1、Unit 12,Homeostasis,position,same,Metabolic equilibrium actively maintained by several complex biological mechanisms that operate via the autonomic nervous system to offset disrupting change,organism nzm organ n organic nk,胰高血糖素,肝糖,thermo: heat, hot,thermostat,thermoplastic adj. 熱塑性的n. 熱塑性塑料 thermoc

2、hemistry 熱化學，熱力學 thermobarometer 溫度計 thermoregulation 溫度調(diào)節(jié),depolarization,separate, divide,deoxygenate v. 去氧 dehydration n. 脫水 deamination n. 脫氨基,corticoid= corticosteroid,gluco: sugar glyco,glucocorticoid,glycogenolysisglycogenesis,glyco-: sugar b. glycogen: 肝糖，糖原 c. olysis: analysis d. esis: synth

3、esis,Definition,1. What is homeostasis? 2. What does homeostasis in living organisms involve? 3. Why is homeostasis necessary?,Homeostasis Mechanism,1. What does homeostasis require organism to be able to do? 2. cybernetics. 3. negative feedback loops 4. positive feedback loops,Negative feedback occ

4、urs when the result of a process influences the operation of the process itself in such a way as to reduce changes. Negative feedback tends to make a system self-regulating; it can produce stability and reduce the effect of fluctuations. Negative feedback loops where just the right amount of correct

5、ion is applied in the most timely manner can be very stable, accurate, and responsive.,Positive feedback is a process in which the effects of a small disturbance on a system can include an increase in the magnitude of the perturbation. That is, A produces more of B which in turn produces more of A.,

6、Homeostasis at the Cellular Level,1. Why do all organisms perform homeostasis at a cellular level? 2. Why do single-celled organisms have a more difficult homeostatic task than multicellular organisms? 3. Please explain the important role of negative feedback loops by using an example.,Blood Circula

7、tion in Homeostasis,1. What are the main functions of the circulatory system in homeostasis? 2. The levels of substances within the blood are under control of other organs. The respiratory system and the nervous system _ The liver and the pancreas_ The kidneys_ The endocrine glands_ The hypothalamus

8、_,metabolite metblat n.代謝物 metabolism mtblzm n. 新陳代謝 metabolic metblk a. metabolize mtblaz vt.,Blood Circulation in Homeostasis,1. What are the main functions of the circulatory system in homeostasis? 2. The levels of substances within the blood are under control of other organs. The respiratory system and the nervous system _ The liver and the pancreas_ The kidneys_ The endocrine glands_ The hypothalamus_,Maintenance of Blood Glucose Levels,1. What is the most complicated homeostatic system known? 2. What hormones control blood glucose levels? 3. What hormones stimulate glycogenolysis