Blood plasma is the liquid part of the blood. Blood plasma makes up about 55% of the body’s total blood volume. The blood plasma itself is 90% water. The remaining 10% is made up of substances such as oxygen, carbon dioxide, hormones, waste products and plasma proteins. Such proteins include fibrinogens. Blood proteins play a role in various processess, such as blood coagulation and the transport of substances.

Blood plasma carries nutrients from the digestive system to the rest of the body. Blood plasma also transports carbon dioxide produced during cell respiration from tissues to the lungs. Blood warms up as it flows through the liver and the muscles, and this heat is transmitted with the help of blood plasma to the outermost parts of our body.

Although our body has blood vessels that are almost 100,000 kilometers long in total, not all cells are located close to this network. The more distant cells need food and oxygen just like all other cells. The thinnest blood vessels constantly leak fluid into the intercellular space and thus receive the substances they need. This tissue fluid returns to the bloodstream either through capillary veins or through lymphatic vessels.