BY Shelbi Megan Bonnie and Shivali Diversity among

BY: Shelbi, Megan, Bonnie, and Shivali

Diversity among Animals • Main Types: • • • Suspension feeders ex: Baleen Whales Substrate feeders ex: Caterpillars Fluid feeders ex: Mosquitoes Bulk feeders ex: Constrictors Their digestive systems are modified according to their food source.

Blood Glucose Fluctuation • When food is digested the blood glucose level rises causing the pancreas to secrete insulin into bloodstream • Insulin facilitates absorption of glucose into body cells, thus as it is stored as glycogen the blood glucose level drops • Pancreas then secretes glucagon, which opposes the effect of insulin, glucagon then promotes breakdown of glycogen within the cells and the release of glucose into the blood increasing the blood glucose level. • This system allows individuals to pull from the glycogen stores if food becomes scarce.

Appetite Regulation • Leptin: produced by fat tissue, appetite suppressant • Ghrelin: secreted by stomach wall, triggers feelings of hunger • Insulin: secreted by pancreas upon rise in blood sugar, can suppress appetite • PYY: secreted by small intestine, appetite repressor • Proper balance of these can keep people at a stable weight

Essentials • Lacking in any of the eight essential amino acids results in malnutrition • Methionine, Valine, Threonine, Phenylalanine, Leucrine, Isoleucine, Tryptophan, Lysine • There also essential vitamins, and fatty acids (those with double bonds)

Organs of Digestion

Swallowing Reflex

The Stomach • Contains gastric juice: mixture of hydrochloric acid (from Parietal glands), mucus (mucus cells), and pepsinogen (from chief cells) • Stores food and performs preliminary steps of digestion • Smooth muscle churns contents every 20 seconds, results in acid chyme

Small Intestine • reaches up to 21 ft when stretched out - small in diameter when compared to the large intestine • The longest section of the alimentary canal (digestive tract) • Location where of most of the enzymatic hydrolysis of food macromolecules and most of the absorption of nutrients into the blood occur.

Composed of three sections q duodenum- enzymatic action jejunum- finalizes the food digestion process, absorbs nutrients and water q q ileum- absorbs nutrients and water

Duodenum: Enzymatic Action • Where acid chyme mixes with digestive fluids from other organs • Bicarbonate from the alkaline solution produced by the pancreas acts as a buffer, offsetting the acidity of the chyme • Pancreatic proteases (protein-digesting enzymes) are activated once they are located in the duodenum’s extracellular space.

Bile • Mixture of substances that is stored in the gallbladder which then releases the bile into the duodenum as needed • Produced by the liver • Bile salts -act as detergents to aid in the digestion and absorption of fats

Enzymatic Digestion • Brush border- epithelial lining -Contains digestive enzymes • Enzymatic digestion is completed as the mixture of chyme and digestive fluids is transported along the small intestine. • The jejunum and ileum sections of the small intestine function mainly in the absorption of nutrients and water.

Types of Digestion Carbohydrate digestion-Polysaccharides and disaccharides to monosaccharides • Protein digestion-Proteins to amino acids • Nucleic acid digestion-DNA, RNA to nitrogenous bases, sugars, and phosphates • Fat digestion -Fat globules to glycerol, fatty acids, and glycerides

Absorption of Nutrients • Large folds in the lining of the small intestine • Villi- fingerlike projections -Increase surface area of the lining to increase nutrient absorption • Microvilli-Cover the villi, increasing the surface area even more • Capillaries penetrate the core of each villus • Nutrients are absorbed across the intestinal epithelium and unicellular epithelium to capillaries or lacteals -Lacteal- small vessel of the lymphatic system -Make up the second layer of epithelial cells that separate nutrients in the lumen from the blood stream. • The surface area of the villi and microvilli is about the same as the area of a tennis court.

Small Intestine Structure

Large Intestine • Colon • Connected to the small intestine in the form of a T • The cecum (one arm of the T) contains the appendix, a useless appendage.

Role of the Colon: • To recover water that has entered the alimentary canal as the solvent of the various digestive fluids. • Reclaims much of the 7 L of water secreted into the lumen each day that was not absorbed by the small intestine. • Feces- wastes of the digestive tract -as they are moved slowly down the colon, they become more solid • Bacteria live in the colon, such as Escherichia coli (E coli). -intestinal bacteria live on unabsorbed organic material -bacteria produce gases and vitamins • Rectum- the terminal portion of the colon • Between the rectum and the anus are two sphincters, one voluntary and one involuntary. • Elimination of digestive waste is caused by contractions of the colon

Dental Adaptations • Dentition reflects the diet of an animal • Nonmammalian vertebrates have less specialized dentition -Poisonous snakes have fangs to inject their prey with venom -Snakes swallow their prey whole • Further adaptations exist for: -Carnivores §Cats (meat) -Herbivores §Horses (vegetation) -Omnivores §Humans (vegetation and meat)

• Carnivores: -pointed incisors and canines to kill prey and cut flesh -jagged premolars and molars crush and shred food • Herbivores: -teeth with broad, rigid surfaces that grind tough plant material -incisors and canines are modified for biting off vegetation • Omnivores: -32 permanent teeth -beginning at the middle line of the upper and lower jaw are: 2 incisors for biting 1 pointed canine for tearing 2 premolars for grinding 3 molars for crushing.

Stomach and Intestinal Adaptations • Length of vertebrate digestive system is correlated with its diet • Herbivores and omnivores: -longer alimentary canals relative to their body size • vegetation is harder to digest because of the cell walls • a longer tract allows more time for digestion and more surface area for nutrients to absorb • Carnivores: -large, expandable stomachs

Symbiotic Adaptations: • animals don’t produce enzymes that hydrolyze cellulose • vertebrates house symbiotic bacteria and protists in fermentation chambers in their alimentary canals • the bacteria have enzymes that can digest cellulose • The cellulose in converted into simple sugars, as well as vitamins and amino acids • depending on the animal, the symbiotic microbes may vary in their location within the digestive tract • thus most nutrients made by bacteria in the large intestine are never absorbed • Some rodents recover these nutrients by eating some of their feces and passing the food through their system twice.

Ruminants: • An animal with an elaborate, multicompartmentalized stomach specialized for a herbivorous diet. • Stomach has four chambers • The diet a ruminant absorbs is much richer than the grass the animal originally ate. -rumen- where the food goes when the cow first chews and swallows -reticulum- the cow periodically regurgitates and rechews the “cud” -omasum- the cow reswallows the cud, and water is absorbed -abomasum- the cud passes here for digestion by the cow’s own enzymes.