Hyperthermia And Hypothermia
A. Hype Hypert rthe herm rmia ia If heat gain exceeds the ability of the body to lost heat, then body temperature increases above normal levels, a condition called hyperthermia. Hyperthermia can result from exposure to hot environments, exercise, fever, and anesthesia. Exposure to a hot environment normally results in the activation of heat loss mechanisms, and body temperature is maintained at normal levels. This is an excellent example example of a negativ negative-f e-feedb eedback ack mechani mechanism. sm. Hoever Hoever,, prolon prolonged ged exposu exposure re to a hot environment can result in heat exhaustion. The normal negative-feedback mechanisms for controlling body temperature are operating, but they are unable to maintain a normal body temperature. Heavy seating results in dehydration, decreased blood volume, decreased blood pressure, and increased heart rate. Individuals suffering from heat exhaustion have a et, cool skin because of the heavy heavy seati seating. ng. They usuall usually y feel feel eak, eak, di!!y di!!y, and nausea nauseated ted.. Treat Treatmen mentt includ includes es reducing heat gain by moving to a cooler environment, reducing heat production by muscles by ceasing activity, and restoring blood volume by drinking fluids. Heat stroke is a breakdon of the normal negative-feedback mechanisms of temperature regulation. If the temperature of the hypothalamus becomes too high, it no longer functions appropriately. "eating stops, and the skin becomes dry and flushed. The person becomes confused, irritable, or even comatose. In addition to the treatment for for heat heat exha exhaus usti tion on,, heat heat loss loss from from the the skin skin shou should ld be incr increa ease sed. d. This This can can be accomplished by increasing evaporation from the skin by applying et cloths or by increasing conductive heat loss by immersing the person in a cool bath. Exercise increases body temperature because of the heat produced as a by-product of muscle activity. #ormally vasodilation and increased seating prevent body temperature increases that are harmful. In a hot, humid environment the evaporation of seat is decreased, and exercise levels have to be reduced to prevent overheating. $ever $ever is the develo developme pment nt of a higher higher-t -thanhan-nor normal mal body tempera temperatur turee follo folloing ing the inva invasi sion on of the the body body by micr microo oorg rgani anism smss or fore foreig ign n subs substa tance nces. s. %ymp %ympho hocyt cytes es,, neutrophils, and macrophages release chemicals called pyrogens &pi'ro-(en!) that raise the temp temper erat atur uree set set point point of the the hypot hypothal halam amus us.. *ons *onse+u e+uen entl tly y body body temp tempera eratu ture re and and metabolic rate increase. $ever is believed to be beneficial because it speeds up the chem chemiical cal reac reacti tion onss of the imm immune une syst system em and and inhi nhibit bits the the gro groth th of some ome microorganisms. Although beneficial, body temperatures greater than degrees * &/
degr degree ee $) can can be harm harmfu ful. l. Aspir spirin in loe loers rs body body tem tempera peratu ture re by aff affecti ecting ng the the hypothalamus, resulting in dilation of skin blood vessels and seating. 0alignant hyperthermia is an inherited muscle disorder. 1rugs used to induce general anesthesia for surgery cause sustained, uncoordinated muscle contractions in some individuals. *onse+uently body temperature increases. Thera Therape peut utic ic hyper hyperthe therm rmia ia is an induc induced ed local local or gene genera rall body body incr increa ease se in temperature. It is a treatment sometimes used on tumors and infections. 2. Hypo Hypoth ther ermi miaa If heat loss exceeds the ability of the body to produce the heat, body temperature decreases belo normal levels. Hypothermia is a decrease in body temperature to 34 degrees * &54 1egree $) or belo. Hypothermia usually results from prolonged exposure to cold environments. environments. At first, first, normal normal negative-fe negative-feedback edback mechanisms mechanisms maintain maintain body temperature. Heat loss is decreased by constricting blood vessels in the skin, and heat production is increased by shivering. If body temperature decreases despite these mechanisms, mechanisms, hypot h ypothermia hermia develops. The individual' individual'ss thinking thinking becomes becomes sluggish, sluggish, and movements are uncoordinated. heart, respiratory, and metabolic rates decline, and death results unless body temperature is restored to normal. 6earming should occur at a rate of a fe degrees per hour. hou r. $rostb $rostbite ite is damage damage to the skin skin and deeper deeper tissue tissuess result resulting ing from from prolon prolonged ged exposure to the cold. 1amage results from cold in(ury to cells, in(ury from ice crystal formation, formation, and reduced reduced blood flo to affected affected tissues. tissues. The fingers, fingers, toes, ears, nose, and cheeks are most commonly affected. 1amage from frostbite can range from redness and discomfort to loss of the affected part. The best treatment is immersion in a arm ater bath. 6ubbing the affected area and local dry heat should be avoided. Therapeutic hypothermia is sometimes used to slo metabolic rate during surgical procedures such as heart surgery. surgery. 2ecause metabolic rate is decreased, tissues do not re+uire as much oxygen as normal and are less likely to be damaged.
