Hormones and Homeostasis Flashcards
Describe how the body responds to hyperthermia to restore a homeostatic temperature.
Body temperature is monitored and controlled by a “body thermostat” in your brain called the hypothalamus. If the hypothalamus senses that your body temperature is too high (hyperthermia), this could result in tissues/organ damage (above 40 degrees Celsius is deadly). So, thermoreceptors in your skin send signals to the hypothalamus that tells it that the body temperature is too high. The hypothalamus then releases chemical signals that trigger vasodilation (arterioles get bigger, fill with blood, transfer heat to skin and out of body) and increase sweat gland activity (evaporative cooling.
Outline the role of thyroxine in maintaining metabolic rate and body temperature.
Thyroxin is a hormone secreted by the thyroid gland of the endocrine system. It acts on all cells in the body and causes an increase in the body’s metabolic rate/increases the body’s rate of energy release and use. Thyroxin causes an increase in carbohydrate and lipid metabolism (more oxidation of glucose and fatty acids). This causes an increased oxygen consumption and the hydrolysis of ATP: thereby causing an increase in the body’s temperature.
Outline the causes and consequences of hypothyroidism.
Hypothyroidism occurs when there is an insufficient amount of thyroxin in the body. This, in turn, is caused by prolonged deficiency of iodine in the diet, which prevents the production of thyroxin since it contains iodine. Consequences of hypothyroidism include symptoms like weight gain, loss of energy, feeling cold all of the time, forgetfulness, and depression.
Describe the role of melatonin in the control of circadian rhythms.
Melatonin controls the 24-hour circadian rhythm. It’s production and amount released is dictated by the amount of light detected by the retina. This means that amount in melatonin is proportional to night time duration (longer nights = more melatonin production). Over long periods of time, the amount and timing of melatonin secretion becomes entrained in the body. Melatonin affects sleep-wake cycles and seasonal reproduction. In diurnal animals (like human beings), melatonin promotes sleep during the night time due to the lack of light detected by the retinas, However, melatonin levels naturally decrease over time.
