CHAPTER 1 - Homeostasis has to do with the existence of a stable internal environment. The internal environment is different from the external environment and requires many homeostatic mechanisms to maintain the internal conditions. - Homeostasis is absolutely essential for life. Disease occurs when our body has lost control of its homeostatic mechanisms. - An intrinsic mechanism is one that requires the organ itself to respond to a change. (Ex: low oxygen levels in the blood stream will cause cells of our body to release chemicals to release more oxygen to the cells) - An extrinsic mechanism is one where the nervous system or the endocrine system will kick in to respond to a change. ( Ex: low oxygen levels in the blood stream will cause our body to release a hormone that will regulate the oxygen flow to our body) - All homeostatic mechanisms have three basic components: • Receptor • Control Center • Effector - Afferent Information (Sensory Information) is any information coming into the body. - Efferent Information (Command Information) – sends commands to the body to do something - Negative Feedback (Bionegative Feedback) – always works to oppose a change to keep conditions close to a set point. ( Ex: If your body temperature rises, temperature receptors in the skin will send Afferent information via neurons to the central nervous system in the hypothalamus to send out an Efferent command to lower the body temperature. Our body sweats, gives off heat, and body temperature is lowered.)
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