venules
Small blood vessels
Venules are the smallest veins in the body, microscopic vessels that collect blood from capillaries and channel it toward larger veins for return to the heart.
They form the low-pressure side of the circulatory system, complementing arterioles on the arterial side: Blood passes from arterioles through capillaries into venules.
Cells lining blood vessels
- vasculatureBody's network of vessels
- microcirculationFlow through minute vessels
- arteriolesSmallest arterial vessels
- capillariesTiniest blood vessels
basement membrane · smooth muscle · lumen · connective tissue
Movement through vessels
- circulationMovement through a system
- microcirculationFlow through minute vessels
- oxygenationAdding breathable gas
- carbon dioxide removalExtracting atmospheric greenhouse gas
Protective tissue response
- thrombosisClot forming in vessel
- phlebitisInflamed vein condition
- edemaPathological tissue puffiness
- congestionExcessive accumulation causing blockage
petechiae · hemorrhage · ischemia · vasculitis · extravasation · hyperemia · embolism · infarction
Arterial walls contracting inward
- vasodilationRelaxation of vessel walls
- nitric oxideReactive nitrogen-oxygen compound
- prostaglandinsLipid-derived signaling compounds
- adrenergic receptorsCatecholamine-sensitive membrane proteins
endothelium
Cells lining blood vessels
- vasculatureBody's network of vessels
- microcirculationFlow through minute vessels
- arteriolesSmallest arterial vessels
capillaries · basement membrane · smooth muscle · lumen · connective tissue
blood flow
Movement through vessels
- circulationMovement through a system
- microcirculationFlow through minute vessels
- oxygenationAdding breathable gas
carbon dioxide removal · permeability · diffusion · filtration · oncotic pressure
inflammation
Protective tissue response
- thrombosisClot forming in vessel
- phlebitisInflamed vein condition
- edemaPathological tissue puffiness
congestion · petechiae · hemorrhage · ischemia · vasculitis · extravasation · hyperemia · embolism · infarction · hypoxia
vasoconstriction
Arterial walls contracting inward
- vasodilationRelaxation of vessel walls
- nitric oxideReactive nitrogen-oxygen compound
- prostaglandinsLipid-derived signaling compounds