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Being healthy includes keeping the blood’s acidity or alkalinity at a normal level. This is shown on the pH scale. The pH scale goes from 0 (very acidic) to 14 (very basic or alkaline). A pH of 7.0 is neutral, right in the middle. Blood is usually slightly basic, with a normal pH between 7.35 and 7.45. The body usually keeps the blood’s pH close to 7.40.
Doctors check if a person’s acid-base balance is good by measuring the pH, carbon dioxide (an acid), and bicarbonate (a base) in the blood.
Blood pH Regulation
Much of the acid in the body is carbonic acid. This acid forms when carbon dioxide mixes with water. Carbon dioxide is made in the body’s tissues during respiration.
The lungs and kidneys are the main organs that keep the blood’s pH balanced. They often work together to do this. There are also chemical buffers in the body’s cells that help.
The lungs can quickly control blood pH by exhaling carbon dioxide. This can change the pH in seconds. For example, when you exercise, you make more carbon dioxide, so you breathe faster to stop the blood from getting too acidic.
The kidneys control blood pH by removing acids in urine. They also make and control bicarbonate, which raises blood pH. These changes take longer than those from breathing, sometimes taking hours or days.
How pH of Blood is Maintained?
Keeping our blood pH level healthy is very important for our body to work properly. The blood pH should be between 7.35 and 7.45. Our body has three main ways to keep the blood pH in this range:
- Chemical Buffers: These are special molecules in our blood and cells that can balance acids and bases. They act quickly, within seconds to minutes, to neutralize any extra acid or base until other systems can take over.
- Respiration: Our lungs help control blood pH by removing carbon dioxide (CO2), which is produced by our cells. When CO2 levels in the blood go up, it makes the blood more acidic. The lungs respond by breathing faster and deeper to get rid of CO2 and bring the blood pH back to normal. This happens within minutes.
- Kidneys: The kidneys work more slowly, taking hours to days to adjust blood pH. They filter the blood and remove extra acid or base through urine. They also help manage bicarbonate, a key part of the blood’s buffering system.
These three systems work together to keep the blood pH stable. It’s a great example of how our body’s complex feedback mechanisms keep us healthy.
Causes of Abnormal blood pH
Too high or too low pH levels in the blood can show that an organ is not working properly. Acidosis (low pH) or alkalosis (high pH) usually happen because the lungs or kidneys aren’t working well. Changes in blood pH can be caused by various health issues like diabetes, poisoning, infections, or heart, lung, or kidney diseases.
High Blood pH (Alkalosis)
High blood pH means the blood is too alkaline. This can be due to temporary illnesses or serious conditions.
Causes of high blood pH include:
- Losing too much fluid through urination, vomiting, or diarrhea.
- Kidneys not removing excess alkaline substances from the blood.
Low Blood pH (Acidosis)
Low blood pH means the blood is too acidic, with a pH of 7.35 or lower. Acidosis is more common than alkalosis. Main causes of acidosis include:
- Ketoacidosis in diabetes.
- Metabolic acidosis from kidney disease or failure.
- Respiratory acidosis from lung diseases like pneumonia, bronchitis, asthma, or chronic pulmonary disease.
So, having a normal blood pH is important for the body to function well. High or low blood pH is not a disease itself but is a sign of other health problems. It helps doctors diagnose diseases early.
This was a short note on blood pH. For more information, you can explore notes on blood composition and other important topics for NEET.
pH of Blood in Human Body FAQs
What is the pH of human body blood?
The pH of human blood is about 7.4.
What is the pH of blood and urine?
Blood pH is around 7.4, while urine pH ranges from 4.6 to 8.
Why is blood pH not 7?
Blood pH is slightly alkaline at 7.4 to support body functions.
What is the pH of normal blood?
Normal blood pH is about 7.4.
What happens if blood pH is too high?
If blood pH is too high, it can cause alkalosis, leading to muscle twitching and confusion.
What is the highest pH of blood?
Blood pH can rarely go above 7.45; higher levels are dangerous.
How does the body maintain blood pH?
The body maintains blood pH through buffers, breathing, and kidney function.
What helps maintain blood pH?
Buffers in the blood, breathing, and kidneys help keep blood pH stable.
How is blood pH kept constant?
Blood pH is kept constant by buffers, the respiratory system, and the kidneys.
