Question

Why is the pH of arterial blood higher than the venous blood?

Answer 1

The pH is an important property of our blood. It is measured as the degree of its acidity and alkalinity. Any solution’s acidity or alkalinity is indicated on the pH scale.

Complete Answer:
The pH scale ranges from $0$ to$14$. Here $0$ means strongly acidic and $14$ means strongly basic or alkaline. In this scale $7.0$ is the neutral which is the middle point of the scale. Our blood has the normal pH range from $7.35$ to $7.45$ on pH scale. Which is slightly basic. Generally, our body maintains the average pH level of blood is $7.40$.
So, if the pH is lower, that means acidity is higher. And if the pH is higher, then the acidity is lower, that means the solution is alkaline.

| Arterial Blood| Venous Blood
---|---|---
pH Level| $7.35{\text{ }}-{\text{ }}7.45$| $7.32{\text{ }}-{\text{ }}7.42$

That means the acidity of our venous blood is higher than the acidity of our arterial blood. Here we can see a very small amount of pH level difference is found between our arterial blood and our venous blood. The reason behind it is, in our venous blood carbon dioxide is dissolved. The dissolved carbon dioxide produces the carbonic acid. This carbonic acid makes the venous blood a little bit more acidic than the blood of our artery, because our artery carries oxygen in it.

Note:
The venous blood is more acidic than the blood of our artery simply due to the metabolism. Because, in this process our cells produce carbon dioxide that venous blood receives from the cells through gaseous exchange and carries it to the lungs for gaseous exchange. And we all know that oxygenated blood flows through the arteries and the carbon dioxide enriched blood flows through the vein.