Metabolism and Thermoregulation Flashcards
Define kilocalories
equivalent to 1000 calories amount of energy needed to raise one kilogram of water by one degree Celcius
Describe basal metabolic rate (BMR)
amount of energy expended by the human body at rest when the digestive system is inactive minimum energy level required by the human body to keep the vital organs functioning
Factors that affect BMR
age muscle must be measured about 12 hours after eating approx 70% of the daily energy expenditure
State the normal range of body temperature
Normally, internal body temperature is kept at a steady 37 degrees Celcius. The efficiency of the human body is optimized between the temperature range of 36 degrees Celcius and 40 degrees Celcius.
How is heat generated in the body?
Thermogenesis results from the conversion of potential energy into kinetic energy.
How is excess heat removed from the body?
Radiation - the body emits infrared radiation. Half our daily heat loss occurs through radiation. Conduction - the body transfers heat through contact Convection - air molecules near the surface of the skin are warmed, they rise and are replaced with cooler molecules and the process begins again Evaporation - sweat abscrbs energy from the underlying skin and change to a vapor and rise away from our bodies. At rest our bodies lose 20% of our daily heat loss to evaporation. On hot days, evaporation becomes the primary mechanism for heat loss.
How does the body stay warm or cool in adverse temperatures?
In hot conditions, vasodialation causes blood near the surface to lose more heat, body produces more sweat to be evaporated. In cold conditions, vasoconstriction diverts blood away from the surface and retain more heat, piloerection occurs in the skin hairs trapping air near the skin producing a warmer microclimate near the skin, cellular respiration is increased as the muscles shiver.
State the role and the function of the hypothalamus as the thermostat of the body.
Sensory receptors called thermoreceptors detect changes in body temperature. The hypothalamus has an internal memory where the optimal body temperature info is stored. The hypothalamus will signal for vasodilation and sweating when the bodys temperature rises and vasoconstriction, piloerection, and shivering when the bodys temperature falls.
Discuss fever and its function during illness or infection.
- important immunological(chemical) reactions are sped up by the higher temp
- some pathogens will not function in the body with fever
- white blood cells function more efficiently
- improves the healing process
