Quick Bio Question PLEASE HELP!

[JenOneN]

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I know this is a stupid question, but I want to make sure I am understanding this correctly. Why aren't lymphatic vessels and thus the lymphatic system present in the CNS and bones?

Thanks!

 

[jhugti]

lymphatic vessels are indeed present in bones, both in the haversian canals and in the periosteum. bone marrow, as the ultimate source of blood cells, is a crucial part of the lymphatic system. regarding the cns, the lymphatic system's primary role of fluid balance is taken on by the cerebrospinal fluid.

 

[tigress]

Well, they are present in bones. Each osteon (Haversian system) has blood vessels, nerves, and lymphatics in the center canal. Each osteocyte sends a little projection into the canal to get to these things.

The brain has its own fluid, cerobrospinal fluid, and does not come in contact with blood itself (the 'blood-brain barrier"). Cerebrospinal fluid functions to remove wastes as well as provide nutrients. It's sort of separate from some of the typical body systems.

 

[JenOneN]

My textbook says: lymphatic vessels are not present in bone marrow....

I think I'm confused here? Is it because the cells enter the circulation, so there's no need for lymphatic vessels?

 

[malumd2b]

your book is indeed right. Eventhough the above posters were partially right about the role of the components of bone and cns, bone does not contain much fluid tissue and the cns drains directly into venous system. You can fine all about it at this link:
http://academic.pgcc.edu/~aimholtz/AandP/206_ONLINE/Lymph/lymph1.html
hope that helps.

 

[jhugti]

your textbook is correct- the marrow itself is contained in a central cavity in longbones and flatbones, only the latter being relevant to producing blood cells. If I remember correctly, the Haversian systems are only present in long bones, as flat and irregular bones are composed of layers of spongy bone.

edit: beat me to it- that website's diagrams are pretty much identical to ones I was going to link you to. 👍