Lecture 17 Flashcards
What are the 3 forms of carbohydrates
Starch
Lactose
Sucrose
What enzyme breaks down starch into small polymers
Salivary amylase enzyme
What are polymers broken into in the SI
Disaccharides
What enzyme breaks down polymers into diaccharides
Pancreatic Amylase
Where are brush border cells found
Intestimal lumen
What is the role of brush border cells
Break di into monosaccharides
How is starch broken down by brush border cells
Starch: glucose disaccharides broken into glucose monomers by brush border cells
How is lactose broken down by brush border cells
Lactose: broken by beta-galactosidase (secreted by brush border cells) into its monomers galactose and glucose
How is sucrose broken down by brush border cells
Sucrose: broken by sucrase (secreted by brush border cells) into its monomers glucose and fructose
What happens to the monomers broken down in the brush border cells
Monomers then transported across intestinal epithelium into the bloodstream and absorbed into body cells
What is glycolisis
Cell metabolism
What is the beginning and end products of glycolysis
Glycolytic pathways metabolize glucose into pyruvate
What are the byproducts from glycolisis
Result in formation of energy molecules ADP and NADH
How do galactose and fructose enter glycolisis
Galactose and fructose converted into glucose-6-phosphate and then enter glycolysis
Whats the results of Maltose in the brush border cells and enzyme used to convert it
Maltose = 2 glucose
Converted by enzyme maltase
Whats the result of sucroses in the brush border cells and enzyme used to convert it
Sucrose = fructose + glucose
Converted by enzyme sucrase
Whats the result of lactose in the brush border cells and enzyme used to convert it
Lactose = galactose + glucose
Converted by enzyme lactase
Whats the result of starch in the brush border cells and enzyme used to convert it
Starch = glucose + glucose + glucose …
What deficiency causes celiac disease
Deficiency in lactase causing lactose intolerance
Explain what a lactase deficiency means
Lactose not properly broken into glucose and galactose by lactase
Where does protein digestion begin
Stomach
Explain the 3 steps of protien digestion and AA transportation
- Proteins broken into smaller peptides
- Epithelial cells secrete peptidases to break down larger peptides into individual AAs
- AAs transported throughout body via bloodstream to produce energy (in liver)
Where does lipid digestion begin
Mouth
Where is lingual lipase released and what does it break down
Released from tounge, breaks large fats into smaller components
Where is gastric lipase secreted
Stomach
What is the role of bile salts in lipid digestion
Once in the duodenum, bile salts coat fat droplets, creating aqueous suspension
What is the role of pancreatic lipase in lipid digestion
Pancreatic lipase present hydrolyze triglycerides into smaller components (free fatty acids and monoglycerides)
What happens to fatty acids and monoglycerides in lipid digestion
Fatty acids and monoglycerides absorbed my small intestine for further processing
How do bile salta emulsify fats
Bile salts are amphipathic (hydrophilic and lipophilic) , attraction to water and oil breaks fat globules into fat droplets, further making it easier for enzymes to break down fat
What do fat droplets consist of
Fat globule + bile salt
Where is lipase secreated from
Pancreas
What is the role of lipase in lipid digestion
Breaks triglycerides (from fat droplets) into monoglycerides and fatty acids
How do lipid protiens (specifically chylomicrons) enter circulation
Chylomicrons are too large to cross the capillary wall so are first absorbed into the lymphatic system then re enter circulation via the thoracic duct near the heart
What is ileal chyme
A chemical and particle rich liquid
Where does ileal chyme enter the LI
From the ileum (ileocecal valve)
What is part of ileal chyme
Any unabsorbed nutrients
Hormones and chemical messengers
Soluble fiber (prebiotic)
Insoluble fiber (bulking agent)
Microbes (probiotics and other)
Cellular debris
Excretion products from the liver
What 5 things happen in the LI
- Colonic epithelium absorb water and simple ions
- Resident microbes digest and absorb what chemicals they can
- The resident microbes produce some vitamins
- Resident microbes produce gasses during their digestion and consumption of ileal chyme
- Microbes inter microbial ecosystem and multiply
Explain hedonic vs homeostatic hunger
Hedonic hunger
The drive to obtain pleasure in the absence of an angry deficit
Homeostatic hunger
Increased motivation to eat following depletion of energy sources
