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Ectotherm  is when an animal depends on the weather for the regulation of it's body temperature.

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Table of Contents

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ectotherm, any so-called cold-blooded animal-that is, any animal whose regulation of body temperature depends on external sources, such as sunlight or a heated rock surface. The ectotherms include the fishes, amphibians, reptiles, and invertebrates. The body temperature of an aquatic ectotherm is usually very close to the temperature of the surrounding water. Ectotherms do not require as much food as warm-blooded animals ( endotherms) of the same size do but may be more dramatically affected by temperature fluctuations.

Ectotherms that live in regions where temperatures fluctuate seasonally avoid extremes by taking shelter in burrows or similar locations or by becoming dormant to some degree (e.g., in winter, fish may rest near the bottom of a body of water). In addition, ectotherms employ biochemical strategies to combat the effects of extreme temperatures. Since excessive heat can damage proteins in an animal's body, during periods of heat stress, ectotherms release heat-shock proteins, which help stabilize other proteins and thus prevent their denaturation (modification of a protein's molecular structure).

In colder environments, where ectotherms may be exposed to freezing temperatures, some species may alter their body chemistry to restrict the growth of ice crystals in their cells and tissues or to prevent ice crystal formation altogether. Many ectotherms can manufacture and flood their bloodstream and tissues with cryoprotectants-ice-inhibiting compounds, such as proteins, sugars, and sugar alcohols (e.g., sorbitol and glycerol)-or they can use other dissolved substances, such as salts, already present in the bloodstream. Such adaptations protect the animals' cells from freezing by lowering the freezing point of water. For example, the wood frog ( Lithobates sylvatica) survives the winter by manufacturing excess sugars (specifically, by converting glycogen into glucose) that protect the animal's cells and tissues, though much of the water in the frog's body may freeze. Similarly, ray-finned fishes inhabiting polar marine environments have high internal salt concentrations that inhibit freezing, and they produce glycoproteins that serve as cryoprotectants.

The Editors of Encyclopaedia Britannica John P. Rafferty.

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ectotherm | Definition, Advantages, & Examples

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ectotherm, any so-called cold-blooded animal-that is, any animal whose regulation of body temperature depends on external sources, such as sunlight or a heated rock surface. The ectotherms include the fishes, amphibians, reptiles, and invertebrates. The body temperature of an aquatic ectotherm is usually very close to the temperature of the surrounding water.

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Hyperthermia occurs when the body over heats.

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The Impact of Hyperthermia

The highest temperature recorded on earth was 58 degrees Celsius, at a desert in Libya. This level of temperature would certainly evoke hyperthermia, which is overheating, or body temperature above the normal range.

In fact, heat is one of usual causes of climate-related mortalities around the world. A major heat wave during the 1980s took away 1,250 lives. Thus, this just shows the importance of this following discussion. [1,2]

Normal Temperature of the Human Body

The normal body temperature of humans ranges from 36.5 to 37.5 degrees Celsius.

However, during late afternoons, when the atmospheric temperature is at its peak, the normal body temperature can still reach to as high as 37.7 degrees Celsius. Temperatures recorded below and above these levels are considered to be the conditions hypothermia and hyperthermia, respectively. Consequently, any abnormality in body temperature can lead to experiencing medical problems. [3, 4, 5, 6, 7]

Fever versus Hyperthermia

Both fever and hyperthermia are characterized by elevations in the body temperatures. What is the main difference between the two?

In fever, the hypothalamus reprograms and controls the body's thermostat, as response to the presence of infection. On the other hand, the reprogramming function of the hypothalamus is nonexistent during hyperthermia.

As a result, the body cannot maintain its temperature properly, it rises extremely causing hyperthermia's detrimental effect: organ damage and death.[8]

Definition

Hyperthermia is a condition in which the body either produces more heat, such as in fever, or absorbs more heat, thru excessive sun exposure. It is described as having an elevated body temperature brought about by failure in thermoregulation. [9, 10]

Hyperthermia is defined as a temperature more than 37.5 - 38.3 °C (100 - 101 °F) - (Ref : Wikipedia)

Image 1 : A patient having hyperthermia from prolonged heat and sun exposure.
Source: www.hypothermia-hyperthermia.wikispaces.com

Causes of Hyperthermia: What Can Increase Its Risk?

