Key takeaways
- Thermoregulation is the process by which the body maintains a steady internal temperature. The thermoregulation system includes the hypothalamus, sweat glands, circulatory system, and skin.
- The three mechanisms of thermoregulation are efferent responses, afferent sensing, and central control.
- Without effective thermoregulation, people can develop hypothermia or hyperthermia, which can become life threatening if severe.
The human body maintains a temperature of about 98.6°F (37°C) using thermoregulation. Sweating, shivering, and narrowing or dilating blood vessels are all examples of how thermoregulation works in the body.
If an individual is unable to regulate their temperature, they could overheat, leading to hyperthermia. The opposite is also true: If the core temperature falls below a safe level, it will cause hypothermia.
Thermoregulation is how mammals maintain a steady body temperature.
Unlike reptiles, which have body temperatures that change with their environment, mammals need to maintain a consistent body temperature at all times. In humans, the healthy range is within half a degree of
The human body uses
- efferent responses
- afferent sensing
- central control
Efferent responses are behaviors humans use to regulate their body temperature, such as:
- putting on a coat before going outside
- moving into the shade on a hot day
- seeking shelter from harsh winds or rain
Afferent sensing involves a system of temperature receptors around the body to identify whether the core temperature is too hot or cold. The receptors relay the information to the hypothalamus, which is part of the brain.
The hypothalamus acts as the central controller, using this sensory information to produce hormones that regulate body temperature.
These hormones send signals to various parts of the body so that they can respond in the following ways:
| Response to heat | Response to cold |
|---|---|
| sweating | shivering, or thermogenesis |
| dilated blood vessels, known as vasodilation | constricted blood vessels, known as vasoconstriction |
| decrease in metabolism | increase in metabolism |
The healthy temperature range for the human body is very narrow. If the body cannot maintain a temperature within this range, thermoregulation disorders can develop.
Hyperthermia
Hyperthermia occurs when the body’s heat-regulating mechanisms fail and body temperature rises too high. There are several types of hyperthermia, including:
- heat cramps, which present as heavy sweating and muscle cramps during exercise
- heat exhaustion, which is more serious and causes a range of symptoms
- heatstroke, which is a medical emergency
The symptoms of heat exhaustion are:
Heatstroke causes similar symptoms, but with some important differences, including:
- flushed or hot skin, which may be dry or damp
- a fast, strong pulse
- a body temperature of
104°F (40°C) or higher
Hypothermia
Hypothermia occurs when the body loses heat faster than it can produce it. Prolonged exposure to cold temperatures can cause hypothermia. The symptoms
- shivering
- confusion
- exhaustion or feeling very tired
- fumbling hands
- slurred speech
- drowsiness
- memory loss
In young children and babies, hypothermia causes lethargy and cold skin, which may appear bright red in those with light skin tones.
Several factors can affect thermoregulation, including environmental conditions, diseases, and certain medications.
Extreme weather
Extreme weather can significantly affect the body’s ability to regulate temperature. For example, hypothermia could occur if a person has exposure to:
- cold air
- cold water
- sweat
On the opposite end of the spectrum, hyperthermia can occur due to hot weather or sun exposure. It can also develop in warm weather if a person engages in behavior that prevents the body from cooling itself down, such as:
- wearing too much insulating clothing
- not drinking enough fluids
- intense exercise, especially outdoors
- being in large crowds
Infections
When a person has an infection, harmful microorganisms invade the body and multiply. These pathogens can thrive at typical body temperatures, but higher temperatures make it more difficult for some of them to survive.
For this reason, part of the immune response to infections is often a fever. This occurs when the body raises its temperature to kill infection-causing organisms.
Many doctors recommend letting a fever run its course so that the body can adequately protect itself. However, problems can arise if the body temperature becomes too high, hindering necessary functions.
If someone has a fever above
Other diseases
Some diseases can also affect thermoregulation. These include:
Endocrine disorders
The endocrine system comprises glands and organs that produce hormones, such as the pancreas, thyroid, pituitary gland, and adrenal glands. If something interferes with hormone production, it can affect body temperature.
For example, an underactive thyroid, or hypothyroidism, can lead to a lower body temperature, while an overactive thyroid, called hyperthyroidism, can cause a higher body temperature.
Central nervous system (CNS) disorders
The CNS includes the brain, spinal cord, and nerves. Conditions that affect the CNS can interfere with thermoregulation by impairing afferent sensing and central control.
Some examples of these conditions
- brain injuries
- spinal cord injuries
- neurological diseases, such as Parkinson’s or multiple sclerosis
- tumors
Medications
Certain medications can disrupt thermoregulation as a side effect, causing a temporary rise in body temperature. Some people refer to this as “drug fever.”
Examples of medications that can have this effect include:
- antimicrobials, such as antibiotics
- nonsteroidal anti-inflammatory drugs (NSAIDs)
- first-generation anticonvulsants
- antidepressants
Usually, effective thermoregulation quickly returns when a person stops taking the drug. People should always consult a doctor before changing their medication dosage.
Some people are more likely to experience thermoregulation-related health conditions, including:
- Older adults: Older adults tend to have
lower body temperatures than younger adults and may not develop fevers when they have infections. Sometimes, they can develop hypothermia instead. They can also have lower muscle mass, reduced immunity, and a diminished shiver reflex, all of which affect thermoregulation. - Children: In contrast, children and babies must
rely on others to help them regulate their body temperature by keeping them warm and clothed, or helping them cool down. - Pregnant people: Pregnancy raises body temperature, making it more likely someone will get sick during hot weather.
Other people who may be more at-risk include:
- outdoor workers
- athletes who train outdoors
- people without air conditioning
Mammals use thermoregulation to maintain a narrow temperature range. This is essential for health, as it allows organs and bodily processes to work effectively.
If a person’s body temperature strays too far from 98.6°F (37°C), they can develop hyperthermia or hypothermia. Various factors can contribute to this, including infections, extreme weather, medications, and other health conditions.
Thermoregulation disorders can be a medical emergency. If a person has symptoms of hypo- or hyperthermia, it is important to dial 911 or the number of the nearest emergency department.