophen toxicity when consumed with Tylenol?
EtOH impairs methionine metabolism needed to generate glutathione and induces CYP-450 enzymes that increase acetaminophen metabolism to NAPQI.
Lowering or raising metabolic rate decreases injury caused by ischemia or hypoxia?
lowering
Describe reperfusion injury.
refers to the exacerbation of free radical injury sometimes caused by the restoration of blood flow, which brings oxygen to cells with damaged mitochondria or overwhelmed scavenging capacity, resulting in the production of reactive oxygen species by those injured mitochondria or simply more reactive oxygen species than can be scavenged.
How is calcium influx an important mechanism of cell injury?
It opens the mitochondrial transition pore and activates phospholipases (damaging membranes), proteases, endonucleases and ATPases.
When does injury to a cell become irreversible?
The point of no return is thought to be passed when mitochondrial injury is so severe that the cell cannot generate the energy (ATP) to repair itself. Also correlated with outer membrane damage so severe that the cell cannot keep enough of its constituents in to continue functioning.
How long can the brain be ischemic before infarcting?
4 mins
How long can the heart be ischemic before infarcting?
20 mins
How long can the liver be ischemic before infarcting?
2 hours
The most sensitive and specific blood tests for myocardial damage are the cardiac-specific proteins:
What are their functions?
Troponin T and Troponin I.
Regulate calcium mediated contraction of cardiac myocytes.