Gastrointestinal Flashcards
What are the main components of the ailmentary tract?
Mouth Pharynx Oesophagus Stomach Small Intestine Large Intestine
What are the accessory organs to digestion?
Teeth Tongue Salivary Glands Liver Gall bladder Pancreas
What does the digestion system function to do?
To breakdown and absorb food
What are the two types of ‘digestion’
Mechanical (chewing, mixing and propulsion)
Chemical (Large molecules –> small molecules via enzymes etc)
Describe absorption
Digestion products are absorbed by epithelial cells in the gut from there, nutrients are transferred into the blood, these vessels deliver nutrients to the tissues.
What are the 6 layers of the gut wall in order?
Epithelium Lamina propria Muscularis mucosa Submucosa Muscularis (inner (circular)) (outer (longitudinal)) Serosa
What muscular movement propels food within the alimentary tract?
Peristalsis
Does any digestion or absorption occur in the oesophagus?
No
What is the lower esophageal sphincter and what does it do?
It is a ring of smooth muscle that controls the entry of food to the stomach and preventing acid reflux
What are the 4 main regions of the stomach?
Fundus
Cardia
Body
Pyloris
What occurs in the cardia of the stomach?
Mucus secretion
What occurs in the fundus of the stomach?
Secretion of HCl and enzymes
What occurs in the Body of the stomach?
Secretion of HCl and enzymes
What does the pyloric sphincter do?
controls the exit of chyme to duodenum
What are the 4 main things that occur in the stomach?
- Food storage
- Mechanical digestion
- Chemical digestion
- Peristalsis
What does mucus/mucus surface cells in the stomach do?
Protects the stomach wall from the effects of the stomach acid
What do neck cells produce?
mucus
What do parietal cells secrete?
HCl and intrinsic factor
What do chief cells secrete?
Digestive enzymes (pepsinogen) HCl catalyses conversion to pepsin
What do the enteroendocrine cells do?
The secrete gastrin which stimulates HCl acid production
Is pancreatic juice acid or alkaline? Why is it the pH it is?
alkaline
to buffer acidic chyme
What digestive enzymes does pancreatic juice contain?
Amylase
Trypsin
Chymotripsin
Lipase
What two factors control the release of enzymes in pancreatic juice?
Secretin and CCK
Where is bile produced?
Liver
Where is bile stored?
Gallbladder
What 3 things make up bile?
Water
Bile salts
Bile pigments (billirubin)
What control is bile secretion under?
Hormonal (CCK) causing contraction of gallbladder
What is the stimulus for bile secretion?
Chyme in the duodenum
What are the three parts of the small intestine?
Duodenum
Jejunum
Ileum
Where does most digestion and absorption take place?
Jejunum
What are lacteals?
Lymphatic vessels in the villi
What 3 things increase the small intestines surface area?
Length
Villi
Microvilli
How is mechanical digestion performed locally in the small intestine?
Segmentation
What is segmentation in the S.I.?
Localised non propulsive movement of the gut that mixes chyme and gut enzymes and brings it in contact with the mucosa
What are the 4 main parts of the L.I.?
Caecum, Colon, Rectum, Anus
What are the four subdivisions of the colon?
Ascending, Transverse, Descending and Sigmoid
What occurs in the large intestine?
Final digestion and absorption
Formation and expulsion of faeces
Gas production (bacteria)
How are glucose and galactose absorbed?
Secondary active transport
What is secondary active transport?
The use of ATP and a co transporting molecule (such as sodium)
The sugar and Na must both bind to the transport molecule
How is fructose absorbed?
Facilitated diffusion