A number of factors can increase one's chances of acquiring hyperthermia, this includes: [3, 4, 9, 11]

Being out and exposed in direct heat for a long period of time

In close distance to a heat-inducing equipment for an extensive amount of time

Inability to rehydrate

Inability to seek and relocate to an area with a greater amount of shade and a lesser degree of temperature level

Included in the younger age group

Increased poverty

Engaging in outdoor daytime activities for a lengthy period of time

Certain medical disorders including pheochromocytoma, thyrotoxicosis, status epilepticus and brain hemorrhage.

Having heat exhaustion and heat strokes, which are comprised of too much metabolic heat production, excessive environmental heat, and nonfunctioning heat losing mechanism

Intake of medications such as monoamine oxidase inhibitors (MAOIs), selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants

Use of illicit drugs, like cocaine, amphetamine, lysergic acid diethylamide (LSD), Phencyclidine (PCP), and ecstasy, or MDMA.

Clinical Manifestations

With the aim of increasing heat loss, blood vessels begin to dilate in the presence of an elevated body temperature. This mechanism produces a dried, hot skin, lacking sweat and the concomitant ability of skin cooling. Along with this, headaches, hypotension, dizziness, and nausea and vomiting may also be evident, if dehydration is present.[3, 11]

Symptoms of heat exhaustion can ensue. These include body malaise, dizziness, nausea, vomiting, headaches, and muscle cramps. If neglected, this eventually leads to heat stroke, a potentially fatal condition. Manifestations of which consist of heat rash, heat cramps, nausea, disorientation, seizures and dizziness.[8]

Diagnosing Hyperthermia

This condition can initially be considered based on the complete and thorough medical history and physical examination elicited. A concomitant elevation of the body temperature in the presence of humid and hot surroundings would lead one to consider heat stroke.

An increased body temperature after taking a medication for which hyperthermia is a known adverse reaction can result to a person having drug-induced hyperthermia.[3, 11]

Furthermore, hyperthermia can also be a diagnosis of exclusion. If antipyretic medications lower the core temperature of the human body, even if it does not totally retain its normalcy, hyperthermia can then be ruled out.

Additional blood tests and diagnostic examinations can then be performed to consider other sources, and causes of temperature elevation.[3, 9, 11]

Treatment Modalities for Hyperthermia

Elimination of the underlying reason for temperature increase must be done. If hyperthermia is caused by extensive sun exposure, then transferring to a cool, shaded place, with enough water intake should be enough to alleviate symptoms.

Drug-related hyperthermia, on the other hand, should be managed by prompt termination of drug administration. Antipyretic agents, Paracetamol, Ibuprofen and Aspirin, can also diminish hyperthermia.[11]

Cooling techniques can be further subdivided into passive and active methods. Passive cooling and temperature lowering may be achieved by staying at a well shaded, cool area, with all clothing immediately removed. Active means of cooling, on the other hand, pertains to sponge baths using cool water, utilizing a fan or airconditioning, and consumption of cool drinking water.

These all would regain proper functioning of the human body's cooling mechanisms, which are mainly thru evaporation and sweating. [3]

Image 2 : Immediate management for hyperthermic patient should include cold compress application, usage of a fan, fluid intake, and elevation of feet, for those with hypotension.
Source: www.isshomeostasis.wikispaces.com

A hyperthermic patient can also be immersed on a tub of cool water. This method can get rid of a huge quantity of body heat in a short amount of time. In achieving its goal, it vasoconstricts the skin and prohibits heat from breaking out of the body. It is said to be the most effective cooling method for hyperthermia. [12, 13]

Image 3 : Immersion of a hyperthermic patient on a tub of cool, even iced water.
Source: www.landesbioscience.com

Hyperthermia can be a medical emergency when faced with symptoms such as unconsciousness and disorientation. This is usually observed in patients with body temperature exceeding 40 degrees Celsius. This requires management at a hospital, wherein lavage with an iced saline, intravenous hydration, and even hemodialysis, for severe intractable cases, may be done.[11]

Preventive Measures for Hyperthermia

The following measures must be done to avoid great extents of temperature elevation:[8]

Avoid too much sun exposure. If not possible, try to stay at a shaded area, where it is cool and there is less heat and humidity

Stay clear of activities that generate more heat

Increase oral fluid intake

Drink cool, non-alcoholic and noncaffeinated beverages

May consume beverages with enough sodium content to restore electrolytes lost from the body (fruit juices and sports drinks).

