The Plasma Proteins

• Plasma proteins make up about 7 percent of plasma
• Three major classes of plasma proteins: albumins, globulins, fibrinogen
• Albumins

  • make up about 60 percent
  • major contributors to osmotic pressure
  • transport fatty acids, thyroid hormones, steroid hormones, other substances
• Globulins

  • second most abundant proteins
  • make up 35 percent of plasma proteins
  • include immunoglobulins and transport globulins
• Immunoglobulins, also called antibodies, aid in the body's defense
• Transport globulins bind small ions, hormones, or compounds that either are insoluble or will be filtered out of the blood by kidneys
• Fibrinogen

  • makes up 4 percent of plasma proteins
  • largest and essential for clotting
  • form fibrin, basic framework of blood clot
• To prevent clotting, clotting proteins are removed, leaving a fluid known as serum
• Protein lipid combinations, called lipoproteins, dissolve in plasma and can be transported as insoluble lipids to peripheral tissues