Gastrointestinal System Flashcards
secretion (n.)
release of enzymes, hydrochloric acid, and hormones to aid in digestion
What are the four processes of the GI tract?
Digestion, secretion, absorption, and motility
motility (n.)
smooth muscle contraction that is necessary to move materials through stomach and intestines
digestion (n.)
breakdown and dissolving of large particles into small particles that can be absorbed
absorption (n.)
transport of small particles across the epithelial layer of intestine into blood or lymph
What are the three pancreatic enzymes that break peptide bonds in proteins?
Trypsin, chymotrypsin, and elastase
What is the function of carboxypeptidase?
Splits off terminal amino acid from carboxyl end of protein
What is the function of amylase?
Splits polysaccharides into glucose and maltose
What are the three disaccharides?
Sucrose, lactose, and maltose
What two molecules make up sucrose?
Glucose and fructose
What two molecules make up lactose?
Glucose and galactose
What two molecules make up maltose?
Two glucose molecules
What is the internal environment?
Blood and plasma (interstitial fluid)
What is the name of the membrane of intestinal epithelial cells facing the lumen of the intestine?
Luminal (brush border) membrane
What is the name of the membrane between intestinal epithelial cells and interstitial fluid (capillaries)?
Basolateral membrane
What is the inactive form of pepsin?
Pepsinogen
What cells release pepsinogen?
Chief cells
What do parietal cells release?
HCl and intrinsic factor
What converts pepsinogen into pepsin?
Hydrochloric acid
What two substances first emulsify fat droplets?
Bile salts and phospholipids
What do bile salts and phospholipids emulsify fat droplets into?
Emulsion droplets
What substances breakdown emulsion droplets?
Bile salts and pancreatic lipase
What are emulsion droplets further emulsified into?
Micelles
Why are fat droplets broken down so much only to be partial reformed?
To allow for rapid diffusion into epithelial cells
Fatty acids are added to triglycerides inside epithelial cells, packaged as _______, and are secreted into the blood.
chylomicrons
What cellular structure adds fatty acids to triglycerides inside epithelial cells of villi?
Smooth endoplasmic reticulum
What activates trypsinogen?
Membrane-bound enterokinase
What is the activated form of trypsinogen?
Trypsin
What’s the volume of the stomach when empty?
50 mL
What is the volume of the stomach when full?
1.5 L
What’s the rate of peristaltic waves in the stomach?
~3 waves/min
What small intestine structure prevents retrograde movement of material into the stomach?
Pyloric valve
Where is gastrin produced?
Antrum of the stomach
Where is CCK produced?
Small intestine
Where is secretin produced?
Small intestine
What are the stimuli for gastrin release?
Amino acids and peptides in the stomach; parasympathetic nerves
What is the stimulus for CCK release?
Amino acids and fatty acids in small intestine
What is the stimulus for secretin release?
Acid in the small intestine
What are the factors inhibiting gastrin release?
Acid in the stomach; somatostatin
Which hormones stimulate acid secretion in the stomach?
Gastrin
Which hormones inhibit acid secretion in the stomach?
CCK and secretin
What effect does gastrin have on stomach acid secretion?
Stimulatory
What effect does CCK have on stomach acid secretion?
Inhibitory
What effect does secretin have on stomach acid secretion?
Inhibitory
Which hormones stimulate stomach motility?
Gastrin
Which hormones inhibit stomach motility?
CCK and secretin
What effect does gastrin have on stomach motility?
Stimulatory
What effect does CCK have on stomach motility?
Inhibitory
What effect does secretin have on stomach motility?
Inhibitory
Which hormone stimulates stomach growth?
Gastrin
What effect does gastrin have on stomach growth?
Stimulatory
What effect does CCK have on bicarbonate secretion in the pancreas?
Potentiates secretin’s actions
What effect does secretin have on bicarbonate secretion in the pancreas?
Stimulatory
What effect does CCK have on enzyme secretion in the pancreas?
Stimulatory
What effect does secretin have on enzyme secretion in the pancreas?
Potentiates CCK’s action
Which hormones stimulate growth of the exocrine pancreas?
Gastrin, CCK, and secretin
What affect does CCK have on bicarbonate secretion in the liver?
Potentiates secretin’s action
What effect does secretin have on bicarbonate secretion in the liver?
Stimulatory
Which hormone stimulates gallbladder contraction?
CCK
Which organs secret bicarbonate?
Pancreas and liver
What pancreatic enzyme digests triglycerides into free fatty acids and a monoglyceride?
Lipase
The enteric nerves in the GI wall synapse with other autonomic neurons. (T/F)
True
Glucose is transported across the basolateral membrane of the small intestine by facilitated diffusion. (T/F)
True.
What enzymes break down carbohydrates/starch?
Salivary amylase, pancreatic amylase, and brush border enzymes
What monomer are carbohydrates/starches broken down into?
Monosaccharides
Where are monosaccharides absorbed?
Luminal epithelial membrane of small intestine
What are the three monosaccharides?
Glucose, fructose, and galactose
What two enzymes begin protein digestion?
HCl and pepsin
What proteases are created in the pancreas?
Trypsin, chymotrypsin, and carboxypeptidase
What protease is secreted by small intestine glands?
Aminopeptidase
What is the inactive form of trypsin, and what activates it?
Trypsinogen, activated by membrane-bound enterokinase (enteropeptidase)
What is the inactive form of chymotrypsin?
Chymotrypsinogen
What is the inactive form of carboxypeptidase, and what activates it?
Procarboxypeptidase, activated by membrane-bound enterokinase (enteropeptidase)
What are the layers of the GI tract?
Mucosa, submucosa, muscularis externa, and serosa
What layers make up the mucosa?
Epithelium, lamina propria, and muscularis mucosa
