1.5 Functions of the GIT Flashcards
What are the three phases of swallowing
Oral, pharyngeal and oesophageal
What occurs in the oral phase of swallowing?
back of tongue moves up to push the bolus down from the oral cavity to the pharynx
What is the reflex sequence in the pharyngeal phase of swallowing?
Soft palate closes the nasopharynx - larynx moves up against the epiglottis - UOS relaxes - peristalsis wave to oesophagus
What occurs in the oesophageal phase of swallowing and what controls it?
Controlled by the swallowing centre
Strand of circular muscle behind the bolus of food pushing it down and the muscles in front will relax
What is the role of pepsin?
Breaks down proteins into peptides
What are the three types of movements in the small intestine?
Migrating motor complex
segmentation
Peristalsis
What is teh role of pancreatic amylase?
Digest CHO (mainly polysaccharides) into oligosaccharides
What is the role of trypsin and chymotrypsin
hydrolyize proteins
What is the role of pancreatic lipases?
break down lipids into fatty acids and monoglyceride
What is the role of bile salts?
emulsification and absoprtion of lipids, cholesterol and phospholipids
creates better access for lipase to lipids and absorption of lipid products
What are the brush border enzymes in the small intestine and what do they do?
Oligosaccharidases: digest oligosaccharides into monosaccharides
Peptidases: digest oligopeptides tino amino acids
How are monosaccharides, amino acids, fatty acids, cholesterol and phospholipids absorbed in the small intestine?
Monosaccharides and amino acids: specific membrane transporters on epithelial cells of the mucus
Fatty acids, cholesterol and phospholipids: simple diffusion through mucosal epithelial cells
What occurs during mass peristalsis of the large intestine?
A wave of contraction is propagated along the large intestine and occurs 1-3 times a day. During this time the haustra disappear and the colon will remain contracted for a long time before the haustra will re-appear
What are the functions of the myenteric and sub mucosal plexus?
Myenteric: controls motor function
Submucosal: mucosal function of secretion and absorption
How are red blood cells broken down?
Hb –> Globin and Heme –> Bilirubin (macrophage)
Bilirubin joins with albumin in the blood
Once in the liver the bilirubin will be released and join with glucuronic acid to form conjugated bilirubin
This conjugated bilirubin is secreted in the bile into the GIT for excretion
