The other fluid

The idea

Plasma, proteins and blood cells escaping through capillary pores into intercellular spaces form lymph, a colourless, low-protein tissue fluid; draining through lymph vessels into veins, it carries absorbed fat from the intestine and returns excess fluid to blood.

Leaking a little

Blood vessels called capillaries have tiny pores in their walls.

What do you think happens to a little of the blood fluid at these pores?

• Some of it escapes into the spaces between cells
• Nothing can escape
• All of the blood escapes

Follow the fluid

Open each tab.

A second flow

Through tiny pores in the capillary walls, some plasma, proteins and blood cells escape into the spaces between cells. This forms lymph, also called tissue fluid. It is like plasma but colourless and with less protein. Lymph drains into lymph vessels that open into larger veins. It carries absorbed fat from the intestine and brings excess fluid back to the blood.

Plasma, proteins and blood cells escaping through capillary pores into intercellular spaces form lymph, a colourless, low-protein tissue fluid; draining through lymph vessels into veins, it carries absorbed fat from the intestine and returns excess fluid to blood.

Notes

Lymph (tissue fluid) forms from plasma, proteins and cells escaping through capillary pores; it is colourless with less protein, drains through lymph vessels into veins, carries absorbed fat and returns excess fluid to blood.

Check yourself

How is lymph formed?

Compared with plasma, lymph is ...

Lymph vessels finally open into ...

What does lymph carry from the intestine?

• It is made by the liver from bile. Bile is made by the liver; lymph forms from material that escapes from capillaries.
• Some plasma, proteins and blood cells escape through the pores of capillaries into intercellular spaces — correct. Yes!
• It is made by platelets plugging leaks. Platelets plug leaks in the blood vessels; lymph forms from material escaping through capillary pores.
• red and has more protein. Lymph is similar to the plasma of blood but is colourless and contains less protein.
• red and has the same protein. Lymph is colourless and contains less protein than plasma.
• colourless and has less protein — correct. Yes!
• larger veins — correct. Yes!
• the left ventricle. The lymph vessels finally open into larger veins.
• the alveoli. Alveoli are in the lungs, where gases are exchanged.
• Bile. Bile is made by the liver and flows into the small intestine.
• Digested and absorbed fat — correct. Yes!
• Oxygen. Oxygen is carried by the red blood corpuscles.