HOMEOSTASISdr. Hawin Nurdiana, M.Kes

PHYSIOLOGY, PHYSIO = FUNCTION/FAAL ATAU KERJA (sesuatu yg ada hub. dgn mekanisme) & LOGY= LOGOS ILMU.

Ilmu faal: suatu ilmu yg mempelajari mekanisme fungsionil regulatory system yg menjaga secara optimal integritas internal environment dlm menunjang proses kehidupan mahluk hidup (the basic unit of living matter)

WELLCOME TO PHYSIOLOGY

What is homeostasis?maintaining the internal environment at a constant level or between narrow limits Blood pH is one aspect that must be maintained at all timesWhat are some other examples?

Additional Concepts:The internal environment of the organism: mostly composed of the extracellular fluid

The ECF includes plasma interstitial fluid

How does the organism stay alive?Organ systems work together to maintain a relatively constant internal environment to which the cells are exposedIn other words: the organ systems carry out homeostasis

Mechanisms of HomeostasisSensory receptorsDetect stimulusIntegrationSelects response

EffectorCarry out response

Negative FeedbackSituation in which a change in a certain direction provides information that causes a system to change less in that direction

Maintenance of body temperature

Positive FeedbackSituation in which a change in a certain direction provides information that causes a system to change more in that direction

ChildbirthHemostasis systemPotensial aksi syaraf

How does homeostasis work?Feedback loops!Rate of metabolicchemical reactionsHeat lossfrom aircooling skinHeat in bodyPositive feedback loopBloodtemperature inhypothalamusExcess temperatureperceived by brainNegative feedback loop

Water level homeostasis

Gas level homeostasis

Response to HeatSweatingDilating Blood Vessels

ShiveringConstriction of dermal blood vesselsResponse to Cold Environment

Thermoregulation in ectotherms

Regulation of glucose levels

Positive Feedback MechanismsCharacteristics:Time limitation Intensification of stress

Typical Positive Feedback Process

Homeostatic Regulation of Child Birth through Positive FeedbackPressure of Fetus on the Uterine WallNerve endings in the uterine wall carry afferent messages to the HypothalamusProduction and Release of Oxytocin into the BloodIncreasing strength of uterine contractionsIntensifiesUterine contraction

Positive feedback mini-loops are built into pathway to speed up production of chemicals needed to form the clot. Feedback in Coagulation

Potensial aksiJika terdapat rangsang pada sel syaraf (neuron) akan menyebabkan perubahan permeabilitas membran sarafaliran ion sodium (Na+) masuk kedalam neuron menghasilkan respon depolarisasi yang menyebabkan aliran masuk ion Na+ lebih lanjut potensial aksi

Harmful Effects of Positive FeedbackPositive feedback can be harmful. Two specific examples of these harmful outcomes would be:Fever can cause a positive feedback within homeostasis that pushes the body temperature continually higher. If the temperature reaches 45 degrees centigrade (113 degrees Fahrenheit) cellular proteins denature bringing metabolism to a stop and death.Chronic hypertension can favor the process of atherosclerosis which causes the openings of blood vessels to narrow. This, in turn, will intensify the hypertension bring on more damage to the walls of blood vessels.