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Animals Eat Food Chap 41 (nutrition). Overview: The Need to Feed Food is taken in, taken apart, and taken up in the process of animal nutritionFood is.

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Presentation on theme: "Animals Eat Food Chap 41 (nutrition). Overview: The Need to Feed Food is taken in, taken apart, and taken up in the process of animal nutritionFood is."— Presentation transcript:

1 Animals Eat Food Chap 41 (nutrition)

2 Overview: The Need to Feed Food is taken in, taken apart, and taken up in the process of animal nutritionFood is taken in, taken apart, and taken up in the process of animal nutrition In general, animals fall into three categories:In general, animals fall into three categories: Herbivores eat mainly autotrophs (plants and algae) Herbivores eat mainly autotrophs (plants and algae) Carnivores eat other animals Carnivores eat other animals Omnivores regularly consume animals as well as plants or algal matter Omnivores regularly consume animals as well as plants or algal matter

3 Fig. 41-1

4 Concept 41.1: An animals diet must supply chemical energy, organic molecules, and essential nutrients An animals diet provides chemical energy, which is converted into ATP and powers processes in the bodyAn animals diet provides chemical energy, which is converted into ATP and powers processes in the body Animals need a source of organic carbon and organic nitrogen in order to construct organic moleculesAnimals need a source of organic carbon and organic nitrogen in order to construct organic molecules Essential nutrients are required by cells and must be obtained from dietary sources Essential nutrients are required by cells and must be obtained from dietary sources

5 Essential Nutrients There are four classes of essential nutrients: There are four classes of essential nutrients: Essential amino acidsEssential amino acids Essential fatty acidsEssential fatty acids VitaminsVitamins MineralsMinerals

6 Fig Beans and other legumes Corn (maize) and other grains Lysine Essential amino acids for adults Tryptophan Isoleucine Leucine Phenylalanine Threonine Valine Methionine

7 Fig. 41-3

8 Vitamins Vitamins are organic molecules required in the diet in small amounts Vitamins are organic molecules required in the diet in small amounts 13 vitamins essential to humans have been identified13 vitamins essential to humans have been identified Vitamins are grouped into two categories: fat- soluble and water-solubleVitamins are grouped into two categories: fat- soluble and water-soluble

9 Table 41-1

10 Table 41-2

11 Undernourishment An undernourished individual willAn undernourished individual will Use up stored fat and carbohydratesUse up stored fat and carbohydrates Break down its own proteinsBreak down its own proteins Lose muscle massLose muscle mass Suffer protein deficiency of the brainSuffer protein deficiency of the brain Die or suffer irreversible damageDie or suffer irreversible damage Malnourishment can cause deformities, disease, and deathMalnourishment can cause deformities, disease, and death Malnourishment can be corrected by changes to a dietMalnourishment can be corrected by changes to a diet

12 Fig. 41-4

13 Suspension Feeders Many aquatic animals are suspension feeders, which sift small food particles from the waterMany aquatic animals are suspension feeders, which sift small food particles from the water

14 Fig. 41-6a Humpback whale, a suspension feeder Baleen

15 Substrate Feeders Substrate feeders are animals that live in or on their food source Substrate feeders are animals that live in or on their food source

16 Fig. 41-6b Leaf miner caterpillar, a substrate feeder Caterpillar Feces

17 Fluid Feeders Fluid feeders suck nutrient-rich fluid from a living host Fluid feeders suck nutrient-rich fluid from a living host

18 Fig. 41-6c Mosquito, a fluid feeder

19 Bulk Feeders Bulk feeders eat relatively large pieces of food Bulk feeders eat relatively large pieces of food

20 Fig. 41-6d Rock python, a bulk feeder

21 Digestion is the process of breaking food down into molecules small enough to absorb Digestion is the process of breaking food down into molecules small enough to absorb In chemical digestion, the process of enzymatic hydrolysis splits bonds in molecules with the addition of waterIn chemical digestion, the process of enzymatic hydrolysis splits bonds in molecules with the addition of water Absorption is uptake of nutrients by body cells Absorption is uptake of nutrients by body cells Elimination is the passage of undigested material out of the digestive compartment Elimination is the passage of undigested material out of the digestive compartment

22 Fig IngestionDigestion Absorption Elimination Undigested material Chemical digestion (enzymatic hydrolysis) Nutrient molecules enter body cells Small molecules Mechanical digestion Food Pieces of food

23 Digestion types In intracellular digestion, food particles are engulfed by endocytosis and digested within food vacuolesIn intracellular digestion, food particles are engulfed by endocytosis and digested within food vacuoles Extracellular digestion is the breakdown of food particles outside of cells Extracellular digestion is the breakdown of food particles outside of cells It occurs in compartments that are continuous with the outside of the animals bodyIt occurs in compartments that are continuous with the outside of the animals body

