👉 The principal fluid in the human body is blood, a vital liquid that circulates throughout the circulatory system. Composed mainly of water (about 60%), along with proteins, nutrients, hormones, and waste products, blood transports oxygen and essential nutrients to cells while removing carbon dioxide and toxins. It plays a crucial role in maintaining body temperature, supporting immune function, and facilitating chemical reactions necessary for life. Blood is classified into two main types: red blood cells (hematocrit), which carry oxygen, and white blood cells (leukocytes), which defend against infections.
