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Regents Biology Animal Nutrition Human Digestion.

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Presentation on theme: "Regents Biology Animal Nutrition Human Digestion."— Presentation transcript:

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2 Regents Biology Animal Nutrition Human Digestion

3 What do you need to live? You make energy using: food oxygen You build your body using: food for raw materials amino acids, sugars, fats, nucleotides ATP energy for synthesis O2O2 food ATP

4 Different diets; different lives All animals eat other organisms Herbivores eat mainly plants gorillas, cows, rabbits, snails Carnivores eat other animals sharks, hawks, spiders, snakes Omnivores eat animals & plants cockroaches, bears, raccoons, humans humans evolved as hunters, scavengers & gatherers

5 Getting & Using Food Ingestion taking in food Digestion mechanical digestion breaking up food into smaller pieces chemical digestion breaking down food into molecules small enough to be absorbed into cells enzymes

6 Absorb absorb across cell membrane diffusion active transport Eliminate undigested material passes out of digestive system Getting & Using Food

7 Human digestive system

8 Swallowing (& not choking) Epiglottis flap of cartilage closes trachea (windpipe) when swallowing food travels down esophagus Peristalsis involuntary muscle contractions to move food along

9 Ingestion Mouth mechanical digestion teeth breaking up food chemical digestion saliva amylase enzyme digests starch

10 mucin slippery protein (mucus) protects soft lining of digestive system lubricates food for easier swallowing buffers neutralizes acid to prevent tooth decay anti-bacterial chemicals kill bacteria that enter mouth with food Ingestion

11 mouth breaks up food digests starch kills germs moistens food

12 Stomach Functions 1. food storage can stretch to fit ~2L food 2. disinfect and mix food HCl = pH 2 kills bacteria 3. chemical digestion pepsin enzyme breaks down proteins But the stomach is made out of protein! What stops the stomach from digesting itself? mucus secreted by stomach cells protects stomach lining

13 stomach kills germs breaks up food digests proteins stores food sphincter mouth breaks up food digests starch kills germs moistens food

14 Used to think ulcers were caused by stress tried to control with antacids Now know ulcers caused by bacterial infection of stomach H. pylori now cure it with antibiotics Ulcers inflammation of stomach inflammation of esophagus Colonized by H. pylori Free of H. pylori white blood cells cytokines inflammatory proteins (CagA) cell damaging proteins (VacA) helper T cells neutrophil cells H. pylori Coevolution of parasite & host

15 Small intestine Function 1.chemical digestion major organ of digestion & absorption 2. absorption through lining over 6 meters(~20 feet long)! small intestine has huge surface area = 300m 2 (~size of tennis court)

16 Small Intestine Continued: Acid food from stomach enters and mixes with digestive juices from the accessory organs. pancreas liver gall bladder

17 Pancreas Digestive enzymes will digest proteins digest starch Buffers are present to neutralize acid from stomach Also regulates Glucose levels

18 stomach kills germs breaks up food digests proteins stores food mouth breaks up food digests starch kills germs moistens food pancreas produces enzymes to digest proteins & starch

19 Liver Function produces bile bile stored in gallbladder until needed breaks up fats act like detergents to breakup fats bile contains colors from old red blood cells collected in liver = iron in RBC rusts & makes feces brown bile contains colors from old red blood cells collected in liver = iron in RBC rusts & makes feces brown

20 pancreas produces enzymes to digest proteins & starch stomach kills germs breaks up food digests proteins stores food mouth breaks up food digests starch kills germs moistens food liver produces bile - stored in gall bladder breaks up fats

21 Absorption by Small Intestines Absorption through villi & microvilli finger-like projections increase surface area for absorption

22 small intestine breaks down food - proteins - starch - fats absorbs nutrients stomach kills germs break up food digest proteins store food mouth break up food digest starch kill germs moisten food pancreas produces enzymes to digest proteins & starch liver produces bile - stored in gall bladder break up fats

23 Large intestine (colon) Function re-absorb water use ~9 liters of water every day in digestive juices > 90% of water reabsorbed not enough water absorbed diarrhea too much water absorbed constipation

24 Youve got company! Living in the large intestine is a community of helpful bacteria Escherichia coli (E. coli) produce vitamins vitamin K; B vitamins generate gases by-product of bacterial metabolism methane, hydrogen sulfide

25 stomach kills germs breaks up food digests proteins stores food mouth breaks up food digests starch kills germs moistens food small intestine breaks down food - proteins - starch - fats absorb nutrients pancreas produces enzymes to digest proteins & carbs liver produces bile - stored in gall bladder breaks up fats large intestine absorbs water

26 Appendix Vestigial organ

27 Rectum Last section of colon (large intestines) eliminate feces undigested materials extracellular waste mainly cellulose from plants roughage or fiber masses of bacteria

28 Eating a balanced diet What happens if an animals diet is missing an essential nutrient? deficiency diseases scurvy vitamin C (collagen production) rickets vitamin D (calcium absorption) blindness vitamin A (retinol production) anemia vitamin B 12 (energy production) kwashiorkor protein

29 Vegetarian diets Need to make sure you get enough protein 20 amino acids to make protein 12 amino acids humans can produce 8 we have to eat = essential amino acids Grains (like corn) have 6 (missing 2) Beans (like soybean & red beans) have 6 (missing different 2) mix beans & grains for complete group of amino acids rice & beans taco/tortilla & beans tofu & rice peanut butter & bread

30 Feedback: Maintaining Homeostasis Balancing glucose levels in blood pancreas insulin liver takes up glucose for storage cells take up glucose from blood liver releases glucose to blood depress appetite stimulate hunger glucagon


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