1. ADR claimed that he could tell the differences between endothermic and ectothermic animals. The tissue of bones under microscope has different observation result. If canals can be found out in the tissue, it must be endothermic, which can offer high metabolic rate.
2. An experience by O overturned above theory. And the tissues differences turn out to be the result of exercise, which is an exertion factor
3. Further explanation of above experiment result
Illustrating the rationale behind haversian canals, O points out that bones are strained and stressed. They made of an elastic material. If the bone suffers from long term stress, it can lead to a full fracture. And then the bone will put new bones in its place.
main point:
different ideas to classify the difference between endothermic and ectothermic anamils
结构:
R的观点:dense with harversian canels in bones 可以说明他们是热血动物,因为需要新陈代谢燃烧能量;
O的观点:反对,这个只能说明他们在运动,因为运动会让他们骨头产生压力破损,会有新骨头替代,导致dense with canles in bones
Paragraph:
1. Ricqles find the difference between endothermic and ectothermic anamils
● method: put their bones to microscope
● result: striking similarities to the bone of birds and mamamles
● principle: bone fast grow(require a high metabolic rate to fuel)->mature: haverisian canals appear->destroy old bone & repace it with new material=>>endothermic
2+3: Owerkowicz attacked the R's bone structure opinion
● reason: dense canals caused by physical exertion rather than endothermy
● experiment: cold blooded lizard->when have an active lifestyle->showed some kind of complex channels like mamals, birds adn dinorsaurs
● conclusion: exercise rather than animals' thermal physiolody shape bone's microstructure
4. details/principles of Owerkowicz's findings: why some animals have dense with haversian canels:
● remodeling: bones are elastic materials->withstand forces(when they exerise with strained and strssed bones)->occiassionally to a tiny stress fracture->loding continue, lead to a full fracture->new bone in its place
观点对比型文章,先说DR的旧观点及解释,再详细说TO的新观点、实验和解释。
P1:描述De Ric的观点——可以通过显微镜观察骨骼判断是恒温动物还是冷血动物,并说明了观点的原理——texture of the bone and presence of the canals可以推测出动物的骨骼生长快,从而推测出是恒温动物。
P2-3:描述TO对上述观点的批评及实验。实验内容是对比有氧运动的蜥蜴和不进行有氧运动的蜥蜴,发现运动的蜥蜴也出现了Haversian canal是由于运动而不是温血。
P4:描述了TO对实验结果的解释。当动物运动时,骨骼会拉紧和紧张,偶尔会产生断裂,从而骨骼需要弥补这部分空间(remodel)。骨骼稠密并且有Haversian canal说明动物好动,而不是说明动物冷血或温血。
生词
ectotherm n. 冷血动物;变温动物
endotherm n. 温血动物,恒温动物
come under fire 受到批评
exertion n. 努力;发挥;运用