Animal Nutrition Human Digestion

Regents Biology 2006-2007

Animal NutritionHuman Digestion

Regents Biology

What do animals need to live? Animals make energy

using: food oxygen

Animals build bodies using: food for raw materials

amino acids, sugars, fats, nucleotides

ATP energy for synthesis

O2

food

ATP

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How do animals get their food?

suspension feeding substrate feeding

fluid feeding bulk feeding

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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

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Getting & Using Food Ingest

taking in food

Digest mechanical digestion

breaking up food into smaller pieces chemical digestion

breaking down food into molecules small enough to be absorbed into cells

enzymes

Absorb absorb across cell membrane

diffusion active transport

Eliminate undigested material passes out of

digestive system

intracellulardigestion

extracellulardigestion

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Digestive systemsEverybody’s got one!

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Human digestive system

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Swallowing (& not choking)

Epiglottis flap of cartilage closes trachea (windpipe) when swallowing food travels down esophagus

Peristalsis

involuntary muscle contractions to move food along

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Ingestion Mouth

mechanical digestion teeth

breaking up food chemical digestion

saliva amylase

enzyme digests starch 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

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mouthbreak up fooddigest starchkill germsmoisten food

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StomachFunctions

food storage can stretch to fit ~2L food

disinfect food HCl = pH 2

kills bacteria

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

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stomachkills germs break up fooddigest proteinsstore food

sphincter

sphincter

mouthbreak up fooddigest starchkill germsmoisten food

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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 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

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Revolutionizing healthcare

J. Robin Warren

Barry Marshall

2005 Nobel prize in medicine

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Small intestine Function

chemical digestion major organ of digestion & absorption

absorption through lining over 6 meters! small intestine has huge surface area =

300m2 (~size of tennis court)

Structure 3 sections

duodenum = most digestion jejunum = absorption of nutrients & water ileum = absorption of nutrients & water

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Duodenum 1st section of small intestines

acid food from stomach mixes with digestive juices from:

pancreas liver gall bladder

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Pancreas Digestive enzymes

digest proteins trypsin, chymotrypsin

digest starch amylase

Buffers neutralizes

acid from stomach

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stomachkills germs break up fooddigest proteinsstore food

mouthbreak up fooddigest starchkill germsmoisten food

pancreasproduces enzymes to digest proteins & starch

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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

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pancreasproduces enzymes to digest proteins & starch

stomachkills germs break up fooddigest proteinsstore food

mouthbreak up fooddigest starchkill germsmoisten food

liverproduces bile

- stored in gall bladderbreak up fats

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Absorption by Small Intestines Absorption through villi & microvilli

finger-like projections increase surface area for absorption

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small intestinesbreakdown food

- proteins- starch- fats

absorb nutrients

stomachkills germs break up fooddigest proteinsstore food

mouthbreak up fooddigest starchkill germsmoisten food

pancreasproduces enzymes to digest proteins & starch

liverproduces bile

- stored in gall bladderbreak up fats

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Large intestines (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

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You’ve 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

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stomachkills germs break up fooddigest proteinsstore food

mouthbreak up fooddigest starchkill germsmoisten food

small intestinesbreakdown food

- proteins- starch- fats

absorb nutrients

pancreasproduces enzymes to digest proteins & carbs

liverproduces bile

- stored in gall bladderbreak up fats

large intestinesabsorb water

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AppendixVestigial organVestigial organ

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Rectum Last section of colon (large intestines)

eliminate feces undigested materials

extracellular waste mainly cellulose from plants roughage or fiber

masses of bacteria

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Different diets; different bodies Adaptations of herbivore vs. carnivore

teeth length of digestive system number & size of stomachs

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Teeth Carnivore

sharp ripping teeth

“canines” Herbivore

wide grinding teeth

molars Omnivore

both kinds of teeth

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Length of digestive system Herbivores & omnivores

long digestive systems

harder to digest cellulose (cell walls) bacteria in intestines

help

Carnivores short digestive

systems protein easier to

digest than cellulose

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Eating a balanced diet What happens if an animal’s 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 B12 (energy production)

kwashiorkor — protein

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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 & grainsfor complete group of amino acids

rice & beans taco/tortilla & beans tofu & rice peanut butter & bread

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Feedback: Maintaining Homeostasis Balancing glucose levels in blood

pancreas

pancreas

insulin

liver takes upglucose

for storage

cellstake up

glucose from blood

liver releasesglucose to blood

depress appetite

stimulatehungerglucagon

Regents Biology 2006-2007

Any Questions??