24 Fig Gastrovascular cavity Food Epidermis Mouth Tentacles Gastrodermis

25 Animals with simple body plans have a gastrovascular cavity that functions in both digestion and distribution of nutrientsAnimals with simple body plans have a gastrovascular cavity that functions in both digestion and distribution of nutrients More complex animals have a digestive tube with two openings, a mouth and an anusMore complex animals have a digestive tube with two openings, a mouth and an anus This digestive tube is called a complete digestive tract or an alimentary canalThis digestive tube is called a complete digestive tract or an alimentary canal It can have specialized regions that carry out digestion and absorption in a stepwise fashionIt can have specialized regions that carry out digestion and absorption in a stepwise fashion

26 Fig. 41-9a Esophagus Mouth Pharynx CropGizzard Typhlosole Intestine Lumen of intestine Anus (a) Earthworm

27 Fig. 41-9c (c) Bird Stomach Gizzard Intestine Esophagus Anus Crop Mouth

28 Concept 41.3: Organs specialized for sequential stages of food processing form the mammalian digestive system The mammalian digestive system consists of an alimentary canal and accessory glands that secrete digestive juices through ductsThe mammalian digestive system consists of an alimentary canal and accessory glands that secrete digestive juices through ducts Mammalian accessory glands are the salivary glands, the pancreas, the liver, and the gallbladderMammalian accessory glands are the salivary glands, the pancreas, the liver, and the gallbladder Food is pushed along by peristalsis, rhythmic contractions of muscles in the wall of the canalFood is pushed along by peristalsis, rhythmic contractions of muscles in the wall of the canal Valves called sphincters regulate the movement of material between compartmentsValves called sphincters regulate the movement of material between compartments

29 Fig a Cecum Anus Ascending portion of large intestine Gall- bladder Small intestine Large intestine Small intestine Rectum Pancreas Liver Salivary glands Tongue Oral cavity Pharynx Esophagus Sphincter Stomach Sphincter Duodenum of small intestine Appendix

30 Fig b Anus Liver Pancreas Small intestine Large intestine Rectum Stomach Gall- bladder A schematic diagram of the human digestive system Esophagus Salivary glands Mouth

31 The Oral Cavity, Pharynx, and Esophagus The first stage of digestion is mechanical and takes place in the oral cavityThe first stage of digestion is mechanical and takes place in the oral cavity Salivary glands deliver saliva to lubricate food Salivary glands deliver saliva to lubricate food Teeth chew food into smaller particles that are exposed to salivary amylase, initiating breakdown of glucose polymersTeeth chew food into smaller particles that are exposed to salivary amylase, initiating breakdown of glucose polymers

32 The tongue shapes food into a bolus and provides help with swallowingThe tongue shapes food into a bolus and provides help with swallowing The region we call our throat is the pharynx, a junction that opens to both the esophagus and the trachea (windpipe)The region we call our throat is the pharynx, a junction that opens to both the esophagus and the trachea (windpipe) The trachea leads to the lungsThe trachea leads to the lungs The esophagus conducts food from the pharynx down to the stomach by peristalsisThe esophagus conducts food from the pharynx down to the stomach by peristalsis Swallowing causes the epiglottis to block entry to the trachea, and the bolus is guided by the larynx, the upper part of the respiratory tractSwallowing causes the epiglottis to block entry to the trachea, and the bolus is guided by the larynx, the upper part of the respiratory tract Coughing occurs when the swallowing reflex fails and food or liquids reach the windpipeCoughing occurs when the swallowing reflex fails and food or liquids reach the windpipe

33 Fig Larynx Trachea Epiglottis up Pharynx Tongue Glottis Esophagus Esophageal sphincter contracted Food To stomach To lungs Epiglottis down Esophageal sphincter relaxed Glottis up and closed Epiglottis up Esophageal sphincter contracted Sphincter relaxed Relaxed muscles Contracted muscles Relaxed muscles Stomach Glottis down and open

34 Digestion in the Stomach The stomach stores food and secretes gastric juice, which converts a meal to acid chymeThe stomach stores food and secretes gastric juice, which converts a meal to acid chyme The esophagus conducts food from the pharynx down to the stomach by peristalsisThe esophagus conducts food from the pharynx down to the stomach by peristalsis Swallowing causes the epiglottis to block entry to the trachea, and the bolus is guided by the larynx, the upper part of the respiratory tractSwallowing causes the epiglottis to block entry to the trachea, and the bolus is guided by the larynx, the upper part of the respiratory tract Coughing occurs when the swallowing reflex fails and food or liquids reach the windpipeCoughing occurs when the swallowing reflex fails and food or liquids reach the windpipe

