digestion + absorption of nutrients Flashcards
where is the first point of digestion for carbs + what enzyme does this ?
in the mouth
alpha amylase
what cells secrete alpha amylase into the small intestine ?
pancreatic acinarf cells
what enzyme does the lower part of the intestines contain ?
maltase
what secretion is the pancreas involved in ?
- insulin
- somatostatin
- other endocrine hormones
what brakes down starch into maltose ?
1,6-glucosidase
what breaks down starch into glucose ?
a-amylase
what brakes down lactose into glucose ?
lactase
what breaks down sucrose into fructose + glucose ?
sucrase
what is the small intestine made of ?
- doudenum
- jejunum
- ileum
what is found at the base of the small intestines folds ?
tubular invaginations extending to muscular mucosae
what is the name of the crypts of the intestine called ?
lieberkuhn
what are the function of the crypts of lieberkuhn ?
generative + secretory functions
what are the glands found in the upper duodenum ?
what do they secrete ?
Brunner glands
neutral/ alkaline mucous
what is does each mucosal villi ?
- arteriole
- capillary network
- vein
- central lympatic / lacteal
how are monosaccharide digested ?
Na glucose coupled transporter at mucosal surface of villi
taken into the endohelium
energy provided by Na/K ATPase pump at basolateral membrane
glucose leaves via GLUT2 transporter at serosal membrane into the interstitium
flows into the liver
what releases pepsin ?
chief cells
what activates pepsin ?
acid environment in stomach
what pancreatic enzymes are activated in the intestine lumen ?
- carboxpeptidas
- trypsin
- chymotrypsin
what protein breakdown happens in the stomach ?
what enzymes breaks it down ?
protein to polypeptides
pepsins + carboxypeptidases
what protein breakdown happens in the intestine ?
polypeptides to tri + dipeptides
trypsin + chymotrypsin
what are the 2 different ways proteins can cross the mucosal membrane ?
via proton co transports
via sodium coupled amino acid co transports
how do small peptides cross the mucosal membrane ?
what happens once there inside ?
how do they exit into the basolateral membrane ?
via the proton coupled cotransporter
broken down by intracellular peptidase into amino acids
exit via specific facilitated amino acid transport proteins
describe the route of amino acids into + out of the brush boarder
individual sodium coupled proteins enter epithelium via amino acid and sodium coupled co transporter
leave into basolateral membrane via specific facilitated amino acid transport proteins
how is hydrogen maintained outside of the epithelium ?
there is a sodium pump on the mucosal membrane that pumps it back out
describe the absorption of short chain fats + glycerol
can pass through enterocyte
describe the absorption of triglycerides :
- broken down into free fatty acids + monoglycerides
- become embedded in micelles
- passively absorbed into epithelial cells of small intestine
how are cholesterol , phospholipids and fat soluble vitamins digested ?
incorporated by chylomicrons
are then transported into circulation by lacteal
what are mixed micelles composed of ?
bile salts
mixed lipids e.g fatty acids
what are examples of fat soluble vitamins ?
- vitamin A
- vitamin D
- vitamin E
- vitamin K
what are examples of water soluble vitamins ?
- vitamin B group
- thiamin B1
- riboflavin B2
- niacin B3
- pyridoxine B6
- folate / folic acid B12
- biotin
- pantothenic acid
- vitamin C
how are water soluble vitamins absorbed ?
- has its own membrane transport process into the enterocyte
- are absorbed from small intestine
- folate , biotin, riboflavin can be transported across colonic epithelial cells
how are fat soluble vitamins absorbed ?
- carried by micelles to brush border
- leave micelle + diffuse into enterocyte
- inside enterocyte they become incorparted into chylomicrons
- enter blood stream via lacteal
