Homeo Hom eostasis stasis an and d fe feedb edback ack me mech chanism anism Ass. s.Le Lec. . Inas S. Mohammed med Biomedi Bi medical Engineering cal Engineering Un University sity of of Techno nolo logy 1 6 January 6 y 2017
De Definition inition of Ho Home meostas ostasis is Homeos omeostas tasis is: : The he tendenc tendency of of an an or organis ganism m or or cell cell to to regula gulate te its its inter internal nal en envir ironm onment ent and and ma mainta intain in equ equilibriu ilibrium, m, us usual ually by by a a system tem of of feed eedbac back k con contr trols ols, , so o as as to s to sta tabiliz bilize health and f e health and functioning. unctioning. Ever ery or organ gan in in the the body body contributes contributes to to homeos homeostas tasis is. . A A comple complex x set et of of chemical, hemical, ther thermal, mal, and and neur neural al factor actors inter interact act in in comple complex x way ays, , both both helping helping and and hindering hindering the the body body w while it w hile it wor orks ks to maintain homeos to maintain homeostas tasis is. . Homeos omeostas tasis is can be cons can be consider idered in ed in regar gards ds to to a cell, a cell, tis tissue, ue, or organ, biological gan, biological system, tem, or or en envir ironmental onmental system. tem. Actively maintained by organs and tissues 2 6 6 January y 2017
Defin init ition ion of Homeostas ostasis is Lungs provide oxygen consumed by cells, and remove carbon dioxide produced by cells Kidneys regulate ion concentrations by disposal of waste product. Arrest of bleeding. Prevent excessive blood loss. 1- Vasoconstriction of damaged blood vessels. 2- Platelet plug forming. 3- Coagulation or blood clotting. 3 6 6 January y 2017
TYPES PES OF FEED EEDBACK BACK ME MECHANISM CHANISM The here e ar are tw e two o typ types es of of fee eedb dbac ack k mec mecha hanism: nism:- 1-Nega gativ tive e feedbac eedback mec k mechanis hanism. m. 2- Positive feedback mechanism. Negative ative feedbac back k mechanism ism Nega gativ tive e feedbac eedback k : : Is the primar the primary mec mechanis hanism m thr through ough whic hich h your endocrine s our endocrine system tem maintains “ homeostasis “. *Example :- The control of blood sugar (glucose) by insulin is another good example of a negative feedback mechanism. When blood sugar rises, receptors in the body sense a change . In turn, the control center (pancreas) secretes insulin into the blood effectively lowering blood sugar levels. Once blood sugar levels reach homeostasis, the pancreas stops releasing insulin. 6 January 6 y 2017 4
PO POSITIV TIVE E FE FEED EDBACK BACK ME MECH CHANI ANISM Pos ositiv itive e feedbac eedback mec k mechanis hanism: m: Incr ncreas ease e in f in function unction in r in res espons ponse e to a s to a stimulus timulus *Exa *Example mple : - A- A A good e good example xample of of a a pos positiv itive e feedbac eedback s k system tem is is child hild bir birth. th. During During la labor bor, , a a hormone hor mone called called oxy xytocin tocin is is releas eleased tha ed that intens t intensif ifies ies and s and speeds peeds up up contr contractions actions. . The he incr increas ease in e in contr contractions actions caus causes es mor more e oxy xytocin tocin to be r to be releas eleased and the c ed and the cycle le goes goes on until on until the ba the baby by is is bor born. pos n. positiv itive e feedbac eedback k mec mechanis hanism. m. B- Another good e Another good example xample of of a pos a positiv itive e feedbac eedback mec k mechanis hanism m is is blood blood clotting. lotting. Once a nce a ves essel el is is dama damaged, ged, pla platelets telets star tart to c t to cling ling to to the injur the injured ed site ite and r and releas elease e chemicals hemicals tha that a t attr ttract mor act more e pla platelets telets. . The pla he platelets telets continue to pile continue to pile up and up and releas elease e chemicals hemicals until until a c a clot lot is is for ormed. med. 6 6 January y 2017 5
PO POSI SITIVE TIVE & NE NEGATIVE ATIVE FEEDBAC EEDBACK K ME MECHANISM ANISM *No Note te :- Just remember that positive feedback mechanisms enhance the original stimulus and negative feedback mechanisms inhibit it. 6 6 January y 2017 6
FEEDBACK DBACK MECH CHANI ANISM SM A feedback mechanism is a process that uses the conditions of one component to regulate the function of the other. It is done to either increase or dampen the change in the system. When the process tends to increase the change in the system, the mechanism is known as positive feedback. Negative feedback is when the process seeks to counter the change and maintain equilibrium. *Ho Home meost stasis asis is the tendency ency to resist t change e in order r to ma maintai ain n a stable, le, relatively ively constan ant t internal rnal enviro ronment nment . 6 6 January y 2017 7
THE THE END END 6 6 January y 2017 8
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