Main components and structure of plasma and blood cells

Plasma & RBC

Plasma constitutes the majority of whole blood volume, about 46-63% (Martini, Nath, & Bartholomew, 2011). Plasma is the matrix of blood, contributing to blood's unique composition. Plasma has three main components: plasma proteins, water, and other solutes (Patton & Thibodeau, 2009). Plasma proteins are too large in size to get across capillary walls; therefore after the majority of these proteins are synthesized by the liver, they go into the bloodstream and remain there (Martini, Nath, & Bartholomew, 2011). The majority of plasma proteins are albumins. Albumin's role is to contribute to the osmotic pressure of plasma; they also serve as carrier proteins, transporting various hormones and fatty acids (Tortora & Derrickson, 2011). Globulin is another plasma protein whose role is to transport ions, thyroid and steroid hormones, and lipids; they also contain our antibodies that help our immune system (Martini, Nath, & Bartholomew, 2011). Fibrinogin is an essential plasma protein for blood clotting in case of injury. Other essential plasma proteins are peptide proteins such as insulin, glycoproteins, and prolactin, whose levels within plasma can vary widely (Patton & Thibodeau, 2009).

Plasma is also composed of other solutes whose concentrations differ according to whether the plasma is traveling in venous blood or arterial blood; that is, whether the blood is oxygenated or deoxygenated (Patton & Thibodeau, 2009). Electrolytes such as sodium, potassium, bicarbonate, and calcium are important solutes for proper cell activity. Organic nutrients like amino acids, lipids, and carbohydrates, that comprise plasma, are used for cell metabolism and growth (Martini, Nath, & Bartholomew, 2011). Organic wastes also make up plasma -- uric acid, urea, and bilirubin all get transported to their site of excretion (Tortora & Derrickson, 2011). Water makes up the large majority of plasma, about 90% (Martini, Nath, & Bartholomew, 2011).

Red blood cells make up about 99% of the formed elements in whole blood. Because of their unique and specialized structure, they are essential for the transportation of oxygen and carbon dioxide to and from the different body systems (Martini, Nath, & Bartholomew, 2011). Red blood cells are shaped like biconcave disks which allow for it to have a large surface area. This large surface area permits the quick absorption and release of bound oxygen and with more volume, the exchange between red blood cells and the surrounding plasma is facilitated (Patton & Thibodeau, 2009). Their shape and size also allow for the red blood cells to stack on top of one another in order to flow better through very narrow blood vessels. Their flexible structure also allows them to slightly change shape in order to get through narrow capillaries (Martini, Nath, & Bartholomew, 2011).