Vascular plexus: In the skin, blood vessels form layers of decreasing diameter. In the low dermis / subcutis fat layer are venules and arterioles known as the deep plexus tributaries supply deep structures such as hair, sweat gland Intricate connections to network called the superficial plexus As you ascend – vessels are getting smaller Superficial plexus in the superficial papillary dermis these supply the capillary loops – which supply the epidermis. In some areas these papillary loops are more developed such as the face which explains why when men cut themselves shaving they bleed for quite some time. Blood flow regulation: In the deep plexus there are precapillary sphincters which decrease the diameter of the communicating vessels and thereby reduce blood flow. They are under the influence of the autonomic nervous system Variations in surrounding temperature can have dramatic effects on blood flow In hot environments, dilatation of sphincters results in educed peripheral resistance and increased flow Flow Arteriovenous Anasatomosis – Only present at specific sites exposed to maximal cooling In some areas of the body there are direct communications between the arteries and veins known as anastamosis. This are primarily in the feet and earlobes AV Anastamoses have strong muscular innervated by adrenergic vasosconstrictors In extreme cold constriction of anastamoses results in significant reudction in cutaneous blood flow Weibel-Palade Body Secretory granules in vascular endothelial cells Formed from Golgi network Round/ovoid shape with tubular inclusions Release vWF and P Selectin in response to injury Function Cell Trafficking – Normal skin has very few lymphocytes
Vascular plexus: In the skin, blood vessels form layers of decreasing diameter. In the low dermis / subcutis fat layer are venules and arterioles known as the deep plexus tributaries supply deep structures such as hair, sweat gland Intricate connections to network called the superficial plexus As you ascend – vessels are getting smaller Superficial plexus – in the superficial papillary dermis these supply the capillary loops which supply the epidermis. In some areas these papillary loops are more developed such as the face which explains why when men cut themselves shaving they bleed for quite some time. Blood flow regulation: In the deep plexus there are precapillary sphincters which decrease the diameter of the communicating vessels and thereby reduce blood flow. They are under the influence of the autonomic nervous system Variations in surrounding temperature can have dramatic effects on blood flow In hot environments, dilatation of sphincters results in educed peripheral resistance and increased flow Flow – Arteriovenous Anasatomosis Only present at specific sites exposed to maximal cooling In some areas of the body there are direct communications between the arteries and veins known as anastamosis. This are primarily in the feet and earlobes AV Anastamoses have strong muscular innervated by adrenergic vasosconstrictors In extreme cold constriction of anastamoses results in significant reudction in cutaneous blood flow Weibel-Palade Body Secretory granules in vascular endothelial cells Formed from Golgi network Round/ovoid shape with tubular inclusions Release vWF and P Selectin in response to injury Function – Cell Trafficking Normal skin has very few lymphocytes