GI Tract I Flashcards
What is the function of the GI tract
supply water, electrolytes, circulate blood, secrete digestive juices
What are the structural components of the GI tract
buccal cavity, oesophagus, stomach, duodenum, jejunum, ileum, caecum, rectum, anal cavity
What is the function of the buccal cavity
mastication, mix with saliva, mechanically break down food
Where does digestion begin
mouth
What does the buccal cavity form
soft bolus
What does the buccal cavity provide
lubrication, saliva
What does saliva contain
alpha amylase
What is the function of saliva
break down starch
Where does the oesophagus convey food to
stomach via upper sphincter
Describe the structure of the oesophagus
conduit between oropharynx and stomach, fibro-muscular tube
What doe the oesophagus consist of
muscles, mucosa, submucosa, connective tissue
What is the function of the oesophagus
convey food to stomach - peristaltic contraction
What is the stomach
elastic bag - holds masticated food
What does the stomach add
gastric acid, digestive enzymes
Where does the stomach lie
upper left part of abdominal cavity agains diaphragm
What does the stomach release
proteases, HCl
What is the function of proteases in the stomach
break up proteins
What is the function of HCl in the stomach
act as bacterial - stop proliferation
What is the product of the stomach
chyme
How does the stomach produce chyme
peristalsis
Where is the chyme from the stomach released into
duodenum
What is the duodenum
small intestine
What is the function of the duodenum
break down, absorption
Where does the bulk of digestion occur
duodenum
What is secreted in the duodenum
intestinal juices, digestive enzymes
Where does the duodenum lie
directly adjacent to stomach
What is the function of the duodenum
enzymatic breakdown of chyme
How many regions does the duodenum have
4
What structure regulates the emptying of the stomach
duodenum
How does the duodenum regulate the emptying of the stomach
hormones; - secretin and cholecystokinin
What is the jejunum/ileum
small intestine
What secretes digestive enzymes into the jejunum/ileum
pancreas, liver via pancreatic duct
What is the function of jejunum/ileum
absorption
What line the inner surface of the jejunum
villi
What is the function of the villi of the jejunum
increase SA for greater absorption and blood supply
Describe the structure of the villi in the jejunum
brush border of microvilli on villi
Transport of ….. across epithelial cells is passive in the jejunum
sugars e.g. fructose
What have to be transported actively into the GI tract
amino acids, small peptides, glucose
What is different about the ileum compared to the jejunum
smaller lumen, thinner walls, more fat inside mesentery
What is the function of the ileum
absorbs B12, bile salts and products of digestion that weren’t absorbed in the jejunum
What does the ileum have
abundant peyer’s patches
What are Peyer’s patches
encapsulated typhoid nodules
What do Peyer’s patches contain
large numbers of immune system cells
What is the caecum
first part of large intestine
What is the function of the caecum
absorb salt and water, mix mucous into chyme
In what animal is the caecum larger?
herbivores
What does the caecum house in herbivores
cellulose digesting enzymes
In what animals is the caecum absent?
carnivores - replaced by appendix
What is the function of the rectum
absorption of electrolytes, water, thickens and stores faeces
What does the stretching of renal walls stimulate
stretch receptors, desire to defaecate
What is the function of the anal cavity
store faeces, regulate defection, lubricate
What components are part fo the upper GI tract
buccal cavity, oesophagus, stomach, duodenum
What components are part of the small intestine
duodenum, jejunum, ileum
What components are part of the lower GI tract
colon, rectum, anal canal
