Gastrointestinal Flashcards
Saliva initiatives the digestion of _____ and ______.
starch and fat
Which salivary gland is a serous gland and is the major source of amylase?
Parotid
Which gland is mostly a mucous gland?
Sublingual
Which gland is a mixed gland that secretes water, electrolytes, and mucin at rest?
Submandibular
The minor salivary glands secrete mostly mucous except for which one?
von Ebner’s gland
The minor salivary glands contribute _____ of total saliva.
5-10%
________ glands are involved with taste and secrete lingual lipase.
von Ebner’s
The pH of saliva is highly buffered at _____.
6.7-7.4
What are some of the inorganic salts that make up saliva?
- Na
- K
- Chloride
- Bicarbonate
Explain salivary fluid secretion mechanism.
Cl- is secreted into the lumen and Na+ slips through tight junctions to follow it
T/F: Secretory ducts are permeable to H2O.
False
Many solutes are reabsorbed in the duct
_______ secretion is effected by flow rate.
Secondary
In the duct. Acinar secretion not effected by flow rate.
_______ is the most abundant protein in saliva.
Mucin
Gives saliva viscosity
_______ initiates the breakdown of starch.
Amylase
Parotid gland
The sublingual and submandibular gland are innervated by ______.
CN VII
The parotid gland is innervated by ____.
CN IX
Parasympathetic stimulation releases _________ onto the acing cells and results in a watery secretion.
acetylcholine
__________ induces PKA-mediated exocytosis resulting in more protein rich saliva.
Norepinephrine
Via sympathetic nerves
__________ is an autoimmune disorder that causes dry eyes, dry mouth, and joint pain.
Sjorgren’s syndrome
Where is the majority of nutrients absorbed into the blood?
Small intestine
What are the five categories of useable food?
- Carbs
- Protein
- Fat
- Vitamins
- Minerals
The _________ are essential for digestion and absorption of carbohydrates.
brush border ectoenzymes
Complex carbohydrates are broken down into __________.
monosaccharides
via digestive enzymes and ectoenzymes
Monosaccharides are passed into blood via ______.
GLUT2
Proteins are broken down into peptides in the _______ and the _________.
stomach and small intestine
________ is produced in the stomach and cleaved to ________ to degrade protein.
Pepsinogen; pepsin
The ________ releases pro-enzymes into small intestine to digest proteins.
pancreas
_______ is an essential protease for cleavage of proteins.
Trypsin
The brush border enzyme, ___________, is used to activate pro-enzymes.
enteropeptidase
Peptides are broken down into _________ which are transported across the epithelial membrane.
amino acids
Where are transporters for amino acids found on the epithelial cells?
Brush border and basolateral membrane
What are the two classes of amino acid transporters?
Na+ dependent
Na+ independent
T/F: Protein is degraded by HCl and proteases.
True
_______ breaks down triglyceride into monoglyceride and fatty acids.
Lipase
What are the three sources of lipase?
- Lingual lipase
- Gastric lipase
- Pancreatic lipase
Fatty acid absorption occurs mainly in the ______.
duodenum
T/F: Fats are not water soluble, but lipase are.
True
T/F: Free fatty acids and monoglycerides are found in systemic circulation.
False
Triglycerides
What are the steps in breaking down and absorbing fats?
- Emulsification
- Micelle formation
- Diffusion monoglycerides and fatty acids
- Formation of triglyceride in epithelial cell
- Exocytosis of triglyceride
Bile salts and ________ are involved in emulsification.
phospholipids
Bile salts and _________ are involved with micelle formation.
pancreatic lipase
Which vitamins are fat soluble?
A, D, E, K
T/F: Fat soluble vitamins passively diffuse through intestinal epithelial cells.
True
Solubilized in micelles
Fat soluble vitamins are released into the body with _________.
chylomicrons
How are almost all water soluble vitamins absorbed into epithelial cells?
Facilitated or active transport
All except for B12
Most water absorption occurs in the ________.
small intestine
What is highest in areas where glucose and galactose or amino acids are being transported?
Absorption of Na+
T/F: Calcium is actively absorbed by all segments of the intestine.
True
T/F: Salts are soluble at high pH.
False
Low pH
The absorption of _____ is strongly enhanced by vitamin D.
