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Welcome back to A2 BIOLOGY!. F214 Here we come!. Remaining A2 course consists of:. F214 - Communication, Homeostasis and Energy – 1 hour 15 mins exam, 60 (90 ums) marks. F216 – Practical Skills – 40 (60 ums) marks. F214 – June exam – calendar to come.

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Welcome back to A2 BIOLOGY!


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    1. Welcome back to A2 BIOLOGY! F214 Here we come!

    2. Remaining A2 course consists of: • F214 - Communication, Homeostasis andEnergy – 1 hour 15 mins exam, 60 (90 ums) marks. • F216 – Practical Skills – 40 (60 ums) marks.

    3. F214 – June exam – calendar to come • Excretion – liver and kidneys – Quantitative Assessment • Photosynthesis – Qualitative Assessment • Need for Communication and Homeostasis • Hormones • Nerves • Respiration 12 weeks to cover it + practicals in

    4. AIMS • Define the term excretion. • Explain the importance of removing metabolic wastes from the body, including carbon dioxide and nitrogenous waste. • Describe the histology and gross structure of the liver. • Homework – Complete pages 6, 7, 9 + 10 in booklet for tomorrow.

    5. A2 Excretion – what is being excreted from these organs?

    6. Excretion is the removalof metabolicwaste from the body. • Metabolic wastes are by-products of normal cell processes. • Metabolic wastes are toxic if allowed to accumulate. • (2 or 3 marks) (See page 2)

    7. So, what is secretion? (p 2) • Release into the body of...? • These useful cell products are still produced by................ • Endocrine glands secrete.........? • Exocrine glands secrete............?

    8. Define the term excretion on your own paper – 2 marks. • Excretion= __________________________ ____________________________________ • Metabolic waste = __________________ ________________________________ • Now for the detail concerning carbon dioxide and nitrogenous waste – prepare for a market place on your assigned topic and then take your own notes when being taught by another student.

    9. (Either)Carbon dioxide…….Prepare for a market place! Flow chart the story of • how carbon dioxidetravels from • where it is produced, to • whereit is excreted from the body. • Include the detail of transport in the blood on page 37 A2 text book (or………..)

    10. Nitrogenous compounds……prepare for a market place! (p. 36/37) Flow chart the story of: • how excess amino acids are deaminated (keydefinition) in the liver, • how the toxic and soluble ammoniais converted to less soluble and less toxic urea, • how urea reaches the kidney, and • what happens to the remaining “ketoacid” (left over from the deamination of an amino acid). (or…………….)

    11. Why must these substances be removed?Prepare for a market place….. Produce a diagram which explains: • The 3 main effects of toxic carbon dioxide, • The symptoms of respiratory acidosis. • Why excess amino acids are deaminated rather than being excreted.

    12. Five minutes to go! Can you finish before the jar fills up with marbles?

    13. Time’s up!

    14. Time to move with in your groups of 3 pairs! • One person in each pair is the mover (A). • All the movers move to the next pair. • Now the person who has stayed still (B) teaches the incomer (A) the story and they take notes. • Next B moves to rejoin their partner (A) and is taught the new info and so on. • Four moves should do it!

    15. Toxic uric acid (another nitrogenous waste product) can cause Gout! • Creatinine is another nitrogenous waste product in urine.

    16. True or False? • Excretion is the removal of undigested food by the process of defecation. • Urea is produced in the liver from excess amino acids. • Deamination requires oxygen and produces a keto acid + carbon dioxide. • Urea is formed from ammonia + water. • Keto acids are respired or stored as fats or carbohydrates. • Excess carbon dioxide can cause respiratory acidosis.

    17. Blood proteins can act as buffers, soaking up hydrogen ions to prevent acidosis. • Blood pH below 7.35 results in tremor, confusion and fast breathing rate. • Carbaminohaemoglobin has a higher affinity for oxygen than haemoglobin. • Carbonic anhydrase produces carbonic acid which dissociates into hydrogen ions and hydrogen carbonate ions.

