Cell Injury Flashcards
explain ionizing radiation
it produces reactive oxygen species or radicals that destroy DNA and cell membranes
Ionizing radiation does what to water
it hydrolyzes it to a hydrogen and hydroxyl free radical. x-rays hits a molecule of water, it can ionize the molecule to produce a hydrogen ion and a hydroxyl ion or it can split paired electrons.
how are non-proliferating cells damaged by radicals
via lipid peroxidation of membrane phospholipids. Polyenoic fatty acids are the ones damaged because of their double bonds
what is produced once lipid peroxidation has stopped
low molecular weight aldehydes are produced
what is reperfusion injury
return of blood to ischemic tissue results in production of O2 derived free radicals, which further damage tissue
leads to a continued rise in cardiac enzymes (e.g. troponin) after repercussion of infarcted myocardial tissue.
what compounds are considered activated oxygen radicals
partial reduction of O2 yields superoxide (O2), hydrogen peroxide (H2O2), and hydroxyl radicals(OH)
if you decrease oxygen content, what protein do you produce
you produce erythropoietin.
what are some clinical findings in hypoxia
cyanosis, confusion, cognitive impairment, lethargy
what are the causes of tissue hypoxia
ischemia, hypoxemia, and hemoglobin related abnormalities
Define ischemia and hypoxia
ischemia is the reduction of blood flow either from the arterial side or the venous outflow from tissue.
hypoxemia is the reduction of PaO2 which is the partial pressure of oxygen in the arterial blood
what are the six causes of hypoxemia
- Decreased inspired Po2 (for example in high altitudes)
- Respiratory acidosis
- Ventilation defect
- Perfusion defect
- Diffusion defect
- Cyanotic congenital heart disease
What is methemoglobinemia?
Methemoglobin is converted to the ferrous state (Fe2+) by the reduced nicotinamide adenine dinucleotide (NADH) reductase system located off of the glycolytic pathway in RBCs. Electrons from NADH are transferred to cytochrome b5 and then to metHb by cytochrome b5 reductase to produce ferrous Hb. Newborns are particularly at risk for developing methemoglobinemia after oxidant stresses owing to decreased levels of cytochrome b5 reductase until at least 4 months of age.
Patients with methemoglobinemia have what diagnostic characteristic?
chocolate colored blood due to increased concentration of deoxyhemoglobin
In carbon monoxide poisoning what happens to the PaO2 and the SaO2?
The SaO2 decreases without affecting the PaO2
Carbon monoxide inhibits
cytochrome oxidase in the ETC. Cytochrome oxidase normally converts O2 into water. Inhibition of the enzyme prevents O2 consumption, shuts down the ETC, and disrupts the diffusion gradient that is required for O2 to diffuse from the blood into the tissue
