In Humans & Animals

Importance of Thermoregulation Thermoregulation is the ability to maintain a desired body temperature in the face of changes in external temperature An optimal body temperature is required for essential life processes Remember that enzymes (essential to our survival) work best at certain temperatures

Thermoregulation in Humans In humans, the temperature regulation center of the body is a region of the brain called the hypothalamus It has a set temperature of 98.6ºF The hypothalamus monitors blood temperature and receives input from thermoreceptors in the skin

Thermoregulation in Humans The hypothalamus acts like a thermostat Changes in the core body temperature or in the skin are registered by the hypothalamus, which then coordinates the appropriate responses to counteract the changes and restore normal body temperature Once it is reached, the corrective mechanisms are switched off

Thermoregulation in Humans If your body gets too cold… Increased metabolic rate produces heat Body hairs raise and increase the insulating air layer around the body Blood flow to limbs decreases, keeping warm blood near the core (vital organs) Shivering produces internal heat

Thermoregulation in Humans If your body gets too hot… Decreased metabolic rate reduces amount of heat generated by the body Body hairs flatten to reduce insulating air layer around the body to help heat loss Flow of blood to extremities increases to keep warm blood away from core (vital organs) Sweating cools the body by evaporation

Thermoregulation in Humans The hypothalamus can adjust the set- point to a higher temperature in the case of the body needing to fight an infection The body temperature then increases above the normal range, resulting in a fever Fever is your body doing what it needs to defend itself against an infection

Thermoregulation in Animals Animals can be classified into two groups based on the source of their body heat Ectotherms depend on the environment for their heat energy (like heat from the sun) Endotherms generate most of their body heat from internal metabolic processes Many animals fall somewhere in between the two extremes however

Ectotherms Examples: fish and reptiles Mechanisms of thermoregulation: Basking in the sun is common for reptiles to warm up before they can be active Increasing blood flow to the surface can help lose heat quickly Some lizards reduce points of contact with the hot ground (like standing on 2 legs instead of 4) to reduce heat uptake via conduction

Endotherms Examples: mammals and birds Mechanisms of thermoregulation: Increased metabolic activity generates heat Panting and sweating cool through evaporation (mammals usually do one or the other) Wool, hair, or fur traps air next to the skin providing an insulating layer to keep warm Heat can be generated by shivering In cold weather, many mammals cluster together to retain body heat