Unit 7: The Small Intestine (Module 3)

duodenum, jejunum, ileum

three regions of the small intestine

epithelium, lamina propria, muscularis mucosae

three layers of the mucosa

absorption

the epithelium of the mucosa is specialized for…

brush border enzymes

enzymes that are located in the cell membrane to assist with breakdown.

maltase, lactase, peptidases, nucleosidases, enterokinase

examples of BBE

fatty acids, amino acids, and sugars move across cells into the ____

lamina propria

blood; lacteals

after passing through to the lamina propria, sugars and amino acids enter the ____ while fats enter ____

muscularis mucosae

layer that moves villi to mix chyme

salivary amylase

Which enzyme(s) are found in the mouth to digest carbohydrates (if any)?

none

Which enzyme(s) are found in the stomach to digest carbohydrates (if any)?

pancreatic amylase

Which enzyme(s) are found in the small intestine lumen to digest carbohydrates (if any)?

maltase, lactase

Which enzyme(s) are found in the brush border enzymes to digest carbohydrates (if any)?

none

Which enzyme(s) are found in the mouth to digest protein (if any)?

HCl, Pepsin

Which enzyme(s) are found in the stomach to digest protein (if any)?

carboxpeptidase, chymotrypsin, trypsin

Which enzyme(s) are found in the small intestine lumen to digest protein (if any)?

peptidases (enterokinase)

Which enzyme(s) are found in the brush border enzymes to digest protein (if any)?

none

Which enzyme(s) are found in the mouth (and active) to digest lipids (if any)?

lingual lipase

Which enzyme(s) are found in the stomach to digest lipids (if any)?

bile, pancreatic lipase

Which enzyme(s) are found in the small intestine lumen to digest lipids (if any)?

none

Which enzyme(s) are found in the brush border enyzmes to digest lipids (if any)?

none

Which enzyme(s) are found in the mouth to digest nucleic acids (if any)?

HCl

Which enzyme(s) are found in the stomach to digest nucleic acids (if any)?

ribonuclease, deoxyribonuclease

Which enzyme(s) are found in the small intestine lumen to digest nucleic acids (if any)?

nuclfosidases

Which enzyme(s) are found in the brush border enzymes to digest nucleic acids (if any)?

segemntations

motility of the small intestine where circular muscles constrict and relax to mix; stimulated by distention (pressure on wall) and initiated by myenteric plexus

peristalsis

motility of small intestine that moves chyme toward the large intestine; referred to as the migrating motility complex (MMC)

90-120 minutes

how long does it take to travel the entire length of the migrating motility complex?

circular and longitudinal

which layers are used for peristalsis?

parasympathetic

nervous system that increases movements

sypathetic

nervous system that inhibits movements

peristaltic rush

over distention or irritant cause rapid movements; chyme move swiftly into the large intestine, not allowing time for reabsorption and causing diarrhea

90%

____% of nutrient absorption occurs within the small intestine

10%

___% of nutrient absorption takes lace in the large intestine and stomach

facilitated diffusion

fructose is absorbed through the apical surface via…

secondary active transport; Na+

glucose and galactose are absorbed through the apical surface via ____ with ___

active transport; secondary active transport, Na+

amino acids are absorbed through _____ or _____ with ___

secondary active transport, H+

dipeptides are absorbed through _______ with ___

dipeptides and tripeptides

___ & ___ are broken down within the cell once passing the apical surface

simple diffusion

fatty acids and monoglycerides enter the epithelium via ____

triglycerides; chylomicron

once inside the cell, new ____ are formed. The triglycerides are packaged with phospholipids and cholesterol, which are then surrounded by a protein coat forming a complex known as a _______

lacteals

what are lipids absorbed into?

mucosa of small and large intestines

where are electrolytes absorbed?

PTH, aldosterone, calcitriol

what are some regulatory factors for electrolyte absorption?

A,D,E,K

what are the fat soluble vitamins?

B and C

what are the water soluble vitamins?

diffusion

how are vitamins transported into the bloodstream (except B)?

presence of lipids and bile

what are the regulatory factors for fat soluble vitamins?

intrinsic factor; active transport

for vitamin B to be absorbed, ____ is needed. It is done via ______

osmosis

water enters the epithelium of the small intestine via _____

electrolytes

water follows the absorption of _____

small intestine

most water reabsorption occurs in the ______

large intestine

whatever water reabsorption doesn’t take place in the small intestine happens in the ______