1. Digestion

3. Stages of Food Processing Ingestion – the act of taking in food Ingestion – the act of taking in food Digestion – the process of breaking food down into molecules small enough for the body to absorb Digestion – the process of breaking food down into molecules small enough for the body to absorb –Enzymatic hydrolysis process in digestion in which macromolecules are split from food by the enzymatic addition of water Absorption – an animal’s cells take up small molecules such as amino acids and simple sugars from the digestive compartment Absorption – an animal’s cells take up small molecules such as amino acids and simple sugars from the digestive compartment Elimination – undigested material passes out of the digestive compartment Elimination – undigested material passes out of the digestive compartment

4. Digestion Types How do you digest food without digesting yourself? How do you digest food without digesting yourself? Intracellular digestion – digestion within food vacuoles (membrane bound organelles) Intracellular digestion – digestion within food vacuoles (membrane bound organelles) A cell engulfs food by phagocytosis or pinocytosis A cell engulfs food by phagocytosis or pinocytosis Newly formed food vacuoles fuse with lysosomes containing enzymes Newly formed food vacuoles fuse with lysosomes containing enzymes Examples include sponges Examples include sponges

5. Digestion Types Cont. Extracellular digestion – within compartments that are continuous with outside of animal’s body Extracellular digestion – within compartments that are continuous with outside of animal’s body Allows for consumption of larger prey Allows for consumption of larger prey Many animals with simple body plans have a digestive sac with a single opening (gastrovascular cavity) Many animals with simple body plans have a digestive sac with a single opening (gastrovascular cavity) Functions in both digestion and distribution of nutrients Functions in both digestion and distribution of nutrients –Ex. hydras

6. More Complex Extracellular Digestion Most animals have a digestive tube extending between two openings (mouth and anus) (called a complete digestive tract or alimentary canal) Most animals have a digestive tube extending between two openings (mouth and anus) (called a complete digestive tract or alimentary canal) b/c food moves in single direction, tube can be organized into specialized sections b/c food moves in single direction, tube can be organized into specialized sections Another advantage is that it allows for the ingestion of additional food before earlier meals being completely digested Another advantage is that it allows for the ingestion of additional food before earlier meals being completely digested

7. Mammalian Digestion Food travels along the digestive tract by peristalsis (contraction of smooth muscles) Food travels along the digestive tract by peristalsis (contraction of smooth muscles) At some points the muscular layer is modified into ring-like valves which regulate the passage of material between chambers of the tract (sphincters) At some points the muscular layer is modified into ring-like valves which regulate the passage of material between chambers of the tract (sphincters)

8. In Your Mouth Oral Cavity – uhhh yeah.....its the mouth Oral Cavity – uhhh yeah.....its the mouth Saliva contains salivary amylase that hydrolyzes starch and glycogen Saliva contains salivary amylase that hydrolyzes starch and glycogen Chewed food is molded into a ball by your tongue (bolus) and pushed to the back of your throat Chewed food is molded into a ball by your tongue (bolus) and pushed to the back of your throat Epiglottis (flap of cartilage) Epiglottis (flap of cartilage) –up during breathing –down during eating Pharynx – junction leading to lungs or stomach video

9. Stomach Stomach breaks down proteins with the enzyme pepsin. It works to break the peptide bonds of amino acids. Stomach breaks down proteins with the enzyme pepsin. It works to break the peptide bonds of amino acids. Afterwards the chyme flows to the duodenum Afterwards the chyme flows to the duodenum

10. Stomach In order to prevent self-digestion.... In order to prevent self-digestion.... One, pepsin is secreted in an inactive form (pepsinogen) which doesn’t activate until it comes in contact with hydrochloric acid One, pepsin is secreted in an inactive form (pepsinogen) which doesn’t activate until it comes in contact with hydrochloric acid HCl is released when food is present HCl is released when food is present Two, there is a layer of mucus covering the stomach. It is eroded and replaced constantly Two, there is a layer of mucus covering the stomach. It is eroded and replaced constantly

11. More Stomach Acid chyme – name for the nutrient-rich broth that leaves the stomach Acid chyme – name for the nutrient-rich broth that leaves the stomach The acid chyme leaves the stomach through an opening known as the pyloric sphincter The acid chyme leaves the stomach through an opening known as the pyloric sphincter It takes about 2-6hrs for a meal to leave the stomach It takes about 2-6hrs for a meal to leave the stomach

12. Liver Used for Used for –detoxification –protein synthesis –production of biochemicals necessary for digestion –Produces bile which performs the emulsification of fats (cleaving the C-C bonds within a fatty acid chain, breaks down globs of fat).

