PLTW HBS Digestion

what are the main functions of the digestive system

breaking down foods for nutrient absorption, absorbing nutrients into the bloodstream, eliminating waste from the body

mouth/oral cavity, including salivary glands

teeth break down food mechanically (chewing), tongue helps mix foods and pushes it towards throat, salivary glands produce saliva to moisten food and start carbohydrate digestion

pharynx

passagway for food, liquids and air, directs food into esophagus

esophagus

transports food from mouth to stomach through peristalsis (wave-like muscle contractions)

stomach

breaks down food chemically (via gastric acid) and mechanically (via churning), produces enzymes and acid ot digest proteins and kill bacteria

small intesting and villi

main site for nutrient absorption, villi increase surface area for absorption

liver

produces bile for fat digestion, detoxifies harmful substances, stores glucogen, vitamins and minerals

gallbladder

stores and concentrates bile produced by the liver, releases it into the small intestine to aid fat digestion

pancreas

produces digestion enzymes (amylase, lipase, protease) and bicarbonate to neutralize stomach acid

appendix

no clear function, plays a role in gut immunity

large intestine

absorbs water and electrolytes, forms and stores feces

rectum and anus

rectum stores feces before elimination, anus controls the release of feces

mechanical digestion

physical breakdown of food to incease surface area for enzymes (ex. mouth, stomach)

chemical digestion

enzymatic breakdown of food into simpler molecules (ex. mouth, stomach, small intestine)

why do we need an epiglottis

prevents food from entering trachea (windpipe) and directs it into the esophagus

why do we need peristalsis

esnures the one-way movement of food through the digestive tractsof

soft palate

soft, flexible part at the back of the roof of your mouth, blocks nasal passages

hard palate

bony front part of the roof of your mouth, helps with chewing and swallowing

what are the two sphincters of the stomach

lower esophageal/cardiac, and pyloric

how is the stomach not damaged by its acid

stomach is lined with mucus that protects it from the corrosive effects of hydrohloric acid

what is another non-digestive function of this acid

it kills harmful bactera and pathogens that may enter with food

how can your stomach hold different amounts of food

the stomach has elastic walls that can expand or contract based on food intake

what is the relationship between the liver and gallbladder

the liver produces bile and the gallbladder stores and concentrates it for latr use in fat digestion

can a person survive without a gallbladder

yes, a person can survive. bile will still be produced by the liver, but it will slow down digestion since it doesn’t have a storage reservoir

what is the stomach ph

1.5-3.5

what is the small intestine ph

6-7.5

what are the liver’s non digestive functions

detoxify chemicals and drugs, stores vitamins and minerals, regulating blood sugar levels, produces blood clotting proteins

bolus

soft mass of chewed food mixed with saliva, first step in digestion

chyme

a semi-liquid substance formed when food mixes with stomach acid and digestive enzymes