Heat Loss and Blood Flow of the Feet Under Hot and Cold Conditions

1948 ◽  
Vol 1 (1) ◽  
pp. 20-34 ◽  
Author(s):  
Lois H. Love
Keyword(s):  
Blood Flow ◽  
Heat Loss

Changes in serotonin contents in brain affect metabolic heat production of rabbits in cold

1978 ◽  
Vol 235 (1) ◽  
pp. R41-R47
Author(s):  
M. T. Lin ◽  
I. H. Pang ◽  
S. I. Chern ◽  
W. Y. Chia
Keyword(s):  
Blood Flow ◽  
Amino Acid ◽  
Heat Loss ◽  
Acid Decarboxylase ◽  
Evaporative Heat Loss ◽  
Decarboxylase Inhibitor ◽  
Ambient Temperatures ◽  
Amino Acid Decarboxylase ◽  
Metabolic Heat ◽  
Normal Limits

Elevating serotonin (5-HT) contents in brain with 5-hydroxytryptophan (5-HTP) reduced rectal temperature (Tre) in rabbits after peripheral decarboxylase inhibition with the aromatic-L-amino-acid decarboxylase inhibitor R04-4602 at two ambient temperatures (Ta), 2 and 22 degrees C. The hypothermia was brought about by both an increase in respiratory evaporative heat loss (Eres) and a decrease in metabolic rate (MR) in the cold. At a Ta of 22 degrees C, the hypothermia was achieved solely due to an increase in heat loss. Depleting brain contents of 5-HT with intraventricular, 5,7-dihydroxytryptamine (5,7-DHT) produced an increased Eres and ear blood flow even at Ta of 2 degrees C. Also, MR increased at all but the Ta of 32 degrees C. However, depleting the central and peripheral contents of 5-HT with p-chlorophenylalanine (pCPA) produced lower MR accompanied by lower Eres in the cold compared to the untreated control. Both groups of pCPA-treated and 5,7-DHT-treated animals maintained their Tre within normal limits. The data suggest that changes in 5-HT content in brain affects the MR of rabbits in the cold. Elevating brain content of 5-HT tends to depress the MR response to cold, while depleting brain content of 5-HT tends to enhance the MR response to cold.

Blood flow, calcium deposition and heat loss in reindeer antlers

1978 ◽  
Vol 104 (1) ◽  
pp. 122-128 ◽  
Author(s):  
Knut Hove ◽  
Johan B. Steen
Keyword(s):  
Blood Flow ◽  
Heat Loss ◽  
Calcium Deposition

Correlation of heat output and blood flow in the finger, especially in cold-induced vasodilation

1960 ◽  
Vol 15 (2) ◽  
pp. 201-208 ◽  
Author(s):  
Merrill Edwards ◽  
Alan C. Burton
Keyword(s):  
Blood Flow ◽  
Heat Loss ◽  
Bath Temperature ◽  
Heat Output ◽  
Deep Body Temperature ◽  
Blood Temperature ◽  
Cold Blood ◽  
The Subject ◽  
Thermal Lag ◽  
Deep Body

A combined finger-plethysmograph and gradient calorimeter has been devised, especially to study cold-induced vasodilation in the finger. By using an electrical heater and a flow-heater it was shown that the thermal lag depends on thermal capacities, conductivities and temperature distribution, so that heat loss and flow are correlated only in the steady state. The actual drop of blood temperature from inflow to outflow was calculated. Results were: a) skin temperature was a better estimate of outflow than bath temperature, b) with general vasodilation, the inflow temperature was close to deep body temperature, but c) with vasoconstriction, digital arterial temperature might be as low as 14°C, and the calculated minimum blood flow (Greenfield) 70% too low. Plethysmography was possible during the hunting reaction in spite of a 30% decrease in venous distensibility. When the subject was cold, blood flow and heat loss, both in constriction and dilation phases, were reduced two or three times, probably due to the increased viscosity of blood. Submitted on August 3, 1959

Heat loss from feet of herring gulls at rest and during flight

1976 ◽  
Vol 230 (4) ◽  
pp. 920-924 ◽  
Author(s):  
RV Baudinette ◽  
JP Loveridge ◽  
KJ Wilson ◽  
CD Mills ◽  
K Schmidt-Nielsen
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Wind Tunnel ◽  
Heat Loss ◽  
Heat Production ◽  
Heat Dissipation ◽  
Larus Argentatus ◽  
Herring Gull ◽  
Herring Gulls

The role of the feet of herring gulls (Larus argentatus) in heat dissipation was estimated during rest and wind-tunnel flight. We determined the blood flow to the feet and the arteriovenous temperature difference and thus estimated heat loss from the feet. Determinations of oxygen consumption and respiratory water loss at rest gave a heat production of about 8 W; 37-56% of this heat was lost from the feet (air temp = 10-35 degrees C). During flight heat production was estimated to be about 57 W and heat loss from the feet was 46 W, about 80% of the heat production in flight. Thus the webbed feet are an important avenue of heat loss in the herring gull.

