Cutaneous circulation.pptx 2024 for adults

Education

1. Cutaneous circulation Dr Pushpa Lata Sachan Associate professor C I M S & H ,Lucknow

2. Cutaneous circulation Functional anatomy –Blood supply of the skin of apical regions ( Fingers, feet , toes ,palm, nose lip ,ear lobes etc.) is different from non apical regions (the body tarso ) of the body . Apical areas an arteriolar network exist at the boundary of dermis and subcutaneous tissue .

3. From this network arterioles ascend from deep dermis to superficial layer of dermis . Capillary loops originate from superficial dermal network and perfuse the dermal papilla and epidermis . Non apical areas – here vascular pattern is modified . Arteriovenous anastomoses mainly occur in superficial dermal tissue. It Is very few or absent in non apical areas

4. Normal blood flow to the skin varies from 1 to 150 ml per 100g of tissue per min . The skin blood vessel are supplied by sympathetic fibers . No parasympathetic innervation is seen in the skin . Activation of sympathetic fibers results in vasoconstriction . Vasodilation occurs by decreasing the sympathetic activity .

5. Regulation of cutaneous blood flow Is regulated by decreasing the sympathetic activity . Cutaneous blood flow is regulated by neural ,thermal and metabolic factors . Neural regulation – cutaneous blood vessels are supplied by sympathetic vasoconstrictor fibers . There is no vasodilator system supplying the skin blood vessels .

6. Thermal regulation Thermal regulation – cutaneous blood flow is mainly regulated by body temperature . Increased body temperature causes vasodilation and decreased body temperature causes vasoconstriction .

7. Temperature Regulation centre of Hypothalamus HYPOTHALAMIC CONTROL MECHANISM

8. E X PO S U R E

9. Metabolic regulation Is not important for cutaneous circulaton . Local production of bradykinin in the sweat causes cutaneous vasodilation .

10. Applied physiology Vascular response to injury – White response Triple response White response – Skin is stroked lightly with pointed object , stroke line become pale this is called as white reaction . This occur due to decreased blood flow in the capillaries due to contraction of precapillary sphincter in response to injury . The response is observed in about 15 second .

11. Triple response When the skin is stroked with pointed object -the response to injury manifest as triple response . This is called as triple response as it three component red , wheal and flare . Red reaction – the skin becomes red in about 10 seconds .Redness occur due to capillary dilation that increases capillary blood flow .Capillary dilation occur due to direct response of capillaries to pressure .

12. Wheal –swelling is called wheal .This occur within few minutes following red reaction. It occur due to increased permeability of capillaries and post capillary venules . Histamine released from local mast cells causes vasodilation and increases capillary permeability that result in extravasation of fluid .

13. Flare - Spreading out of redness from the site of injury to surrounding area is called as flare . It occur due to arteriolar dilation . arteriolar dilation occur by activation of axon reflex . From the site of injury impulse is conducted in the afferent fiber . Sensory neuron give branches to blood vessel .

14. The impulse in addition to its conduction to the spinal cord orthodomically , it also relayed antidromically to blood vessels Axon reflex is an example of antidromic conduction of impulse. The ending of sensory fibers on the blood vessels release substance P and CGRP that produce arteriolar dilation . Redness spreads out from injury to surrounding skin in the form of flare .

15. Reactive hyperemia This is defined as increased blood flow in an area when blood supply to the area is reestablished following a brief period of occlusion . The blood flow to the skin increase when the circulation is reestablish after the short period of occlusion.

16. Reactive hyperemia also occur in visceral organs . It occur due to vasodilation produced by hypoxia during occlusion . When circulation reestablished blood flow increases through dilated blood vessels and skin becomes red