NTRI 2000 Lecture Notes - Lecture 9: Intrinsic Factor, Chyme, Esophagus

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5 Feb 2017
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NTRI 2000
Lecture 9
Chapter 3: The human body: a nutritional perspective
Digestion
o We use enzymes to break down chemical into things that we can absorb
o Mouth
Components of saliva
Water
Ions including bicarbonate
Antibodies (especially IgA and other antibacterial proteins)
Enzymes (salivary amylase, salivary lipase)
o Esophagus
Muscular tube connecting pharynx (throat) to stomach
Food moves by a series of coordinated contractions known as peristalsis
Esophagus sphincter relaxes, allowing food to enter the stomach. The
sphincter prevents backflow back into the esophagus
If the food does backflow, this is known as heartburn
o Stomach
Large sac for holding food- slows thigs dow, let’s a little go at a tie
Stomach contains gastric juice (water, hydrochloric acid, and enzymes)
and intrinsic factor
Hydrochloric acid- why heartburn burns
o Used to unfold proteins
Intrinsic factor necessary for vitamin B-12 to unfold
Muscle of stomach churns gastric contents into chyme
Dyloric sphincter controls the rate of chyme entering the small intestine
Stomach keeps from digesting itself because the stomach is lined with a
thick layer of ucous so gastric juices do’t coe ito cotact with the
stomach. Also, HCL and enzymes are only released when eating
Aspirin can wear the mucous layer which can cause the gastric
juices to make a hole in the stomach- also known as an ulcer
o Small intestine
Intestinal hormones released
Secretin- releases bicarbonate from pancreas- only releases when
there’s acid there, so it eutralizes the acid
Cholecystokinin (CKK)- releases digestive enzymes from pancreas.
CKK also contracts the gall bladder, bile releases into the small
intestine. Bile is important in the digestion of fats. Bile is made in
the liver.
Pancreas just stores bile
Villi- fingerlike-projections (folds), contains capillaries, purpose is for
more surface area
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