Purpose of the gut Flashcards
What is the function of the GI system?
Food ingestion Food digestion Food absorption Egesting left over contents Waste product excretion e.g. bilirubin
Outline the basic structure of the GI tract and some features that segment it (do not list organs)
A tube from mouth to anus lined with epithelium making the lumen external to the body.
Several accessory organs excrete into the GI tract.
Sphincters divide the tract up into functional segments
List the sphincters in the GI system.
Upper oesophageal Lower Oesophageal Pyloric Ileum-caecal Anal sphincters
What problem occurs if the lower oesophageal sphincter is not effective?
Reflux
What makes the gut complex?
It needs to be permeable (it has a thin epithelium) to help absorption but resistant to passage of toxins or pathogens into the body.
The contents need hydrating to aid diffusion of food into the body but then needs drying out to stop dehydration and diarrhoea.
Which nervous system controls the gut?
Enteric nervous system
List the accessory organs
Salivary glands
Liver
Gall bladder
Pancreas
What structures does food pass through in the Gi tract (In order of passage)
Mouth (+Tongue ) Pharynx Oesophagus Stomach Duodenum (SI) Jejunum (SI) Ileum (SI) Cecum (LI) Ascending Colon (LI) Transverse Colon (LI) Descending Colon (LI) Sigmoid Colon (LI) Rectum Anus
Which intestine is longer?
Small (majority of absorption is done here so we need a large surface area and good contact time)
What is the longest segment of the small intestine and indicate its length?
350cm- Ileum
Which part of the small intestine is 250cm long?
Jejunum
Which part of the small intestine is the shortest and connects to the stomach?
Duodenum
Which part of the colon is longest?
Transverse (40cm)
The gut converts food into …… , ……… , and …….
Monosaccharides
Small peptides or amino acids
Fatty acids and glycerol
What must the gut keep out or expel?
Toxins must be kept in the lumen.
Expels waste products- bilirubin -excess cholesterol
The stuff that is of no nutritional value
How does the GI tract broadly achieve its function?
port of entry for food Mechanical disruption Chemical digestion Temporary storage Kills pathogens peristalsis absorbs nutrients exit point for waste elimination
What does the mouth do?
Mechanically disturbs food with the teeth to break it down physically
Lubricates and starts chemical disgestion of bollus with saliva/ enzymes
Infection control
After the food leaves the stomach it is called …..
Chyme
Food is liquefied by vigorous contraction of which GI organ?
Stomach
What two areas are seen in the stomach?
Upper area which dictates basal tone and distends as it fills.
Lower area which is more muscle and grinds food by contracting (additional muscularis externa layer here - the inner oblique one seen here)
How does the stomach help food storage?
We eat faster than we can break down food so the stomach distends by receptive relaxation stretching the usually folded rugae. This controls the rate of flow of chyme into the duodenum.
Where else are GI contents temporarily stored in the GI tract other than the stomach?
colon- only evacuated a few times a day.
Saliva contains what enzyme types?
Amylase
Lipase
What is the function of amylase?
Break down starch
