This lesson describes the structure of the mammalian liver, focusing on the blood vessels and bile canaliculi, as well as the hepatocytes. The PowerPoint and accompanying resources are part of the 1st lesson in a series of 2 lessons which cover point 5.1.2 (b) of the OCR A-level biology A specification. As shown on the cover image, the lesson begins with a challenge, where the students have to recognise that the liver is supplied with oxygenated blood by the hepatic artery. Three editions of the quiz “SAY WHAT YOU SEE” are used to introduce three key terms in an engaging and memorable fashion which are hepatic portal vein, sinusoids, and bile canaliculi. Following the introduction of the hepatic portal vein and sinusoids, the students will understand that the liver is supplied by two vessels and that the blood mixes in the sinusoids. Time is then taken to focus on the hepatocytes, through 3 exam-style questions that consider the type of epithelium these liver cells are found in, the microvilli on their surface and the organelles which are abundant based on function. Moving forwards, the lesson discusses the function of the stellate cells that are found in the space of Disse, before a task challenges their recall of content from a previous lesson to reveal the name of the cells that move within the sinusoids, the Kupffer cells. Students will learn that these macrophages breakdown the haemoglobin in old erythrocytes to form bilirubin. This reminds them that liver cells produce bile and the remainder of the lesson discusses how this fluid flows along the bile canaliculi to the ductules which form the common hepatic duct. The 2nd lesson in this 2-part series describes the functions of the mammalian liver.

This lesson describes how the loop of Henle acts as a countercurrent multiplier to increase the reabsorption of water. The PowerPoint and accompanying resource are part of the 2nd lesson in a series of 2 lessons which have been designed to cover point 9.9 (iii) of the Edexcel A-level biology B specification but also considers the structure of the kidney in the kangaroo rat and therefore also covers point 9.9 (v). The lesson begins by challenging the students to recognise that the glomerular filtrate entering the loop will only contain water, ions and urea if the kidneys are functioning properly. Time is then taken to look at the structure of the loop of Henle, focusing on the descending and ascending limbs, and their differing permeabilities. Students will be reminded that this part of the nephron is located in the renal medulla, before a step-by-step guide is used to describe how the transfer of ions, particularly sodium ions, from the ascending limb to the descending limb, creates a very negative water potential in this region of the kidney. This allows water to move out of the descending limb to the tissue fluid and then into the capillaries. The next part of the lesson challenges students to consider the bigger picture as they learn that this decreasing water potential in the medulla allows water to be reabsorbed from the filtrate in the collecting duct too. The remainder of the lesson uses the real-world examples of the hopping mouse and kangaroo rat to check student understanding, and there are also prior knowledge checks to encourage students to make links to relevant content from earlier topics. All answers are embedded into the PowerPoint.

This lesson describes the meaning of excretion, as well as the role of the liver, kidneys, lungs and the skin in the removal of carbon dioxide and urea. The engaging PowerPoint and accompanying resources have been designed to cover point 5.1.2 (a) of the OCR A-level Biology specification and also explains the importance of excretion for homeostasis. The lesson begins by reminding students that excretion is one of the 7 characteristics of living organisms, as introduced within MRS GREN when they were younger. An A-level worthy definition of excretion is then introduced, and time is taken to ensure that students recognise that substances must be products of metabolism to be deemed to be excreted. In line with this, the students are challenged to spot that urea and carbon dioxide need to be excreted whilst faeces is egested. Moving forwards, the role of the liver and then the kidneys in the excretion of urea are described. There is a focus on terminology, specifically prefixes and suffixes, to allow students to understand the meaning of deamination which occurs in the liver. The lesson doesn’t go into huge detail about this process and the subsequent ornithine cycle as these are both covered in an upcoming lesson about the functions of the liver. The transport of carbon dioxide is revisited and prior knowledge checks are used to allow the students to assess their recollection of hydrogen carbonate ions and carbaminohaemoglobin. All answers to these checks as well as any understanding checks are embedded into the PowerPoint. The final part of the lesson explores how the skin is involved in excretion and a link is made to the maintenance of internal conditions within narrow limits by homeostasis.