-
a. SMALL INTESTINE
i. __is a C-shaped structure
ii. Jejunum and Ileum
1. explain it?
iii. __ sphincter)
- Duodenum
- Highly coiled region of the small intestine
- loose
- Ileocolic (ileocecal
-
What is completed in digestion?
a. All of digestion is completed in the small intestines, which is the reason why the accessory glands, the pancreas and liver, have to send juices in there
-
Enzymes and Small Intestine
- 1. Not all of the enzymes that work with the small intestine come from the small intestines, or juices
- a. Additions Enzymes from pancreas
- b. Juices from pancreas and liver (sodium bicarbonate and bile, respectively)
-
Most __ in small intestine.
absorption
- i. All the nutrients are absorbed
- ii. Lots of water is absorbed
-
Anything not absorbed is __.
moved to the colon
-
a. Because digestion must be complete in small intestine and because water absorption has to take place, there are modification
What are they?
-
plicae
i. Plicae: circular or pleated folds that distend when chyme starts entering
-
villi
- i. Villi: Simple columnar has undulating waves within the wall
- 1. Villi: fingerlike projections of the lumen
- a. Goes below into submucosa; doesn’t stop at mucosal region
- i. Portion that goes below forms the glands of the small intestine, called the Krypts of Lieberkuhn
-
microvilli
1. Each simple columnar cell, on apical (free) border, have microvilli
-
All modifications do what?
increase SA in the small intestine
-
Krypts of Lieberkuhn
- i. Where you have the intestinal glands
- ii. Produce a variety of enzymes
- iii. Releases hormones
- 1. Chyme entersà distension of small intestineà causes parasympathetic to stimulate release of digestive juicesàenterokinase
-
Enterokinase--hormone like substance
Once there is chyme in the small intestine,
- Released from: small intestine
- function: activates trypsinogen to trypsin
- a. Once there is chyme in the small intestine, pancreas and glands release their material
- i. Trypsinogen (protein-splitting enzyme in inactive form active by enterokinase and forms trypsin)
-
-
What is released by pancreas when chyme enters small intestine?
- ii. Two other zymogens released by pancreas
- 1. Procarboxypeptidase
- 2. Chymotrypsin iii. Both are activated by trypsin
-
CKP
- a. Controls release of bile from the gallbladder and pancreatic enzymes (trypsinogen, chymotrypsinogen) from those structures into the duodenum
- i. Produced by small intestine when chyme enters
- 1. Distension causes parasympathetic stimulation
-
No enzyme in small intestine does what?
functions under acidic conditions
-
What does the environment of hte small intestine require?
- 1. Requires neutralization
- a. Done by secretin, secreted by Krypts
- i. Hormone released by glands of small intestine; travels to pancreasà causes pancreass to release sodium bicarbonate salts, which are going to travel through pancreatic duct and into duodenum and neutralize the chyme
- ii. Due to reaction of acidic chyme coming in (control)
-
Only when chyme enters does hwat?
i. does the hormones be released; secretin is released in response to acidity
-
a. Beauty of the invagination of the submucosa
- i. Design brings the submucosa up into the core of each villus
- 1. Brings capillaries of those two systems close to the area where absorption will occur because absorption is going to go through the simple comlumnar cells into the core
- a. They’ll be picked up by either the lymphatic or blood vascular system
-
Each villus has a __, whose function is to __.
- core of submucosa
- bring blood capillaries and nerves in close proximity to the systems
-
Parts of the Colon
- i. cecum- blind pouch
- 1. In man, off blind pouch is the appendix
- 2. No function; place where undigested seeds and junk can get caughtà appendicitis
- ii. Ascending colon:
- 1. Goes up right side of body until it gets to liver and turns
- iii. Transverse: straight (across abdominal)
- 1. Hits spleen
- iv. Descending
- 1. Down left
- v. When it hits the lower lumbar vertebrae, it makes an S-shaped curveà sigmoid colon
- vi. Rectum
- vii. Anus
-
Core of the Villus
if it were empty
- i. cecum- blind pouch
- 1. In man, off blind pouch is the appendix
- 2. No function; place where undigested seeds and junk can get caughtà appendicitis
- ii. Ascending colon:
- 1. Goes up right side of body until it gets to liver and turns
- iii. Transverse: straight (across abdominal)
- 1. Hits spleen
- iv. Descending
- 1. Down left
- v. When it hits the lower lumbar vertebrae, it makes an S-shaped curveà sigmoid colon
- vi. Rectum
- vii. Anus
-
Colon
Function
Nodigestion
i. Absorption of some necessary water, drugs, some vitamins, and formation of the feces
|
|
