3.10.10 Tissue fluid and the Lymphatic System

1
3.10.10 Tissue fluid and the Lymphatic System

• Objectives-
• To understand the exchange of materials at the
  capillaries.
• To be able to describe the formation of tissue
  fluid.
• To understand the role of the lymphatic system.

2
Exchange at the capillaries.

• Hydrostatic pressure is created by the heart
  squeezing the blood.
• Pressure in arterioles is higher than in venules.
• This causes molecules that are small enough to
  squeeze through capillary pores.
• This is called ultrafiltration.

3
Contd.

• Water leaves the artery end of the capillaries
  due to the high pressure.
• At the venule side water re-enters down a
  diffusion gradient by osmosis.
• Other molecules move dependent upon diffusion
  gradient eg oxygen, carbon dioxide, sugars etc.

4
What is tissue fluid made up from? (p199)
5
The Lymphatic System.

• Lymph system is made up of lymph vessels that
  begin in the capillaries and gather to form a
  drainage system for some fluids left in the
  tissues.
• The liquid in the system is called lymph.
• The largest lymph vessels drain into the veins of
  the neck.

6
Important Points about the Lymphatic System.

• Lymph nodes produce white blood cells and
  antibodies.
• Lacteals lymph vessels found in the lining of
  the small intestine to absorb lipids.
• Oedema swelling of tissues if fluid is not
  draining properly eg heart disease, pregnancy.