Digestion Flashcards
Intracellular digestion
Metabolism, oxidation of glucose and fatty acids for energy
Extracellular digestion
process by which nutrients are extracted from food; breakdown of food into constituent organic molecules
Mechanical digestion
physical breakdown of large food particles, no chem bonds broken
Chemical digestion
enzymatic cleavage of chemical bonds
Absorption
transport of products from digestion into circulatory system
Route of digestive tract
Food->oral cavity->pharynx->esophagus->stomach->small intestine->large intestine->rectum->expulsion
Enteric nervous system
contains neurons that regulate G.I. tract; neurons trigger peristalsis: rhythmic contractions that move materials through digestive tract
Oral cavity- role in digestion
1) Chew food to break large particles and increase surface area
2) saliva contains enzymes that break chem. bonds and lubricates food
3) Presence of food in mouth triggers neural circuit which stimulates salivary glands
4) tongue forms food into bolus, forced into pharynx
Pharynx
connects oral cavity to esophagus; food prevented from entering larynx by the epiglottis, if food enters larynx, leads to choking
Esophagus
Tube that connects pharynx to stomach; top of esophagus contains skeletal muscle (under voluntary control, bottom contains smooth muscle (involuntary control); lower esophageal sphincter relaxes and opens to allow food to pass through
Peristalysis
series of wave-like contractions that move food through digestive tract; exposure to chemicals or pathogens can reverse, leading to vomiting
Salivary amylase
hydrolyzes starches
lipase
hydrolyzes lipids
Stomach
highly muscular organ, used HCl and enzymes to further digest food for maximum absorption in small intestine
