Introduction to Endothelium

Cells lining the blood vessels and lymphocytes are called 
Endothelium.  Endothelial cells a form a thin layer on the interior
surface of all vessels and function is various important physiological
functions.  For years, this layer was thought to be inert, serving only to
filter water and other small molecules across the blood vessels.  However,
it has been recently observed that endothelium acts as a source of
substances that can aid vascular smooth muscle in relaxation or
contraction.  These substances may promote responses such as inflammation
and blood clotting.




There are three types of capillary endothelium which we discussed in
class.  The first is  continuous capillaries found in muscle, lung,
fat, connective tissue, and the nervous system.  The second
type of endothelium capillaries is fenestrated capillaries which
are found in tissues which participate in fluid exchange.  Lastly,
the third type of capillary endothelium is   Discontinuous or
sinusoidal capillaries found in red blood cells.  Fenestrated and
discontinous endothelium allow passage of large molecules to pass through
intracellular spaces of the endothelium.  

Sample Problems:

Matching:

A. Fenestrated Capillary Endothelium

B. Continuous Capillary Endothelium

C. Discontinuous Capillary Endothelium





1.  Synovial joint tissues (i.e.  these participate in fluid exchange)


2.  Red blood cells

3.  Muscles and lungs 

Answers:

1-A, 2-C, 3-B

For more information on this topic, please refer to Berne & Levy , p. 157-160

Also, check out the following links that may be helpful:

• Cardiac Endothelium
• EMBASE entry onf Endothelium
• And, as always, if you have questions, or if you can suggest a helpful link, please e-mail me.

No!
Please don't make me go to any of those pages!
I want to go somewhere completely different!

This page was written by Karolynn Bayaca
Karol's world , a student in this course.

BME 403 Pages maintained by the T.A., Douglas Miles.