The mechanisms of heat loss contributing to Joel’s feelings of coldness are conduction, due to the loss of his hat somewhere on the trail and also his wet clothes; convention, which is happening because of the cold wind blowing; and lastly evaporation which is occurring as he breathes in the cold air and exhales it as warm moist air. 2.
To help Joel maintain a normal body temperature, his body will begin to send signals to conserve and generate heat. This can be done through vasoconstriction which keeps sweat glands inactive and conserves heat, and also by shivering which generate heat through muscle contractions. 3.
Thermoregulation, a homeostatic process, is responsible for initiating and controlling the physiological responses helping to keep Joel warm. His body temperature is being monitored by his hypothalamus which has triggered his sympathetic vasomotor center to initiate vasoconstriction of the dermal blood vessels in his extremities. The nervous system is also alerted by the hypothalamus to induce muscle contraction in order to generate internal heat and keep his core near normal temperatures. 4.
Joel feels little blood flowing to his hands and feet due to the vasoconstriction occurring. During this process the blood going to his extremities is being rerouting away from the dermal surface to a network of deep veins wrapped around deep arteries. When this occurs diffusion known as countercurrent exchange begins which traps heat closer to the body core and limits heat loss to the environment by reducing the temperature gradient between the arterial blood and the cold whether Joel is in. 5.
Joel’s body was more than likely in the beginning stages of the hypothermia. His body began shivering strongly to generate more heat to try to maintain normal temperatures. The vigorous shivering will increase the rate of heat generated and warm the deep vessels by as much as 400 percent. It was caused by stimulation of his thyroid which leads to the release of...
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