Short and long loop nephrons

The purpose of this article is to consider the question: what is the importance to the urinary concentrating mechanism of having nephrons with two different configurations? The question is important, since of the two types of nephron, only one has loops of Henle in the inner renal medulla, the region with the highest osmotic pressure. While a definitive answer is not yet available, several features are described which lay the basis for a speculative conclusion

Assessing High School Biology Academic Achievement by Comparing Traditional Versus Virtual Dissection of Rat Specimens

American\u27s lagging student performance on standardized assessments in critical subject areas such as science has in-part led to numerous educational reforms including No Child Left Behind and Race to the Top, resulting in an increased focus on student achievement. International and national government officials note the direct correlation between the value of science and driving the economic prosperity of a nation adding increased pressure to improve science scores in the United States. Local districts and schools struggle with how to improve student achievement in order to meet the requirements of state and federal educational reforms. The purpose of this mixed-methods study was to examine the learning effectiveness through the work of implementing rat dissection for comparison between the traditional hands-on method and the alternative virtual simulation. Student achievement was measured by pre-test, posttest assessments and a lab practicum, which measured students\u27 recall knowledge on rat anatomy. Students\u27 attitudes were measured by a post-dissection attitude survey. The sample consisted of 311 high school biology students from 20 classes taught by three instructors. The school had a student enrollment of approximately 2400 with a minority population of 70%. Prior to the activity, each teacher administered a pre-test assessment to the classes. Next, each teacher divided the classes in half. One group conducted the hands-on dissection activity on a rat, and the other group completed the Rat Dissection 1.1 virtual program activity. Each group then took a posttest assessment and completed the lab practicum. Subsequently, the groups switched and completed the opposite activity. Finally, a survey was administered. The data was examined using an independent samples t test and a MANOVA model. Results indicated that students who participated in the hands-on dissection activity made significantly larger gains on the post-test assessment, but not on the lab practicum. Student attitude was also analyzed by calculating frequencies of the survey questions. Results indicated a preference of two to one in favor of the hands-on dissection method