Why does our skin SWEAT automatically but BLEED only when the surface is punctured?

I understand sweat comes from glands and blood comes from veins but if "sweat" can come to the outter skin surface through pores, why doesn't "blood' come to the outter skin surface though pores?
Why does our skin SWEAT automatically but BLEED only when the surface is punctured?
Sweat is, as you said, created by glands. Those glands are connected to pores on the outer layer of skin, so when they secrete the sweat comes outside of the body. The mind controls this, when you get to hot.


Blood on the other hand, is in the veins. The veins are not connected to the pores on the outside of the body, so the only way that you can 'bleed' is if your vein is punctured. The veins don't secrete blood like glands secrete---whatever it is that gland happens to secrete.


If this didn't answer your questions, feel free to email me! :D
Why does our skin SWEAT automatically but BLEED only when the surface is punctured?
because blood isn't "connected" to the pore like sweat is.
Reply:Because the blood vessels are in no way connected to the pores. Sweat glands are connected to the pores.





There is no evolutionary reason for us to ooze blood from our skin. There is a reason to ooze sweat though (body temperature regulation)
Reply:Because blood is in veins, not in glands located in the pores...
Reply:Think of blood vessels as tiny little tubes. The tubes have tiny little holes in them which allows certain smallish substances to move in and out like glucose, oxygen, carbon dioxide, protein, vitamins etc. Even highly deformable cells like some white blood cells can move in and out through these holes. But the thing that make blood red, red blood cells, are too large an too stiff to move through the holes.
Reply:because you're not trying hard enough