Introduction to histology
This unit provides an introduction to histology, the study of tissues. It also describes how histology can aid in the diagnosis of disease and explains how histology services are organised within a hospital. First published on Tue, 26 Jun 2012 as Author(s):
4 Summary of video At the beginning of the video clip, Dr Simon Campbell pointed out that, in the development of any drug, there are a number of criteria that must be satisfied. There must be a clinical need – a medical condition or disease that requires effective treatment. Secondly, there has to be a commercial opportunity; because drug development is so expensive, pharmaceutical companies are less likely to invest resources in developing new therapeutic agents where there is already an adequate range of su
2 Video activity The video clip included in this section looks at the development of one particular drug. It examines the complex multidisciplinary process that was involved in its discovery. Before you watch the video, read through the Pre-viewing notes. 2.14 Summing up Dr. Peterson concludes the audio sequence with a summary of all the points covered. 2.9 Conflicting morphological characters This clip looks at conflicting morphological characters and at how it is possible to resolve them, with the aid of a table of molecular characters (Figure 9). Dr 2.5 What does relationship mean in systematics? W. Hennig In this clip, Dr. Patterson introduces his third systematist, a German entomologist named Willi Hennig. This offers a third meaning of ‘relationship’, which is illustr 2.4 What does relationship mean in systematics? E. Mayr Dr. Patterson looks at the second of his three systematists, Ernst Mayr. Mayr’s answer to the meaning of ‘relationship’ in systematics comes from the point of view o 2.3 What does relationship mean in systematics? G.G. Simpson Dr. Patterson continues to look at Simpson’s answer to the meaning of ‘relationship’ in systematics, and illustrates this by referring to a diagrams showing how the 2.2 Darwin, Linnaeus and Simpson In the first clip, Dr. Colin Patterson introduces and explains Darwin’s ‘tree of life’, image, shown below (Figure 3). This was the only image included in his book, 1.4 Grades and clades If species are grouped together because they show a similar extent of accumulated anagenetic change with respect to their ancestors, then the taxa so formed constitute grades. In Figure 1, morphological change is represented along the horizontal axis. The three columns show grades of anagenetic modification, with pa 1.3 Relationships between species Using the idea of blood relationships in people as an analogy, can you think of two distinct types of relationship between species? One is the relation 1.2 Taxa and relationships Until the mid-20th century, inferences about evolutionary relationships between species were generally based upon as wide a range of evidence as could be mustered. Evolutionary systematics is the name given to this eclectic approach, because of its explicit focus on evolutionary conclusions. The disparate nature of the evidence used (ranging from the taxonomic attributes and geographical distribution of living organisms to the stratigraphical distribution of fossils) meant that there w Learning outcomes By the end of this unit you should be able to: understand the patterns and processes of evolution above the species level appreciate the differences between the three methods of phylogenetic analysis: evolutionary systematics, phenetics, cladistics. Introduction This unit is from our archive. It is an adapted extract from the Science (S365) module that is no longer in presentation. If you wish to study formally at The Open University, you may wish to explore the courses we offer in this Curriculum Area This unit is concerned with macroevo 2.7 … and becoming more intelligent Intelligence is a useful commodity: it can help an animal to make sense of its environment and cope with the demands of social behaviour (including courtship and competition). Hunters tend to be relatively intelligent, and otters, pinnipeds and cetaceans, for example, share a playful curiosity that is characteristic of animals that catch other animals for a living. Some especially extravagant claims have been made for the intelligence of the toothed whales, largely because these animals use c 4.2 Ionic and covalent bonding We begin by applying simple bonding theories to molecular chlorine gas (Cl2) and non-molecular sodium chloride (NaCl), whose structures were discussed in Section 1. Figure 28 shows the result. 3.3.1 Writing out electronic configurations In Section 3.2, we described Figure 21 as an energy-level diagram, which represented the build-up of electronic configurations as electrons were inserted into sub-shells of progressively increasing energy. However, Figure 21 has been designed for just one purpose: to generate the correct electronic configurations in our tho 1.6 Binding forces in molecular and non-molecular substances – a first look As we shall see in Section 4, elementary bonding theories imply that materials as different as salt, iodine and aluminium are held together by different types of chemical bond. However, all binding forces between atoms are essentially electrical, and arise from a balance of forces acting between positively charged nuclei and negatively charg 3.4 Probability currents The expressions we have derived for reflection and transmission coefficients were based on the assumption that the intensity of a beam is the product of the speed of its particles and their linear number density. This assumption seems very natural from the viewpoint of classical physics, but we should always be wary about carrying over classical ideas into quantum physics. In this section we shall establish a general quantum-mechanical formula for the beam intensity. The formula will be consi 3.1 Overview Scattering calculations using wave packets are so laborious that they are generally done numerically, using a computer. However, in many cases, scattering phenomena can be adequately treated using a procedure based on stationary states. This approach can give valuable insight into the scattering process without the need for computer simulations. Session 3 introduces the stationary-state approach to scattering. The discussion is mainly confined to one dimension, so a stationary-state sol
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