Digestive System Flashcards
What four processes make up digestive system?
Digestion Secretion Absorption Motility
What are the exocrine secretions of the stomach?
Hydrochloric acid Pepsin Mucus and Intrinsic factor
also produces hormone gastrin
What performs most digestion?
Small intestine through hydrolytic enzymes also absorbs food molecules
What does the small intestine secrete into its lumen?
Water salts mucus into its lumen and the liver/gallbladder secretes bile into it
What does the liver secrete?
Bile salts into SI and Bicarbonate for acid neutralization
pancreas also secretes bicarb
Four tunics of GI wall?
Mucosa: epi +lamina propria + muscularis mucosa
Submucosa: CT + submucosal plexus
Muscularis Ext.: smooth mm. circ and long. myenteric plexus between
Serosa: CT outer layer connects to wall
adventitia is esophagus
What makes up brush border?
microvilli
where does most absorbed fat enter?
Enters the lymph through the lacteal by diffusion and eventually is emptied to thoracic duct and into circulation
What makes up the hepatic portal vein?
Inferior mesenteric vein and splenic vein
What form are carbs mostly ingested as?
Starch, sucrose, lactose
How is cellulose broken down?
In the large intestine by bacteria
What is sucrose made of?
Glucose + Fructose
What is lactose made of?
Galactose + Glucose
What enzyme forms majority of carb digestion in the SI, where does it come from?
amylase in the pancreatic juice
What enzymes are found in the brush border of the SI?
Lactase sucrase maltase and alpha-dextrinase
How is fructose absorbed into SI?
Through facilitated diffusion usihng GLUT-5 and fructose concentration gradient
Glucose and galactose enter SI mucosal epi cells through ___.
SGLT-1
secondary active transport uses ATP allows complete absorption
How do fru glu and gal move from interstitial fluid into blood?
Using GLUT-2 facilitated diffusion
What enzymes in SI produce peptide fragmentws?
trypsin and chymotrypsin pepsin
What breaks peptide fragments into free amino acids in SI?
pancreatic enzyme carboxypeptidase and aminopeptidase
How do free amino acids enter epithelial cells?
sodium co transport
How do chains of 2-3 amino acids enter cells?
secondary active transport coupled to H
How do amino acids move from cells to interstitial fluid?
facilitated diffusion
How are most lipids ingested?
Triglycerides
can’t be absorbed need to be broken down by lipase