The Febrile Infant

1979 ◽  
Vol 1 (2) ◽  
pp. 35-36
Author(s):  
ARNOLD L. SMITH
Keyword(s):  
Blood Flow ◽  
Heat Loss ◽  
Core Body Temperature ◽  
Fundamental Goal ◽  
Febrile Infant ◽  
Abnormal Increase ◽  
The Face ◽  
Sorting Process ◽  
Core Body ◽  
Body Heat

Sorting out the child at risk, from those with illness that is not a threat to their health, is a fundamental goal of pediatrics. One of the most common complaints, which prompts us to initiate the sorting process, is fever. In the article by McCarthy (p 51), guidelines to aid in the sorting process are suggested. Fever, an abnormal increase in core body temperature, results primarily from a decrease in heat loss; decreased trunk and extremity skin blood flow decreases the surface area available for convection and body heat loss decreases—mom feels the forehead or the face for increased temperature, areas less affected by thermoregulatory vasoconstriction.

scholarly journals Body temperature, cutaneous heat loss and skin blood flow during epidural anaesthesia for emergency caesarean section

Anaesthesia ◽  
2018 ◽  
Vol 73 (12) ◽  
pp. 1500-1506 ◽  
Author(s):  
C. J. Mullington ◽  
D. A. Low ◽  
P. H. Strutton ◽  
S. Malhotra
Keyword(s):  
Blood Flow ◽  
Body Temperature ◽  
Caesarean Section ◽  
Heat Loss ◽  
Skin Blood Flow ◽  
Epidural Anaesthesia ◽  
Emergency Caesarean Section ◽  
Emergency Caesarean

Sweating and skin blood flow during exercise: effects of age and maximal oxygen uptake

1991 ◽  
Vol 71 (1) ◽  
pp. 236-242 ◽  
Author(s):  
C. G. Tankersley ◽  
J. Smolander ◽  
W. L. Kenney ◽  
S. M. Fortney
Keyword(s):  
Blood Flow ◽  
Heat Loss ◽  
Sweat Rate ◽  
Weighted Average ◽  
Exercise Bout ◽  
Physically Active ◽  
Warm Environment ◽  
Age Related ◽  
Repeated Exercise ◽  
O2 Pulse

Individuals greater than or equal to 60 yr of age are more susceptible to hyperthermia than younger people. However, the mechanisms involved remain unclear. To gain further insight, we examined the heat loss responses of 7 young (24–30 yr) and 13 older (58–74 yr) men during 20 min of cycle exercise [67.5% maximal O2 uptake (VO2max)] in a warm environment (30 degrees C, 55% relative humidity). Forearm blood flow (FBF) and chest sweat rate (SR) were plotted as a function of the weighted average of mean skin and esophageal temperatures [Tes(w)] during exercise. The sensitivity and threshold for each response were defined as the slope and Tes(w) at the onset of the response, respectively. When the young sedentary men were compared with a subgroup (n = 7) of the older physically active men with similar VO2max, the SR and FBF responses of the two groups did not differ significantly. However, when the young men were compared with a subgroup of older sedentary men with a similar maximal O2 pulse, the SR and FBF sensitivities were significantly reduced by 62 and 40%, respectively. These findings suggest that during a short exercise bout either 1) there is no primary effect of aging on heat loss responses but, rather, changes are associated with the age-related decrease in VO2max or 2) the decline in heat loss responses due to aging may be masked by repeated exercise training.

scholarly journals Morphological dependency of cutaneous blood flow and sweating during compensable heat stress when heat-loss requirements are matched across participants

2016 ◽  
Vol 121 (1) ◽  
pp. 25-35 ◽  
Author(s):  
Sean R. Notley ◽  
Joonhee Park ◽  
Kyoko Tagami ◽  
Norikazu Ohnishi ◽  
Nigel A. S. Taylor
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Heat Loss ◽  
Cutaneous Blood Flow ◽  
Cutaneous Blood

Physiological adjustment to repeated wind exposure in sheep

1969 ◽  
Vol 11 (4) ◽  
pp. 493-498 ◽  
Author(s):  
J. G. Griffiths ◽  
J. M. Doney
Keyword(s):  
Blood Flow ◽  
Heat Loss ◽  
Air Flow ◽  
Progressive Increase ◽  
Gradual Decrease ◽  
Wind Exposure ◽  
Tissue Insulation

SUMMARYAn experiment was undertaken to examine the possibility that progressive adjustments in tissue insulation on the trunk might occur following repeated wind cooling. Two sheep were exposed at right angles to an air flow of 12 mph for 6 hr daily on each of 7 consecutive days.When first exposed to the wind the heat loss from the fleece-covered surfaces increased due to a reduction in insulation and apparently increased vaso-dilatation. After the first day there was a progressive increase in surface vaso-constriction before exposure and a gradual decrease in the extent of the vaso-dilatation during exposure. The results indicate the possibility of centrally-induced peripheral adjustments in blood flow occurring on the trunk of the sheep in response to repeated wind cooling.

Method for measuring regional heat losses in man

1980 ◽  
Vol 49 (3) ◽  
pp. 533-535 ◽  
Author(s):  
A. R. Gin ◽  
M. G. Hayward ◽  
W. R. Keatinge
Keyword(s):  
Blood Flow ◽  
Heat Flow ◽  
Heat Loss ◽  
Local Heat ◽  
Heat Losses ◽  
Cutaneous Blood Flow ◽  
Rubber Sheet ◽  
Tissue Insulation ◽  
Flow Devices ◽  
Cutaneous Blood

Flexible heat flow devices were constructed from 0.4-mm-thick nylon-reinforced rubber sheet, with multiple copper-constantan thermocouples on each side to measure mean temperature difference across the sheet. A method of calibration is described that corrects for the alteration of local heat loss produced by the device itself. It was shown that such errors would otherwise be large when cutaneous blood flow was high, and tissue insulation low, even with devices as thin as these.

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