Problems
417
• Cryogenics: Rapid freezing of live tissue in which water crystals do not have time
to grow and rupture cells has successfully held fish (cold-blooded) in suspended
animation. They can be brought back to life by warming. 76
• Hypothermia: Uses low temperatures to slow the metabolic processes, such as
during surgery. Body temperatures below 35 ◦ C are considered hypothermic.
Temperatures below 28 ◦ C lead to unconsciousness, while below 20 ◦ C is lethal.
Immersion in water at 10 ◦ C for over 1 h leads to death. At 0 ◦ C, death occurs
in less than 15 min. The cerebral metabolic activity decreases by 7% for each
degree Celsius drop in temperature.
• Hyperthermia: Uses higher temperatures to increase blood circulation to reduce
stiffness, inflammation, edema; therapy for rheumatoid arthritis, relieve neck
and upper back pain from muscle tightness, relieve headaches and migraines.
Vasodilator IR, microwaves, ultrasonic diathermy uses electromagnetic currents
for muscle relaxation (including Ultrasonic therapy, shortwave diathermy, and
microwave diathermy). Hyperthermia can destroy warts, neoplasms, and infected
tissue. Higher temperatures are used to cauterize blood to stop bleeding. However, whole body temperatures above 41 ◦ C (106 ◦ F) can cause delirium, brain
lesions, and stroke.
• Refrigeration: As a method to hold tissue in quasi-stasis. Bacterial growth
continues above the freezing point, but at a reduced rate.
• Freeze drying: Preserves the micro-structural elements of tissue. A dehydration
process is employed to remove water from perishable food. The material is first
cooled, and then placed in a partial vacuum to cause evaporation of water. In this
condition, nutrients in food can last indefinitely.
• Incubators: Devices to hold new born requiring neonatal care in a thermally
advantageous environment.
Problems
9.1 If your internal temperature is 37 ◦ C, your skin temperature is 35.5 ◦ C, the
average effective thickness of your skin is 5 mm your exposed body area is 1.2
square meters, and the heat conductivity of your skin is 18 kcal-cm/(m 2 h-K),
estimate the heat loss (in watts) by conduction through your skin.
9.2 A resting adult generates about 100 W of power in the form of heat put into
the environment. If the temperature of the environmental air is 22 ◦ C, how much
disorder (entropy) does this adult generate every day.
76 A professor of the faculty of The George Washington University Chemistry Department would
perform this ‘trick’ on a goldfish every year in freshman chemistry in the 1960s through immersion
in liquid nitrogen.
417
• Cryogenics: Rapid freezing of live tissue in which water crystals do not have time
to grow and rupture cells has successfully held fish (cold-blooded) in suspended
animation. They can be brought back to life by warming. 76
• Hypothermia: Uses low temperatures to slow the metabolic processes, such as
during surgery. Body temperatures below 35 ◦ C are considered hypothermic.
Temperatures below 28 ◦ C lead to unconsciousness, while below 20 ◦ C is lethal.
Immersion in water at 10 ◦ C for over 1 h leads to death. At 0 ◦ C, death occurs
in less than 15 min. The cerebral metabolic activity decreases by 7% for each
degree Celsius drop in temperature.
• Hyperthermia: Uses higher temperatures to increase blood circulation to reduce
stiffness, inflammation, edema; therapy for rheumatoid arthritis, relieve neck
and upper back pain from muscle tightness, relieve headaches and migraines.
Vasodilator IR, microwaves, ultrasonic diathermy uses electromagnetic currents
for muscle relaxation (including Ultrasonic therapy, shortwave diathermy, and
microwave diathermy). Hyperthermia can destroy warts, neoplasms, and infected
tissue. Higher temperatures are used to cauterize blood to stop bleeding. However, whole body temperatures above 41 ◦ C (106 ◦ F) can cause delirium, brain
lesions, and stroke.
• Refrigeration: As a method to hold tissue in quasi-stasis. Bacterial growth
continues above the freezing point, but at a reduced rate.
• Freeze drying: Preserves the micro-structural elements of tissue. A dehydration
process is employed to remove water from perishable food. The material is first
cooled, and then placed in a partial vacuum to cause evaporation of water. In this
condition, nutrients in food can last indefinitely.
• Incubators: Devices to hold new born requiring neonatal care in a thermally
advantageous environment.
Problems
9.1 If your internal temperature is 37 ◦ C, your skin temperature is 35.5 ◦ C, the
average effective thickness of your skin is 5 mm your exposed body area is 1.2
square meters, and the heat conductivity of your skin is 18 kcal-cm/(m 2 h-K),
estimate the heat loss (in watts) by conduction through your skin.
9.2 A resting adult generates about 100 W of power in the form of heat put into
the environment. If the temperature of the environmental air is 22 ◦ C, how much
disorder (entropy) does this adult generate every day.
76 A professor of the faculty of The George Washington University Chemistry Department would
perform this ‘trick’ on a goldfish every year in freshman chemistry in the 1960s through immersion
in liquid nitrogen.