Regents Biology Animal Nutrition Human Digestion.
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Transcript of Regents Biology Animal Nutrition Human Digestion.
Regents Biology
Animal NutritionHuman Digestion
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
O2
food
ATP
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
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
Absorbabsorb across cell membrane
diffusionactive transport
Eliminate undigested material passes out of
digestive system
Getting & Using Food
Human digestive system
Swallowing (& not choking)
Epiglottis flap of cartilage closes trachea (windpipe) when swallowing food travels down esophagus
Peristalsis involuntary muscle contractions to move food along
Ingestion Mouth
mechanical digestion teeth
breaking up food chemical digestion
salivaamylase
enzyme digests starch
mucin slippery protein (mucus) protects soft lining of digestive
system lubricates food for easier
swallowingbuffers
neutralizes acid to prevent tooth decay
anti-bacterial chemicals kill bacteria that enter mouth
with food
Ingestion
mouthbreaks up fooddigests starchkills germsmoistens food
StomachFunctions
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
stomachkills germs breaks up fooddigests proteinsstores food
sphincter
sphincter
mouthbreaks up fooddigests starchkills germsmoistens food
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
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
= 300m2 (~size of tennis court)
Small Intestine Continued: Acid food from stomach enters and
mixes with digestive juices from the accessory organs. pancreas
liver gall bladder
Pancreas Digestive enzymes will
digest proteins digest starch
Buffers are present to neutralize acid from stomach
Also regulates
Glucose levels
stomachkills germs breaks up fooddigests proteinsstores food
mouthbreaks up fooddigests starchkills germsmoistens food
pancreasproduces enzymes to digest proteins & starch
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
pancreasproduces enzymes to digest proteins & starch
stomachkills germs breaks up fooddigests proteinsstores food
mouthbreaks up fooddigests starchkills germsmoistens food
liverproduces bile
- stored in gall bladderbreaks up fats
Absorption by Small Intestines Absorption through villi & microvilli
finger-like projections increase surface area for absorption
small intestinebreaks down food
- proteins- starch- fats
absorbs 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
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
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
stomachkills germs breaks up fooddigests proteinsstores food
mouthbreaks up fooddigests starchkills germsmoistens food
small intestinebreaks down food
- proteins- starch- fats
absorb nutrients
pancreasproduces enzymes to digest proteins & carbs
liverproduces bile
- stored in gall bladderbreaks up fats
large intestineabsorbs water
AppendixVestigial organVestigial organ
Rectum Last section of colon (large intestines)
eliminate feces undigested materials
extracellular waste mainly cellulose from plants roughage or fiber
masses of bacteria
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
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
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