Thermoregulation by sagar

Thermoregulation and hibernation in animals

1. THERMOR E GUL A TION & HIBERNATION BY :- SANGHSHARAN SAGAR Asst.Lecturer Gyanoday college of Nursing neemuch M.P.

2. S YNOPSIS INTRO D U C TION DEF I NIT I ON TYP E S P o ik i l ot h erm i c ( Co l d -bloode d ) anima l s Homeothermi c ( W arm-bloode d ) anima l s HI B E R N A TION C ONC L U S ION R E F ER E NC E S

3. INT R ODUCTION Active life is limited to a narrow temperature range. Beyond this range many animals can survive in an inactive or torpid state. A large number of animals included all aquatic invertebrates have the same temperature as their surroundings. But birds and mammals generally maintain a nearly constant temperature in spite of wide variations in the surroundings temperature.

4. DEFINITION Thermoregulation is temperature within function efficiently. t h e m ai n t enan c e of b o dy a r an g e th a t en a bl e cel l s to

5. TYP E S Poikilotherms (Cold-blooded) :- Those animals in which body temperature is varied with the environmental conditions are called Poikilotherms. eg. –fishes, amphibians and reptiles..

6. 1. Aquatic Poikilotherms: - Thermoregulation in aquatic Poikilotherms is a simple phenomenon. Heat exchange in aquatic animals are largely by conduction and convection. Thermal environment of aquatic animals is relatively stable, Still seasonal variations do occurs in the surface layers of the sea and the lakes.

7. Figure 2: Most endotherms are also homeotherms, like the domestic cat, whereas most ectotherms are poikilotherms, like the wall lizard. The fangtooth (deep-sea-fish) and the naked mole rat are exceptions.

8. Co n tinue…. 2 ) T er r e s t r i al P o ik i l other ms :- T er r e s tr i al P o ik i l ot h erms maintain their body temperature almost equal to that of the environment. However terrestrial animals face greater temperature fluctuations. The heat balance of such animals is more related to their water balance as compared to the aquatic animals. In order to raise the body temperature the evaporation and heat loss by conduction are to be reduced and the heat gain by radiation and metabolic heat production are to be increased.

9. Co n tinu e …. Example, Lizards and other reptiles burrow at night when the desert or mountain temperatures are at their lowest. Some heat from the day remains underground and the reptiles body is prevented from freezing. At sun rise the lizard, which may have reached a body temperature as low as 5 degree during the night slowly emerges from its burrow to orient it self to the sunlight so that the maximum heat is obtained. By proper orientation lizards can attain body temperatures that are as much as 30 degree above that of the air.

10. Homeo t herm s : - A ni mals th a t mai nt ain a f airly c o n st ant b o d y t e mpe r a tu r e i n s pi t e of g r e a t v ari a ti o ns of external temperature Homoeothermic animals. Eg.- Birds and mammals a r e s aid t o be

11. TE M PER A TU R E R E GUL A TIO N IN HOM E O T H E R M I C ANI M ALS For a body to maintain a constant temperature, the heat loss must be equal to heat loss. Heat loss :- it occurs by the following means. Conduction:- Conduction of heat consists of direct transfer of the kinetic energy of molecular motion and it always occurs from a region of higher temperature to one of the lower. Convection:- The transfer of heat in fluids is almost invariably accelerated by the process of convection which refers to mass movement of the fluid. The natural convection is caused by temperature difference. Radiation:- Heat transfer by radiation takes place in the absence of direct contact between objects. The intensity and the wavelength of this radiation depends upon the temperature of the radiating surface and its emissivity.

12. Co n tinu e … Evaporation:- The amount of heat required to achieve the phase change from liquid water to vapour is known as heat of vaporization. The heat of vaporization changes slightly with the temperature at which the evaporation takes place. Heat gain:- The heat is gained by the following means. From environment: The body can gain heat from the environment through conduction, convection and radiation. Heat production (Thermogenesis): The Du Bois temperature balance shows that the following factors increase heat production. Active heat production is achieved through exercise and shivering. Basal heat production depends on unconscious tensing of muscles, disease and specific dynamic action of food.

13. HIB E RN A TION Hibernation is a state of inactivity and metabolic depression in endotherms. To cope with the limited food resources and low temperatures, some mammals hibernate in underground burrows. In order to remain in ͚stasis͛ for long period, these animals must build up brown fat reserves and be capable of slowing all the body functions.

14. Co n tinue…. True hibernators (e.g., groundhogs) keep their body temperature down throughout their hibernation, while the core temperature of false hibernators(e.g., bears) varies with them sometimes emerging from their dens for brief periods. Some bats are true hibernators which rely upon a rapid, non-shivering thermogenesis of their brown fat deposit to bring them out of hibernation.

15. CONCLUSION Thermoregulation is the process of maintaining body temperature for normal functioning of the cells. Poikilotherms depends on environment for their body temperature while Homeotherms maintain their body temperature by itself.

16. R E F ER E NC E S

17. THAN K Y OU