Quiz 1_Learning Objectives Part 1_Spencer Flashcards
- Distinguish reversible from irreversible cell injury.
Example: Steatosis arises from exposure of hepatocytes to EtOH. The EtOH is metabolized to acetate, and also stimulates triglyceride synthesis and inhibits fatty acid oxidation. VLDL secretion is also inhibited. Thus, hepatocytes build up fat stores. If you then abstain from EtOH, the steaotosis will reverse and the hepatocyte will be normal.
Mallory’s hyaline arises from exposure of hepatocytes to EtOH which then causes aggregation of cytokeratin filaments. Histologically this appears as a dense rope like body in the cytoplasm of hepatocytes.
- Identify the cytological changes that are associated with irreversible injury.
Decrease basophilia, nuclear changes, cytoskeleton alterations.
- Explain how steatosis occurs due to alcohol ingestion.
EtOH is converted to acetaldehyde which is converted to acetate. The increased NADH/NAD ratio favors TAG synthesis and inhibits FAO. The ethanol also inhibits release of VLDLs, so TAGs build up inside hepatocytes even more. Decrease lipoprotein synthesis so you can’t export it.
- Name and distinguish 4 types of pathological necrosis.
Coagulative is the most common and involves denaturation of cell proteins. Hallmarks: look for “ghosts”, loss of basophilia. Liquefactive involves extensive acute inflammation and is secondary to bacterial or fungal infections. Caseous is a combination of those two types and has a “cheese” appearance both grossly and histologically (partly from cavitation). Example is TB. Gangrenous is when bacteria colonize an already-necrotic tissue.
- Explain the relationship between hemochromatosis and cirrhosis.
Hemochromatosis (disease) is iron overload from a genetic abnormality. The iron overload causes cirrhosis (reversible). Hemosidderosis = observable symptoms.
- Diagram the mechanisms active in cellular apoptosis.
Intrinsic: cell injury occurs and this triggers the Bcl-2 family sensors. The Bcl-2 effectors induce cytochrome c and other pro-apoptotic proteins to initiate caspases. Executioner caspases then cause DNA fragmentation and exocytose apoptotic bodies for ingestion by phagocytes.
Extrinsic: receptor-ligand interactions occur (Fas, TNF receptor) and activate adapter proteins. These activate the same initiator/executioner caspase pathway described above.
- Name four features of cellular injury that are reversible.
Metabolic/oxidative phosphorylation activity, cellular pH, influx of Ca/etc, phospholipid metabolism
- Describe the electrolyte shifts that occur in ischemic cell injury leading to cell death.
There is an influx of Ca2+, H2O, Na+, and an efflux of K+. These shifts are mainly modulated through the decreased ATP available intracellularly.
- Explain the role of Ca++ ions in irreversible cell injury.
The increased Ca++ in the cytosol causes increased ATPase activity, decreased phospholipids, disruption of membrane proteins (via increased protease activity), and increased endonuclease activity.
- Name seven categories of causes of cell injury. One example is toxic chemicals.
Anoxia, immune/autoimmune, microbiologic, nutritional, physical agents (eg trauma, fever), toxic chemicals
- Explain the difference between etiology and mechanism in cell injury.
Etiology is cause, mechanism is pathogenesis.
- Explain the mechanism of cellular ATP deficit caused by anoxia, carbon monoxide poisoning, and cyanide poisoning.
Anoxia is just less oxygen reaching tissues. CO poisoning is due to competitive inhibition for O2 binding on Hb. CN blocks oxidative phosphorylation in mitochondria
- State the molecular mechanism for CCl4 toxicity, and explain why gut lining cells escape toxic effects of CCl4.
CCl4 → CCl3 + Cl. CCl3 is a free radical and it causes cell injury. Gut lining escapes because CCl4 is activated in cytochromes in the liver.
- State the critical feature of molecular structure of a free radical.
Free electron.
- List an example of a poison that is made toxic by metabolic alteration.
CCl4, benzoapyrene
- List an example of a poison that does not require metabolic activation in order to become toxic.
Strong acids and bases, heavy metals, CO
- Use the example of cis-platinum (a chemotherapeutic agent) in describing the various mechanisms of molecular damage/alterations that lead to cell death.
Cis-platinum causes DNA synthesis to shut down, cell division to stop, apoptosis, necrosis. Essentially the Pt forms a covalent bond with certain structures such as DNA.
- List a differential diagnosis for abdominal pain in a young male/female adult.
- List a differential diagnosis for abdominal pain in a young male/female adult.
- Discuss the physiological mechanism and some causes of vomiting.
Vomiting is caused by 1) irritation of vagal/sympathetic afferents in pharynx, heart, peritoneum, mesentery, bile ducts, stomach, bowels via the medullar reticular center, or 2) from gastric irritation, distension, intracranial pressure, metabolic disturbances, drugs, pharyngeal stimulation, emotional upset.
- Explain what information and implications derive from the following laboratory tests if they are abnormal:
bilirubin – defective bilirubin metabolism
prothrombin – monitor extrinsic pathway, monitor Coumadin therapy. Screens for liver disease, K deficiency, factor deficiency, DIC
ALT – liver disease, confirms AST is from liver
AST – acute liver injury
amylase – watch for pancreatitis/abdominal issues
- Demonstrate how to use a modified Rumack-Matthew normogram for acetaminophen
Y axis = acetaminophen concentration, X axis = hours after ingestion. Measure below line = no toxicity, above line = probably toxicity.
- Explain how acetaminophen is rendered toxic to hepatocytes.
Overdose → NAPQI is formed → outstrips glutathione supply → NAPQI binds to proteins and causes cell death.
- State 4 mechanisms by which n-acetylcystine (NAC) prevents acetaminophen toxicity.
- Limits formation of NAPQI by helping supply glutathione (by providing cysteine which is then converted)
- Increases detox capacity of hepatocytes to deal with NAPQI
- Name the cause of and treatment for hepatic encephalopathy.
Hepatic encephalopathy is confusion, altered consciousness, and coma resulting from liver failure. It is caused by accumulation of toxic substances that are normally dealt with by the liver. Treat with laxative lactulose to prevent toxic metabolic processes in the intestine.
