Reading Assignment: POHS pp. 1038-1065
Self Quiz: 1, 3 - 8
Applying Concepts: None; Question 4 is down right scary as it suggests the pancreatic enzymes empty into the bile duct rather than the hepatopancreatic ampulla.
Additional thought questions:
1) Name and describe two mechanisms which prevent the gut tract from digesting itself.
All animals are heterotrophs derive energy and essential nutrients from other organisms nutritional requirements energy - molecules used to produce ATP (carbohydrates, lipids, amino acids) measured in Calories (= kilocalories) stored as glycogen (carbohydrate) - short term stored as fat - long term molecular building blocks - basic organic molecules (carbon skeletons) that cannot be synthesized; e.g., acetyl groups specific ones required vary between organisms used to construct other necessary compounds (e.g., fatty acids, steroid hormones, etc.) includes essential amino acids includes essential fatty acids specific biochemical functions mineral elements - Table 47.1 vitamins - Table 47.2 most function as coenzymes Adaptations for feeding wide variety of nutritional lifestyles detritivores predators herbivores carnivores omnivores feeding mechanisms filter feeding fluid feeding substrate feeding bulk feeding Digestion - the breakdown of food substances into simpler molecules 3 types of digestive systems intracellular pseudo gut - combination of intra-and extra-cellular true gut or tubular gut - digestion is extracellular Mechanisms of extracellular digestion acid digestion enzymatic digestion mechanical reduction fermentation - use of symbiotic microorganisms Overview of the vertebrate digestive system oral or buccal cavity alimentary canal generalized structure lumen mucosa submucosa muscular layer serosa (except in esophagus) accessory organs - liver, gall bladder, pancreas Movement of food through the digestive system swallowing or deglutition peristalsis Structure and function of the vertebrate digestive system oral cavity - mechanical and enzymatic digestion stomach - storage; mechanical, acid and enzymatic digestion small intestine - subdivisions duodenum - largely digestive enzymatic digestion (Table 47.3) - pancreas and small intestine bile - produced in liver, stored in gall bladder, secreted to duodenum; emulsifies fat ileum and jejunum - largely absorptive large intestine (colon) - site of water and ion absorption bacterial symbionts vermiform appendix Digestion of cellulose enzyme cellulase not present in vertebrate gut dependent upon symbiotic bacteria (fermentation) mammals: foregut and hindgut fermentors ruminant stomach Control and regulation of digestion Gut controlled by both nervous and endocrine systems Nervous system CNS - extrinsic enteric nervous system - intrinsic Endocrine system - hormones most are local (non-systemic), acting within digestive tract e.g., gastrin, cholecystokinin, secretin Control and regulation of fuel metabolism - skip in the interest of time Nutrient deficiency diseases Funk the concept of dietary diseases (not a new rock group) beriberi kwashiorkor scurvy pellegra rickets pernacious anemia goiter Toxic compounds in food hydrophilic vs lipophilic bioaccumulation synthetic toxins
Topics not covered in lecture for which you will be responsible:
undernourishment and overnourishment - p. 1041 malnutrition - 1041 zymogens - p. 1049 and Fig. 47.15 digestion and absorption of fat - p. 1055 and Fig. 47.16 VLDL, LDL and HDL - p. 1058