1. Chapter 41: Animal Nutrition Diane De Guzman Phoptorn Sutanaphaiboon

2. 41.1 An animal’s diet must supply chemical energy, organic molecules, and essential nutrients

3.  Nutrition is the process by which an organism takes in and uses its food for energy and building cells.  There are 3 types of dietary categories:  Carnivores  Herbivores  Omnivores

4. Essential Nutrients  Essential nutrients are material that animal cells need that cannot synthesize.  Animals need essential nutrients to make ATP for cell functions and perform biosynthesis.  Essential nutrients can be broken up into 4 classes:  Essential Amino acids  Essential Fatty acids  Vitamins  Minerals

5. Essential Amino Acids  Essential Amino acids are amino acids that must be obtained from food  Animals can synthesize most amino acids to make protein.  A diet that lacks a certain amount of essential amino acids can cause protein deficiency.  Protein deficiency is more common in children.  Found in foods such as meat, eggs, and cheese.  Also found in plant protein such as corn and legumes.

6. Essential Fatty Acids  Essential fatty acids are fatty acids that an animals need but cannot make. Most animals can make most of their fatty acids.  Can be found in food such as grain, seeds, and vegetables.  Deficiencies are very rare

7. Vitamins  Vitamins are organic molecules with diverse functions that are required in small amounts.  Humans need 13 essential vitamins to survive.  Vitamins are divided into two groups:  Water Soluble  Vitamin B, Vitamin C, Folic Acid,  Fat Soluble  Vitamin A, Vitamin D, Vitamin E  Too much fat soluble vitamins can be harmful because it increases toxic levels, however overdoses of water soluble vitamins because they leave the body in the urine.

9. Minerals  Minerals are inorganic nutrients that are required in small amounts.  Some examples of minerals include:  Calcium, Phosphorous, Potassium, Sodium, Iron, Iodine  Mineral intake varies between species.  Mineral overdose can cause homeostatic unbalance and toxic side effect.  For example, too much salt of sodium chloride can lead to high blood pressure.

10. Dietary Deficiencies  There are two types of deficiencies: Undernourishment and Malnourishment  Undernourishment  A diet that consistently supplies less chemical energy than required  Some examples include: anorexia and bulimia  Undernourishment can cause a variety of problems for the body that can be irreversible or even fatal  Malnourishment  The long term absence from a diet with essential nutrients  Can cause body problems such as deformities, disease or worse death.  Some examples include blindness from vitamin A deficiency

11. 41.2: The main stages of food processing are ingestion, digestion, absorption, and elimination Baleen SUSPENSION FEEDERS Feces SUBSTRATE FEEDERS BULK FEEDERS FLUID FEEDERS Caterpillar Animals feed using one of 4 main feeding mechanisms

12.  Food processing is divided into 4 stages:  Ingestion: the act of eating food whether solid or liquid  Digestion: the breaking down of food into small absorbable molecules; food molecules are broken down by enzymatic hydrolysis, where enzymes break the the molecular bonds of food by adding water.  Absorption: the absorbing of the broken down food molecules into the body for use  Elimination: The elimination of undigested waste from the body.

13. Digestive Compartments  Intracellular Digestion  The hydrolysis of food inside food vacuoles after phagocytosis or pinocytosis.  Food vacuoles fuse with lysosomes so that they can break down food safely in a cell  Few animals such as sponges do this  Extracellular Digestion  The breakdown of food in compartments continuous with the outside of the body  Relies on a gastrovascular cavity, that functions in digestion and distribution of nutrients in animals such as cnidarians(jellies) and flatworms  Most animals use a complete digestive tract/alimentary canal to digest and absorb food.  Animals have a mouth & anus; they can also eat more food while previously eaten food are digested.

14. 41.3: Organs specialized for sequential stages of food processing form the mammalian digestive system  The Human digestive system has the alimentary canal and various glands, such as the saliva glands, pancreas, liver and gallbladder.  Food is pushed down by peristalsis, the automatic contractions of smooth muscles in the alimentary canal  Sphincters are ring like valves that regulate the passage of food through the canal

15. The Oral Cavity, Pharynx and Esophagus  Food enters the alimentary canal through the oral cavity/mouth  Food is then grinded up by the teeth and saliva from salivary glands moisten the food  Amylase, an enzyme in saliva, breaks down sugars into smaller sugars  Bolus(chewed up food) is then sent to the pharynx, where it is sent down the esophagus  The epiglottis closes the path to the trachea when eating so to avoid choking.

16. Digestion in the Stomach  The bolus is then sent down to the stomach by peristalsis, the automatic contractions of smooth muscles  The stomach secretes gastric juices that mixes with the food to make chyme  Protien in the bolus is then digested in the stomach by protease such as pepsin.  The stomach secretes mucus to protect its lining from its own acidic juices.

