The mammalian circulatory system is a closed double circulation system where blood is pumped from the heart to lungs and throughout the body in separate loops. Tissue fluid leaks from capillaries into tissues and is almost identical to blood plasma but contains fewer proteins and no red blood cells. About 90% of tissue fluid returns to capillaries while the remaining 10% is collected by lymphatic vessels containing one-way valves and transported via lymph nodes, which help protect the body from disease. Blood itself is composed of plasma and three main cell types.

2. IMPORTANT!
The mammalian circulatory
system is a closed double
circulation system
WHY?

6. BLOOD PRESSURE VARIATION

7. BLOOD PLASMA AND TISSUE FLUID
 Tissue fluid is almost identical in composition to
blood, except…
 Tissue fluid contains far less proteins (which are
too large to escape from capillaries)
 Tissue fluid does not contain red blood cells

8. FORMATION AND RETURN OF
TISSUE FLUID

10. LYMPH
 About 90% of the fluid that leaks from capillaries
returns to them
 The remainig 10% is collected by a series of tubes
called lymph vessels or lymphatics.
 Lymphatics contain tiny valves, which allow
large molecule of proteins to pass through.
 Lymph nodes: involved in protection against
disease.

11. BLOOD
 Blood is a tissue formed by plasma and three
different kinds of cells.

13. SOME USEFUL LINKS
 Blood pressure
https://cnx.org/contents/A4QcTJ6a@3/Blood-
Flow-Blood-Pressure-and-
 Tissue fluid and lymph
https://www.youtube.com/watch?
v=IQIPrQUo1D4
 Composition of the blood
http://www.slideshare.net/vidhidoshi9619/blood-
38779086