Nutrition and Energy (Carbohydrate Absorption and Metabolism) Flashcards
What forms of carbohydrate digestion occur in the mouth?
Mechanical digestion: Teeth and tongue
Chemical Digestion: Salivary Amylase
What bonds does salivary amylase break?
Glycosidic bonds
What are the three simple carbohydrates that typically come out of carbohydrate digestion in the mouth?
Maltose, Dextrin and Glucose
If a food has a relatively higher amount of amylopectin over amylose, why will it digest faster?
Because the multiple branches of amylopectin allow enzymes to act upon the molecule at multiple places at once
What forms of carbohydrate digestion occur in the stomach?
Mechanical digestion: Muscular movements (Peristalsis) of the stomach grind food and increase it’s surface area for enzyme action
What happens to the salivary amylase when it reaches the stomach?
The acidic environment inactivates it
Where in the gastrointestinal tract does the most starch digestion occur?
In the small intestine
What enzyme does the pancreas secrete for carbohydrate digestion?
Pancreatic amylase
What carbohydrate digesting enzymes are embedded in the villi of enterocytes? What do they break down?
Maltase - Breaks down Maltose
Sucrose-isomaltase - Breaks down branched chains from starch
How does glucose reach the bloodstream from the intestinal lumen?
Active transport into enterocytes, then facilitated diffusion into the bloodstream
Do resistant starch and soluble dietary fibre get digested and absorbed into the body?
No, they are fermented by gut bacteria (microbiota)
What is the product of microbiota fermentation of soluble fibre and resistant starch? What are it’s benefits?
Short Chain Fatty Acids,
Provide gut cells with energy,
Protect from pathogens and illness,
Protects them from being broken down or becoming cancerous
What are the functions of insoluble dietary fibre?
Regulating bowel motions,
Binding substances such as bile, cholesterol and some minerals for excretion,
Attracts water to stool and prevents constipation
Where does excess glucose end up?
Excess glucose is stored as glycogen in the liver (and some in muscles), and any excess after that is converted into fatty acids and stored in adipocytes.
Between meals, what happens to glycogen?
It is broken down in the liver to maintain blood glucose levels,
It is broken down in muscles to provide muscles with energy
