cellular injury, up close

🍌what organelle plays a central role in cellular energetics and cell death signaling? how?

mitochondria

ATP production via oxidative phosphorylation

drives active transport (Na+ → K+ or Na+ → Ca2+)

🍌what are ROS (reactive oxygen species)?

a normal product of cellular metabolism in mitochondria

🍌liver cells function

sensitive to a rise in epinephrine levels

activate glycogenolysis

increase blood glucose for energy to fight or flee

🍌adrenal and muscle cells function

adrenal cortex detect ACTH

• produce and secrete cortisol

• muscle cells increase protein catabolism

• increase amino acids to fuel resistance and/or adaptation

extrinsic factors that can contribute to cellular injury

environment

stress

exposure to toxins

mechanical trauma (physical stressor)

intrinsic factors that can contribute to a cellular injury

genetics

hormonal changes/imbalances

immune malfunctions

structural defects

🍌toxic contributors to cellular injury

intrinsic

extrinsic

🍌infectious contributors to cellular injury

viral

fungal

protozoan

bacterial

🍌physical contributors to cellular injury

thermal, mechanical

🍌deficit contributors to cellular injury

water

oxygen

nutrients

temperature

waste disposal

🍌targets of cellular injury

mitochondria

membranes (cell and organelles)

protein synthesis and transport machinery

cytoskeleton

genetic apparatus (DNA)

what can accumulate in cells?

fluid

fat

proteins

materials that cannot be processed or transported appropriately:

• endogenous enymes

• exogenous substances → foreign toxins

why does accumulation injure the cell?

toxicity

immune response

overcrowding/resource consumption (cell membrane can rupture)

what is the first step that leads to hydropic swelling?

lack of sufficient ATP

• can’t move things out of the cell (active transport)

• you need to rely on osmosis or passive transport

what is the second step that leads to hydropic swelling?

Na+/K+ pump failure

what is the third step that leads to hydropic swelling?

Na+ ions accumulate within the cell

what is the fourth step that leads to hydropic swelling?

water follows Na+

• water moves into the cell to dilute everything that’s in there → osmosis

intracellular edema

what is intracellular edema?

first indication of injury

what is edema? where does it occur?

abnormal accumulation of fluid

occurs in organs and interstitial tissue

what are the 4 mechanisms of accumulation?

abnormal metabolism

alterations in protein folding

deficiency of enzymes

accumulation of indigestible materials

abnormal metabolism

faulty metabolism of intracellular substances

cell cannot process or move things out properly

alterations in protein folding

accumulation of abnormal substance due to faulty synthesis or transport

deficiency of enzymes

lack of specific enzymes needed for digestion of substances

ex: lysosomes aren’t breaking things down properly

accumulation of indigestible materials

pigments or particles the cell is unable to degrade

what does the suffix -megaly mean?

generalized enlargement of a specific organ due to edema or other intracellular accumulations

• ex: hepatomegaly, splenomegaly