The exact responses to high and lo temperatures are described in the table belo7 Effector
Response to low temperature
Smooth Smooth muscles muscles in arteriol arterioles es in the skin.
0uscles con contract causing vasoconstriction . Le Less ss heat heatis carr carrie ied d from from the the core core to the the surface of the body, maintaining core core temper temperatu ature. re. Extrem Extremiti ities es can turn blue and feel cold and can even be damaged &frostbite ). #o seat produced.
Sweat glands
Erector pili muscles in skin attached to skin hairs#
Skeletal muscles
Response to high temperature
0uscles relax causing vasodilation . More heatis carr carrie ied d from from the the core core to the the sur surface face,, her heree it is lost ost by and convection radiationconduction is general generally ly lo, lo, except except hen hen in ater). "kin turns red. 8lands secrete seat onto surface of skin, here it "incee ate aterh rhas as a evaporates . "inc high latent heat of evaporation , it takes heat from the the body body.. High humidity humidity , and tight tight clothi clothing ng made made of man! man! made made fibres fibres reduce the ability of the seat to evaporate and so make make us uncomfo uncomforta rtable ble in hot eather. "ranspirationfrom from tree treess has has a dramat dramatic ic coolin cooling g effect effect on the surrounding air temperature. Muscles contract contract , raising skin Muscl Muscles es rela rela% %, loe loerring ing the the hairs and skin hair hairss and and allo alloi ing ng air air to trapping an skin insulating layer of still$ warm circulate over the skin, airnext next to the the skin skin.. #ot #ot very very enco encour urag agin ing g conv convec ecti tion on and and effective in humans, (ust causing evaporation. 9goosebumps:. Shivering 7 0uscles contract and #o shivering. relax repeatedly, generating heat by friction and from metabolic reac reacti tion onss &res &respi pira rati tion on is only only ; efficient7 /; of increased respiration thus generates heat).
Adrenal Adrenal and thyroid thyroid glands
'ehaviour
&lands secrete secrete adrenaline adrenaline and respectively, y, hich thyr thyro o%ine %ine respectivel increases increases the metabolic metabolic rate in different different tissues, especially the liver, so generating heat. *urlin *urling g up, huddlin huddling, g, findin finding g shelter, putting on more clothes.
&lands stop secreting adrenaline and thyroxine.
"tretc "tretchin hing g out, out, findin finding g shade, shade, simming, removing clothes.
Hipertermia (an Hipotermia
A. Hipe Hipert rter ermi miaa
%atihan meningkatkan suhu tubuh karena panas yang dihasilkan sebagai produk sampingan sampingan dari aktivitas aktivitas otot. 2iasanya 2iasanya vasodilatas vasodilatasii dan peningkatan peningkatan berkeringat berkeringat
mencega mencegah h kenaik kenaikan an suhu suhu tubuh tubuh yang yang berbah berbahaya aya.. 1alam 1alam lingkun lingkungan gan lembab lembab dan penguapan panas mengakibatkan keringat menurun dan (uga tingkat latihan harus dikurangi untuk mencegah overheating. 1emam merupakan peningkatan suhu tubuh yang lebih tinggi dari normal setelah invasi tubuh oleh mikroorganisme atau !at asing. %imfosit, neutrofil, dan bahan kimia makr makrof ofag ag rili riliss yang yang dise disebu butt piro pirogen gen yang yang menai menaikk kkan an suhu suhu pada pada hipot hipotal alam amus us.. Akibat Akibatnya nya suhu suhu tubuh tubuh dan metabo metabolis lisme me mening meningkat kat.. 1emam 1emam diyaki diyakini ni bermanf bermanfaat aat karena karena memper mempercepa cepatt reaksi reaksi kimia kimia dari dari siste sistem m kekebal kekebalan an tubuh tubuh dan mengham menghambat bat pertumbuhan beberapa mikroorganisme. 