how do nutrient get to cells of veins and arteries?

[phillybadboy]

capillaries are single and are in direct contact with blood. i know that some veins or arteries have capillaries running through them but some do not right? so for the veins and arteries that don't have veins and arteries running through them, these veins and arteries are composed of multilayered cells, the cells on the innermost layer is in direct contact with blood, but how do nutrients get to cell layers not in direct contact with blood? do nutrient reach other cell layers by going between paracellular by inner cell layers or transcellular through inner cell layers?

[Melmd]

I think they are called "vasa vasorum" which penetrates the outer (tunica adventitia) layer and middle (tunica media) layer almost to the inner (tunica intima) layer of large arteries/veins, this guys supply the needed nutrients for the viability of the blood vessels.

[phillybadboy]

but not all veins and arteries have capillaries going through them right? for the veins and arteries that don't have capillaries running through them, how do nutrient get to the inner layers that is not in the innermost layer?

[Melmd]

Yeah it inervates the tunica externa (outer layer of the vessel) as well as the tunica media (middle layer) of the vessels and by with diffusion thus nutrients are delivered. The tunica externa since it is directly in contact with blood it just diffuses directly. This is only true with large blood vessels but with specialized vessels in the body such as kidney and liver, they also have different mechanism of nutrient transport to the blood vessels.

[phillybadboy]

i know about the larger vessels and vasa vasorum, i'm actually asking about the smaller blood veins and arteries that don't have capillaries running though them, the smaller blood vessels (veins, arteries) are composed of multilayer cells, how do nutrient get to cells that are not in the innermost layer of the vessel? does it go between the spaces of the cells(paracellular)? or does it go through the cells(transcellular)?

[Melmd]

Originally Posted by phillybadboy

i know about the larger vessels and vasa vasorum, i'm actually asking about the smaller blood veins and arteries that don't have capillaries running though them, the smaller blood vessels (veins, arteries) are composed of multilayer cells, how do nutrient get to cells that are not in the innermost layer of the vessel? does it go between the spaces of the cells(paracellular)? or does it go through the cells(transcellular)?

It is still diffusion from one cell to the other, the plasma membrane have channels on each surface for the transfer of essential nutrients.

as you can see here the vasa vasorum still supplies the smooth muscle layer of an artery.


Picture is from http://www.rci.rutgers.edu/~uzwiak/A...d_Vessels.html

[systemet]

Originally Posted by phillybadboy

i know about the larger vessels and vasa vasorum, i'm actually asking about the smaller blood veins and arteries that don't have capillaries running though them, the smaller blood vessels (veins, arteries) are composed of multilayer cells, how do nutrient get to cells that are not in the innermost layer of the vessel? does it go between the spaces of the cells(paracellular)? or does it go through the cells(transcellular)?

I think that both processes occur. I'm not sure as to the relative contribution of each.

Smooth muscle cells in the vessel wall are also connected by gap junctions, that would allow nutrients to flow from one cell to the next. How big a role this plays, I'm not sure.

The nutrient requirements of smooth muscle cells are also relatively low. Unlike the other muscle types, smooth muscle hydrolyses ATP at a slower rate, so there's less ATP consumed per unit time. They also have the ability to "latch", that is the cross-bridges can remain attached for a long period of time without dissociating, enabling smooth muscle cells to produce a constant level of isometric tension for a long period of time without consuming large amounts of ATP. This also minimises nutrient requirements.

[systemet]

Originally Posted by Melmd

Yeah it inervates the tunica externa

I think you want the word "supplies" or "perfuses" instead here, as "innervation" implies that neurons are involved. [I'm not trying to be picky, but this detracts from your responses.]

[phillybadboy]

systemet, not all veins and arteries have vasa vosorum right? and what do you mean when say smooth muscle cells have gap junctions and flow from on cell to another? do you mean these gap junctions allow nutrient out of one smooth muscle and into another?

[Melmd]

Originally Posted by systemet

I think you want the word "supplies" or "perfuses" instead here, as "innervation" implies that neurons are involved. [I'm not trying to be picky, but this detracts from your responses.]

I stand corrected! yup innervate is for nerves!