Introduction: Heat and the Human Body (03:58)

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Humans maintain generally constant 37 degrees Celsius body temperatures regardless of surrounding conditions. Skin nerves signal the brain when too hot or cold, triggering adaptive mechanisms; endothermic animals generate warmth from within, allowing properly functioning chemical processes.

Surface Area (07:06)

Maintaining constant core temperature requires heat loss equal gain. When cold, the body reacts by huddling; when hot, people spread out. Heat transfer is impacted by surface area, surface material thickness and type, and condition differences; cooling slows as substances near surrounding temperatures.

Blood (05:24)

Blood carries oxygen and glucose to cells and wastes away from them, maintaining constant body temperatures by transferring heat via heart powered convection current. Arteries constrict or dilate, controlling flow to surface vessels, and adapting exposure in skin to environmental conditions.

Sweating and Shivering (09:10)

When core temperatures drop, humans generate heat by shivering; when hot, the body sweats and cools as the moisture evaporates. Fans and proper ventilation can accelerate evaporation; high humidity can prevent it. Other animals have different coping mechanisms, but all adaptations are governed by chemistry and physical laws.

Hypothermia and Hyperthermia (08:21)

When body core temperatures fall below the normal range, humans get potentially fatal hypothermia. Sudden exposure to cold water can cause cold shock and abrupt death. Increase in core heat results in hyperthermia, treated by cooling and rehydration of the victim.

Credits: Episode Six: Heat and the Human Body (00:19)

Credits: Episode Six: Heat and the Human Body