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NUR 339 Test 2
- What is the role of different secretions of the GI tract in digestion and absorption of
nutrients?
- Alimentary canal
Extends from oral cavity to anus (25-30 feet in length)
- Provides the body with fluids, nutrients, and electrolytes in a form that can be used at the
- Disposes of waste products resulting from digestive process
cellular level
- Oral cavity
- Chewing mechanically breaks food into small particles, which are swallowed more easily and
offer larger surface area for enzymatic processes
- Food mixes with saliva
Lubricates food bolus for swallowing Initiates starch digestion
- Esophagus
- Musculofibrous tube H10" long
- Main function
Convey food bolus from pharynx to stomach--peristalsis
- Each end is a sphincter
Upper sphincter prevents air from entering esophagus during inspiration Lower sphincter prevents gastric acid reflux into esophagus 1 / 4
- Stomach
- Serves as a reservoir Can hold 1000mL (6 pack of beer)
- Churns/mixes food with digestive juices
- Secretes mucus, hydrochloric acid, enzymes, intrinsic factor (necessary for vitamin B12
- Initiates protein metabolism
- Only alcohol and some medications are absorbed in the stomach
absorption)
- Small intestine
- Duodenum, jejunum, ileum
- H20' in length
- Contains numerous glands that secrete Digestive enzymes, hormones, and mucus
- Most digestion and absorption occur in small intestine, including most oral med- ications
- Large intestine
- Cecum, colon, rectum, anus
- Colon secretes mucus, absorbs water
- Mesentery
- Double layer of peritoneum that encloses jejunum and ileum & attaches to [posterior]
abdominal wall
- Contains blood vessels, nerves, lymphatic vessels
- Supports and nourishes
- Mesocolon surrounds and nourishes parts of large intestine
- Momentum
- Double layer fold of peritoneum going from stomach to other organs—large intestine or liver 2 / 4
- Contains lots of fat
- Protects underlying organs
- Forms adhesions—bands of fibrous scar tissue—to wall off inflamed/ infected underlying
areas
- Pancrease
- Secretes enzymes for digestion Amylase - breaks down carbs
Lipase - breaks down fats Trypsin - breaks down proteins
- 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
- Gallbladder
- Stores and concentrates bile
- Releases bile when fats are in duodenum
- Liver
- Receives 25-30% of cardiac output
75% is venous blood from Portal System
stomach, intestines, spleen, pancreas Remainder is arterial blood via hepatic artery
- Detoxifies/alters substances
- Oxidation, hydrolysis, conjugation 3 / 4
- metabolism of CHO, fat, protein
- glucose/glycogen conversion
- Synthesizes vital coagulation factors
- Serves as body's blood reservoir
- Ejects blood into general circulation in response to stress, blood volume, SNS stimulation
- Serves as blood filter and detoxifier
- Most medications are metabolized in the liver, excreted by kidneys
- Few medications activated with liver metabolization
- 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
- 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
- How is stomach acid produced
Parietal cells secrete H+ into stomach lumen in exchange for K+ through proton pump [H+/K+
- / 4
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