By OpenStax College – Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013., CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=30148163

In blood, there are several components. Erythrocytes, or red blood cells, make up a portion of around 40-45% (actual numbers vary among genders and disease processes), different blood cells, and then plasma, which is the majority of blood component (around 55%). Plasma contains water, proteins, nutrients and other components.