2025/2026
How many ATP does oxidative phosphorylation yield? - 36
in ATP depletion, what are the four critical points where ATP production may be impaired? - 1. Hypoxia
2.
ischemia - reduced blood flow
Explain hypoxia in terms of ATP depletion - obstruction --> ischemia --> decreased ATP production --> a)
sodium/potassium ion pump fails, and b) increased anaerobic glycolysis
explain what happens when the Na-K-ATPase pump fails due to decreased ATP production - normally,
most sodium ions are outside the cell and most potassium ions are inside the cell
when the pump fails, sodium freely enters the cell with H2O and calcium, and potassium freely exits the
cell
as a result, the cell swells and and protein synthesis stops
where does protein synthesis occur in a cell? - Rough ER with ribosomes on the surface
explain what happens where there is an increase in glycolysis due to decreased ATP production -
glycogen is decreased, lactate is increased, intracellular pH is decreased
decreased pH results in pyknosis, karyorrhexis, and karyolysis
define free radicals - unstable compounds with an unpaired electron
why are free radicals bad? - they bind to the phospholipid bilayer of a cell and drill holes in its membrane
,what are reactive oxygen species? - highly reactive forms of oxygen typically from the mitochondria
why are antioxidants important - protect cells from free radicals and ROS
are antioxidants increased or decreased in oxidative stress - decreased :(
what are three diseases linked to oxygen-derived free radicals? - 1. Atherosclerosis
2. Cancer
3. Diabetes
define oxidative stress - Injury induced by free-radicals and ROS
two endogenous accumulations - 1. Lipids
2. Bilirubin
define reperfusion injury - when blood flow is restored to ischemic tissues, additional damage can occur
resulting in cell death
proposed reasons for reperfusion injury (5) - 1. oxidative stress
2. nitrogen-based free radicals
3. increased intracellular calcium
4. inflammation
5. complement activation
explain oxidative stress as it relates to reperfusion injury - reoxygenation generates ROS and nitrogen
species, which damages membrane proteins and phospholipids
what four ROS are generated in oxidative stress? - 1. Hydroxyl radical
, 2. superoxide radical ion
3. nitric oxide-derived peroxynitrite
4. hydrogen peroxide
what happens when nitrogen-based free radicals are formed in reperfusion injury? - further damage to
the cell membrane occurs and calcium overloads the mitochondria
explain bilirubin - a pigment that is released when RBC break down --> pigment is released into the
bloodstream as unconjugated bilirubin, which cannot be excreted into the urine --> taken up by the liver
cells --> binds to glucuronic acid --> becomes conjugated bilirubin, which can be excreted in the urine
two ways bilirubin leaves the liver cells - 1. diffusion once bilirubin concentration is high
2. some bilirubin becomes bile --> exits liver cell through hepatic duct/common bile duct, then into the
duodenum
three issues with hyperbilirubinemia - 1. hemolytic jaundice
2. hepatocellular jaundice
3. obstructive jaundice
explain hemolytic jaundice - excessive amounts of hemoglobin is broken down, resulting in too much
bilirubin in the bloodstream that cannot be delivered to the liver cells
signs of hemolytic jaundice - yellow discoloration of the skin and connective tissue
explain hepatocellular jaundice - normal amount of bilirubin, however, liver cells do not function at
either a) uptake, b) conjugation, or c) excretion
explain obstructive jaundice - hepatic/common bile duct is obstructed resulting in conjugated bilirubin
accumulating in the liver cell, resulting in more bilirubin diffusing into the bloodstream than normal
pyknosis - clumping of the nucleus