Upper GI tract Flashcards
What does the circular muscle do and what does the longitudinal muscle do in the stomach?
CIRCULAR:
-SEGMENTATION (weaker contractions
)
- keeps the food in thestomach for some time so it can be properly broken down
- 80% of contractions
LONGITUDINAL:
-PERISTALSIS
20% of contractions
-propels CHYME towards the colon
-more powerful contractions as moves food from the Lower Oesophageal sphinter to the Pyloric sphincter
What are the 5 parts that make up the foregut?
- Oesophagus
- Stomach
- Liver
- Pancreasa
- Bilary system( liver, gall bladder and bile ducts work together to secrete bile)
What 2 things make up the midgut?
- Small intesine
- Part of the large intestine
What 2 things make-up the Hind gut?
- Colum
- Rectum
What are the 4 layers of the GI tract?
MUCOSA-mainly epithelium(secretary and absorpative)
SUBMUCOSA-connective tissue and capillaries
MUSCULARIS(2 layers of muscle):
-CIRCULAR MUSCLE LAYER(constricts the bowel=divides it into segments =food passes between segments and stays for a while in each segmwent allowing absorption happening)
-LONGITUDINAL OUTER MUSCLE LAYER -propagates food through the intestinal tract
SEROSA/ADVENTITIA-connective tissue and epithelium(protective layer/lining)
There are subtle differences as you go from the Oesophagus down towards the rectum
How many teeth do we have and what is the makeup?
32:
- 8 incisors
- 4 canines
- 8 premolars
- 12 molars
Which muscles in the oral cavity are part of the GI tract?
MASSETOR MUSCLES -largest Jaw muscle responsible for biting
-several muscles that control the position of the mandible
What does the tongue do as part of GI tract?
propogates food into the pharynx
What is the function of the Oesophagus?
Porpagates food from the Pharyunx to the stomach
What is the structure and function of the Epithelium lining the Oesophagus?
SQUAMOS CELLS(non-keratinising)
PROTECTIVE LINING- e.g, against hot temperatures
MUCUS SECRETUNG GLANDs-lubricate food as it goes down
MUSCLES-Upper and Lower Sphincter
What happens to the lining of the Oesophagus on prolonged exposure to Acid?
Squamos epithelium cells change to columnar epothelium cells as these can secrete mucus to protect against the acid
METAPLASIA -change in cell type
What is the eosophical hiatus?
opening in the diaphragm through which the esophagus and the vagus nerve pass.
How is acid reflux prevented by the gastro-eosophagel junction?
- diaphragm pinches at the bottom of the Eosophagus preventing acid from going up
- acute angle between the oesophagus and stomach
- mucosal fold(rugae) in this area that prevents acid going up
- Oesophagus is 2 cm in the abdomen(+ve pressure) and goes through the thorax(-ve pressure) the differential betweent he different pressure means the lower end of the oesophagus in the abdomen is kept in a collapsed state which prevents the acid from going up
- Eosophageal ligaments suspend the juction at a certian angle
What is a Hiatus Hernia?
The Eosophageal Hiatus becomes enlarged=some of the stomach migrates into the chest = Gastro-Oesophageal junction is kept open=Acid reflux
What are the stages of swallowing?
STAGE 0: ORAL PHASE
- chewing and saliva prepare Bolus
- Both Sphincters CONSTRICTED
STAGE 1: PHARYNGEAL PHASE
- Pharyngeal musculature guides Bolus towards the oesophagus
- Both Sphincters OPEN
STAGE 2: UPPER OESOPHAGEAL PHASE
- upper sphincter contracts
- Superior muscle rings contract
- inferior muscle rings dialates
- sequential contraction of longitudinal muscle
STAGE 3: LOWER OESOPHAGEAL PHASE
- Lower sphincter closes as food passes through