22.2 : Characteristics and Functions of Blood

Approximately 8% of the body mass comprises whole blood, a specialized connective tissue vital for transportation, regulation, and protection.

The presence of cells, dissolved proteins, and electrolytes in the liquid extracellular matrix of blood makes it about five times more viscous than water.

Blood is a warm fluid with a temperature of around 100.4 degrees F and an alkaline pH ranging from 7.35 to 7.45.

Its primary function is to carry oxygen and carbon dioxide between tissues and the lungs.

When saturated with oxygen, it is bright red in color, whereas oxygen-depleted blood is darker.

Blood also transports nutrients from the digestive tract and secretions like hormones from endocrine glands to various tissues.

The proteins and solutes dissolved in the blood serve as buffering agents to regulate the pH of interstitial fluids.

Additionally, it absorbs and redistributes the heat generated by active skeletal muscles. 

In case of injury, blood proteins induce clotting to prevent excessive blood loss.

Specialized blood cells can clear foreign particles and secrete proteins, such as antibodies, to protect against disease.