digestive structure list

oral cavity

first part of digestive tract; site of ingestion, chewing, and initial chemical digestion

labia (lips)

form anterior boundary of oral cavity; help keep food in mouth

orbicularis oris

closes lips, purses/protrudes lips; innervated by facial nerve (cn vii)

buccinator

compresses cheeks to keep food between teeth; innervated by facial nerve (cn vii)

temporalis

elevates mandible (closes jaw); innervated by trigeminal nerve (cn v)

masseter

prime mover of jaw closure; elevates mandible; innervated by trigeminal nerve (cn v)

central incisors (2 front teeth); lateral incisor (next to central); canines (cuspids); 1st/2nd premolars (bicuspids), after canines, before 1st molars; 1st molars, 2nd molars, 3rd molars (wisdom teeth)

teeth order

hard palate

bony anterior roof of mouth; creates friction for chewing

soft palate

muscular posterior roof; closes nasopharynx during swallowing

uvula

projection from soft palate; prevents food entering nasal cavity

parotid gland

largest salivary gland; mostly serous secretion (amylase); innervated by glossopharyngeal nerve (cn ix)

submandibular gland

mixed secretion (mostly serous); innervated by facial nerve (cn vii)

sublingual gland

mostly mucous secretion; innervated by facial nerve (cn vii)

nasopharynx

air passage only (not digestive)

oropharynx

passageway for food and air

laryngopharynx

directs food to esophagus (& air to trachea)

esophagus

muscular tube that moves food to stomach via peristalsis

stomach

stores food, converts bolus to chyme, begins protein digestion

rugae

folds that allow stomach expansion

cardiac sphincter

upper sphincter of stomach, prevents acid reflux into esophagus

pyloric sphincter

lower spincter of stomach, regulates emptying of stomach into duodenum

liver

produces bile; processes nutrients; detoxifies blood

right lobe

largest lobe of liver

left lobe

smaller lobe of liver

caudate lobe

posterior lobe of liver

quadrate lobe

inferior lobe of liver

round ligament (ligamentum teres)

remnant of fetal umbilical vein, hanging off falciform ligament (which separates lobes of liver)

hepatic portal vein

carries nutrient-rich blood from gi tract to liver

proper hepatic artery

supplies oxygenated blood to liver

common bile duct

carries bile to duodenum, made when common hepatic duct and cystic duct join

cystic duct

connects gallbladder to bile duct

common hepatic duct

drains bile from liver

gallbladder

stores and concentrates bile

pancreas

produces digestive enzymes and bicarbonate

pancreatic duct

carries pancreatic juice to duodenum

major duodenal papilla

opening where bile and pancreatic juice enter duodenum

small intestine

main site of digestion and absorption

villi

fingerlike projections that increase surface area for absorption

lymphatic duct (lacteal)

absorbs fats into lymphatic system

capillary

absorbs nutrients into bloodstream

intestinal crypts (crypts of lieberkühn)

secrete intestinal juice; contain stem cells

longitudinal layer

outer muscle layer; shortens tract

circular layer

inner muscle layer; constricts lumen

muscularis mucosae

thin muscle layer causing local mucosal movement

duodenum

first part of small intestine; receives chyme, bile, and pancreatic juice

plicae circulares

circular folds that slow chyme to increase absorption

jejunum

main site of nutrient absorption

ileum

absorbs remaining nutrients; connects to large intestine

ileocecal junction

connection between small and large intestine

large intestine (colon)

absorbs water and forms feces

cecum

first part of large intestine

vermiform appendix

lymphoid organ with immune function, attached to cecum

ascending colon

second part of large intestine, upward section on right side

transverse colon

third part of large intestine, horizontal section across abdomen

descending colon

fourth part of large intestine, downward section on left side

sigmoid colon

fifth part of large intestine, s-shaped segment leading to rectum

rectum

stores feces

anal canal

final passageway for defecation

teniae coli

three bands of longitudinal smooth muscle in colon

haustra

pouch-like segments of colon

epiploic appendages

fat-filled pouches on colon

vagus nerve

parasympathetic nerve that stimulates digestive activity

bolus

chewed food mixed with saliva, formed in oral cavity

chyme

semi-liquid mixture of partially digested food in stomach

peristalsis

wave-like contractions that move food through gi tract

segmentation

mixing movements in small intestine (not propulsion)

intrinsic factor

protein from stomach required for vitamin b12 absorption

bile

produced by liver; emulsifies fats (does NOT digest them chemically)

enteric nervous system

"gut brain"; controls gi motility

myenteric plexus

controls gi motility (between muscle layers of muscularis externa)

submucosal plexus

regulates secretion and local activity (above submucosa)

DJ ilium (duodenum -> jejunum -> ileum)

small intestine order

cecum -> ascending colon -> transverse colon -> descending colon -> sigmoid colon -> rectum -> anal canal

large intestine order

gi (gastrointestinal) tract

aka alimentary canal, tube extending from mouth to anus, includes mouth, pharynx, esophagus, stomach, small intestine, large intestine

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

accessory digestive organs