17. Digestion in the Small Intestine  The first section of the small intestine is known as the duodenum.  The duodenum is the major site of the chemical digestion.  In the duodenum, acid chyme mixes with secretions from the pancreas and the liver. Pancreatic Secretions:  The pancreas releases a bicarbonate fluid, which acts as a buffer against acidic contents from the stomach. Bile Production by the Liver:  Bile is made in the liver and stored in the gall bladder. Bile emulsifies fats; that is, bile coats fat droplets turning large fat droplets into small fat droplets, which are easier to digest.

18. Chemical Digestion in the Duodenum can be summarized as follows:  Carbohydrates: The breakdown of starch and glycogen began with salivary amylase in the mouth. In the small intestine, pancreatic amylases break starch, glycogen, and small polysaccharides into the disaccharide maltose. The breakdown of maltose and other disaccharides into their monomers occur at the wall of the duodenal epithelium.  Proteins: Pepsin begins the breakdown of proteins in the stomach. In the duodenum, trypsin, and chymotrypsin break down polypeptides into smaller chains. Dipeptidases, carboxypeptidase and aminopeptidase break apart polypeptides into amino acids.

19.  Nucleic Acids: The breakdown of nucleic acids starts with the hydrolysis of DNA and RNA to their respective nucleotides. The nucleotides are then broken down to nitrogenous bases, sugars, and phosphate groups. Most of the enzymes responsible for nucleic acid digestion enter the duodenum from the pancreas.  Fats: Digestion of fats starts in the small intestine. Bile coats the fat droplets and keeps them from clumping. The enzyme lipase, which is produced in the pancreas, hydrolyzes the small fat droplets.

20.  The epithelial lining of the small intestine has folds called villi, which in turn bear projections called microvilli- both of which radically increase the surface area available for absorption.  In each villus are capillaries for the absorption of monomers and a lymph vessel (lacteal), which absorbs small fatty acids. Passive – facilitated diffusion and active transport are used to move monomers across the intestinal membrane and into blood vessels.  The capillaries and veins that drain the nutrients away form the villi form the hepatic portal vessel, a blood vessel that goes to the liver.  Hormones are chemical messengers that travel to target tissues through the blood stream. Hormones help to coordinate the digestive process: Gastrin, Enterogastrone, Secretin and cholecystokinin (CCK).

21.  The large intestine (colon), is connected to the small intestine by a sphincter. The point of connection is the site of the cecum, a small pouch with an extension called the appendix.  The main functions of the large intestine are to compact waste and recover water. The large intestine includes a rich flora of mostly harmless bacteria, including Escherichia coli. The presence of E. coli in lakes and streams is a useful indicator of contamination by untreated sewage.  At the end of the colon is the rectum, where feces are stored until they are eliminated.

22. 41.4 Some Dental Applications  Dentition is an animal’s assortment of teeth.  A mammal’s dentition is generally correlated with its diet.  Mammals have specialized dentition that best enables them to ingest their food.  Herbivores generally have longer alimentary canals than carnivores, reflecting the longer time needed to digest vegetation.  Diet: cellulose of plant cell walls.  Many vertebrates house large populations of symbiotic bacteria and protists whose enzymes actually digest the cellulose. (a) Carnivore (b) Herbivore (c) Omnivore Incisors Canines Premolars Molars

23. 41.5 Homeostatic mechanisms contribute to an animal’s energy balance  Food balances the expenditure of energy for metabolism and activity, and storage. Energy Sources and Stores  Nearly all of an animal’s ATP generation is based on the oxidation of energy rich organic molecules: carbohydrates, proteins, and fats  Animals store excess calories primarily as glycogen in the liver and muscles.  Energy is secondarily stored as adipose  When fewer calories are taken in than are expended, fuel is taken from storage and oxidized.

25. Overnourishment and Obesity  Overnourishment causes obesity, which results from excessive intake of food energy with the excess stored as fat  Obesity contributes to Type 2 diabetes, cancer of the colon and breasts, heart attacks, and strokes.  Researchers have discovered the several of the mechanisms that help regulate body weight.  Homeostatic mechanisms are feedback circuits that control the body’s storage and metabolism of fat over the long term.  Hormones regulate the long-term and short- term appetite by affecting a “satiety center” in the brain.  The complexity of weight control in humans is evident from studies of the hormone leptin.

26. Mice that inherit a defect in the gene for leptin become very obese.

27. Obesity and Evolution  The problem of maintaining weight partly stems from our evolutionary past, when fat hoarding was a means of survival.  A species of birds called petrels become obese as chicks, in order to consume enough protein from high- fat food, chicks need to consume more calories than they burn.