Digestive System Part 1
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2 parts of digestion
Physical breakdown (Chewing) and chemical breakdown (Salivary Glands/Hydrolysis)
What are the resulting molecules and what do they do?
Monosaccharides, fatty acids, AA etc. diffuse into the bloodstream and then diffuse into the cells
Another name for the digestive tract
Gastrointestinal tract (Gut)
True or false, food passes through the tract
True
How long is the digestive tract?
6.5-9m
Another name for chewing
Mastication
Chemical breakdown steps
• Saliva (secreted by salivary glands) • Lubricates mouth • Dissolves food
What is the salivary amylase?
Starch (polysaccharide) digestion into disaccharides Ex. Maltose
What does the food turn into as you swallow?
Bolus
What is the trachea covered by?
The epiglottis (flap of tissue)
What is the esophagus?
A muscular portion of tract between the mouth and stomach
What is the movement in the esophagus?
Muscles contract and relax (peristalsis) moves food down
What is the lower esophageal sphincter?
Muscle at the bottom of esophagus relaxes to let food into the stomach.
Another name for the lower esophagus sphincter
Cardiac sphincter
What happens if the LES is weak?
Acid reflux/heartburn
What does the stomach do?
Uses physical digestion (peristalsis) to push food around the stomach
What is chyme?
When food is mixed with gastric juice
What does mucus in the stomach do?
Prevents damage from stomach acid
What is the chemical digestion in the stomach?
• Gastric juice (contains H2O, mucus, and salts, and pH of 1-3) + (kills bacteria and releases when food is present only) • Pepsin (enzyme in stomach that digests proteins, it hydrolyzes proteins to make polypeptides)
What is HCl and what does it do?
Hydrochloride acid, it kills most bacteria in the stomach
What is the HCl responsible for?
Activating 2 enzymes in the stomach (pepsin and rennin (slows movement of milk through small intestine))
What else is HCl responsible for?
Ulcers (mucus lining is destroyed and heliobacter infects exposed area)
Is there absorption in the stomach?
Yes, not a lot absorption of nutrients yet, but absorbs water, alcohol, and anti-inflammatory drugs
What is at the bottom of the stomach?
Pyloric sphincter