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Lecture 2

Biology 103 week 2 annotated notes

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BIOL 103
Virginia K Walker

Check  list  for  last  week’s  assignments:  you bought your lab pass and have your lab book  you attended three lectures  you  checked  out  the  location  of  the  walrus  for  Virginia’s  office  hours    your clicker is registered  you read selected sections of Chapters 39 if  you  didn’t  understand             the lectures  you reviewed the formation of peptide bonds from Biol 102  you did your assigned homework: (a) know the parts of the digestive system- Fig 39.5 and associated text (b) you read about ruminants, pg. 917 (c) you read about crops, the gizzard & stomach (pg 916-917) Absorption Absorption of the digested products, vitamins, minerals and water occurs in the small intestine. This is assisted by the huge surface area of the small intestine contributed by the villi (contains lacteals, and capillaries) and microvilli. Homework: please read about absorption pg. 918-919 Digestion in insects • Similar to digestion in vertebrates, but no pepsin Why? • A few interesting adaptations: salivary glands (discussed) active proteases eliminated with feces II. Excretion & Ion Transport General Reference: Chapter 46 (47) as well as some review of Biology 102 in Chapter 6 After digestion, individual amino acids are absorbed by cells lining the small intestine and then enter the blood. But what happens then? What do we need amino acids for? Can we store amino acids in the circulatory system, like insects or plants? Liver: deamination enzyme + + cofactor· H 3 + 2 O amino acid a form that can be stored and/or used for energy = deaminated amino acid or α-ketoglutaric acid Liver (urea cycle): NH +3CO 2 + H 2 deamination: + + cofactor· H 3 2 O ammonia = nitrogenous waste product in +ish & other aquatic organisms urea cycle: NH 3 CO 2 + H 2 If you have forgotten osmosis, please review Fig. 6.14 (6.12) for homework Saltwater fish (bony fish) – they are: • Hypotonic; in danger of dehydrating with water lost across the gills. • Therefore, they have to drink lots of water • Excreted ammonia is diluted with a minimum amount of water = concentrated urine • Excess salt is transported out of body by specialized cells in the gills Just  to  complete  the  story….Freshwater fish: • Are  in  danger  of  being  “water  logged”  (hypertonic) • Produce large amounts of dilute urine • Specialized gill epithelial cells transport Na and + Cl from  water  into  fish’s  capillaries  (concentrate   salts) Relative salt concentration in various animals and the ionic concentration (Cl ) of seawater sea water Relative ionic conc (mOsm/L) 0 fresh water gold fish amphibians sharks marine fish marine inverts Human disease: Liver cirrhosis caused by alcoholism, infectious disease (e.g. hepatitis) or fatty liver disease. It is one of the leading causes of death in the middle years in western countries. One consequence is that the damaged liver cannot efficiently carry out the urea cycle. In  birds,  reptiles  and  insects…. (again in the liver, or analogous organ or tissue) ~15 steps NH + CO 3 2 uric acid ( WHY is uric acid the nitrogenous waste of birds?) The anatomy of a bird egg. Uric acid is stored in the allantois and is left behind at hatchgn Guano: birds excrete uric acid and this is found in droppings with digestive waste. It was important in earlier years as a fertilizer Summary: (see Fig 46.2) (47.2) (or NH4) A number of interesting adaptations 1. Lungfish (Protopterus ) Dr. Kwong of National University of Singapore studies lungfish to try to understand their adaptation to high ammonia concentrations. He hopes to apply this work to human patients with liver failure. 2. Salmon Ocean Fresh water concentrated urine lots of dilute urine Salmon have to make to make these drastic changes twice in their lives. The gill epithelial cells are able to transport both Na and Cl against the concentration gradient (using ATP) 3. Eels The American eel is found in fresh and sea waters along the coasts and into Lake Ontario. (Fisheries and Oceans Canada, American Eel, Underwater World- Ontario Ministry of Natural Resources). To get rid of these nitrogenous wastes, organisms need excretory organs Three functions: 1. Filtration - acts like a filter to remove water and small solutes from body fluids or blood while leaving behind blood cells, proteins & other large solutes 2. Reabsorption – useful material in the filtrate recaptured and returned to blood 3. Secretion – may put additional solutes into the filtrate (can aid in the elimination of toxins) Fig. 46.6 (47.6) in Brooker et al. Vertebrates have a kidney containing specialized tubules with cells that actively transport ions for salt and water homeostasis and nitrogenous waste elimination. The rest of the urinary system consists of the ureters, urinary bladder and urethra Fig. 46.10 The nephron Functional unit of the kidney in higher vertebrates (several million nephrons in each kidney) Nephrons are composed of: 1. Capillary network in the renal corpuscle (Bowman’s  capsule  +   glomerulus). This forms filtrate 2. A long tubule that performs secretion and reabsorption. 3. A collecting duct that empties into the central cavity of the kidney Simplified version of Fig. 46.10(c) Homework: pg. 1082-1087 (1071-top of 1075). Please
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