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Roger lecturingAs a Cambridge Natural Sciences Tripos (NST) undergraduate, you will study three science subjects and a mathematics course in your first year (Part IA). Physiology of Organisms represents one of the science subjects that you can choose.

University teaching in NST IA Physiology of Organisms consists of three, one-hour lectures each week, on Tuesdays, Thursdays and Saturdays at noon. In the Michaelmas term, there is one practical class every two weeks, from 12-1PM and then from 2-5PM on either Wednesdays or Fridays (four practicals in total), while in the Lent term there is a practical class nearly every week (seven practicals). There is only one practical class in the Easter term. In addition, you would usually have a one-hour Physiology of Organisms supervision each week, organised by your College.

Michaelmas Term

The first term of the Physiology of Organisms course contains lectures given by the Department of Physiology, Development & Neuroscience (PDN). We begin with an overview of physiological ideas and problems, focusing initially on cells, transport processes and the concept of homeostasis. We then study neurobiology, giving an in-depth consideration to how electrical signals are carried around the body. We then examine general topics of animal physiology – how the basic organ systems work, and how they respond to environmental challenges. Although mammalian physiology is taught in most detail, this is a comparative physiology course and so we also consider some of the different strategies found in other animals, such as fish and insects. For example, we discuss different mechanisms of gas exchange for animals living in air and water, how the cardiovascular system works in different organisms and how osmoregulation in a freshwater fish might differ from that of a desert mammal.

Some students, reading this, might think that much of this is familiar, having been covered at school. While you may well have been introduced to these concepts, you will soon find that the approach we take in Cambridge is very different! This course will challenge you to reassess your understanding of physiology, and will open your eyes to whole new scientific worlds.

Lent Term

The first lectures of the second term remain focused on animal physiology, using some of the concepts developed earlier to look at metabolism and thermoregulation.

Most of the second term lectures, however, are given by the Department of Plant Sciences. They concern the physiology of vascular plants, in which we investigate how plants interact with the environment to obtain raw materials and how these are processed and distributed within the plant. Control of growth and development is a major contributor to the spread and survival of plants at all stages of the life cycle, and we explore the functional links between changes in the world outside and the physiological responses that enable plants to counter or exploit them. The diversity of plants, adapted to varying environments in different parts of the planet, is underpinned by an extraordinary range of physiological strategies, and we examine the interplay of anatomy, biochemistry and molecular mechanisms at the heart of a selection of representative types. Next, the physiology of micro-organisms is introduced. After the basic physiological strategies of bacterial and fungal growth are described, the course turns to a consideration of how such microbes might live on and inside plants. The mechanisms used by microbes to attack host plants and the defence responses of the host plant are then analysed. Finally the impact of infection on host plant physiology is assessed, as exemplified by the effects on crop yield and plant water relations.

Easter Term

The first set of lectures in the third term are given by the Department of Zoology. You will look at how the size of organisms profoundly affects features such as metabolic rate, structure and locomotion, and how these principles affect not just animals but plants too. The course ends with a return to neurobiology, focusing on sensory systems in different organisms. There is then a revision break before the exams.

Practical classes

To appreciate the subject of physiology to the full, you need to develop your practical skills and ability to undertake laboratory manipulations. Practical classes help you understand how biological systems operate and provide a sense of their complexity and unpredictability... and how 'facts' get created in the first place. You need to think for yourself - an ability which the memorization of lecture notes tends to destroy! Like the famous Cambridge scholar William Harvey, who discovered the mechanism of the circulation of the blood, you must think carefully about what you see in front of you, and compare what you observe yourself to what you have been told by others. This is what science is all about, and what our practical classes are for.

The practical classes are hosted and run by the Departments of Physiology, Development & Neuroscience (PDN), Plant Sciences and Zoology. They are designed to complement the lecture material, introduce you to experimental techniques and help you to think like a scientist!

In the PDN-based practicals of the first term, you will study the properties of membranes, measure action potentials, record muscle contractions and investigate the structure and function of organ systems. In the second term you will examine the activity of your own heart, discover how the body responds to exercise and devise your own experiments to assess how work-rate affects sweating. The Plant Sciences practicals, also in the second term, explore how leaves control water loss and gas exchange, how enzymes are regulated and how plants respond to viral infection. In the third term, you will explore oxygen uptake by aquatic organisms of different sizes within the Department of Zoology.

The examination

The examination in Physiology of Organisms takes usually place in early June. There are two papers, the first focusing on experimental practical analysis and the second a theory paper, which typically involves both essays and short-answer questions. Don't worry if you have only limited experience of essay-writing from school - your College supervisions over the course of the year will prepare you for this part of the exam! More information can be found on our Moodle website.