Lecture 2-3 - Homeostasis and Membrane Transport.pdf -...

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Lesson 2: HomeostasisHOMEOSTASIS:Maintenance of relatively stable internal conditions (even if the outsideworld is continuously changing)A dynamic state of equilibrium or balance (not just a one-way process)Necessary for normal body functioning and to sustain lifeMain Controlling Systems:Nervous System: Responsible for transmitting stimuliEndocrine System: Hormones or chemical signals (stimulation andinhibition)💡Homeostatic Imbalance: A DISTURBANCE in homeostasis results in DISEASES(As we age, our body organs become less efficient, and our internal conditions becomeless and less stable. Homeostatic imbalance = less stability = disease/infirmity). Inhomeostatic imbalance, the cells may not get everything that they need or toxic wastesmay accumulate in the bodyThree Components of Homeostatic Control Systems:1.) ReceptorResponds to the changes in the environment (STIMULI)Receiving/perceiving stimulus from the external or internal environment of thebodySends information to the control center ALONG AN AFFERENT PATHWAY2.) Control CenterConsists of the BRAIN & SPINAL CORDTranslates and interprets the stimuli received by the receptorsDetermine set point (extent of creation/deviation from the accepted levels)Analyzes informationDetermines appropriate response3.) EffectorConsists of the muscles, glands, and organs capable of giving an EFFECT,creating responses and reactionsProvides a means for response to the stimulusInformation flows from control center to the effector ALONG AN EFFERENTPATHWAYFeedback Mechanisms:1.)Negative Feedback:Includes MOST HOMEOSTATIC CONTROL MECHANISMS; responsible really forHOMEOSTASISSHUTS OFF OR OPPOSES the original stimulus or REDUCES ITS INTENSITYWorks like a household thermostatInhibition or the slowing down of a process2.)Positive Feedback:Rare in the human body; a feedback mechanism resulting in the AMPLIFICATIONor GROWTH of the original stimulusIncreases the original stimulus to push te variable fartherReactions occur at a FASTER rateIn the body, positive feedback occurs in BLOOD CLOTTING , FRUIT RIPENING. andDURING THE BIRTH OF A BABY💡In childbirth, the child pushes on the cervix (STIMULUS), and the signal is sent to thebrain. The brain releases OXYTOCIN to stimulate the uterus/cervix to contract. As the

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