Cutaneous circulation & splanchnic circulation

1. CUTANEOUS CIRCULATION & SPLANCHNIC CIRCULATION

2. Circulation Of Skin

3. Arrangement of blood vessels in skin Cutaneous arterioles Meta arterioles – resistance vessels Capillaries – large surface area for heat exchange Venules – large sub papillary venous plexus AV anastamosis – more prominent in acral regions

4. Acral Regionns And Non Acral Regions

5. TEMPERATURE REGULATION

6. Blood Flow Resting blood flow - 10-15ml/ min/100g of skin Exposure to cold – falls to one tenth of resting flow i.e 1ml/min/100g Exposure to heat – increase ten times , produces heavy circulatory load – unconciouness Regional variation in Cutaneous blood flow Skin color and blood flow

7. Regulation Of Cutaneous Blood Flow Skin needs little O2 0.3ml/min/100g (compared to ) So nervous >metabolic control Nervous control – sympathetic supply alone

8. Hypothalamic Control Mechanism Under resting condition During exposure to heat – four steps AV anastomoses dilate Progressive Cutaneous dilation sweat gland activation Bradykinin produces dilation During exposure to cold

9. Others Baroreceptor reflex Cortical control mechanism Blanching of skin Phenomenon of blushing

10. BLANCHING

11. BLUSHING

12. CUTANEOUS VASCULAR RESPONSES White reaction – due to vasoconstriction & appears about 15 sec

13. TRIPLE RESPONSE Red reaction- within 10 sec , due to histamine and bradykinn , local response Flare – spreading redness, after few min, mediated by axon reflex diffusely spreading irregular redness Wheal - local exudation and edema due to histamine and substance p

14. AXON REFLEX

15. DERMOGRAPHISM

16. Reactive Hyperaemia Increased blood flow after a transient occlusion

17. COLD VASODILATION Cont’d