pptx, 2.46 MB
pptx, 2.46 MB
docx, 15.99 KB
docx, 15.99 KB
docx, 14 KB
docx, 14 KB

This lesson describes the importance of homeostasis using negative feedback control and also describes the meaning of positive feedback. The PowerPoint and accompanying resources have been designed to the content with point 9.1 of the Edexcel A-level Biology B specification and explains how this feedback control maintains systems within narrow limits but has also been planned to provide important details for upcoming topics such as osmoregulation, thermoregulation and the depolarisation of a neurone.

The normal ranges for blood glucose concentration, blood pH and body temperature are introduced at the start of the lesson to allow students to recognise that these aspects have to be maintained within narrow limits. A series of exam-style questions then challenge their recall of knowledge from topics 1-8 to explain why it’s important that each of these aspects is maintained within these limits. The students were introduced to homeostasis at GCSE, so this process is revisited and discussed, to ensure that students are able to recall that this is the maintenance of a state of dynamic equilibrium. A quick quiz competition is used to reveal negative feedback as a key term and students will learn how this form of control reverses the original change and biological examples are used to emphasise the importance of this system for restoring levels to the limits (and the optimum). The remainder of the lesson explains how positive feedback differs from negative feedback as it increases the original change and the role of oxytocin in birth and the movement of sodium ions into a neurone are used to exemplify the action of this control system.

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Topic 9: Control systems (Edexcel A-level Biology B)

This bundle contains 19 lessons which are engaging and highly detailed in order to cover the difficult content as set out in topic 9 (Control systems) of the Edexcel A-level Biology B specification. The lesson PowerPoints and accompanying resources contain a wide variety of tasks which cover the following specification points: * Homeostasis is the maintenance of a state of dynamic equilibrium * The importance of maintaining pH, temperature and water potential in the body * The meaning of negative feedback and positive feedback control * The principles of hormone production by endocrine glands * The two main modes of action in hormones * The organisation of the mammalian nervous system into the CNS and PNS * The structure of the spinal cord * The location and functions of the main parts of the brain * The division of the autonomic nervous system into the sympathetic and parasympathetic systems * The transport of sodium and potassium ions in a resting potential * The formation of an action potential and the propagation along an axon * Saltatory conduction * The function of synapses * The formation and effects of excitatory and inhibitory postsynaptic potentials * The structure of the human retina * The role of rhodopsin * The distribution of rods and cone cells * The control of heart rate by the autonomic nervous system * The gross and microscopic structure of the kidney * The production of urea in the liver and its removal from the blood by ultrafiltration * Selective reabsorption in the proximal tubule * Water reabsorption in the loop of Henle * Control of mammalian plasma concentration * The differences between ectotherms and endotherms * The regulation of temperature by endotherms If you would like to sample the quality of this lesson bundle, then download the homeostasis, mammalian nervous system, resting and action potentials and the formation of urea and ultrafiltration lessons as these have been uploaded for free.

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