Flashcards in 4.1 Digestive System Nutrient Digestion Deck (53)
Complex carbohydrates must be ________ digested into ________ before absorption into blood
Monomers (glucose, fructose)
What chemicals are involved in carbohydrate absorption in the small intestine?
Pancreatic amylase, brush border enzymes
Brush border enzymes...
Complete the breakdown of starch to individual glucose molecules
First step of protein digestion in small intestine
Proteolytic enzymes are released from pancreas
Enteropeptidase activates ________ to _______, which then activates other proteolytic enzymes
Activated pancreatic proteolytic enzymes break proteins into ______ and ______
Peptides and amino acids
Brush border peptidases break peptides into...
Single amino acids to be absorbed through epithelial cell into blood
Protease proenzymes are activated by....
Bile salts released from the liver and gall bladder emulsify lipid droplets to form....
_________ functions within micelles to digest each ________ into a _________ and ____________
Two free fatty acids
Monoglycerides and free fatty acids enter an _________ _____, while bile says remain in the intestinal lumen to be reabsorbed and recycled.
What happens in the epithelial cells during lipid digestion?
Triglyceride molecules are reassembled... then wrapped / packaged and then exocytosed
In the epithelial cells, lipids are wrapped with protein to form a.....
What happens after chylomicrons are formed?
They are packaged within secretory vesicles and exocytosed grin the cells and absorbed into lacteals
How are lipids absorbed into the blood?
Lymphatic lacteals carry chylomicrons back to blood, circle without going directly to liver
How are packaged lipids absorbed differently than all other nutrients?
Virtually all other blood borne nutrients pass first through the liver before entering systemic circulation
Chylomicrons are taken up by...
Fat cells in periphery
Very bad, similar to chylomicron but made by liver
Released from fat cell (fat keeps most of the triglycerides).. Delivers triglyceride and cholesterol to tissues
Good, released by tissues and returned to liver (moves cholesterol back to gut / bile)
NET REDUCTION IN CHOLESTEROL
Capillary endothelium captures LDLs and HDLs by...
Receptor mediated endocytosis
LDL receptor density is a ____ trait
Higher LDL receptor density is associated with..
Increased LDL clearance rate -> Better cardiovascular health
Amount of HDL production determined by..
Both genetics and lifestyle (Diet and exercise)
Formation of plaques in vessels
Atherosclerosis: Excess LDL accumulates in and around...
Vascular endothelium and smooth muscle cells
What happens after the accumulation of LDL?
Macrophages attempt and fail to clean up the mess.. become "foam cells"
Foam cells are the basis for
An atherosclerotic plaque
Two major risks of LDL accumulation
1) Narrowing of the vessel lumen
2) Clot formation at the site of the atherosclerotic plaque
Phases of Digestion
Anticipatory and preparatory phase initiated by brain
Smell, taste, or thought of food activates...
Hunger due to dynorphin release
ANS, Activates parasympathetic nervous system
-Anticipatory activation of salivary glands and gastric secretions
Food enters stomach for digestion
Stretch receptors in stomach activated by...
Chemoreceptors in stomach activated by...
Increase in pH
Local afferent signals of the stomach
Submucosal plexus and vasovagal reflex
Afferent signals from stomach cause..
Increase in parasympathetic NS, activate gastric secretions and gastric motility
Gastrin (Hormone from G cells) is stimulated by...
Increase in pH, gastric distension, and partially digested proteins
Gastrin is secreted into..
Effects of gastrin
↑ gastric secretions
↑ contraction of lower esophageal sphincter
↑ gastric motility
Relaxation of pyloric sphincter, stimulates growth of stomach mucosa
Food enter duodenum
Intestine speeds / slows food volume coming out of stomach via...
Distention of activates enterogastric reflex
Stretch receptors - Medulla - lowers PNS activity - Reduces gastric motility and gastric emptying
Intestinal phase: Enteroendocrine cells release these two major hormones
Secretion stimulated by..
Increase in secretion stimulated by partially digested proteins and fats in chyme
-Pancreatic enzyme secretion by acinar cells
-Gall bladder contraction
Secretion stimulated by..
Bicarbonate secretion by pancreatic intercalated duct cells and hepatocytes (bile)
Other effects of CCK and Secretin
Inhibit gastric emptying and gastric secretions, respectively and are pancreatic growth factors
Hormone produced by adipose tissue, stimulates satiety center in hypothalamus