9.5 Digestion in the small intestine Flashcards
The imprtance of the small intestine? (1 sentence)
General overview (what are the parts of the small intestine) ?
(Main function)
What is being digested?
How did food enter the small intestine?
Continues the digestion of carbohydrates (started in the mouth, stopped in the stomach due to acidity, and now continuing in the the duodenum), continuing the digestion of proteins (pepsinogen-pepsin –> stops –> typsinogen –> trypsin), first site of lipid digestion
Dudendom
(Digestion of carbs, lipids and proteins)
(acid is neutralized)
(Accessory organs are at work and are involved)
Jejunum
(Digestion continues, but main focus is starting absorbtion)
(Overlapping, digestion is not an immediate stop)
Illeum
(Majour nutrients are absorbed
Food enters by the pyloric spincter relaxing, not all of the chyme is entering at once. (Prevention of overloading, effective digestion of lipids)
What does the Duodenum do? (Not the accessory organs)
releases CCK (Cholecystokinin) hormone
Releases prosecretin (inactive) until it is converted into secretin (active)
What is CCK? (Cholecystokin?)
A hormone released by the lining of the duodenum and released into the blood stream.
1) Signals for the pancreas to secrete various of substances
2) Signals the stomach to slow down the speed of digestion (so that the small intestine can effectively digest fats)
WHat is Prosecretin? What does it turn into?
Prosecretin the inactive version of secretin, and it is secreted from the duodenum before being activiated
1) stimulates the liver to make more bile
2) stimulates the pancreas to releases enymes and biocarbonate ions (which is invovled with neutrazliation)
3) regulates digestive rates (prevents more food from entering the duodenum, before the current batch of food is past the small intestines)
What does the pancreas do?
1) Background information to lipids
2) Is the pancreas part of the digestive track?
3) What does the pancreas secrete (signaled by CCK)
Pancreas is a long, flat organ, an accessory organ that secretes substances to the duodenum through the pancreatic duct.
UNDERSTANDING LIPIDS:
Up until the small intestine, LIPIDS have not been digested (amylase = carbs, pepsin = proteins)
therefore, chyme is “fat-riched”
–> reason why cck ignals for the stomach to slow down, because the small itnestine needs time to digest the lipids
Pancreas is an accessory organ and IS NOT PART OF THE DIGESTIVE TRACK. (chyme does not go in the pancreas)
1) Lipases
2) Trypsinogen (inactive when secreted)
3) Pancreatic amylase
4) Bicarbonate ions (NOT AN ENZYME)
What does pancreatic amylase do?
Continue the breakdown of carbohydrates (diasaccarids into monosaccards)
–> continued from the mouth, because the stomach only digests proteins (acidity stops the salivary amylase)
What is trypsinogen? Why? (FLowchart)
Trysinogen is INACTIVE and is activated by ENTEROKINASE (an enzyme)
Trypsinogen –? trypsin, further breaks down proteins.
WHY?
Before trypsinogen is relased: chyme is very acidic because it is food mixed with gastric juices that contain HCL
–> Prosecretin (hormone released by the duodenum) is activated and turned into secretin which releases biocarbonate ions
–> bicarbonate ions are very basic, and it mixes with very acidic chyme, therefore neutralizing the chyme.
–> less acidic chyme = less acidic environment = pepsin is inactive because it thrives in acidic environments.
–> pepsin stops = no digestion of proteins
–> pancreases releases trypsinogen (activated by entokinasism) and trypsin breaks down proteins and thrives in basic environments.
What affects an enzymes reaction?
1) temperature
-> Generally warmer = faster digestion, but each enzyme has its own optimized environment
2) Acidicity
acidic = pepsin
basic = trypsin
Where is bile made, where is it stored?\
What is the importance of a liver
What is the importance of a gallblader?
Made in the liver, which is the LARGEST internal organ (considered as a gland)
Liver also
-> Detoxifies blood
-> Stores glycogen and fat soulble vitamins
Stored in the gallvladder, which releases bile through the bile duct, gallblader releases bile by squeezing it out (it gets the signal to squeeze bile out when undigested lipids enter the duodenum)
What are ducts in the body?
Ducts in the body are channels that lead from exocrine (substance secreting) glands or organs. They are passages with well-defined walls, through which secretions flow.
What are lipsases? What accessory organs does this involve? Even though it is secreted by the pancreas?
Groups of Enzymes that break down lipids (fats)
–> Small intestine/duodenum is the first site of action of digesting lipids.
Chyme is fat rich = lipids are preset as fat globules (globs/drops)
–> lipases cannot pentrate beyond the surface of the fat blobules (they are too thick)
therefore, liver and gallbladder becomes involved (the 2 OTHER accessory organs, not in digestive track)
–> lipases secreted by pancreas
–> bile is made by liver
–> bile is stored by gall bladder
What is bile? Importance?
A substance that emulsfies fats, which means it breaks fats into tiny droplets (crushing it into liquid)
Allows lipases to have much greater surface area, which increases the lipid digestion, smaller droplets = liapses can pentrate through
