Secretory Functions of the GI System Flashcards
Two main types of protein secretions
Digestive Enzymes
Mucus (primarily for lubrication)
Four types of Alimentary Tract Glands
Mucous Goblet Cells
Surface Pit Cells
Tubular Glands
Complex Glands
Three things that activate the enteric nervous system
Tactile stimulation, chemical irritation, and distention of the wall of the gut
When the myenteric and submucosal plexuses become activated, this causes ___
general increase in gastrointestinal activity, including secretions
What does the Golgi do with protein enzymes and hormones for secretion?
The Golgi Apparatus refines the proteins and packages them into secretory vesicles.
Two types of stimulation that trigger stimulation of the cell triggers exocytosis of the substance (secretion).
Neural or Hormonal stimulation
Salivary secretions are a combination of these two types of protein secretions
Serous (containing Ptyalin, an Amylase) - Initiates starch digestion
Mucus (containing Mucin) - Lubrication and surface protectant
As the salivary secretion moves through the gland, _____ are reabsorbed or secreted to create the optimal solution.
electrolytes
Saliva production is regulated by the ______ nervous system
parasympathetic
Two main types of stomach glands and their secretions
Gastric Glands, AKA Oxyntic Glands
Hydrochloric acid, pepsinogen, intrinsic factor, and mucus.
Pyloric Glands
Secrete mucus and the important hormone Gastrin.
The lining of the stomach secretes a protective mucus to prevent it being destroyed by the pH, which is between ___ and ___
1.0 and 2.5
Gastric Glands in the stomach and what they secrete (SCEMP)
Surface Mucous cells - mucin
Chief Cells - Pepsinogen
Enterochomaffin-Like Cells - Histamine
Mucous neck cells - mucin
parietal cells - HCL
These two secretions denature proteins
HCL and pepsinogen/pepsin
Two functions of mucus secretions in stomach mucosa
Creates a protective Alkaline gel between mucosa and the strong acid inside the stomach.
Contributes to the lubrication of food for transportation.
Which pump is used heavily in transporting H+ ions into the stomach
Hydrogen potassium pump
______ and ______ stimulate parietal cells
Acetylcholine; Histamine from ECL cells
_____ Stimulates ECL Cells
Gastrin
Where are Gastrin “G” cells found?
Gastrin “G” Cells are found in the Pyloric glands in the Stomach, in the Duodenum, and in the Pancreas
3 Stimulators of Gastrin
The presence of the products of protein digestion in the stomach.
Distention of the stomach.
Vagal nerve stimulation.
Secretion of _____ will cause inhibition of Gastrin Cells
Secretion of Somatostatin from Delta “D” cells, activated by the presence of large amounts of H+.
Pepsinogen is ______ in its secreted form
Inactive
Pepsin is proteolytic, meaning that it ___
digests protein
What is intrinsic factor?
A glycoprotein that is secreted by parietal cells that is required for the absorption of Vitamin B12.
A vitamin B12 deficiency can lead to something called
Pernicious Anemia (macrocytic)
Pancreatic juices flow through the pancreatic duct, then join with the common bile duct at the _____
Hepatopancreatic Ampulla (Ampulla of Vater)
In addition to enzymes, the pancreas also secretes
large amounts of bicarbonate ions
Types of pancreatic secretions and what they digest
Trypsin - Protein Digestion
Pancreatic Amylase - Carbohydrate digestion
Pancreatic Lipase, Cholesterol Esterase and phospholipase - Fat digestion
The secretion of these various digestive enzymes is initiated by three important stimuli
Acetylcholine, Cholecystokinin, and Secretin.
When food enters the duodenum, ____ and ____ are secreted
Cholecystokinin and Secretin
Initially, the proteolytic enzymes (Trypsin, Chymotrypsin, and Carboxypolypeptidase) are in their inactive forms (ex: Trypsinogen), waiting to be activated by ____ in the small intestine
enterokinase
cells in the Pancreatic Acini secrete the substance _____, which prevents activation of _____ inside the pancreas
Trypsin Inhibitor; Trypsinogen
If the pancreas becomes damaged and Trypsin inhibitor becomes overwhelmed, this can lead to ______
Acute Pancreatitis
Amylase or lipase levels at least ____ normal are generally considered diagnostic for acute pancreatitis.
3 times above
Function of Bicarbonate in the pancreas
Bicarbonate makes pancreatic secretions alkali to neutralize the hydrochloric acid
Cell type that secrete bile
Hepatocytes
Bile serves two main functions:
Helps to emulsify, digest and absorb fats from the chyme.
Serves as a way for the body to excrete waste products from the body, like Bilirubin and excess cholesterol.
When Chyme (which contains fat and protein) reaches the Duodenum, _____ secrete Cholecystokinin (CCK).
duodenal epithelial cells
Which substance leads to Gallbladder contraction, Sphincter of Oddi relaxation
Bile and Pancreatic Juice delivery to duodenum
Cholecystokinin
________ are large mucous glands located in the wall of the duodenum between the pylorus and the sphincter of Oddi
Brunner’s Glands
Brunner’s Glands secrete alkaline mucus in order to ___________
protect the duodenal wall from the highly acidic gastric contents entering through the pyloric sphincter.
The flow of electrolytes and water that provides a watery vehicle for the absorption of nutrients from the chyme happens here
Crypts of Lieberkuhn
Secretion of mucus serves what functions in the Colon?
Protects against excoriation
Provides adherent medium for holding fecal matter together
Protects colonic wall from large amount of bacterial activity
