B2 The upper GI tract 1 Flashcards
Name the 11 key structures of the GI tract
1) oesophagus
2) lower oesophageal sphincter
3) stomach
4) pancreas
5) small intestines
6) large intestines
7) anus
8) duodenum
9) pyloric sphincter
10) gall bladder
11) liver
What are the 3 parts of the small intestines called?
1) duodenum
2) jejunum
3) ileum
What are the 2 main parts of the large intestines called?
1) caecum
2) colon
What occurs in the mouth?
mastication, chewing and addition of saliva
What does salivary amylase breakdown?
Starch
The production of saliva is under which control?
autonomic control
Is saliva production part of sympathetic or parasympathetic?
sympathetic
What are the NTs and receptors of salivary production?
NT - ACh
receptor- muscarinic
What is the pH of the stomach?
1-1.5
Acidity in the stomach sterilises food, why?
to prevent food poisoning
Chief cells of gastric mucosa release what?
pepsinogens
The acid environment activates release of pepsinogen, but to form what?
pepsin
What is meant by autocatalytic with reference to pepsin?
new pepsin chops up pepsinogen
What is the function of pepsin?
proteolysis of proteins to polypeptides
What acts within peptide chain?
endopeptidase
What are the 3 parts of gastric control?
1) cephalic phase 30%
2) gastric phase 50-60%
3) intestinal phase 5%
How does the cephalic phase work?
food, taste, smell, mastication causes parasympathetic stimulation, ACh stimulates acid release from periatal cells. Acid release stimulates gastrin release (hormone stimulates acid reduction)
How does the gastric phase work?
food distension causes local release of ACh, histamine acts as NT in stomach to activate acid release, gastrin. Local vasovagal reflexes to release ACh
What protects the stomach lining?
pepsinogen mucus
Why is the pH of the duodenum between 5-6
secretes bicarbonate so higher pH to protect duodenum so reduce activity of pepsinogens
Which enzymes are secreted by the enzyme?
lipase- breaks lipids/fats down
amylase- starch
proteolytic enzymes
What does vitamin B12 bind to in the stomach?
intrinsic factors
Does stomach cancer have poor prognosis?
yes 18%
What are the signs of stomach cancer?
gastric bleeding
weight loss
55 years old
abdominal masses
