Digestive System Notes
Digestive System Notes BIOL 241
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This 3 page Class Notes was uploaded by Wilson on Thursday October 29, 2015. The Class Notes belongs to BIOL 241 at Indiana University of Pennsylvania taught by Dr. Duchamp in Fall 2015. Since its upload, it has received 40 views. For similar materials see Comparative Vertebrate Anatomy in Biology at Indiana University of Pennsylvania.
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Date Created: 10/29/15
1 What does the digestive system do Breakdown food a Mechanical moving food around Chemical break down proteins can come from organs or outside glands b Absorption of nutrients Excretion 2 How is the mechanical breakdown of food enhanced in archosaurs birds crocs Proventriculus C a Glandular stomach Produces gastric juice The chemicals and food swallowed flows into the gizzard which is muscular There is an extreme physical digestion going on here Keep in mind that mammals are the only animals that chew food before they swallow many animals have physical means of breaking down food inside of themselves 3 The small intestine This part of the digestive system is not meant for physically breaking down food Location and appearance 4 a b Liver a C Posterior to the stomach up to 23 sections 1 Duodenum a Neutralizes acids from the stomach b First part of the stomach c Receives secretions from liver and pancreas 2 Jejunumileum a These are sometimes b distinct regions sometimes not Functions 1 Absorption of nutrients columnar epithelium cells a Increased surface area mucosa b Folds that add surface area i Villi ii Line circular folds iii Microvilli located on the end of columnar cells iv These are all ways to increase surface area Develops from the endoderm b Functions I ii iii iv Produces bile to emulsify fat breaks fat into droplets so that there is more surface area for chemical reactions Stores nutrients Processes proteins carbohydrates and fat Detoxifies nitrogenous waste Connections to the blood circulatory system Hepatic artery 1 Deliver oxygenated blood to the liver ii Hepatic portal 1 Delivers deoxygenated blood from the lower digestive tract and associated organs 2 Both oxygenated and deoxygenated blood enters the liver iii Hepatic veins 1 Deliver blood from the liver to the venous system 5 Gall Bladder a b C Location i Middle of the liver ii Absent in cyclostomes and most birds Functions i Stores and concentrates bile Bile ducts i Connect the liver to the gall bladder 2 way flow ii Concentrated flow goes out of the gall bladder down the main bile duct iii Connect both to duodenum 6 Pancreas a Derived from the endoderm glands are made up of epithelial cells b Pancreatic juice C i Help neutralize acids raise pH ii Has protease amylase and lipase iii Empties into the duodenum Function of pancreatic islets i Help process sugar ii Secretes hormones into blood iii Regulate blood sugar levels d Mixed gland e i Because there is an exocrine function 1 Secrete things into the digestive tract ii Endocrine function 1 Secretes hormones into blood Typically this is near the junction between the stomach and small intestine 7 Large Intestine in some vertebrates a DP95quot Absorption of water is the main function When did this evolve as a distinct region of gitract This evolved whenever vertebrates moved from water to land Long distinct section appears in tetrapods Functions i Water and electrolyte reabsorption humans have about 5L of secretions into the digestive tract a day this is reabsorbed in the large intestine ii Formation of the fecal bolus iii Simple columnar epithelium iv What is the role of goblet cells look like white dots in between cells 1 Secrete mucus in order to keep the fecal bolus moving 8 What can vertebrate herbivores digest Why is herbivory rare a Plant digestion is difficult because of digesting cellulose we do not have the right kind of amalase to do this Microbial fermentation i Required for digestion ii Bacteria produce cellulose iii There needs to be a chamber for microbial fermentation there needs to be a lot of space Hindgut fermentation i Back end of the gut the large intestine is where the fermentation process occurs such as in horses and rhinoceros ii Soluble nutrients absorbed prior to fermentation iii Works well if there is plenty of nutrient rich food iv Larger chambers extract more Foregut fermentation i Large chambered stomachs such as in cows ii Less overall nutrients extracted iii Faster digestion iv Low nutrient portions excreted v Larger chambers equal more complete nutrient extraction Which birds use hindgut fermentation i Large bodied birds such as the flightless birds ii Enlarged ceca serve as fermentation sites Which mammals use foregut fermentation i Moose buffalo ii 34 chambered stomach iii More efficient but slower digestion iv Detoxify plants prior to absorption v Can eat more nutrient poor plants and still be okay vi Soluble nutrients are lost during fermentation vii How are these nutrients recovered 1 When it goes into the reticulum it can also go to the abomasum which is where it recovers 2 They also swallow bits of bacteria to recover this as well 3 Know the order of the digestive system of the cow it s reverse alphabetical order
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