1. What is the role of different secretions of the GI tract in digestion and absorption of
nutrients?
2. Alimentary canal
Extends from oral cavity to anus (25-30 feet in length)
o Provides the body with fluids, nutrients, and electrolytes in a form that can be used at the
cellular level
o Disposes of waste products resulting from digestive process
3. Oral cavity
o Chewing mechanically breaks food into small particles, which are swallowed more easily and
offer larger surface area for enzymatic processes
o Food mixes with saliva
Lubricates food bolus for swallowing Initiates starch digestion
4. Esophagus
o Musculofibrous tube H10" long
o Main function
Convey food bolus from pharynx to stomach--peristalsis
o Each end is a sphincter
Upper sphincter prevents air from entering esophagus during inspiration Lower sphincter
prevents gastric acid reflux into esophagus
,5. Stomach
o Serves as a reservoir Can hold 1000mL (6 pack of beer)
o Churns/mixes food with digestive juices
o Secretes mucus, hydrochloric acid, enzymes, intrinsic factor (necessary for vitamin B12
absorption)
o Initiates protein metabolism
o Only alcohol and some medications are absorbed in the stomach
6. Small intestine
o Duodenum, jejunum, ileum
o H20' in length
o Contains numerous glands that secrete Digestive enzymes, hormones, and mucus
o Most digestion and absorption occur in small intestine, including most oral med- ications
7. Large intestine
o Cecum, colon, rectum, anus
o Colon secretes mucus, absorbs water
8. Mesentery
o Double layer of peritoneum that encloses jejunum and ileum & attaches to [posterior]
abdominal wall
o Contains blood vessels, nerves, lymphatic vessels
o Supports and nourishes
o Mesocolon surrounds and nourishes parts of large intestine
9. Momentum
o Double layer fold of peritoneum going from stomach to other organs—large intestine or liver
,o Contains lots of fat
o Protects underlying organs
o Forms adhesions—bands of fibrous scar tissue—to wall off inflamed/ infected underlying
areas
10. Pancrease
o Secretes enzymes for digestion Amylase - breaks down carbs
Lipase - breaks down fats Trypsin - breaks down proteins
o Secretes hormones that regulate glucose metabolism, blood sugar levels Insulin -decreases
blood glucose
Amylin -insulin's friend' helps insulin work stronger - decreases glucagon produc- tion
Glucagon -increased blood glucose by stimulating the increase of glycogen
11. Gallbladder
o Stores and concentrates bile
o Releases bile when fats are in duodenum
12. Liver
o Receives 25-30% of cardiac output
75% is venous blood from Portal System
stomach, intestines, spleen, pancreas Remainder is arterial blood via hepatic artery
o Detoxifies/alters substances
o Oxidation, hydrolysis, conjugation
, o metabolism of CHO, fat, protein
o glucose/glycogen conversion
o Synthesizes vital coagulation factors
o Serves as body's blood reservoir
o Ejects blood into general circulation in response to stress, blood volume, SNS stimulation
o Serves as blood filter and detoxifier
o Most medications are metabolized in the liver, excreted by kidneys
o Few medications activated with liver metabolization
13. The liver and bile
Formed continuously Carried to the gallbladder for storage
Contains bile salts, cholesterol, bilirubin, fatty acids, electrolytes Bile salts required for
digestion/ absorption of fats Reabsorbed/reused by liver; some excreted in feces
14. How is the gastric mucosal barrier made and how does it protect the stom- ach lining
Prevents stomach cells from being autodigested by acid and pepsin
Tight junctions between epithelial cell to prevent acid penetration
Mucosal cells produce a gel like mucus layer that covers gastric cells providing
barrier
Mucosal cells release bicarbonate ions to create normal pH [7] near gastric cells
Prostaglandins --increase blood flow, mucus production and bicarbonate ion secre- tion
15. How is stomach acid produced
Parietal cells secrete H+ into stomach lumen in exchange for K+ through proton pump [H+/K+
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller gradexam. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $17.99. You're not tied to anything after your purchase.