    18. AIM – to describe the histology and gross structure of the liver.

    19. Liver and its blood vessels and bile duct.

    20. Why are the hepatocytes of the liver supplied with blood from two sources? (See page 4)

    21. Histology of Liver Lobules – central = intra-lobular vein or branch of hepatic vein. See page 38 and booklet pages 4 + 5

    22. A 1 2 3 • 2 of these tissue types you should be able to recognise and label. The third is kidney. B C 4 5

    23. Can you add labels? B C A

    24. Liver Structure • http://www.siumed.edu/~dking2/erg/GI159b.htm • http://www.nottingham.ac.uk/nursing/sonet/rlos/bioproc/liveranatomy/4.html

    25. Section of lobule – can you see a label mistake?! Now make a 3D model INTRALOBULAR

    26. Describe the features which show this hepatocyteis a very active, absorbing cell. Homework Check!

    27. AIM – Investigate the liver as an organ of excretion and detoxification. • Check homework • Production of urea (ornithine cycle). • Production of bilirubin, excreted in bile. • Detoxification, especially of alcohol. • Histology and gross structure of Kidney – dissection. • Homework - Make revision notes or memory map on excretion and liver. • Complete pages 13, 14, 15, 16 and 17. • Test question on Wednesday.

    28. Up to 100,000 lobules each 1-2 mm in diameter. Check answers to questions on page 5 Complete the right hand column of the table, found on page 7. Describe the histology of the liver (homework check p 7)

    29. Küpffer cells open up old red blood cells to release h_______ for recycling. • The ____ ions are stored in the liver. The haem is broken into bilirubin + biliverdin for excretion into the _____ and then faeces.

    30. Functions of the Liver • http://www.nottingham.ac.uk/nursing/sonet/rlos/bioproc/liverphysiology/7.html • Protein Metabolism includes i) deamination and ii)urea production via the ornithine cycle (in cytosol and mitochondria) • See page 8 Excretion booklet and page 40 in the book.

    31. Production of Urea in the Liver. Quiz on white boards. • Define Deamination. • When and why are amino acids deaminated? • Name two raw materials needed for the Ornithine Cycle. • Name two products of the Ornithine Cycle. • Link the following key words into the correct equations: amino acid / ammonia / urea / keto acid / carbon dioxide / water / oxygen / ammonia amino acid + oxygen keto acid + ammonia ammonia + carbon dioxide urea + water

    32. Detoxification in the liver can be of internally or externally gained substances such as….. What is key definition?

    33. Toxins can be rendered harmless in the liver by… (page 11 – include hydrogen peroxide) • Oxidation - • Reduction - • Methylation - replacing an H with a CH3. • Combination with a harmless molecule.

    34. Drugs • http://www.youtube.com/watch?v=mEFPdNv2Ddk • (Drugs make you ugly) If alcohol was discovered today, it would be classified as a class A drug. http://www.youtube.com/watch?v=1a687tDtwyk Let’s check your quizzes page 9 + 10

    35. Detoxification of Alcohol • After our introduction (p11), using your text books, page 41, answer the questions on page 12 of your booklet.

    36. Kidney structure • Once you have labelled your diagrams, page 18, watch how to dissect a sheep’s kidney before carefully doing it yourself, (1 between 4!) identifying the regionsas you do so. • Now use a scalpel to scrape some tissue from the cortex region, smear it into a small drop of water on a slide, and add a cover slip. Can you see glomeruli and convoluted tubulesfrom the nephrons?

    37. Starter - Let’s check page 11, 12, 13, 14, 15, 16 and 17 before the 9 min test……..! 9 min test on excretion and liver structure and function. Question 4 page 55

    38. AIMS - Describe with the aid of diagrams and photographs, the detailed structure of a nephron and its associated blood vessels. • Describe and explain the production of urine, with reference to the processes of ultrafiltration and selective reabsorption. • Homework – page 39, question 2.

    39. Kidney Structure – page 18http://www.kscience.co.uk/animations/kidney.htm

    40. AIMS • Make class plasticine model of nephron and check labels page 19. • Ultrafiltration in the Bowman’s Capsule, page 20/21. • Selective reabsorption in the PCT.

    41. Proximal Convoluted Tubule Bowman’s Capsule Glomerulus Distal Convoluted Tubule What is different when you compare 2 and 3?

    42. Look how thick the PCT cells are.

    43. Glomerulus and Bowman’s Capsulehttp://www.kscience.co.uk/animations/kidney.htm Complete pages 20 -21

    44. Come and label this transverse section. A B

    45. What is this?! Where are you looking from?

    46. Who can show us where the capillaries are buried?

    47. Can you make out the capillaries here too?

    48. Reabsorption in the Proximal ConvolutedTubule. Group work – design a PCT cell. • Think of factors about a membrane which enables it to absorb substances efficiently. • Which types of transport are involved as substances move across the membrane? • Which organelles may be involved in some way with transport across membranes?

    49. Five minutes to go! Can you finish before the jar fills up with marbles?