Why must digestive food be distributed by blood in man and other animal?

The digestive food must be distributed by blood in man and other animals due to several reasons:

1. Absorption of Nutrients: After the process of digestion in the stomach and intestines, the nutrients from the food are absorbed into the bloodstream. These nutrients include glucose, amino acids, and fatty acids, which are essential for the body's functioning.

2. Transportation of Nutrients: The blood, specifically the plasma, acts as a medium to transport these nutrients to different parts of the body. This is important as every cell in the body requires these nutrients for energy, growth, and repair.

3. Waste Removal: The blood also helps in the removal of waste products. After the cells use the nutrients, they produce waste products which are harmful to the body. The blood carries these waste products to the kidneys where they are filtered out and excreted.

4. Regulation of Body Temperature: The distribution of digested food by the blood also helps in maintaining the body's temperature. The blood carries heat, which is a by-product of metabolism, away from the body's core to the skin where it can be lost to the environment.

5. Immune Function: The blood also carries white blood cells and antibodies that help fight off infections and diseases.

In conclusion, the distribution of digested food by the blood is essential for the overall functioning and survival of the body.