Overview
This lecture covers the composition and functions of plasma and plasma proteins, including their roles in transport, osmotic pressure, waste removal, disease, and the basics of erythrocytes and hemoglobin.
Plasma Composition and Functions
- Plasma is a pale yellow fluid making up 55% of total blood volume, mainly water with dissolved nutrients, proteins, hormones, and wastes.
- Key waste products in plasma include urea, uric acid, creatinine, bilirubin, and ammonium ions.
- Most waste is excreted by the kidneys, except bilirubin, which is mostly eliminated via the GI tract.
- Plasma suspends blood cells, aids clotting, and helps transport nutrients and wastes.
Plasma Proteins
- Three major plasma proteins: albumin, globulin, and fibrinogen, mainly produced by the liver.
- Albumin functions as a transport protein (fatty acids, hormones, metals) and maintains colloid osmotic pressure to retain blood fluid.
- Globulins include transport globulins (liver-made) and immunoglobulins (antibodies made by B cells/plasma cells).
- Fibrinogen is essential for blood clot formation, converting into fibrin during coagulation.
- Serum is plasma minus fibrinogen (after clotting has occurred).
Pathology and Clinical Relevance
- Low plasma proteins (especially albumin) lead to decreased osmotic pressure, causing fluid retention and edema.
- Alpha-1 antitrypsin deficiency causes emphysema and liver disease due to a lack of protease inhibition.
- Low ceruloplasmin leads to Wilson's disease, causing toxic copper accumulation in tissues.
Clinical Use of Plasma Components
- Plasma extraction (plasmapheresis) allows use of albumin, clotting factors, immunoglobulins, and specific proteins for treating diseases and conditions (e.g., shock, burns, immune deficiencies).
Erythrocytes and Hemoglobin
- Erythrocytes (red blood cells) make up 99.9% of formed blood elements and primarily transport oxygen via hemoglobin.
- Erythrocytes lack nuclei and organelles at maturity; produced in red bone marrow; lifespan is about 120 days.
- Hemoglobin binds oxygen and some carbon dioxide, giving blood its red color.
Key Terms & Definitions
- Plasma — liquid portion of blood with water, proteins, nutrients, hormones, and wastes.
- Albumin — main plasma protein for transport and osmotic pressure.
- Globulin — group of plasma proteins; includes antibodies (immunoglobulins) and transport proteins.
- Fibrinogen — plasma protein essential for blood clot formation.
- Serum — plasma with fibrinogen (clotting factor) removed.
- Colloid osmotic pressure — pressure by plasma proteins that retains water in blood vessels.
- Erythrocyte — red blood cell specializing in oxygen transport.
- Hemoglobin — erythrocyte protein binding oxygen and some carbon dioxide.
- Alpha-1 antitrypsin — protease inhibitor plasma protein; deficiency causes emphysema.
- Ceruloplasmin — copper-transport protein; low levels cause Wilson's disease.
Action Items / Next Steps
- Review the features and functions of the three major plasma proteins.
- Memorize main waste products found in plasma and their routes of excretion.
- Learn the clinical significance of plasma protein deficiencies.
- Prepare for the next lecture on erythrocyte development and hemoglobin breakdown.