Oxygen is a necessary condition for the body to carry out normal metabolism. In the case of hypoxia, if the body cannot adapt to this low oxygen environment, it will cause a series of pathophysiological reactions. In the case of hypoxia, abnormal changes will occur in the metabolism, function, and morphology of tissues. Excessive hypoxia stress response will lead to failure of various functions of the body, and the nervous system, circulatory system, and respiratory system of the body will be affected. Different degrees of damage eventually lead to the death of important organs such as the brain, heart, and lungs due to insufficient energy supply.
1. The effect of hypoxia on the central nervous system
The central nervous system is most sensitive to hypoxia, with the highest oxygen consumption. The brain tissue accounts for 2% of the body weight, and the oxygen consumption accounts for 20% of the whole body oxygen consumption. The metabolism of brain tissue is mainly aerobic metabolism, and there is almost no anaerobic metabolism. The demand for oxygen is the highest. At the same time, the oxygen and ATP reserves in the brain tissue are very small, so the tolerance to hypoxia is poor, and it is the most sensitive tissue of the body to hypoxia.
The effect of hypoxia on the function of the central nervous system leads to changes in sleep structure, causing insomnia and decreased sleep quality, and as a result, it will aggravate the disorder of the central nervous system. Hypoxia significantly affects the ability of learning and memory, including transient/delayed memory, short-term memory and working memory. 3. Chronic hypoxia is prone to symptoms such as fatigue, lethargy, inattention, and decreased memory. The main manifestations of brain damage caused are The reaction time is prolonged, the coordination and accuracy of movements are reduced, and the labor efficiency is reduced. Hypoxia further aggravates the changes in brain function: excitement, euphoria, disorientation, and then uncoordinated movement, headache, fatigue, etc., and even disturbance of consciousness or death.
Hypoxia directly expands cerebral blood vessels, increases cerebral blood flow and cerebral capillary internal pressure, and increases tissue fluid production; long-term hypoxia can significantly inhibit the mitochondrial inner membrane adenylate transporter (ANT) transport activity, and increase free radicals in the brain. Lipid peroxidation and endogenous inhibitors increase, which in turn affects cell energy metabolism8. The production of lactic acid and oxygen free radicals and lipid peroxides in the brain increase, the antioxidant system is weakened, and the blood-brain barrier is damaged. 3, hypoxia-induced metabolic acidosis increases cerebral vasospasm and permeability, resulting in interstitial Cerebral edema, acute inhalation of low-oxygen air can also increase the pressure of the cerebrospinal fluid, causing intracranial hypertension, hypoxia, reducing ATP production, cell membrane sodium pump dysfunction, intracellular sodium water; cerebral congestion and cerebral edema make intracranial Increased blood pressure and high cerebral pressure can compress cerebral blood vessels and aggravate cerebral ischemia and cerebral hypoxia.
2. The effect of hypoxia on cardiovascular
In mild hypoxia, the body increases cardiac output and circulating blood volume through the adjustment and control of neural reflexes and high-level nerve centers to compensate for the decreased oxygen content in the cells, thereby improving the ability to tolerate hypoxia and adapt to harsh conditions. Low oxygen environment to maintain normal life activities. Intermittent hypoxic adaptation or long-term high altitude hypoxic adaptation can enhance the myocardial tolerance to ischemic injury, limit the size of myocardial infarction, resist apoptosis, promote the recovery of ischemia-reperfusion cardiac systolic function, and resist arrhythmia Hypoxia significantly dilates the coronary arteries, increases the blood flow of the coronary arteries, and stimulates the growth of myocardial capillaries and increases the collateral circulation by promoting the formation and release of endothelial growth factors and other vascular growth factors, thereby improving myocardial blood supply.
3. The effect of hypoxia on the respiratory center
Low oxygen partial pressure acts on the chemoreceptors of the carotid body and aortic body, which can reflexly excite the respiratory center, enhance respiratory movement, increase the respiratory rate and even cause respiratory distress. When the degree of hypoxia slowly increases, this reflexivity The role of excitement of the respiratory center will become dull, and the direct effect of hypoxia on the respiratory center at this time is an inhibitory effect. The body gradually adapts to the hypoxic environment, the sensitivity of hypoxic reaction decreases, and the adaptability of the reaction threshold increases. This phenomenon is called passivation. The weakened response of the respiratory center to hypoxia and/or high CO2 stimulation during sleep can induce breathing disorders, delay the patient’s awakening, extend the duration of apnea, and thereby aggravate hypoxemia , long-term repeated hypoxemia It may directly damage the respiratory central neurons of the patient .
4. The effect of hypoxia on renal function
At present, some researchers have proposed that chronic hypoxia is one of the reasons for the progression of kidney disease [3s, the main pathological manifestations of renal hypoxia are swelling of capillary endothelial cells in the glomerulus, turbid swelling and watery degeneration of renal tubular epithelial cells, and interstitial The number of internal blood vessels is increased, dilated and congested, and the blood vessel wall is obviously thickened.
Chronic hypoxia can induce the proliferation of glomerular mesangial cells and increase the production of extracellular matrix. It also induces the up-regulation of transforming growth factor β1 expression in renal tubular epithelial cells, resulting in down-regulation of matrix metalloproteinases and up-regulation of tissue inhibitors of metalloproteinases, leading to extracellular matrix degradation Accumulation, further acting on renal interstitial fibroblasts, participating in renal interstitial fibrosis.
Hypoxia causes glomerular cell mitochondria swelling and stroma focal edema; renal tubular epithelial cell microvilli are shortened, scarce, cytoplasmic edema, and mitochondrial swelling, which in turn leads to glomerular endothelial cell apoptosis. Hypoxia causes antidiuretic hormone in the body. , Catecholamine secretion increases, promotes the release of renin, and then the formation of vascular tension, which leads to renal artery contraction and renal blood perfusion decrease.
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