- Microwaves affect thermoregulatory behavior in rats - Digital Library
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- ISBN 13: 9780120440207
- Microwaves and thermoregulation
If the body is unable to maintain a normal temperature and it increases significantly above normal, a condition known as heat stroke occurs. The opposite condition, when body temperature decreases below normal levels, is known as hypothermia. Whereas an organism that thermoregulates is one that keeps its core body temperature within certain limits, a thermoconformer changes its body temperature with changes to the temperature outside of its body. It was not until the introduction of thermometers that any exact data on the temperature of animals could be obtained.
It was then found that local differences were present, since heat production and heat loss vary considerably in different parts of the body, although the circulation of the blood tends to bring about a mean temperature of the internal parts. Hence it is important to determine the temperature of those parts which most nearly approaches to that of the internal organs. Also for such results to be comparable they must be made in the same situation. The rectum gives most accurately the temperature of internal parts, or in some cases of sex or species, the vagina , uterus or bladder.
Occasionally the temperature of the urine as it leaves the urethra may be of use. More usually the temperature is taken in the mouth , underarm axilla , ear or groin. Thermoregulation is an important aspect of human homeostasis. Humans have been able to adapt to a great diversity of climates, including hot humid and hot arid.
Microwaves affect thermoregulatory behavior in rats - Digital Library
High temperatures pose serious stresses for the human body, placing it in great danger of injury or even death. In order to deal with these climatic conditions, humans have developed physiologic and cultural modes of adaptation. The skin assists in homeostasis keeping different aspects of the body constant e. It does this by reacting differently to hot and cold conditions so that the inner body temperature remains more or less constant. Vasodilation and sweating are the primary modes by which humans attempt to lose excess body heat.
The effectiveness of these methods is influenced by the character of the climate and the degree to which the individual is acclimatized. Note : Messages from the brain that reach effectors e. Neurons are specialized cells that pass messages around the body in the form of electrical impulses.
Motor neurons are the ones that pass messages from the brain directly to the effector, in this case muscles.
A collection of thousands of neurons is termed a nerve. The process explained above, in which the skin regulates body temperature is a part of thermoregulation. This is one aspect of homeostasis-the process by which the body regulates itself to keep internal conditions constant. Temperature symptoms and medications:. By numerous observations upon humans and other animals, John Hunter showed that the essential difference between the so-called warm-blooded and cold-blooded animals lies in observed constancy of the temperature of the former, and the observed variability of the temperature of the latter.
Almost all birds and mammals have a high temperature almost constant and independent of that of the surrounding air. This is called homeothermy. Almost all other animals display a variation of body temperature, dependent on their surroundings.
This is called poikilothermy. Certain mammals are exceptions to this rule, being warm-blooded during the summer or daytime, but cold-blooded during the winter when they hibernate or at night during sleep. Wakelin Barratt has demonstrated that under certain pathological conditions, a warm-blooded homeothermic animal may become temporarily cold-blooded poikilothermic.
He has shown conclusively that this condition exists in rabbits suffering from rabies during the last period of their life, the rectal temperature being then within a few degrees of the room temperature and varying with it. He explains this condition by the assumption that the nervous mechanism of heat regulation has become paralysed.
The respiration and heart-rate being also retarded during this period, the resemblance to the condition of hibernation is considerable. Again, Sutherland Simpson has shown that during deep anaesthesia a warm-blooded animal tends to take the same temperature as that of its environment. Similar results have been obtained from experiments on cats.
This is due to the skin on the head being relatively thin along with the abundance of blood vessels present. It is also known that in temperature differences, that of the higher temperature will raise. This causes heat to raise to the head and escape through the skin. Seeking shade is one method of cooling. Here Sooty Tern chicks are using a Black-footed Albatross chick for shade. To cope with low temperatures, some fish have developed the ability to remain functional even when the water temperature is below freezing; some use natural antifreeze or antifreeze proteins to resist ice crystal formation in their tissues.
Amphibians and reptiles cope with heat loss by evaporative cooling and behavioral adaptations. To regulate body temperature, an organism may need to prevent heat gains in arid environments. Evaporation of water, either across respiratory surfaces or across the skin in those animals possessing sweat glands, helps in cooling body temperature to within the organism's tolerance range. Animals with a body covered by fur have limited ability to sweat, relying heavily on panting to increase evaporation of water across the moist surfaces of the lungs and the tongue and mouth.
Birds also avoid overheating by panting since their thin skin has no sweat glands. Down feathers trap warm air acting as excellent insulators just as hair in mammals acts as a good insulator; mammalian skin is much thicker than that of birds and often has a continuous layer of insulating fat beneath the dermis — in marine mammals like whales this is referred to as blubber.
ISBN 13: 9780120440207
Dense coats found in desert endotherms also aid in preventing heat gain. Another cold weather strategy is to temporarily decrease metabolic rate and body temperature regulated decrease in body temperature decreases the temperature difference between the animal and the air and therefore minimizes heat loss. Furthermore, having a lower metabolic rate is less energetically expensive.
Many animals survive cold frosty nights through torpor , a short-term temporary drop in body temperature. Organisms when presented with the problem of regulating body temperature not only have behavioural, physiological and structural adaptations, but also a feedback system to trigger these adaptations to regulate temperature accordingly. The main features of this system are; Stimulus, Receptor, Modulator, Effector and then the feedback of the now adjusted temperature to the Stimulus.
This cyclical process aids in homeostasis. In cold environments, birds and mammals employ the following adaptations and strategies to minimize heat loss:. In warm environments, birds and mammals employ the following adaptations and strategies to maximize heat loss:. The periodicity of the sleep cycle is strongly correlated with body size both between and within species. This may be related to the demands of thermoregulation.
During quiet sleep the thermoregulatory mechanisms work normally but there is no response to thermal stress during active sleep. This could have serious implications for small animals see gigantothermy whose body temperature is more easily influenced by ambient temperature because of their lesser thermal capacity. So, as a rule, smaller animals have shorter periods of active sleep, ending before becoming thermally threatening.
In addition to human beings, a number of other animals also maintain their body temperature with physiological and behavioral adjustments. For example, a desert lizard is an ectotherm and is therefore unable to control its temperature through metabolic regulation. However, by altering its location continuously, it is able to maintain a crude form of temperature control. In the morning, only its head will emerge from its burrow. Later, the entire body is exposed. The lizard basks in the sun, absorbing solar heat. When the temperature reaches higher levels, the lizard will hide under rocks or return to its burrow.
When the sun goes down or the temperature falls, it emerges again. Some animals living in cold environments maintain their body temperature by preventing heat loss. Their fur grows more densely to increase the amount of insulation.
Volume Article Contents. Materials and methods. Assessment of testicular core temperatures using microwave thermography M. Rafet Gazvani.
Oxford Academic. Google Scholar. Simon J. Angus J. Charles R.
Microwaves and thermoregulation
Iwan Lewis-Jones. Cite Citation. Permissions Icon Permissions. Abstract A new method for the reliable assessment of testicular core temperature using microwave technology is presented. Issue Section:. Download all figures. View Metrics. Email alerts New issue alert.
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