Tissue Fluid & Lymph

Plasma: The yellow liquid part of blood, it carries dissolved substances such as glucose, amino acids, ions, hormones, large plamse proteins such as albumin, fibrinogen (clotting) and globulin (immune system)

Tissue Fluid: Similar to plasma but baths cells & tissues does not contain plasma proteins & red blood cells

Lymph: Similar to tissue fluid composition varies found in lymph vessels.

Hydrostatic pressure: the pressure of the blood as it surges through the arterioles into the capillaries under the influence of the heart (kPa). Tissue fluid also has Hydrostatic pressure pushing back. Higher at arterial end pushes fluid out. If higher than that of blood fluid is pushed back in.

Oncotic pressure: (or colloid osmotic pressure) is a form of osmotic pressure exerted by plasma proteins. -3.3kPa Pressure created by presence of solutes including plasma proteins, always more negative in capillary, pulls fluid back in.

Tissue Fluid

• Tissue Fluid fills spaces between cells.

• It is the site of diffusion between blood & body cells, providing cells with nutrients & oxygen while removing waste products.

• It also helps fight infection as it forms part of the immune response.

• It has the name composition as palma except it has no plasma proteins and red blood cells.

Formation of Tissue Fluid

• At the arteriole end of capillaries:

  • High Hydrostatic pressure

    • Exerted by a fluid

  • Forces fluid out of capillaries

  • Proteins stay in blood

  • Increased protein content creates water potential gradient (osmotic pressure)

  • The Hydrostatic pressure is greater than the osmotic pressure so net movement of water rises out of the capillaries into the tissue fuild.

• At the venous end of capillaries

  • The Hydrostatic pressure is lower

    • Due to increased distance between the heart and ash the slowing off blood flow as it assessed through he capillaries

  • The water potential gradient remains the same.

  • The osmotic pressure is greater than the Hydrostatic pressure and water begins to flow back into the capillary form he tissue fluid

  • If the blood pressure is high (hypertension) then the pressure at the arterial of end is even greater

    • This pushes more fluid our roof the capillary and the fluid beings to accumulate around the tissue

    • This is called the oedema

Formation of Lymph

• Some tissue fluid renters the capillaries while some enters the lymph vessels

• Large molecules that can not pass through teh capillary Wal enter the lymph

  • Small valves in the vessel walls are the entry point

• The liquid moves along the larger vessels of this system by compression caused by body moveme.

  • Any backlog is prevented by valves

• The lymph eventually renters the bloodstream through veins located close to the heart

• Any plasma proteins that have escaped form teh blood return to the blood through lymph capillaries

  • If the plasma proteins were not removed form tissue fluid they could lower the water potential and prevent teh reabsorption of water not teh blood in he capilalries.

• After r digestion lipids are transported for teh intestines to the blood stream by the lymph system.