Intro to Digestion and Absorption Flashcards
What are the accessory glandular organs?
pancreas , liver and gall bladder
What does the pancreas do?
endocrine cells - islets to secrete insulin and glucagon and exocrine cells are acinar and epithelial cells
What are pancreatic secretions?
2 L of alkaline fluid - bicarb rich and enzymes for intermediate digestion of nutrients, secretions similiar to saliva and is hormonal CCK and secretin
What is Secretin?
27 AA peptide
What is CCK?
contracts gall bladder and sphincter of oddi, 33 AA peptide
What does CCK do?
released due to entry of peptides and fats and stimulates pancreatic secretions such as lipase, amylase, nuclease, proteolytic enzymes
Where are proteolytic enzymes from and how are activated?
pancrease and active in small intestine - involves enterokinase enzyme from mucosa
what is enterokinase?
intestinal brush burder enzyme - activates inactive enzyme precursors
What is the therapeutic use of pancreatic enzymes?
pancreatin orally administered to compensate for defiency and for cystic fibrosis, pancreactectomy or pancreatitis
What is the therapeutic use of digestive enzyme inhibitors?
Orlistat for obesity inhibitor of pancreatic lipase to reduce absorption of fats
Acarbose to inhibit a-glucosidases to delay digestion of starches in diabetic people
Where is bile produced concentrated released?
liver in gall bladder and into small intestine by CCK
what are the functions of bile?
excrete non water soluble substances such as bilirubin and emulsify fats before digestion , bile salts lower surface tension
What is bile made from?
non-polar cholesterol derivative, cholic acids conjugated toglycine, Polar AA and amphiphatic
What do bile salts help to form?
micelles
What does pyloric sphincter allow?
chyme into duodenum and digestion of lipids
What is distinct about small intestine wall?
villi, plicae and microvilli
What are functions of s intestine?
D: mixes chyme and secretions from pancrease
J: chemical digestion and absorption
I: movement of contents to caecum
describe plicae and intestinal villi?
plicae are permenant transverse folds of mucosa and submucosa
intestinal villi of mucosa only
Where are fluid secretory cells in s intestine?
crypts of lieburkuhn - columnar epithelial cells
what are fluid secretions stimulated by in s intestine?
intracellular cAMP levels
What do paneth cells do?
secrete protective enzymes like lysozyme
What do goblet cells and mature columnar epithelial cells do?
mucus, and secrete digestive enzymes like enterokinase
What are common causes of malabsorption?
bile salt low, pancreatic enzyme low, infections, coeliac disease, rapid transit
