Grand tour of alimentary canal Flashcards
functions of digestive system
digestion
secretion
absorption
motility
mouth
foodstuffs broken down by chewing
saliva as lubricant
oesophagus
conduit between mouth and stomach
pancreas
digestive enzymes dor digestion of fats, carbohydrates and proteins
stomach
digestion of proteins
foodstuffs reduced to liquid form
storage
sterilisation
liver
bile salts for digestion/absorption of fats in small intentine
gallbladder
store and concentrae bile
small intestine
final stages chemical digestion and nutrient absorption
large intestine
water absorption, bacterial fermentation
formation faeces
four histological layers
mucosa (epithelium, lamina propria, muscularis mucosae)
submucosa
muscularis externa
serosa/adventitia
mucosa: epithelium
synthesis and secretion digestive enzymes, hormones, mucus
absorbs products of digestion
differs along lenght of gut tube - adapts for function
which areas have stratified squamous epithelium
mouth
oesaphagus
anal canal
which areas have simple columnar epithelium
stomach
small & large intestine
mucosa: lamina propria
loose connective tissue (glands, blood/lymph vessels)
mucosa: muscularis mucosae
thin smooth muscle layer
submucosa
thick, irregular connective tissue
contains neurones, blood evessels, lymphatic vessels
serosa/adventitia
connective tissue outer layer of alimentary canal
serosa/adventitia: outside peritoneal cavity
adventitia attaches oesophagus and rectum to attaching structures
serosa/adventitia: inside peritoneal cavity
serosa surrounds stomach, small intestine and large intestine
muscularis externa
two concentric layers smooth muscle
inner layer: circular muscle (constrict lumen)
outer layer: longitudinal muscle (shortens tube)
produce motility
myenteric plexus between layers
submucosal + myenteric nerve plexuses
enteric nervous system - independant control of gut function
parasympathetic control alimentary function
vagus nerve (expect salivation: CNVII and IX) stimulatory: increase secretion and motility
sympathetic control alimentary function
splanchnic nerve
inhibitory (except salivation)
decrease secretion and motility
arterial supply to GIT
desc abdo aorta: ceoliac trunk, superior mesenteric artery and inferior mesenteric artery