Animal Nutrition Human Digestion 2006-2007
What do animals need to live? Animals make energy using: u food food u oxygen Animals build bodies using: u food for raw materials amino acids, sugars, O fats, nucleotides 2 u ATP energy for synthesis ATP mitochondria
How do animals get their food? filter feeding living in your food fluid feeding bulk feeding
Different diets; different lives All animals eat other organisms u Herbivores eat mainly plants w gorillas, cows, rabbits, snails u Carnivores eat other animals w sharks, hawks, spiders, snakes u Omnivores eat animals & plants w cockroaches, bears, raccoons, humans w humans evolved as hunters, scavengers & gatherers
Getting & Using Food Ingest u taking in food Digest u mechanical digestion breaking up food into smaller pieces u chemical digestion breaking down food into molecules small enough to be absorbed into cells enzymes Absorb u absorb nutrients across cell membranes diffusion active transport Eliminate u undigested material passes out of body intracellular digestion extracellular digestion
Digestive systems Everybody s got one!
Human digestive system
Mouth Functions u mechanical digestion teeth w break up food u chemical digestion (saliva) amylase enzyme w digests starch mucus w protects soft lining of digestive system w lubricates food for easier swallowing buffers w neutralizes acid to prevent tooth decay anti-bacterial chemicals w kill bacteria that enter mouth with food All that in spit!
Swallowing (& not choking) Epiglottis u flap of cartilage u closes trachea (windpipe) when swallowing u food travels down esophagus Peristalsis u involuntary muscle contractions to move food along
mouth break up food digest starch kill germs moisten food
Stomach Functions u disinfect food hydrochloric acid = ph 2 w kills bacteria u food storage can stretch to fit ~2L food u begins digests protein pepsin enzyme from pancrease But the stomach is made out of protein! What stops the stomach from digesting itself? mucus secreted by stomach cells protects stomach lining
mouth break up food digest starch kill germs moisten food stomach kills germs break up food digest proteins store food sphincter sphincter
Ulcers Ulcers caused by excessive HCl New medicines actually control the cells that secrete the HCl into the stomach. Colonized by H. pylori inflammation of stomach H. pylori Free of H. pylori inflammation of esophagus cell damaging inflammatory proteins proteins (VacA) (CagA) cytokines helper T cells neutrophil cells white blood cells
Small intestine Functions u digestion digest carbohydrates w amylase from pancreas digest proteins w Pepsin from pancreas digest lipids (fats) w bile from liver u absorption nutrients move into body cells by: w Diffusion into blood stream This is where all the work is done!
Absorption in Small Intestines Absorption through villi & microvilli u finger-like projections u increases surface area for absorption SMALL INTESTINES 6 meters long, but can stretch to cover a tennis court
mouth break up food digest starch kill germs moisten food liver produces bile - stored in gall bladder break up fats pancreas produces enzymes to digest proteins stomach kills germs break up food digest proteins store food small intestines breakdown food - proteins - starch - fats absorb nutrients
Pancreas Produces digestive enzymes u digest proteins Pepsin u digest starch Amylase Buffers u neutralizes acid from stomach small intestine pancreas
mouth break up food digest starch kill germs moisten food stomach kills germs break up food digest proteins store food pancreas produces enzymes to digest all foods
Liver & Gall Bladder Produces bile u breaks up fats u gallbladder only stores bile that s why you can have your gall bladder removed bile contains colors from old red blood cells collected in liver = iron in RBC rusts & makes Regents feces Biology brown
mouth break up food digest starch kill germs moisten food stomach kills germs break up food digest proteins store food liver produces bile - stored in gall bladder break up fats pancreas produces enzymes to digest proteins & starch
Large intestines (colon) Function u re-absorbs water use ~9 liters of water every day in digestive juices w if don t reabsorb water would die of dehydration > 90% of water re-absorbed w not enough water re-absorbed n diarrhea n can be fatal! w too much water re-absorbed n constipation reabsorb by diffusion
You ve got company! PEE-YOO! Living in the large intestine is a community of helpful bacteria u Escherichia coli: E. coli digest cellulose w digests fruits & vegetables produce vitamins w vitamin K & B vitamins BUT generate gases w by-product of bacterial metabolism w methane, hydrogen sulfide w STINKY!
mouth break up food digest starch kill germs moisten food liver produces bile - stored in gall bladder break up fats pancreas produces enzymes to digest proteins & carbs stomach kills germs break up food digest proteins store food small intestines breakdown food - proteins - starch - fats absorb nutrients large intestines absorb water
Appendix Vestigial organ
mouth break up food digest starch kill germs moisten food liver produces bile - stored in gall bladder break up fats pancreas produces enzymes to digest proteins & carbs stomach kills germs break up food digest proteins store food small intestines breakdown food - proteins - starch - fats absorb nutrients appendix large intestines absorb water
Rectum Last section of large intestines u learn to control this muscle u what s left over? undigested materials w mainly cellulose from plants w called roughage or fiber w keeps everything moving & cleans out intestines masses of bacteria So don t forget to wash your hands!