Blood is a connective tissue that functions to transport oxygen, nutrients, waste, and more throughout the body. It has a slightly alkaline pH of 7.4 and is composed of plasma and formed elements such as red blood cells, white blood cells, and platelets. Plasma is the liquid portion that contains water and proteins to maintain blood pressure and immunity. Red blood cells carry oxygen and carbon dioxide, white blood cells protect against pathogens, and platelets help with clotting. In summary, blood transports essential materials, regulates processes, and protects the body from infection through its cellular components suspended in plasma.