Wear clothes of light, cotton material.

May take a shower during hot humid times

If a shower is not possible at the moment, one can use a damp wash cloth to cool the skin.

If symptoms do persist, a consult to the physician is of immediate need.

Hyperthermia as a Treatment for Cancer

Thermotherapy, also called thermal therapy, is a treatment modality used for cases of carcinoma. Using hyperthermia as its basis, the method exposes the infected tissues of the body to a soaring degree of temperature, even reaching 113 degrees Fahrenheit. This consequently damages cancer cells and decreases tumor size, but is safe to normal ones. [14, 15, 16]

This treatment approach can be done locally, regionally and for the whole body. Performed either thru the external, intraluminal, or interstitial techniques, local hyperthermia applies heat at a small area, such that of a tumor. Regional hyperthermia, meanwhile, may be made for the treatment of larger areas, such as that of a cavity, limb, or organ. Whole body hyperthermia, on the other hand, is used for metastases, and is performed utilizing thermal chambers and heating blankets. [15, 17]

Recent studies dealing with this type of treatment focused on eliminating different types of carcinomas: sarcoma, mesothelioma, melanoma, and cancers of the brain, esophagus, lung, breast, liver, cervix, bladder, rectum, and appendix. [14, 18]

1. http://coolcosmos.ipac.caltech.edu/cosmic_kids/AskKids/earthtemp.shtml

2. http://www.nws.noaa.gov/os/heat/index.shtml

3. http://en.wikipedia.org/wiki/Hyperthermia

4. Marx, J, et al. Rosen's Emergency Medicine: Concepts and Clinical Practice. Mosby/Elsevier. p.2239.

5. Karakitsos, d, et al. Hypothermia Therapy After Traumatic Brain Injury In Children. New England Journal of Medicine. 2008 September. 359(11):1179-80.

6. Axelrod, Y, et al. Temperature Management in Acute Neurologic Disorders. Neurology Clinical. 2008 May. 26 (2): 585-603.

7. Laupland, K, et al. Fever in the Critically Ill Medical Patient. Critical Care Medicine. 2009 July. 37 (7).

8. http://health.howstuffworks.com/wellness/men/sweating-odor/hyperthermia.htm

9. http://www.healthjolt.com/hyperthermia/

10. http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Hyperthermia.html

11. Fausi, A, et al. Harrison's Principles of Internal Medicine. 2008. 17th ed. Mc-Graw Professional. Pp.117-121.

12. Britain Journal of Sports Medicine, 2005.

13. Bouchama, A, et. al. Cooling and Hemodynamic Management in Heatstroke: Practical Recommendations. Critical Care. 2007. 11(3).

14. http://www.cancer.gov/cancertopics/factsheet/Therapy/hyperthermia

15. Van der Zee, J, et al. Heating the Patient: A Promising Approach? Annals of Oncology. 2002; 13 (8): 1173-1184.

16. Hilderbrandt, B, et al. The Cellular and Molecular Basis of Hyperthermia. Critical Reviews in Oncology/ Hematology. 2002; 43 (10):33-56.

17. Wust, P, et al. Hyperthermia in Combined Treatment of Cancer. The Lancet Oncology. 2002; 3 (8): 487-97.

18. Kapp, DS, et al. Principles of Hyperthermia. Cancer Medicine. 5th ed. Hamilton, Ontario: BC Decker, Inc, 2000.

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The highest temperature recorded on earth was 58 degrees Celsius, at a desert in Libya. This level of temperature would certainly evoke hyperthermia, which is overheating, or body temperature above the normal range. In fact, heat is one of usual causes of climate-related mortalities around the world.

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It is used to keep liquids hot or cold

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Thermometers are used to check temperature.

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It happens when your body's temperature is lower than 35 degrees.

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Overview

Hypothermia is a medical emergency that occurs when your body loses heat faster than it can produce heat, causing a dangerously low body temperature. Normal body temperature is around 98.6 F (37 C). Hypothermia (hi-poe-THUR-me-uh) occurs as your body temperature falls below 95 F (35 C).

