page_title: Intracellular pH
section_title: In organelles
hierarchical_section_title: Intracellular pH / In organelles
caption_attribution_description: English: A cell with several important organelles and their various pHs.
context_page_description: Intracellular pH is the measure of the acidity or basicity of intracellular fluid. The pHi plays a critical role in membrane transport and other intracellular processes. In an environment with the improper pHi, biological cells may have compromised function. Therefore, pHi is closely regulated in order to ensure proper cellular function, controlled cell growth, and normal cellular processes. The mechanisms that regulate pHi are usually considered to be plasma membrane transporters of which two main types exist — those that are dependent and those that are independent of the concentration of bicarbonate. Physiologically normal intracellular pH is most commonly between 7.0 and 7.4, though there is variability between tissues. There is also pH variation across different organelles, which can span from around 4.5 to 8.0. pHi can be measured in a number of different ways.
context_section_description: The pH within a particular organelle is tailored for its specific function.
  For example, lysosomes have a relatively low pH of 4.5. Additionally, fluorescence microscopy techniques have indicated that phagocytes also have a relatively low internal pH. Since these are both degradative organelles that engulf and break down other substances, they require high internal acidity in order to successfully perform their intended function.
  In contrast to the relatively low pH inside lysosomes and phagocytes, the mitochondrial matrix has an internal pH of around 8.0, which is approximately 0.9 pH units higher than that of inside intermembrane space. Since oxidative phosphorylation must occur inside the mitochondria, this pH discrepancy is necessary to create a gradient across the membrane. This membrane potential is ultimately what allows for the mitochondria to generate large quantities of ATP.
caption: Approximate pHs of various organelles within a cell.[6]
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