physiology - digestive system Flashcards
Gut —General Functions
motility
absorption
secretion
digestion
Swallowing reflex – Oropharyngeal Stage
3 parts
position of oropharyngeal structures at rest
oral part
pharyngeal part
Swallowing reflex – Oropharyngeal Stage
position of oropharyngeal structures at rest
-swallowing happens voluntarily, tongue presses bolus against hard palate
oral part
- tongue propels bolus to pharynx
- swallowing centre inhibits respiratory centre in brain stem
- elevation of uvula prevents food going into nasal cavity
pharyngeal part
- position of tongue prevents food entering mouth again
- epiglottis folds over closed glottis
Swallowing reflex – Oesophageal Stage
«passes between
« runs from
- pharynx and stomach
- CVI to TXI
Swallowing reflex – Oesophageal Stage
3 parts
beginning of Oesophageal Stage
completion of Oesophageal Stage
beginning of Oesophageal Stage
pharyngoesophageal sphincter closes , oropharyngeal structures returns to rest
completion of Oesophageal Stage
- peristalsis propels food down oesophagus
- gastroesophageal spincter relaxes and swallowing is complete
The Stomach – Function
storage and mixing
digestion … secretory function :HCl / pepsinogen
how many liters of gastric juice/day
2 litres
Stomach Mucosa and Gastric Secretion
exocrine cells
- -mucous cells ….. alkaline mucous
- -chief cells … pepsinogen
- parietal cells … hydrochloric acid
Stomach Mucosa and Gastric Secretion
endocrine/paracrine cells
ECL cells - histamine
G cells - gastrin
D cells -somatosatin
gut function
motility
- food moves down digestive tract due to to peristalsis
- breakdown and mixing of ingested nutrients all the way down until eliminated of unabsorbed waste from the body
gut functions
secretion
- release of enzymes , hormones and other substances that help body digest the food
- hormones tell the body when to produce digestive juices and signal the brain whether you are hungry or full
gut functions
digestion
ingested nutrients are reduced to small molecules that can pass through the gut lining and enter bloodstream
gut functions
absorption
digested nutrients that have passed into blood are now in circulatory or lymphatic system where they can be passed around the body and stored
absorption
lymphatic system
bloodstream
livers
- absorbs fatty acids and vits
- carries simple sugars , amino acids , some vits and salts to liver
- stores processes and delivers these nutrients to the body when needed
digetsive tract wall
mucosa
3 layers
mucous membrane- epithelial lining
lamina propia - connective tissue sheath
muscularis mucosa - smooth muscle layer
all the compose the inner lining of digestive tract
digestive tract wall
submucosa
connective tissue sheath that allows flexibility
digestive tract wall
outer longitundial muscle
inner circular muscle
