Oxygen deprivation on the cellular level is called cell hypoxia. Unless corrected or reversed, intracellular function ceases, eventually leading to cell death. Depending on the extent of the depletion, cells may chemically signal systemic mechanisms which attempt to compensate for the lack of energy and oxygen. Injury and illnesses can initiate cell hypoxia. Treating cell hypoxia entails replacing oxygen, fluids and nutrition.
Without an adequate oxygen supply, electron transport within the cell does not function properly. Electrons build-up, causing a complex progression of cellular failures. Mitochondria, the energy producing organelle within cells, loses membrane potential and quit producing adenosine triphosphate (ATP). Not having a steady supply of nutrition, cells deplete ATP reserves. This action might also trigger an inflammatory process, creating tissue damage.
Cells emit chemical signals which encourage blood flow in an attempt at getting more oxygen. Lactic acid and nitric oxide form, causing an acidic environment. Ineffective electrical impulses affect lysosomes which cease metabolizing cellular waste products. Electron accumulation also interferes with the activity of the sodium-potassium pump, allowing potassium to flood into extra cellular spaces and sodium and water to enter the cell, in turn causing cellular edema and possible rupture. Cell hypoxia also alters cellular calcium supplies required for proper membrane function and the release of neurotransmitters within the cell.
Membrane damage triggers the release of enzymes that begin digesting the cell. Having no protective membrane, the cell dies, causing cell wastes, enzymes and other chemicals to enter the bloodstream. Lactic acid and nitric oxide in sufficient quantities initiate systemic responses. Lactic acid reduces the heart's contracting ability. Acidic signals also desensitize arterioles, decreasing vascular responsiveness to central nervous system hormones. Nitric oxide causes vasodilatation, increases capillary permeability, and initiates clotting mechanisms to inhibit blood loss. Outward signs of hypoxia can include increased respiration rates as the body strives to replace oxygen.
Hypoxia is caused by any circumstance that interferes with oxygen access, including blunt force trauma, fluid loss, and tissue damage from prolonged applied pressure. Illnesses impeding normal blood flow or reducing oxygen intake also contribute to cell hypoxia. Some researchers believe that maintaining a diet high in polyunsaturated fats reduces membrane permeability and the cell's ability to absorb oxygen. Scientists speculate that oxygen-starved cells and the processes that follow, may create environments that encourage cancerous tumor growth.
Treating and managing hypoxia involve general care measures. Supplemental oxygen and intravenous fluids prevent further cell damage and encourage cell replication by ensuring adequate blood flow and oxygen supplies. Providing oral or intravenous nutrition assists cells in acquiring the nutrients necessary for cellular function. Health care providers might also prescribe medications that inhibit the inflammatory process.