Digestion and Absorption of Carbohydrates Flashcards
What is digestion and mobilisation?
the process in the alimentary canal by which food is broken up physically, as by the action of the teeth, and chemically, as by the action of enzymes, and converted into a substance suitable for absorption and assimilation into the body.
Is when the liver and muscle do G6p
In feeding both
In fasting only liver muscle ATP
Diff in the structure of starch/glycogen.?
starch Polysaccharide Alpha 1-4. linkages Amylose ( strictly linear chain ) Amylopectin ( branched chain containing alpha 1-6 linkages) glycogen More branched
Both Amylopectin and glycogen have same linkages?
Yes
Alpha 1-6 glucosidase
Cellulose like he’s ?
B 1-4 linkages
Why must food be broken down?
- Only small molecules can pass through
membranes - Digestive systems are adapted to the type
of food the organism uses
Digestion Composed of Two Processes
?
Physical
Chemical
What physical Digestion??
1-Breakdown larger to small
2- Increase surface area
3-Teeth, gizzard, movements of digestive tract
Features of stomach
expandable muscular sac
Pyloric sphincter
Stores food;
Mechanically break down
What Chemical Digestion??
Breaking down complex food
Enzymes
What is the fate of glucose?
Energy production
Storage as glycogen
Steps of working enzymes on Starch & Glycogen..?
1-begins mouth (salivary α-amylase converts starch to smaller polysaccharides called α-dextrins )
2-Pancreatic α-amylase continues digestion of α-dextrins into maltose, maltotriose and oligosaccharides called limited dextrins .
3-maltose, maltotriose, sucrose and lactose continues by disaccharidases attached brush border (microvilli) of intestinal epithelial cells
4-monosaccharides produced are transported into the intestinal cells
Example of enzymes that convert disaccharide to monosaccharides?
Glucosamylase
Sucrase-Isomaltase Complex
Lactase
Function of Glucosamylase?
Begins at non-reducing ends of limited dextrin and sequentially hydrolyzes α-(1- 4) glycosidic bonds to produce glucose.
digest limited dextrin down to isomaltose.
Function of the Sucrase-Isomaltase Complex? (Maltese)
sucrase-maltase site accounts for 100% of intestinal ability to hydrolyze sucrose in addition to maltase activity.
The isomaltase-maltase site accounts for almost all activity to hydrolyze α 1-6 bonds in addition to maltase activity
Function of lactase ?
hydrolyzes lactose and the β-bonds between glucose or galactose and ceramide in glycolipids
If there is a deficiency of lactase what disease will happen?
Lactase inforance
Carbohydrates can’t be digest by human enzymes ?
Dietary Fiber
Cellulose
Example of Dietary Fiber
Can not be digest by human?
Derivatives of lignan (cellulose, hemicellulose, lignin, pectins, mucilages and gums)
Bacterial flora of the colon metabolize the fibers to?
gases(H2,CO2,CH4) and short chain fatty acids.
Fatty acids are absorbed by?
Function of fiber?
colonic cells.
Fibers soften the stool, thereby reducing pressure on the colonic wall and enhancing expulsion of feces
regulation Hormones gastrointestina tract ?
Gastrin
Secretin
Cholecystokinin (CCK)
Functions of Gastrin regulatory?
it triggers the secretion of gastric
juice.
consists hydrochloric acid, break apart fibrous matter in food and kills bacteria, and pepsinogen, which is a precursor of the protein-splitting enzyme pepsin.
increases the motility of the stomach
increases the motility of the upper small intestine and the gallbladder
Function of Secretin regulatory ?
secretin is released into the bloodstream and
stimulates the acinar cells of the pancreas to secrete
water and bicarbonate
By this mechanism hydrochloric is
promptly diluted and neutralized
Secretin also inhibits the secretion of gastrin, which
triggers the initial release of hydrochloric acid into the
stomach, and delays gastric emptying.
Function of cck Hormones?
stimulates the gallbladder
to contract and release stored bile into the
intestine
stimulates the secretion of
pancreatic juice and may induce satiety.
Health Effects of Starch and Fibers?
- protection from heart disease and stroke
1-Soluble fibers bind with bile and thereby lower blood cholesterol levels.
2-Fiber may also displace fat in the diet. - Reduce the risk of type 2 diabetes by
decreasing glucose absorption. - Enhance the health of the GI tract which can
then block the absorption of unwanted particles . - May protect against colon cancer by removing
potential cancer-causing agents from the body - Promote weight control because
complex carbohydrates provide less
fat and added sugar.
*
Harmful effects of excessive fiber
intake.?
- Displaces energy and nutrient-dense foods
- Abdominal discomfort and distention
- May interfere with nutrient absorption
Gastroesophageal Reflux Disease in general
?
mucosal damage produced
by the abnormal reflux of gastric content
into the esophagus
Factors that can aggravate GERD?
– Diet: caffeine, coffee, peppermint, citrus, alcohol , smoking – Position: Bending, straining – Pregnancy -hiatal hernia
What is hiatal hernia??
hiatal hernia
happens when the upper part of the
stomach and LES (lower esophageal
sphincter) move above the diaphragm
What is Celiac Disease ??
serious sensitivity to gluten, which
is a protein found in wheat, rye, and barley.
Eat gluten, and your immune system
goes on the attack: It damages your villi
Symptoms of celiac disease??
children
include abdominal pain and bloating, diarrhea, constipation, vomiting, and weight loss.
adults
include anemia, fatigue, bone loss, depression, and seizures.
What is Crohn’s Disease ?
inflammatory bowel disease (IBD).
commonly affects the terminal ileum, which connects
the end of the small bowel and the beginning of the
colon.
symptoms of Crohn’s Disease ??
abdominal pain, diarrhea, rectal
bleeding, weight loss, and fever.
What is Ulcerative Colitis ??
inflammatory bowel disease. Symptoms
are similar to those of
Crohn’s.
Glucose Absorption types ?
Active
Na+ dependent:
Passive
Facilitated passive
transport known as Glut 1 -4
glucose transporters.
To enter the cells ??
▪ GLUT-1: Enables basal non- insulin stimulated glucose uptake (erythrocytes) ▪ GLUT-2: Transports glucose into beta cells, a pre- requisite for glucose sensing. ▪ GLUT-3: Enables non-insulin mediated glucose uptake into brain. ▪ GLUT-4: Enables much of the peripheral action of insulin (muscles, adipose)
