Plasma
Plasma is the relatively clear, yellow tinted water (92+%), sugar, fat, protein and salt solution which carries the red cells, white cells, and platelets. Normally, 55% of our blood's volume is made up of plasma. As the heart pumps blood to cells throughout the body, plasma brings nourishment to them and removes the waste products of metabolism. Plasma also contains blood clotting factors, sugars, lipids, vitamins, minerals, hormones, enzymes, antibodies, other proteins and gases. It is likely that plasma contains some of every protein produced by the body--approximately 500 have been identified in human plasma so far.
When blood is put into a test tube and spun in a centrifuge, the blood cells and platelets gravitate to the bottom of the tube, and the plasma is a clear layer on top. Think of the action inside blood vessels; imagine plasma as a river and the blood cells and platelets as leaves floating in it. Plasma is the “stream” in bloodstream. The plasma contains many important proteins, without which you would die.
Proteins are the most abundant substance in plasma by weight and play a part in a variety of roles including clotting, defense and transport. Collectively, they serve several functions:
Three major proteins contained in plasma are:
Amino acids are formed from the breakdown of tissue proteins or from the digestion of digested proteins.
Nitrogenous waste being toxic end products of the breakdown of substances in the body, these are usually cleared from the bloodstream and are excreted by the kidneys at a rate that balances their production.
Nutrients absorbed by the digestive tract are transported in the blood plasma. These include glucose, amino acids, fats, cholesterol, phospholipids, vitamins and minerals.
Gases like oxygen and carbon dioxide are transported by plasma. Plasma also contains a substantial amount of dissolved nitrogen.
Plasma is the relatively clear, yellow tinted water (92+%), sugar, fat, protein and salt solution which carries the red cells, white cells, and platelets. Normally, 55% of our blood's volume is made up of plasma. As the heart pumps blood to cells throughout the body, plasma brings nourishment to them and removes the waste products of metabolism. Plasma also contains blood clotting factors, sugars, lipids, vitamins, minerals, hormones, enzymes, antibodies, other proteins and gases. It is likely that plasma contains some of every protein produced by the body--approximately 500 have been identified in human plasma so far.
When blood is put into a test tube and spun in a centrifuge, the blood cells and platelets gravitate to the bottom of the tube, and the plasma is a clear layer on top. Think of the action inside blood vessels; imagine plasma as a river and the blood cells and platelets as leaves floating in it. Plasma is the “stream” in bloodstream. The plasma contains many important proteins, without which you would die.
Proteins are the most abundant substance in plasma by weight and play a part in a variety of roles including clotting, defense and transport. Collectively, they serve several functions:
- They are an important reserve supply of amino acids for cell nutrition. Cells called macrophages in the liver, gut, spleen, lungs and lymphatic tissue can break down plasma proteins so as to release their amino acids. These amino acids are used by other cells to synthesize new products.
- Plasma proteins also serve as carriers for other molecules. Many types of small molecules bind to specific plasma proteins and are transported from the organs that absorb these proteins to other tissues for utilization. The proteins also help to keep the blood slightly basic at a stable pH. They do this by functioning as weak bases themselves to bind excess H+ ions. By doing so, they remove excess H+ from the blood which keeps it slightly basic.
- The plasma proteins interact in specific ways to cause the blood to coagulate, which is part of the body's response to injury to the blood vessels (also known as vascular injury), and helps protect against the loss of blood and invasion by foreign microorganisms and viruses.
- Plasma proteins govern the distribution of water between the blood and tissue fluid by producing what is known as a colloid osmotic pressure.
Three major proteins contained in plasma are:
- Gamma globulin (also called immunoglobulin): - Gamma globulin is a broad term for a class of proteins that make up the different types of antibodies. The production of antibodies, which help to fight infections, is controlled by the immune system.
- Fibrinogen: - Fibrinogen is a protein involved in blood clotting.
- Albumin: - Albumin are the smallest and most abundant plasma proteins. Reductions in plasma albumin content can result in a loss of fluid from the blood and a gain of fluid in the interstitial space (space within the tissue), which may occur in nutritional, liver and kidney disease. Albumin also helps many substances dissolve in the plasma by binding to them, hence playing an important role in plasma transport of substances such as drugs, hormones and fatty acids.
Amino acids are formed from the breakdown of tissue proteins or from the digestion of digested proteins.
Nitrogenous waste being toxic end products of the breakdown of substances in the body, these are usually cleared from the bloodstream and are excreted by the kidneys at a rate that balances their production.
Nutrients absorbed by the digestive tract are transported in the blood plasma. These include glucose, amino acids, fats, cholesterol, phospholipids, vitamins and minerals.
Gases like oxygen and carbon dioxide are transported by plasma. Plasma also contains a substantial amount of dissolved nitrogen.