Chapter 16 - Digestive System

function of the digestive system

motility, secretion, digestion, absorption, storage and elimination, immune barrier

motility

ingestion, mastication, deglutition, peristalsis, segmentation

secretion

exocrine, endocrine

exocrine

digestive enzymes, hydrochloric acid, water, mucus and bicarbonate

endocrine

hormones that regulate digestion

digestion

breaking down polymers into smaller units both physically and chemically

absorption

nutrients are absorbed into the blood stream or lymph

storage and elimination

temporary storage and ultimately elimination of undigested foods

immune barrier

tight junctions prevent pathogens from entering bloodstream, help promote immune response

formation of polymers

dehydration synthesis used to string monomers together, removes water in the process

destruction of polymers

hydrolysis is the process of separating polymers into monomers, water is added in the process

GI tract

oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, anus

accessory organs

teeth, tongue, salivary glands, gallbladder, pancreas, liver

layers of the GI tract

mucosa, submucosa, muscularis, serosa

mucosa

inner layer responsible for secreting mucus and absorbing nutrients

submucosa

very vascular, important for the absorption of nutrients, has some glands and nerve plexuses

muscularis

smooth muscle layer responsible for peristalsis and segmentation

serosa

outer layer that attaches to its surroundings and protects the organs, the visceral peritoneum covers the organs, and the peritoneum lines the abdominal cavity

the mouth

mastication, saliva, deglutition

mastication

chewing breaks food down into smaller pieces, and the tongue helps mix the food with saliva forming a bolus make it easier to swallow

saliva

contains an antimicrobial agent, mucus, and an enzyme called salivary amylase

deglutition

involves the coordination of 25 pairs of muscles in the mouth, pharynx, larynx, and esophagus

esophagus

carries food from throat to stomach, contains voluntary skeletal muscles,