TEST 3 GIT THEORY Flashcards
gastrointestinal tract consists of
muscular tubes and accessory organs
the muscular tubes in the GIT are
oral cavity, pharynx, oesophagus, stomach, intestine
the accessory organs in the GIT are
teeth, tongue, salivary glands, liver and gallbladder, pancreas
functions of the GI system
ingestion, mastication, digestion, secretion, absorption and excretion
mucosa consists of
epithelium
the two epithelium layers in the mucosa are
simple columnar, stratified squamous
simple columnar
stomach, intestines - for secretion and absorption
stratified squamous
other parts - for protection
muscularis consists of
2 layers - inner circular, outer longitudinal
stomach consists of muscularis:
OCL: innermost oblique, inner circular, outer longitudinal
movements of the GIT
peristalsis: push food bolus front
segmentation: mix food with secretions
blood supply of GIT - arterial supply
- celiac, superior, inferior mesenteric artery
- 1st capillary for nutrient absorption and 2nd at liver for processing
oral cavity consists of
teeth, gingiva, tongue, lingual frenulum, salivary glands, soft palate, uvula, palatine tonsils
oral cavity functions
taste, mechanical breakdown and lubrication of food, digestion of carbohydrates and lipids, breathing and speaking
salivary glands
3 pairs: parotid, submandibular, sublingual
parotid
behind ear, duct opens into vestibule opp. 2nd upper molar tooth
submandibular
below mandible, duct opens at sides of frenulum
sublingual
below tongue, ducts open base of cavity
saliva
1L/day, functions are lubrication, defense and digestion
parts of tooth
crown, neck and root
layers of tooth
enamel, dentin, pulp cavity
types of teeth
incisor, canine, premolar and molar
function of incisor
cut/chip
function of canine
tear
function of premolar, molar
mash/grind
baby teeth
20 teeth - 2 sets: 4 incisors, 2 canines, 4 molars in each jaw
adult teeth
32 teeth - 2 sets: 4 incisors, 2 canines, 4 premolars, 6 molars in each jaw
pharynx consists of
nasopharynx, oropharynx, laryngopharynx
swallowing phases
oral, pharyngeal, oesophageal
oral phase
tongue compress and retracts, soft palate closes nasopharynx, food bolus enters oropharynx
pharyngeal phase
larynx elevates, epiglottis folds close larynx, food enters oesophagus
oesophageal phase
lower oesophageal sphincter opens and food bolus enters stomach
chyme
food mixes and gets partially digested by chyme
rugae
folds of mucosa on inner surface - expansion
2 sphincters
cardiac, pyloric
cardiac sphincter
prevents reflux into oesophagus
pyloric sphincter
regulates gastric emptying
functions of the stomach
storage, mechanical and chemical breakdown of food, production of intrinsic factor
stomach lined by
simple columnar epithelium with mucous cells
gastric pits contain
gastric glands
gastric glands
parietal cells secreting HCL and intrinsic factor for Vit B12 absorption; chief cells secreting pepsinogen
small intestine
duodenum, plica
duodenum
25cm long, C-shaped and receives chyme from stomach, bile and pancreatic juice
plica (circular folds)
lined by villus, lined by simple columnar epithelium. villus has lacteal (fat absorption).
functions of the small intestine
90% of digestion and 90% of absorption of nutrients
large intestine
caecum, colon (ascending, transverse, descending and sigmoid), rectum and anal canal
caecum
expanded pouch in right iliac fossa; appendix from posteromedial side
rectum
temporary storage of faeces
defaecation reflex
peristalsis: relaxation of internal sphincter (involuntary) and external sphincter (voluntary)
large intestine functions
absorption of water, vitamin production and bile recycling
liver lobes
4: right, left, caudate, quadrate
porta hepatis
hepatic portal vein, hepatic artery, common hepatic duct
liver lobule
hexagonal
corners (portal area)
branch of hepatic portal vein, hepatic artery and hepatic duct (V-A-D)
liver functions
synthesis bile, plasma proteins, clotting factors
storage of vitamins, iron, blood
removal of waste products, drugs, toxins
defense - kupffer cells
gallbladder
fundus, body, neck, cystic duct
gallbladder functions
stores, concentrates bile
biliary tree
r&l hepatic duct –> common hepatic duct + cystic duct –> common bile duct + pancreatic duct –> duodenum
pancreas
head, body, tail; retroperitoneal organ
endocrine cells
1% of pancreatic cells, exists as clusters (Islets of Langerhans), secretes insulin
exocrine cells
99% of pancreatic cells, exists as acini, secretes pancreatic juice which drains via pancreatic duct which empties into duodenum with CBD
pancreatic juice made of enzymes (secreted as proactive form)
trypsin, chymotrypsin, pancreatic amylase, pancreatic lipase, nucleases
trypsin and chymotrypsin
acts on proteins
pancreatic amylase
acts on carbohydrates
pancreatic lipase
acts on lipids
nucleases
acts on nucleic acids