13. Gallbladder a small non-vital organ that sits beneath the liver a small non-vital organ that sits beneath the liver Stores the bile produced in the liver Stores the bile produced in the liver Bile becomes more concentrated Bile becomes more concentrated

14. Pancreas a gland organ in the digestive and endocrine system. a gland organ in the digestive and endocrine system. It produces several important hormones, including insulin It produces several important hormones, including insulin secretes pancreatic juice containing digestive enzymes (including bicarbonate which neutralizes the chyme) secretes pancreatic juice containing digestive enzymes (including bicarbonate which neutralizes the chyme) these enzymes help in breakdown of the carbohydrates, protein, and fat in the chyme. these enzymes help in breakdown of the carbohydrates, protein, and fat in the chyme.

15. Within the Small Intestine –peptidases and trypsin digest proteins into smaller proteins –dipeptidases digest small proteins into single amino acids –nucleases digest DNA. –lipases finishes lipid digestion (breaks fatty acid chains from glycerol) –amylases & disaccharidases- digests carbohydrates

16. Duodenum the first section (25cm) of the small intestine the first section (25cm) of the small intestine Most of the actual digestion is done here Most of the actual digestion is done here “Stuff” from the stomach, gallbladder, and pancreas all find their way here “Stuff” from the stomach, gallbladder, and pancreas all find their way here Other “stuff” found here includes maltase, lactase and sucrase Other “stuff” found here includes maltase, lactase and sucrase So....we end up with bile, chyme, and various digestive enzymes present So....we end up with bile, chyme, and various digestive enzymes present

17. Absorption Now that all the food is digested the small intestine absorbs all the nutrients through villi and microvilli. Now that all the food is digested the small intestine absorbs all the nutrients through villi and microvilli. –Increases absorption area –Inside each villi there is a net of capillaries which absorb nutrients (diffusion) into bloodstream as well as lacteal which absorb nutrients into the lymphatic system

18. All nutrient-rich blood is carried to the hepatic portal vein which is a blood vessel that leads directly to the liver. This allows the liver to regulate the level of glucose concentration (about 90mg/100mL). Blood then heads to the heart

19. Large Intestine Large intestine- also called the colon. Aprox 4.9ft long (small intestine aprox 23ft.) Large intestine- also called the colon. Aprox 4.9ft long (small intestine aprox 23ft.) Its primary job is to reabsorb whatever water is left in the chyme Its primary job is to reabsorb whatever water is left in the chyme Takes about 12-24hrs Takes about 12-24hrs Food not broken down in this stage of digestion Food not broken down in this stage of digestion Simply absorbs vitamins created by bacteria inhabiting the colon Simply absorbs vitamins created by bacteria inhabiting the colon Also important in absorbing water and compacting the feces Also important in absorbing water and compacting the feces Stores fecal matter in the rectum Stores fecal matter in the rectum

20. El Colon The cecum hosts a large number of bacteria that aid in the breakdown of plant material such as cellulose The cecum hosts a large number of bacteria that aid in the breakdown of plant material such as cellulose Herbivores have a very large cecum compared to carnivores Herbivores have a very large cecum compared to carnivores Appendix- branches off the beginning of the large intestine. Function unknown Appendix- branches off the beginning of the large intestine. Function unknown

21. Facts About 7L of fluid are used in the digestive tract each day, 90% of this is reabsorbed and reused About 7L of fluid are used in the digestive tract each day, 90% of this is reabsorbed and reused If less water then normal is reabsorbed then diarrhea, if more then constipation If less water then normal is reabsorbed then diarrhea, if more then constipation E. Coli is one of most common bacteria in colon E. Coli is one of most common bacteria in colon Rectum is final portion of colon Rectum is final portion of colon

22. Evolutionary Adaptations Teeth – mammals have very specialized teeth Teeth – mammals have very specialized teeth Stomach – large and expandable for carnivores Stomach – large and expandable for carnivores Omni/herbivores tend to have longer digestive tracts cause plants are harder to digest due to cell walls Omni/herbivores tend to have longer digestive tracts cause plants are harder to digest due to cell walls Symbiotic relationships with bacteria to digest plants Symbiotic relationships with bacteria to digest plants The most elaborate adaptations for herbivores is in the group of animals called ruminants (cattle, deer, sheep) The most elaborate adaptations for herbivores is in the group of animals called ruminants (cattle, deer, sheep)

23. Other http://www.youtube.com/watch?v=Og9- cikC3a0 http://www.youtube.com/watch?v=Og9- cikC3a0 http://www.youtube.com/watch?v=Og9- cikC3a0 http://www.youtube.com/watch?v=Og9- cikC3a0