Exam 5- A+P ch 15,16; cooper ch 13

main steps in processing food

-ingestion

-digestion

-absorption

-elimination

ingestion

taking food into the mouth, chewing, and swallowing it

digestion

breaking down food into smaller molecules

-mechanical vs chemical

absorption

transport of digested food through the wall of the stomach or small intestine into the circulatory system

elimination

removes undigested and unabsorbed food from the body

sequence of digestive tract

mouth → pharynx → esophagus → stomach → small intestine → large intestine → rectum → anus

layers of digestive tract

-mucosa: epithelial tissue

-submucosa: connective tissue (rich in blood and lymphatic vessels, glands and nerves)

-muscularis: muscle layer (peristalsis)

-adventitia (above diaphragm), serosa/visceral (below diaphragm)

salivary glands

-parotid: inferior and anterior to the ears

-submandibular: below jaw

-sublingual: under the tongue

saliva components

-salivary amylase: enzyme that begins the chemical digestion of starches (carbs)

-mucous secretion: lubricates the mouth

*also contains salts, antibodies, and other substances that kill bacteria

epiglottis

small flap of tissue that prevents food from entering the respiratory passageways

peristalsis

waves of muscle contraction

cardiac sphincter

at the lower end of the esophagus to prevent gastric juice from the stomach to splash back to the esophagus

stomach cells

-parietal cells: secrete hydrochloric acid, which kills bacteria and breaks down connective tissues in meat

-chief cells: secrete pepsinogen, an inactive form of pepsin which begins digestion of proteins

chyme

food that is digested and converted into this soupy mixture

pyloric sphincter

guards the exit of the stomach

villi

lines the small intestine and increases its surface area, which allows for more digestion and absorption of nutrients

goblet cells

in the mucosa of the small intestine that secrete alkaline mucous that helps protect the intestinal wall from the acidic chyme and from the action of digestive enzymes

pancreatic juice

secreted from the pancreas and contains a number of digestive enzymes

bile

produced and secreted from the liver; emulsifies fat which mainly takes place in the duodenum

carbohydrate digestion

-begins in the mouth with salivary amylase

starch (salivary amylase)→ smaller carbs + maltose

-duodenum has pancreatic amylase

starch + smaller carbs (pancreatic amylase) → maltose

-enzyme maltase breaks down maltose

maltose (maltase) → glucose + glucose