Tutorials in Biomedical Sciences Biomedical Sciences Year 1 Year 2 Year 3 MT HT TT MT HT TT MT HT TT Prelim Course Part I Part II Body Preliminary Examination Part I Examination (20%) Part II Examination (80%) Brain CELL AND SYSTEMS BIOLOGY Behaviour Research project Cells 10 units of study: 19 options Molecules 3, 2 and 1 unit options Genes Chemistry NEUROSCIENCE Physics Mathematics and statistics Specialised options, with choices determining final degree 3 blocks, each comprising 3 threads, taken by all students Study tailored to students' interests subject Robert Wilkins robert.wilkins@dpag.ox.ac.uk Course Director, Biomedical Sciences Biomedical Sciences • a new 3-year course, replacing Physiological Focus of subject teaching Sciences and PPP (Physiology + Psychology) • lectures • seminars • more chemistry, physics and mathematics • classes • more molecular: integration of biological and • laboratory work molecular processes underlying modern Sets degree course contents biomedical science Provides academic facilities • focus on research: the experimental basis • lecture theatres • libraries for our current understanding • computing centre • two BA degree outcomes: Sets and marks exams Cell and Systems Biology OR Neuroscience Awards degrees
So what do colleges do? Preparing for a tutorial • students are set some work – an essay, a set of notes, a problem sheet • the work relates to material being covered at the time in lectures, practicals • the tutor provides some suggested reading • colleges admit undergraduates • each college houses 250-450 undergraduates • students use the lecture and the reading to • differ in location, age and size inform themselves about the subject • colleges provide accommodation, food, library and computer facilities and financial support • students complete the work • social hub: arts and sports • they are responsible for tutorial teaching What is a tutorial? Preparing for a tutorial It is • students should read all of the material • teaching provided by the college suggested by the tutor, and probably more • a weekly meeting between a tutor and one • they should make notes or two other students – summarising the key points • an opportunity to discuss a subject with – identifying common ground between the someone who is an expert in the topic lecture and the texts – highlighting the inconsistencies It is not • a lecture • an oral examination of knowledge
Reading What will happen? • the tutor will assume that students have • no two textbooks are the same prepared for the meeting and have a • some information will be common to all, but sound grasp of the basics of the subject – the emphasis will be different • without that basis, the tutorial will fail – in some books some information may not be • at the start they will typically be asked covered at all questions that check this and identify any • students need to identify what is really problems that they have encountered important and try to understand why other • this is the opportunity to clarify anything facts have been ignored in some books that they found confusing or contradictory At the tutorial Building on knowledge • the tutorial is not a question and answer • the tutor will then ask questions that build on session (rather than confirm) your knowledge • it is more like a debate, although students • these make stduents think about the 'big picture' don't need to be experienced in debating – HOW? • how was the information found out? • it relies on an exchange of ideas between – WHY? students and tutor • why do things work the way they do? • students need to be ready to present and – SO WHAT? defend their opinions, listen to others and • what is the significance of the information? accept constructive criticism – WHAT'S MISSING? • what don't we know/understand - and why?
Mechanism of acid secretion Gastric acid secretion • pH of lumen can be as low as 1 (10 6 - fold gradient) • intracellular carbonic anhydrase catalyses hydration of CO 2 to yield H + and HCO 3 - • H + ,K + -ATPase pumps H + ions into the lumen in exchange for K + • K + recycles out of the cell through apical K + channels • HCO 3 - exits across basolateral membrane to interstitial fluid, then blood, on Cl - -HCO 3 - exchange • Cl - ions diffuse through apical channels to join H + ions in the lumen. ATPase inhibited by omeprazole ('Losec') • water follows by osmosis. Net result: secretion of HCl, alkalinisation of blood ('alkaline tide') Parietal cells Regulation of ATPase insertion In an unstimulated cell, there are large numbers of tubulovesicles in the subapical cytoplasm Tubulovesicle insertion is initiated by Tubulovesicles contain H + ,K + ATPase. Stimulation of acid secretion triggers cytoskeletal rearrangement induced by tubulovesicle insertion kinase activation by: Stimulated parietal cells posses deep invaginations of apical membrane • ACh (neurocrine) from vagus: binds M 3 muscarinic receptors, triggers IP 3 cascade • gastrin (endocrine): released from G cells in response to stimulation of GRP- containing nerves by vagus or protein digestion products in lumen. Binds CCK B receptors, triggers IP 3 cascade ['Gastrinoma' in pancreas - Zollinger- Ellison syndrome] • histamine (paracrine): released from enterochromaffin-like cells. Binds H 2 H 2 receptors antagonised by ranitidine receptors, activates adenylyl cyclase ('Zantac') cascade
The basic understanding Lots of hormones exert effects through Ca 2+ • From the lecture and their own study, (a) Acetylcholine: salivary gland cells students would be expected to be able to answer some basic questions – what does the stomach do? – how is the structure of the stomach specialised to fulfill its functions? – what is the composition of gastric juice, and how can it vary? (b) Noradrenaline: liver cells – what is the mechanism by which the stomach secretes acid? – what regulates stomach secretion? – how can stomach secretion become excessive and what are the ways in which secretion can be reduced? – how does the stomach protect itself against damage from acid and (c) Histamine: endothelial cells from enzymes that digest proteins? Points to make them think Points to make them think • lots of hormones exert effects through Ca 2+ • lots of hormones exert effects through Ca 2+ • the ATPase doesn't work unless it is in the • the ATPase doesn't work unless it is in the luminal membrane luminal membrane • vagotomy is a really good way to stop acid • vagotomy is a really good way to stop acid secretion secretion • CO 2 hydration is at equilibrium • CO 2 hydration is at equilibrium
Vagotomy is a really good way to stop acid The ATPase doesn't work unless it is in secretion the luminal membrane • vesicle is arranged H + so that ATPase is ~ 'inside out' K + K + X • although ATP is freely available in the cytoplasm, K + cannot recycle • low K + availability within the vesicle 'brakes' the activity of the ATPase Points to make them think Points to make them think • lots of hormones exert effects through Ca 2+ • lots of hormones exert effects through Ca 2+ • the ATPase doesn't work unless it is in the • the ATPase doesn't work unless it is in the luminal membrane luminal membrane • vagotomy is a really good way to stop acid • vagotomy is a really good way to stop acid secretion secretion • CO 2 hydration is at equilibrium • CO 2 hydration is at equilibrium
Why interview? CO 2 hydration is at equilibrium • the interview is an 'audition for a tutorial place' • explore their interests and motivation for the subject • establish what insight they have about the subject and studying it at Oxford • examine how they think – how they handle information • how? why? so what? what’s missing/wrong? Misconceptions • there are trick questions • it's a test of knowledge • everyone gets the same questions • wrong answers are always a bad thing • you will know how it's gone • one bad interview and it's all over • it's an ordeal
Types of question 100 Human • 'warm-up' questions Cow 80 • questions based on your statement % lysis 60 – reading – projects 40 – experience – interests 20 • questions based on schoolwork 0 • current affairs 0 20 40 60 80 100120140160 [NaCl] (mM) • tutorial-style questions – passages to read/graphs to intepret 1.50 1.25 cell volume 1.00 Relative 0.75 0.50 0.25 0.00 0 1 2 3 4 5 6 7 8 9 10 1/[NaCl] (M)
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