When your body temperature drops, your heart, nervous system and other organs can't work normally. Left untreated, hypothermia can eventually lead to complete failure of your heart and respiratory system and eventually to death.

Hypothermia is often caused by exposure to cold weather or immersion in cold water. Primary treatments for hypothermia are methods to warm the body back to a normal temperature.

Symptoms

Shivering is likely the first thing you'll notice as the temperature starts to drop because it's your body's automatic defense against cold temperature - an attempt to warm itself.

Signs and symptoms of hypothermia include:

Shivering

Slurred speech or mumbling

Slow, shallow breathing

Weak pulse

Clumsiness or lack of coordination

Drowsiness or very low energy

Confusion or memory loss

Loss of consciousness

Bright red, cold skin (in infants)

Someone with hypothermia usually isn't aware of his or her condition because the symptoms often begin gradually. Also, the confused thinking associated with hypothermia prevents self-awareness. The confused thinking can also lead to risk-taking behavior.

When to see a doctor

Call 911 or your local emergency number if you suspect someone has hypothermia.

While you wait for emergency help to arrive, gently move the person inside if possible. Jarring movements can trigger dangerous irregular heartbeats. Carefully remove his or her wet clothing, replacing it with warm, dry coats or blankets.

Causes

Hypothermia occurs when your body loses heat faster than it produces it. The most common causes of hypothermia are exposure to cold-weather conditions or cold water. But prolonged exposure to any environment colder than your body can lead to hypothermia if you aren't dressed appropriately or can't control the conditions.

Specific conditions leading to hypothermia include:

Wearing clothes that aren't warm enough for weather conditions

Staying out in the cold too long

Being unable to get out of wet clothes or move to a warm, dry location

Falling into the water, as in a boating accident

Living in a house that's too cold, either from poor heating or too much air conditioning

How your body loses heat

The mechanisms of heat loss from your body include the following:

Radiated heat. Most heat loss is due to heat radiated from unprotected surfaces of your body.

Direct contact. If you're in direct contact with something very cold, such as cold water or the cold ground, heat is conducted away from your body. Because water is very good at transferring heat from your body, body heat is lost much faster in cold water than in cold air. Similarly, heat loss from your body is much faster if your clothes are wet, as when you're caught out in the rain.

Wind. Wind removes body heat by carrying away the thin layer of warm air at the surface of your skin. A wind chill factor is important in causing heat loss.

Risk factors

Risk factors for hypothermia include:

Exhaustion. Your tolerance for cold diminishes when you are fatigued.

Older age. The body's ability to regulate temperature and to sense cold may lessen with age. And some older adults may not be able to communicate when they are cold or to move to a warm location if they do feel cold.

Very young age. Children lose heat faster than adults do. Children may also ignore the cold because they're having too much fun to think about it. And they may not have the judgment to dress properly in cold weather or to get out of the cold when they should.

Mental problems. People with a mental illness, dementia or other conditions that interfere with judgment may not dress appropriately for the weather or understand the risk of cold weather. People with dementia may wander from home or get lost easily, making them more likely to be stranded outside in cold or wet weather.

Alcohol and drug use. Alcohol may make your body feel warm inside, but it causes your blood vessels to expand, resulting in more rapid heat loss from the surface of your skin. The body's natural shivering response is diminished in people who've been drinking alcohol. In addition, the use of alcohol or recreational drugs can affect your judgment about the need to get inside or wear warm clothes in cold weather conditions. If a person is intoxicated and passes out in cold weather, he or she is likely to develop hypothermia.

Certain medical conditions. Some health disorders affect your body's ability to regulate body temperature. Examples include an underactive thyroid (hypothyroidism), poor nutrition or anorexia nervosa, diabetes, stroke, severe arthritis, Parkinson's disease, trauma, and spinal cord injuries.

Medications. Some drugs can change the body's ability to regulate its temperature. Examples include certain antidepressants, antipsychotics, narcotic pain medications and sedatives.

