overview: digestion and absorption nfsc 303 mccafferty
Post on 21-Dec-2015
225 Views
Preview:
TRANSCRIPT
Overview:Digestion and Absorption
NFSC 303
McCafferty
Digestion & Absorption: Overview
Digestion: breakdown of nutrients in the GI tract– Mechanical and chemical
Absorption: transfer of nutrients through the wall of the GI tract, into circulation
Involved in D&A– GI tract
– Auxiliary organs:
________________________________
Pancreas:
– Exocrine function:
– Endocrine function:
Liver: (many functions…)
– Digestive function:
Gallbladder
–
Digestion Mouth
– Mechanical action: biting, chewing– Chemical action:
• Saliva -• Enzymes –
Esophagus– Passage tube to stomach only– Muscular contractions propel food down
•
Stomach– Mechanical “churning” and peristalsis
– Chemical:
• water
• enzymes
• HCl = –
–
Semi-liquid _______________– Released into small intestine in small
amounts
Small Intestine– Most digestion and absorption occur
here
– Peristalsis and Segmentation• chyme mixed with more enzymes
• bicarbonate (to reduce acidity), and
• bile (involved in fat absorption) “Lower” small intestine:
–
–
Large Intestine (Colon): – Removes excess
water and salts (electrolytes), forms feces.
Rectum and Anus:– Feces is held in
rectum until eliminated through the anus.
Absorption
Most absorption occurs in the small intestine… so let’s go back to the small intestine for a moment…
Small intestine wall – thousands of folds
Nutrients pass through the intestinal cells and then into blood or lymph – Capillaries:
– Lymph vessels:
Now we have all the nutrients on the inside of the body. – In the next section, we’ll learn all about
1)carbohydrates,
2) digestion and absorption of CHO, and
3) utilization of CHO once inside the body.
top related