Digestion and Absorption Flashcards
(30 cards)
What/where are Chief cells?
Found in the stomach
Release lipase
Release pepsinogen (precursor to pepsin)
What/where are parietal cells?
Found in stomach
Release intrinsic factor (for B12 absorption)
Release HCL
Functions of HCL
Denatures proteins
Kills pathogens on foods
Activates pepsinogen to pepsin (breaks down proteins)
Activates intrinsic factor
What/where are mucus cells
Release mucus from stomach lining to protect it from HCL
Microvilli
Line the small intestine
Protect the lining of the small intestine
Help w/ nutrient absorption by containing enzymes sucrase, maltase, and lactase
Sections of the small intestine
Duodenum - food continues to break down
Jejunum - major site of nutrient absorption
Ileum - major site of nutrient absorption
Common bile duct
Carries bile from the liver and gallbladder through the pancreas to the small intestine
Cholecystokinin (CCK)
A hormone stimulated by the entrance of fat and protein into the duodenum
CCK then stimulates the release of bile from the gallbladder
Bile
Created in the liver and stored in the gallbladder
In the duodenum bile (containing bile salts) mixes with pancreatic enzymes to speed up digestion and absorption
Helps remove bilirubin produced when the body breaksdown old blood cells
Converts some cholesterol to bile acids which are removed through feces
Enterokinase
Inactive enzymes from pancreas are called zymogens
Enterokinase is a proteolytic enzyme released from the duodenum and activates trypsinogen to trypsin
Reduced w/ SNP and w/ significant microvilli damage (e.g. Crohn’s, Celiac, food allergies or sensitivities, immune-compromised)
Supplemental digestive enzymes can help w/ digestion
Trypsin
Activates other zymogens into digestive enzymes
Ectoenzymes
Oligosaccharides, monosaccharides, and peptidases located in the microvillil
Responsible for final breakdown of carbs (fructose, glucose) and proteins (amino acids)
Bile Salts
Bile salts combined w/ lipase break down fats into free fatty acids which makes them “water-soluble” so they can be absorbed into the lymphatic fluid
Bile salts contain:
Colic acid
Chenodeoxycholic acid
Taurine
Glycine
Cholesterol
Electrolytes
water
Pancreatic lypase
Breaks fats into free fatty acids and monoglycerides w/ help from bile salts that initiate the process
Function/ Sections of the large intestine
Reabsorbs water and ferments starches
Ascending colon
Transverse colon
Descending colon
Fermented starches
During fermentation, prebiotics are converted to butyrate w/ adequate fiber intake
- Feed colonocytes and good bacteria
- Help heal the digestive lining
- Boost the immune system
- Keep cholesterol levels healthy
Soluble fiber
Water-soluble
Attacts water
Reduces cholesterol
Beans, oats, Beta-glucans (yeast, bacteria, fungi), gums, pectins, fruits, veggies
Need 25-35/g of soluble fiber daily
Over 50g/d can prevent fat absorption and inhibit non-fiber absorption increasing sugar and starch levels in the colon
Insoluble fiber
Not water soluble
whole grains, veggies,
Cellulose
Lignans
Non-fermentable fiber
Make up the mass of the stool
e.g. psyllium
Absorption - Passive/simple diffusion
Nutrients move from a high concentration area to a low concentration area
- used for fats (e.g. peanut butter)
Absorption - Facilitated Diffusion
Nutrients move from a high concentration area to a low concentration area ATTACHED TO A LIPID-SOLUBLE PROTEIN CARRIER
- used for carbohydrates
Absorption - Active transport
Moves against the concentration gradient
- used for proteins and ions
Enterocytes
Epithelial cells lining the intestinal wall and contain microvilli
Create tight junctions that allow nutrients to be absorbed but prevent waste and pathogens
What is needed to prevent leaky gut?
- healthy microbiota
- secretory IgA (first line of defense)
- peristaltic movement
- filtration by enterocytes
- healthy mucosal lining
*** glutathione and glutamine