氢离子对人体的影响

The Effect of Hydrogen Ions on Humans


约翰·布伦南

当一种叫做质子酸的物质溶解在水中时，它释放出氢离子，增加了液体中的氢离子浓度。化学家将氢离子浓度的测量方法划分为pH值:pH值越低，氢离子浓度越高。氢离子浓度(pH)在人类生理中起着多种重要作用。

化学家将氢离子浓度的测量方法划分为pH值。pH值范围从0，高酸性到14，高碱性。pH值在人体生理中起着多种重要作用。只要氢离子在含有水的液体中，氢离子就会迅速与H2O结合形成水合氢离子，即H3O+。

蛋白质对人体的功能至关重要，并依赖氢键来维持它们的形状。人体必须将pH值保持在一个稳定的水平，以确保蛋白质保持它们的形状并发挥它们的作用。氢离子也有助于在胃中形成盐酸来消化食物，并形成一种叫做胃蛋白酶的分子，帮助分解食物蛋白质。
你血液中的pH值被严格控制在一个狭窄的范围内，从7.35到7.45，使用的是二氧化碳，一种能量代谢的细胞废物，和吸入的氧气。

pH值范围

氢离子实际上并不是独立漂浮的。当它们处于含有水的液体中时，氢离子就会迅速与H2O结合形成水合氢离子（Hydronium ions)，即H3O+。那么水中氢离子的浓度，实际上就是水合氢离子的浓度;化学家几乎把这两个术语互换使用。在室温下，pH值为7是中性的，这意味着氢离子和氢氧根离子的浓度相等。pH值范围从0，高酸性，到14，高碱性。14表示氢离子浓度非常低，而1表示氢离子浓度非常高。

蛋白质的构象

蛋白质是大分子，在人体中执行许多最重要的任务。它们的结构部分是由蛋白质分子中不同氨基酸之间形成的氢键形成的。改变体内氢离子的浓度可以改变体内蛋白质的形状或结构，所以你的身体有多种机制来保持pH值在一个恒定的水平。然而，细胞内的一些细胞器维持不同的pH值水平，以帮助它们发挥作用。例如，溶酶体是维持低pH值的细胞器，这有助于它们分解破损的细胞成分。

　

胃酸

在胃的内壁，一种叫做壁细胞的细胞分泌氢和氯离子，它们结合起来形成盐酸。这种强酸能显著降低胃部的pH值，有助于杀死细菌，分解食物中的分子。氢离子还通过确保一种叫做胃蛋白酶的酶具有正常的结构来影响消化。胃蛋白酶能分解食物中的蛋白质，促进消化。当胃里的东西进入小肠时，胰腺分泌碳酸氢盐来中和酸性物质，所以不会造成任何不良影响。

血液和肺

你血液中的pH值被严格控制在一个狭窄的范围内，从7.35到7.45。当你的细胞分解糖以获取能量时，它们最终会产生二氧化碳，并扩散回血液中。二氧化碳与水反应生成碳酸，降低血液的ph值。这种轻微升高的氢离子浓度会影响血红蛋白，血红蛋白是红细胞内携带氧气的一种蛋白质，它会释放一些氧气供细胞使用。在这个过程中，血红蛋白会吸收一些额外的氢离子和二氧化碳，并将它们运输回肺部。二氧化碳在肺部的浓度低于血液中的浓度，所以二氧化碳会从血液中扩散到肺部。这里的pH值越高，血红蛋白对氧的亲和力就越高，所以它可以再次吸收氧气。

　

The Effect of Hydrogen Ions on Humans

Updated May 15, 2018
By John Brennan
When a type of substance called a Bronsted acid dissolves in water, it releases hydrogen ions, increasing the hydrogen ion concentration in the liquid. Chemists classify the measure of hydrogen ion concentration as pH: the lower the pH, the higher the concentration of hydrogen ions. Hydrogen ion concentration, or pH, plays a variety of important roles in human physiology.

TL;DR (Too Long; Didn't Read)
Chemists classify the measure of hydrogen ion concentration as pH. The pH scale goes from 0, highly acidic, to 14, highly basic. The pH level plays a variety of important roles in human physiology. Whenever hydrogen ions are in liquid that contains water, hydrogen ions quickly combine with H2O to form hydronium ions, or H3O+.
Proteins are essential to the body’s functioning, and rely on hydrogen bonds to maintain their shapes. The body has to keep the pH at a stable level to make sure the proteins keep their shapes and do their jobs. Hydrogen ions also contribute to the formation of hydrochloric acid in the stomach to digest food, and to form a molecule called pepsin, which helps break down food proteins.
The pH in your blood is tightly controlled to stay in a narrow range, from about 7.2 to 7.4, using carbon dioxide, a cellular waste product of energy metabolism, and inhaled oxygen.
The pH Scale

Hydrogen ions do not actually float around independently. Whenever they are in liquid that contains water, hydrogen ions quickly combine with H2O to form hydronium ions, or H3O+. The hydrogen ion concentration in water, then, is really the hydronium ion concentration; chemists use the two terms almost interchangeably. At room temperature, a pH measurement of 7 is neutral, meaning that there is an equal concentration of hydrogen and hydroxide (OH-) ions. The pH scale goes from 0, highly acidic, to 14, highly basic. A 14 means there is a very low concentration of hydrogen ions, while 1 means there is a very high concentration of hydrogen ions.

Protein Configuration

Proteins are large molecules that carry out many of the most important tasks in the human body. Their structure is shaped partly by special bonds called hydrogen bonds that can form between different amino acids in the protein molecule. Changing the hydrogen ion concentration in the body can change the shape or configuration of proteins in the body, so your body has a variety of mechanisms to keep the pH at a constant level. Some organelles inside your cells maintain a different pH level, however, in order to help them do their job. Lysosomes, for example, are cell organelles that maintain a low pH, which helps them break down worn-out cell components.

Stomach Acid

In the lining of your stomach, cells called parietal cells secrete hydrogen and chloride ions, which combine to form hydrochloric acid. This strong acid dramatically reduces the pH of the contents of your stomach, which helps to kill bacteria and break down molecules in your food. The hydrogen ions also affect digestion by ensuring that an enzyme called pepsin assumes the proper configuration it needs to do its job. Pepsin breaks up proteins in the food you eat for better digestion. When the contents of your stomach pass into your small intestine, your pancreas secretes bicarbonate to neutralize the acidic contents so they don't cause any ill effects.

Blood and Lungs

The pH in your blood is tightly controlled to stay in a narrow range, from about 7.2 to 7.4. When your cells break down sugars to get energy, they end up producing carbon dioxide, which diffuses back into the bloodstream. Carbon dioxide reacts with water to form carbonic acid, decreasing the blood's pH. This slightly elevated hydrogen ion concentration affects hemoglobin, a protein carrying oxygen inside your red blood cells, causing it to release some of its oxygen for the cells to use. In this process, the hemoglobin then picks up some of the extra hydrogen ions and carbon dioxide and transports these back to the lungs. Carbon dioxide concentration in your lungs is lower than in the bloodstream, so the carbon dioxide diffuses out of your blood and into your lungs. The higher pH here increases hemoglobin's affinity for oxygen now, so it can take up oxygen again.

参考文献：

The Effect of Hydrogen Ions on Humans | Sciencing https://sciencing.com/effect-hydrogen-ions-humans-8275765.html