Body Temperature and Regulation

Study Notes

Body temperature is a vital sign, that reflects the internal temperature of the human body, usually measured in degrees Celsius (°C) or Fahrenheit (°F).
Normal body temperature fluctuates within a range, typically between 36.5°C and 37.5°C (97.7°F and 99.5°F).
Normal body temperature is influenced by factors such as time of day, age, and activity level.
Skin temperature, or external temperature, varies depending on the area of the body and environmental factors.
Covered areas of the body, such as the skin of the head, neck, chest, and abdomen, tend to have higher skin temperatures (around 34°C).
Extremities like hands and feet typically have lower skin temperatures (around 28°C).

The human body maintains homeostasis by regulating body temperature through a process called thermoregulation.
The hypothalamus in the brain acts as the body's thermostat, controlling heat production and loss to maintain a stable internal temperature.
The hypothalamus has two centers:
- Heat loss center: Located in the anterior hypothalamus. It detects changes in body temperature and triggers mechanisms to dissipate heat, including sweating and vasodilation (widening of blood vessels).
- Heat gain center: Located in the posterior hypothalamus. It detects changes in body temperature and triggers mechanisms to conserve and generate heat, including shivering and vasoconstriction (narrowing of blood vessels).

Heat loss mechanisms:
- Irradiation: Transfer of heat through electromagnetic waves, like the sun. The body radiates heat to cooler objects in the environment.
- Conduction: Transfer of heat through direct contact with a colder object. For example, heat loss occurs when the body is in contact with cold air or water.
- Convection: Transfer of heat by the movement of fluids, such as air or water. The body loses heat through convection when air currents or water flow over the skin.
- Evaporation: Conversion of liquid to vapor, such as sweat. Evaporation of sweat from the skin requires heat energy, leading to heat loss.
Heat gain mechanisms:
- Shivering: Involuntary muscle contractions that generate heat.
- Sympathetic stimulation: Stimulation of the sympathetic nervous system, leading to vasoconstriction, which helps to conserve heat.
- Food: The breakdown of food, particularly protein, generates heat.
- Thyroid hormone increase: Elevated thyroid hormone levels can boost metabolism and increase heat production.

The skin plays a crucial role in heat exchange between the body and the environment.
Blood vessels near the surface of the skin constrict or dilate to regulate heat loss:
- Vasodilation: Widening of blood vessels near the skin surface, allowing for increased blood flow and heat loss.
- Vasoconstriction: Narrowing of blood vessels near the skin surface, reducing blood flow and minimizing heat loss.

Understanding body temperature regulation is essential in healthcare:
- Diagnosing illnesses: Abnormal temperatures can indicate infections, inflammation, or other medical conditions..
- Monitoring patient conditions: Regular temperature monitoring helps healthcare providers track patient status and intervene when necessary.
- Adjusting treatments: Certain medications or therapies may influence body temperature, requiring adjustments.
Bair Hugger: A warming device used in operating rooms to prevent hypothermia (abnormally low body temperature) during surgery.

Hyperthermia: Increased body temperature above normal (above 37.5°C).
- Cooling measures: Removing layers of clothing, applying cool compresses, taking a cool shower.
- Seek medical attention if high fever persists.
Hypothermia: Decreased body temperature below normal (below 36.5°C).
- Warming measures: Adding layers of clothing, seeking shelter from cold weather, providing warm drinks.
- Seek immediate medical attention in case of severe hypothermia.