The "yellow blood" is most likely referring to blood plasma, the pale yellow liquid component of blood.
Understanding Blood Plasma
Blood plasma is the largest single component of blood, making up approximately 55% of its total volume. It's essentially the liquid matrix within which blood cells (red blood cells, white blood cells, and platelets) are suspended and transported.
Composition of Blood Plasma
Blood plasma is primarily composed of:
- Water: Approximately 92% of plasma is water, which acts as a solvent for transporting other components.
- Proteins: These make up about 7% of plasma and include:
- Albumin: Helps maintain osmotic pressure and transports various substances.
- Globulins: Include antibodies (immunoglobulins) that fight infection and transport proteins.
- Fibrinogen: Essential for blood clotting.
- Other Solutes: The remaining 1% includes electrolytes (sodium, potassium, chloride), nutrients (glucose, amino acids, lipids), hormones, waste products (urea, creatinine), and gases (oxygen, carbon dioxide).
Why is Plasma Yellow?
The pale yellow color of plasma is primarily attributed to the presence of bilirubin. Bilirubin is a yellowish pigment that is a byproduct of the breakdown of heme, a component of hemoglobin (the protein in red blood cells that carries oxygen). The liver processes bilirubin, and it is eventually excreted in bile. Small amounts of bilirubin circulate in the plasma, giving it its characteristic yellow hue.
Functions of Blood Plasma
Plasma performs several critical functions:
- Transportation: Carries blood cells, nutrients, hormones, waste products, and other essential substances throughout the body.
- Maintaining Blood Pressure and Volume: Plasma proteins, particularly albumin, help maintain osmotic pressure, which is crucial for regulating blood volume and preventing fluid leakage from blood vessels.
- Blood Clotting: Plasma contains clotting factors (like fibrinogen) that are essential for forming blood clots and preventing excessive bleeding.
- Immune Function: Plasma contains antibodies (immunoglobulins) that help fight infection and provide immunity.
- Maintaining pH Balance: Plasma contains buffers that help maintain a stable pH balance in the blood.
When Plasma is More Yellow than Usual
In certain medical conditions, plasma may appear more yellow than normal. This can be a sign of:
- Jaundice: Caused by elevated bilirubin levels, often due to liver problems or increased red blood cell breakdown.
- Dehydration: Can concentrate plasma and make its color more intense.
