digestive system organs Flashcards
functions of the digestive system
ingestion, digestion, absorption, defecation
what are the types of digestion
mechanical: physical breakdown of food into smaller particles (teeth, stomach and intestines contractions)
chemical: action of enzymes from saliva, stomach, pancreas and intestines
what are the results of chemical digestion
polysaccharides -> monosaccharides (glucose, galactose and fructose)
proteins -> amino acids
lipids -> glycerol and fatty acids
nucleic acids -> nucleotides
where do lipids get broken down and what does it
broken down in the small intestine
bile breaks it down
what are the types of mechanical contractions for digestion and their functions
peristalsis: used for transport not breaking down (alternating waves of contraction and relaxation of wall muscles in GI tract)
segmentation: used for mixing and breakdown of food (moves food back and forth across internal wall of intestines)
what are the organs of the digestive system and which are accessory organs
mouth, esophagus, pharynx, stomach, spleen, small intestines, large intestines
accessory organs: tongue, salivary glands, pancreas, liver, gallbladder
what are the components of the salivary glands
parotid gland
sublingual gland
submandibular gland
what is the alimentary canal
30 foot long tube extending from mouth to anus
organs that food travel through
these organs directly ingest, digest, absorb, defecate
mouth -> pharynx -> esophagus -> stomach -> small intestine -> large intestines -> anus
what are accessory organs
organs that help with digestion but are generally not in direct contact with food
not part of GI tract
components of the mouth
hard palate: anterior roof
lips: protect opening
vestibule: space between lips and gums
lingual frenulum: anchors tongue to mouth
tongue: attached at hyoid and styloid process
soft palate: posterior roof
uvula: saliva production and speech modulation
palatine tonsil
lingual tonsil
gingivae (gums)
characteristics of mouth
mucous membrane-lined cavity
mechanical breakdown of food
tongue mixes food with saliva to start chemical breakdown of starches
tongue initiates swallowing (deglutition)
anatomy of the pharynx
two skeletal muscle layers:
longitudinal outer layer
circular inner layer
alternating contractions of the muscle layers (peristalsis) propels food to esophagus
components of the walls of the alimentary canal
mucosa
submucosa
muscularis externa
serosa
(in to outer)
components of the mucosa
surface epithelium (stratified squamous or simple columnar epithelium)
lamina propria
smooth muscle layer
components of the submucosa
soft connective tissue with blood vessels, nerve endings, mucosa-associated lymphoid tissue and lymphatic vessels
components of the muscularis externa
smooth muscle for contractions
inner circular layer
outer longitudinal layer
(stomach has extra layer)
components of the serosa
visceral peritoneum (simple squamous epithelium that produces serous fluid)
what is the mesentary
extension of peritoneum
allows lymph and blood vessels to enter/exit GI tract
characteristics of the esophagus
runs from pharynx to stomach through diaphragm
conducts food by peristalsis
has sphincters
what is a sphincter
ring/band of muscle that “divides” organs even if the tract is continuous
smooth muscle, contract to prevent food backflow
what sphincters does the esophagus have
upper esophageal sphincter (where food control becomes involuntary)
lower esophageal sphincter
what is deglutition
swallowing
when food is transported from mouth to stomach through pharynx and esophagus
how does deglutition work
involves complex series of voluntary and involuntary muscular contractions
two phases:
buccal: voluntary, food forced into pharynx by tongue
pharyngeal-esophageal: involuntary
components of the muscularis externa for the stomach
longitudinal layer
circular layer
oblique layer
(out to inner)
