What is the normal pH of Blood?

The normal body pH is slightly alkaline (around 7.4). The pH of blood is an indication of acidity or alkalinity in the body. It is an important indicator of good health. The normal pH is essential for the optimal activity of the body so it is balanced by different physiological processes.
 
The normal blood pH level of a healthy person ranges from 7.35 to 7.45. It is slightly basic or alkaline.

Table of Content:

Blood pH Regulation Causes of Abnormal Blood pH Frequently Asked Questions

Blood pH Regulation

Our body maintains the normal pH by acid-base balance. It is important to maintain homeostasis.

There are various factors that regulate blood pH. The pH of blood plasma depends on CO2, electrolyte and weak acid concentrations. The two main organs that regulate the acid-base balance (pH) of the blood are:

  • Lungs- They are in the gaseous exchange and remove CO2. The brain regulates breathing process so the brain and the lungs maintain blood pH by regulating the speed and intensity of breathing.
  • Kidney- They maintain pH balance through excretion. They remove the excess acid or bases present in the blood.

So, our body maintains pH balance through respiration, excretion and other metabolic activities. Thus kidneys and lungs help to maintain blood pH. Any change in blood pH, i.e acidosis or alkalosis is due to impaired function of these organs.

Causes of Abnormal blood pH

Too high or too low pH is an indication of some organ dysfunction. Acidosis or alkalosis is mostly due to impaired functioning of lungs or kidneys. Any change in the blood pH may be due to various diseases such as diabetes, poisoning, infection, heart, lung or kidney diseases.

High Blood pH

High blood pH or alkalosis occurs when the pH of blood is higher than the normal. It may be caused due to temporary illness or some serious condition.

High blood pH may be due to the following reasons:

  • Excessive loss of fluid such as excessive urination, vomiting, diarrhoea, etc.
  • When kidneys do not remove excessive alkaline substances from the blood.

Low Blood pH

Acidosis denotes an acidic blood condition which is characterised by a blood pH of 7.35 or less. There are various causes for acidosis and it is more prevalent than alkalosis. The main reasons for acidosis include:

  • Ketoacidosis in diabetes.
  • Metabolic acidosis due to kidney diseases or failure.
  • Respiratory acidosis due to lungs diseases such as pneumonia, bronchitis, asthma, chronic pulmonary diseases.

Hence, normal pH of blood is vital for normal body functioning. High or low pH is not a disease in itself but is due to certain disorders. It is a key determinant in the initial diagnosis of diseases.

This was a brief note on pH of Blood. Explore notes on Blood composition and other important concepts related to NEET, only at BYJU’S.

Frequently Asked Questions

Q1

What is pH?

A pH (potential of hydrogen) is used to specify basicity or acidity in an aqueous solution. In other words, a pH scale measures the hydrogen ion concentration in a given solution. Solution with higher hydrogen ion concentration (acidic) shows low pH value. Likewise, an increase in hydroxide ion concentration (basic) results in an increased pH value in humans. The pH value of neutral solution is 7.

Q2

Why is blood pH so significant?

The proper balance between bases and acids in the body’s extracellular fluid is vital for normal physiology. Thus, high or low blood pH acts as an indicator for a disease or disorder.

Q3

What is plasma pH?

The plasma pH depends on CO2, electrolyte and weak acid concentrations. It should ideally be maintained between the pH range of 7.38 to 7.42. Alkalosis and acidosis are the terms used to describe high and low plasma pH, respectively.

Q4

How does the body maintain acid base balance?

The pH balance in the human body is vital for the normal functioning or physiology of the body. The lungs and kidneys help in maintaining this equilibrium or balance through gaseous exchange and excretion respectively.

Q5

How to test blood pH?

A needle is used to draw blood for blood pH tests. After that, a lab receives the blood sample for analysis. ABG (arterial blood gas) testing is a common component of blood gas analysis. It calculates the levels of carbon dioxide and oxygen in your blood.

 

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