35 Fig Interior surface of stomach Esophagus Chief cells Small intestine Epithelium Stomach Sphincter Parietal cell Pepsinogen and HCl are secreted. HCl converts pepsinogen to pepsin. Pepsin activates more pepsinogen. Chief cell Folds of epithelial tissue Pepsin Sphincter Pepsinogen HCl H+H+ Cl – Parietal cells Mucus cells Gastric gland µm

36 Digestion in the Small Intestine The small intestine is the longest section of the alimentary canalThe small intestine is the longest section of the alimentary canal It is the major organ of digestion and absorptionIt is the major organ of digestion and absorption

37 Pancreatic Secretions The pancreas produces proteases trypsin and chymotrypsin, protein-digesting enzymes that are activated after entering the duodenumThe pancreas produces proteases trypsin and chymotrypsin, protein-digesting enzymes that are activated after entering the duodenum Its solution is alkaline and neutralizes the acidic chymeIts solution is alkaline and neutralizes the acidic chyme

38 Bile Production by the Liver In the small intestine, bile aids in digestion and absorption of fatsIn the small intestine, bile aids in digestion and absorption of fats Bile is made in the liver and stored in the gallbladderBile is made in the liver and stored in the gallbladder

39 Secretions of the Small Intestine The epithelial lining of the duodenum, called the brush border, produces several digestive enzymesThe epithelial lining of the duodenum, called the brush border, produces several digestive enzymes Enzymatic digestion is completed as peristalsis moves the chyme and digestive juices along the small intestineEnzymatic digestion is completed as peristalsis moves the chyme and digestive juices along the small intestine Most digestion occurs in the duodenum; the jejunum and ileum function mainly in absorption of nutrients and waterMost digestion occurs in the duodenum; the jejunum and ileum function mainly in absorption of nutrients and water

40 Absorption in the Small Intestine The small intestine has a huge surface area, due to villi and microvilli that are exposed to the intestinal lumenThe small intestine has a huge surface area, due to villi and microvilli that are exposed to the intestinal lumen The enormous microvillar surface greatly increases the rate of nutrient absorptionThe enormous microvillar surface greatly increases the rate of nutrient absorption

41 Fig Muscle layers Microvilli (brush border) at apical (lumenal) surface Vein carrying blood to hepatic portal vein Villi Intestinal wall Key Nutrient absorption Large circular folds Blood capillaries Epithelial cells Villi Lymph vessel Basal surface Lacteal Epithelial cells Lumen

42 Each villus contains a network of blood vessels and a small lymphatic vessel called a lactealEach villus contains a network of blood vessels and a small lymphatic vessel called a lacteal After glycerol and fatty acids are absorbed by epithelial cells, they are recombined into fats within these cellsAfter glycerol and fatty acids are absorbed by epithelial cells, they are recombined into fats within these cells These fats are mixed with cholesterol and coated with protein, forming molecules called chylomicrons, which are transported into lactealsThese fats are mixed with cholesterol and coated with protein, forming molecules called chylomicrons, which are transported into lacteals

43 Absorption in the Large Intestine The colon of the l arge intestine is connected to the small intestineThe colon of the l arge intestine is connected to the small intestine The cecum aids in the fermentation of plant material and connects where the small and large intestines meetThe cecum aids in the fermentation of plant material and connects where the small and large intestines meet The human cecum has an extension called the appendix, which plays a very minor role in immunityThe human cecum has an extension called the appendix, which plays a very minor role in immunity

44 Fig

45 A major function of the colon is to recover water that has entered the alimentary canalA major function of the colon is to recover water that has entered the alimentary canal Wastes of the digestive tract, the feces, become more solid as they move through the colonWastes of the digestive tract, the feces, become more solid as they move through the colon Feces pass through the rectum and exit via the anusFeces pass through the rectum and exit via the anus

46 The colon houses strains of the bacterium Escherichia coli, some of which produce vitaminsThe colon houses strains of the bacterium Escherichia coli, some of which produce vitamins Feces are stored in the rectum until they can be eliminatedFeces are stored in the rectum until they can be eliminated Two sphincters between the rectum and anus control bowel movementsTwo sphincters between the rectum and anus control bowel movements

47 Fig Incisors (c) Omnivore Molars (b) Herbivore (a) Carnivore Canines Premolars

48 Fig Cecum Small intestine HerbivoreCarnivore Colon (large intestine) Stomach Small intestine

49 Fig Esophagus Omasum Abomasum Intestine Rumen Reticulum

50 Overnourishment and Obesity Overnourishment causes obesity, which results from excessive intake of food energy with the excess stored as fat Overnourishment causes obesity, which results from excessive intake of food energy with the excess stored as fat Obesity contributes to diabetes (type 2), cancer of the colon and breasts, heart attacks, and strokesObesity contributes to diabetes (type 2), cancer of the colon and breasts, heart attacks, and strokes

51 Fig a Obese mouse with mutant ob gene (left) next to wild- type mouse. EXPERIMENT


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