| Question |
Answer |
| What increases the surface area? |
Chewing, bile, peristaltis, denaturing of proteins |
| Salivary anylase |
begins to digest starch (carbohydrates) into smaller sugars |
| Lingual lipase |
Minimal digestion of lipids (most prevalent in infants) |
| Bolus |
Food + Saliva |
| What is swallowing regulated by? |
The medulla oblongata |
| Peristaltis |
wavelike motion moving blus from mouth to stomac |
| Gastroesophgeal sphincter |
Lies between the esophagus and stomac. Prevents reflux of stomac content into esophagus. (GERD) |
| Stomac |
J shaped organ between esophagus and small intestine |
| Size of empty stomac |
1\4 cup |
| size of fully stretched stomac |
about 6 cups |
| Four main regions of the stomac |
Cardia, Fundus, Body, Antrum |
| Cardia |
Receives bolus from esophagus |
| Body |
Gastric juice production |
| Antrum |
Distal pyloric region - grinds and mixes food with gastric juice |
| Chyme |
Partially digested food |
| Neck Cells |
Secrete mucus and bicarbonate |
| Parietal Cells |
Secrete HCl and intrinsic factor |
| Cheif Cells |
Secrete pepsinogens |
| Enterpendocrine Cells |
Secrete Hormones |
| G Cells |
secretes gastrin. It works in conjunction with gastric chief cells and parietal cells. |
| Gastric Juice Contains |
Water, Electrolytes, Instrinsic Factor (B12 absoprtion), Hydrochloris Acid, Enzymes, Mucus |
| Pepsin |
Pepsin is an enzyme that is released by the chief cells in the stomach and which degrades food proteins into peptides. |
| Gastric Lipase |
Digests short and medium chain triglycerides |
| What digests proteins in the presence of HCl? |
Gastrin |
| Digestion of lipids is? |
Gastric lipase |
| How long does gastric emptying take? |
1-6 hours |
| Will liquid meals or solid meals take longer to digest? |
Solid meals |
| Will big meals or small meals take longer to digest? |
Small meals |
| Gastric Emptying: Fastest macronutrient to slowest |
1. Starch or carbs 2. Protein 3. Fat 4. Fiber |
| What delays gastric emptying? |
High-fat meals, soluble fiber, monosaccharides, salts |
| What speeds up gastric emptying? |
Large amounts of chyme |
| True or Flase: the small intestine is the primary site for digestion but not absorption? |
False: it is the primary site for digestion AND absorption |
| Duodenum |
The duodenum is largely responsible for the breakdown of food in the small intestine. Chyme first enters from pyloric sphincter; 0,5m long |
| Jejunum |
Nutrients are absorbed; middle section of small intestine; 2-3m long |
| Ileum |
Connects to large intestine through ileocecal sphincter. The function of the ileum is mainly to absorb vitamin B12 and bile salts and whatever products of digestion were not absorbed by the jejunum. ; 3-4m long |
| Four layers of the small intestine |
1. Mucosa 2. Submucosa 3. Muscularis Externa 4. Serosa |
| Mucosa |
Innermost mucus membrane; Produces and releases enzymes, hormones, digestive juices (bicarbonates); This layer comes in direct contact with the food (or bolus), and is responsible for absorption and secretion, important processes in digestion. |
| Submucosa |
Dense connective tissue which regulates secretions from mucosal glands, mucosal mouvement and blood flow |
| Muscularis externa |
Two layers of muscles responsible for peristaltis |
| Serosa |
Membrane protective coating |
| What is another word for microvilli |
Enterocyte |
| For how long are the microvilli active before being sloughed off and replaced byt those in the crypts? |
3-5 day |
| How much of the necessary energy is |
|
| Does the GI tract atrophy after a few days of starvation? |
yes! Optimal GI function needs a constant supply of food rather than fasting or binging. |
| