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