Complications

People who develop hypothermia because of exposure to cold weather or cold water are also vulnerable to other cold-related injuries, including:

Freezing of body tissues (frostbite)

Decay and death of tissue resulting from an interruption in blood flow (gangrene)

Prevention

Staying warm in cold weather

Before you or your children step out into cold air, remember the advice that follows with the simple acronym COLD - cover, overexertion, layers, dry:

Cover. Wear a hat or other protective covering to prevent body heat from escaping from your head, face and neck. Cover your hands with mittens instead of gloves.

Overexertion. Avoid activities that would cause you to sweat a lot. The combination of wet clothing and cold weather can cause you to lose body heat more quickly.

Layers. Wear loosefitting, layered, lightweight clothing. Outer clothing made of tightly woven, water-repellent material is best for wind protection. Wool, silk or polypropylene inner layers hold body heat better than cotton does.

Dry. Stay as dry as possible. Get out of wet clothing as soon as possible. Be especially careful to keep your hands and feet dry, as it's easy for snow to get into mittens and boots.

Keeping children safe from the cold

To help prevent hypothermia when children are outside in the winter:

Dress infants and young children in one more layer than an adult would wear in the same conditions.

Bring children indoors if they start shivering - that's the first sign that hypothermia is starting.

Have children come inside frequently to warm themselves when they're playing outside.

Don't let babies sleep in a cold room.

Winter car safety

Whenever you're traveling during bad weather, be sure someone knows where you're headed and at what time you're expected to arrive. That way, if you get into trouble on your way, emergency responders will know where to look for your car.

It's also a good idea to keep emergency supplies in your car in case you get stranded. Supplies may include several blankets, matches, candles, a clean can where you can melt snow into drinking water, a first-aid kit, dry or canned food, a can opener, tow rope, booster cables, compass, and a bag of sand or kitty litter to spread for traction if you're stuck in the snow. If possible, travel with a cellphone.

If you're stranded, put everything you need in the car with you, huddle together and stay covered. Run the car for 10 minutes each hour to warm it up. Make sure a window is slightly open and the exhaust pipe isn't covered with snow while the engine is running.

Alcohol

To avoid alcohol-related risks of hypothermia, don't drink alcohol:

If you're going to be outside in cold weather

If you're boating

Before going to bed on cold nights

Cold-water safety

Water doesn't have to be extremely cold to cause hypothermia. Any water that's colder than normal body temperature causes heat loss. (8, p2) The following tips may increase your survival time in cold water if you accidentally fall in:

Wear a life jacket. If you plan to ride in a watercraft, wear a life jacket. A life jacket can help you stay alive longer in cold water by enabling you to float without using energy and by providing some insulation. Keep a whistle attached to your life jacket to signal for help.

Get out of the water if possible. Get out of the water as much as possible, such as climbing onto a capsized boat or grabbing onto a floating object.

Don't attempt to swim unless you're close to safety. Unless a boat, another person or a life jacket is close by, stay put. Swimming will use up energy and may shorten survival time.

Position your body to minimize heat loss. Use a body position known as the heat escape lessening position (HELP) to reduce heat loss while you wait for assistance. Hold your knees to your chest to protect the trunk of your body. If you're wearing a life jacket that turns your face down in this position, bring your legs tightly together, your arms to your sides and your head back.

Huddle with others. If you've fallen into cold water with other people, keep warm by facing each other in a tight circle.

Don't remove your clothing. While you're in the water, don't remove clothing because it helps to insulate you from the water. Buckle, button and zip up your clothes. Cover your head if possible. Remove clothing only after you're safely out of the water and can take measures to get dry and warm.

Help for at-risk people

For people most at risk of hypothermia - infants, older adults, people who have mental or physical problems, and people who are homeless - community outreach programs and social support services can be of great help. If you're at risk or know someone at risk, contact your local public health office for available services, such as the following:

Assistance for paying heating bills

Check-in services to see if you and your home are warm enough during cold weather

Homeless shelters

Community warming centers, safe and warm daytime locations where you can go during cold weather

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Hypothermia is a medical emergency that occurs when your body loses heat faster than it can produce heat, causing a dangerously low body temperature. Normal body temperature is around 98.6 F (37 C). Hypothermia (hi-poe-THUR-me-uh) occurs as your body temperature falls below 95 F (35 C).

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A thermostat is a device that regulates temperature.

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They are made to keep you warm.