0eskipun menguntungkan, suhu tubuh lebih dari dera(at * &/ dera(at $) bisa berbahaya. Aspirin menurunkan suhu tubuh dengan mempengaruhi hipotalamus, yang mengakibatkan pelebaran pembuluh darah kulit dan berkeringat. Hipert Hiperterm ermia ia ganas ganas adalah adalah ganggua gangguan n otot otot yang yang diari diariska skan n dari dari obat obat anastes anastesii sebeum operasi, yang dapat mengakibatkan kontraksi otot tidak terkoordinasi pada beberapa individu. Akibatnya suhu tubuh meningkat. Hipertermia terapi adalah peningkatan suhu tubuh lokal atau umum diinduksi suhu. =engobatan ini kadang-kadang digunakan untuk untuk penyakit tumor dan infeksi. infeksi. 2. Hipo Hipottermi ermiaa
rgan >rgan (antun (antung, g, pernapa pernapasan san,, dan tingkat tingkat metabol metabolism ismee menuru menurun, n, serta serta kemati kematian an terkecu terkecuali ali suhu suhu tubuh tubuh dapat dapat dikemba dikembalik likan an ke normal normal.. 6earming harus ter(adi pada tingkat beberapa dera(at per (am. 6adan 6adang g ding dingin in adal adalah ah keru kerusa sakan kan pada pada kuli kulitt dan (ari (aring ngan an lebi lebih h dalam dalam yang yang dihasilkan dari kontak yang terlalu lama dingin. Hasil kerusakan dari cedera dingin untuk sel, cedera dari pembentukan kristal es, dan berkurangnya aliran darah ke (aringan yang terkena.
Hipotermia Hipotermia terapeutik terapeutik kadang-kadang kadang-kadang digunakan digunakan untuk memperlambat memperlambat tingkat meta metabol bolis isme me sela selama ma pros prosed edur ur bedah bedah sepe sepert rtii oper operas asii (ant (antun ung. g. ?aren ?arenaa ting tingkat kat metabol metabolism ismee menuru menurun, n, (aring (aringan an tidak tidak memerl memerlukan ukan oksige oksigen n tingka tingkatt normal normal dan cenderung akan rusak.
6espon untuk suhu tubuh rendah dan tinggi yang di(elaskan di tabel baah ini 7 Effector
6espon suhu rendah &Hypotermia)
6espon suhu tinggi &Hypertermia)
>tot >tot hal halus us art arter erio iole less di kul kulit it
?ont ?ontra raks ksii otot otot meny menyeba ebabka bkan n vasconstriction. ?ekurangan panas dilakukan oleh inti tubuh. Ekstermitas bisa merubah kulit men(adi biru dan dingin, dan bahkan berbahaya.
6elaksasi otot menyebabkan vasodilation. %ebih panas dilakukan dari inti yang timbul, disaat kehilangan dari convection dan radiasi. &conduction umumnya rendah, kecuali saat di air) kulit dapat berubah men(adi arna merah.
Tidak ada produksi keringat.
?elen(ar keringat memproduksi keringat di permukaan kulit, saat penguapan. ?arena air memiliki panas laten yang tinggi penguapan, hal itu dibutuhkan panas dari tubuh, kelembaban tinggi, dan pakaian yang terbuat dari serat buatan manusia mengurangi kemampuan dari keringat untuk menguap dan membuat kita tidak nyaman di musim panas.
?elen(ar keringat
Arrector pili muscle atau otot arektor pili adalah otot kecil yang menempel di folikel rambut.
?ontraksi otot, pemeliharaan rambut kulit dan membatasi lapisan, udara hangat disamping kulit. Tidak efektif di manusia, hanya menyebabkan 9goosebumps:
6elaksasi otot, menurunkan rambut kulit dan memungkinkan lebih sirkulasi udara di kulit, mendorong konveksi dan penguapan.
"keletal muscles
6espon getaran gemetar7 kontraksi dan relaksasi otot ter(adi berulang kali, menghasilkan panas dari gesekan dan dari reaksi metabolisme.
Tidak ada getaran gemetar.
?ele ?elen( n(ar ar tyr tyroi oid d dan dan adre adrena nall
?ele ?elen( n(ar ar adr adren enal alin inee dan dan tyroxin memproduksi secara berurutan, saat meningkatkan tingkat metabolisme di (aringan yang berbeda, terutama hati lebih menghasilkan panas.
?elen(ar adrenaline dan tyroxine berhenti memproduksi.
Tingkah laku
0enekuk badan &ngeruntel), berlindung di tempat yang hangat, memakai ba(u yang lebih.
2erbaring &istirahat), berteduh, berenang, melepas pakaian.
1aftar =ustaka http7@@.mhhe.com@biosci@ap@vander@student@olc@d-reading.html http7@@.biologymad.com@resources@a;homeostatis.pdf
