CHAPTER 39 



The circulation through the skin 



A. D. M. GREENFIELD 



Department of Physiology, The Queen's University of Be/fast, 

 Belfast, Northern Ireland 



CHAPTER CONTENTS 



Introduction 



Arrangement of the Blood Vessels of the Skin 

 Measurement of the Flow of Blood Through the Skin 



Total cutaneous blood flow 

 Color of the Skin 

 Temperature of the Skin 

 Responses of Skin Blood Vessels to Physical Disturbances 



Response of the Circulation Following Periods of Arrest or 

 Insufficiency 

 Reactive hyperemia 



Hyperemia after prolonged insufficiency of the circulation 

 Responses of Skin Vessels to Changes in Transmural Pressure 

 Effect of Local Temperature on the Skin Circulation 

 Local temperatures in the range 15 C to 45 C 

 Local temperature in the range o C to 15 C: Cold vaso- 

 dilatation 

 Prolonged exposure to cold: Trench foot and immersion 



foot 

 Exposure to severe cold : Frostbite 

 Reactions to Injury 

 Mechanical injury 

 Ultraviolet light 

 Arterial gas embolism 

 Nervous Control of Skin Blood Vessels 

 Vasomotor Nerves 



Vasoconstrictor sympathetic nerves 

 Vasodilator sympathetic nerves 



Vasodilatation caused by antidromic stimulation of 

 dorsal root sensory nerves. The axon reflex pathway 

 Innervation of the Blood Vessels of the Skin in Different 

 Areas 

 The human hand and fingers 

 The human forearm 

 Other areas of the human body 

 The skin of animals 

 Late effects of sympathetic denervation 

 Late effects of total denervation 

 Reflex Control of Blood Vessels of the Skin 

 Body temperature regulation 

 Emotion 

 Fainting 



General sensory stimuli 



Response to a deep inspiration 



Response to distention of the bladder 



Hypoglycemia 



Posture 



Responses to baroreceptor stimulation 

 Action of Humoral Agents on the Blood Vessels of the Skin 

 Adrenaline and Noradrenaline 

 Histamine 

 Acetylcholine 



5-Hydroxytryptamine (Serotonin) 

 Adenosine Triphosphate 

 Bradykinin 

 Carbon Dioxide 

 Vasopressin 

 Oxytocin 



INTRODUCTION 



this section deals principally with the circulation 

 through human skin, since this has been so frequently 

 and carefully studied, mostly in unanesthetized sub- 

 jects. In selecting references no attention has been 

 in general paid to priority of discovery. Papers have 

 been chosen for the completeness of the information 

 they contain, for the value of their bibliography, 

 and very often because the work is personally known 

 to the present author. A wider bibliography will be 

 found in several excellent monographs and reviews 

 (1, 19, 22, 44, 115, 119, 139, 148, 152, 155, 165, 

 176, 187, 193). 



The great bulk of observations relates to the cir- 

 culation through the skin of the extremities, and par- 

 ticularly of the digits. Here the striking features are, 

 firstly, the very great variability of the blood flow 

 under different circumstances, greatest in the tips 



'3*5 