Calcium
T/F: Absorption of iron is very efficient.
False
Less than 10% is absorbed
T/F: Both the symp and parasympathetic nervous systems influence the enteric nervous system.
True
What are the three pieces of the enteric nervous system?
- Mucosal plexus
- submucosal plexus
- Myenteric nerve plexus
What types of neurons are in the ENS?
- Motor neurons: muscle contraction and gland function
- Interneurons
- Sensory neurons
What is the difference between a short and long GI reflex?
Short reflex only goes through the GI system.
Long reflex goes through the CNS
Which four hormones play a large role in regulating digestion?
- Gastrin
- CCK
- Secretin
- GIP
T/F: Regulatory hormones often work in feedback loops and have synergistic effects.
True
What is the cephalic phase of GI control?
parasympathetic nerve fibers to the ENS are initiated when receptors in the head are stimulated
What is the gastric phase of GI control?
Neural reflexes and gastrin
What is the intestinal phase of GI control?
Neural reflexes, secretin, CCK, and GIP
The _______ delivers chyme to the duodenum.
stomach
What are the three sections of the stomach?
- fundus
- body
- antrum
What are the two glandular regions in the stomach?
- Oxyntic (funds and body)
2. Pyloric (antrum)
What is secreted in the oxyntic region?
mucus, pepsinogen, HCl
What is secreted in the pyloric region?
mucus, pepsinogen, and gastrin
Which various cells of the stomach secrete which chemicals?
- Parietal cells - HCl and intrinsic factor
2. Chief cells - pepsinogen
T/F: Parietal cells are found in both the oxyntic and pyloric area of the stomach.
False
Oxyntic only
What is secreted by mucous neck cells?
Mucous
____ is the strongest stimulant for HCl secretion.
Histamine
___________ can have direct effects on parietal cells to increase HCl secretion as well as increase histamine release.
Gastrin and Ach
What is the intracellular mechanism for HCl release?
Activation of receptors (gastrin, histamine, ACh) -> second messenger -> H+/K+ anti porter ATPase
Which hormone inhibits HCl secretion?
Somatostatin
Effects G cell and parietal cell
G cells release ______.
gastrin
D cells release _______.
somatostatin
During the gastric phase there is an increase in _______.
gastrin
What stimulates the cephalic portion of HCl control?
Sight, smell, taste of food
When pH of chyme <3, ________ is produced.
secretin
When acid levels are high, ____ will be secreted to lower HCl production.
CCK
Secretin and CCK are __________. They inhibit the secretion or motility in the stomach.
enterogastrones
What does trypsinogen do?
enterokinase in epithelial cells turns it into trypsin which is used to activate intestinal cells
T/F: An increase in intestinal fatty acids and amino acids will lead to an increase in CCK.
True
T/F: An increase in CCK will lead to an increase in secretion of enzymes from the pancreas.
True
Bicarbonate is secreted by the _______.
Pancreas
T/F: An increase in secretin increases bicarbonate secretion.
True
____ strongly potentiates the effects of secretin.
CCK
The ______ produces bile.
liver
T/F: Bile salts are recycled through the enterohepatic circulation.
True
An increase in _____ will lead to gallbladder contraction and bile flow into the duodenum.
CCK
T/F: Peristalsis is a type of muscle contraction that mixes the chyme/bolus in the small intestine.
False
Segmentation
T/F: Segmentation contractions occur during absorption.
True
What type of contractions occur after absorption is completed?
Peristalsis
T/F: Peristalsis is driven by a migrating myoelectric complex.
True
Which intestinal hormone initiates peristalsis?
Motilin
What is the primary purpose of the large intestine?
Actively transport Na+ from the lumen to the blood
Bacterial fermentation of some of the food bolus is done in the _________.
large intestine
How is the chyme moved in the stomach?
Peristalsis from body to pyloric sphincter
Determined by pacemaker cells
How is the chyme moved in the small intestine?
Segmentation and peristalsis
How is the chyme moved in the large intestine?
Slow segmentation contraction
Massive peristaltic like movements
Upon stimulation, _____ levels are increased and this opens the Cl- and K+ channels for saliva release.
Ca2+
Glucose and galactose are brought into the epithelium via ______.
SGLT1
With Na+
Fructose is brought into the epithelial cell via ______.
GLUT5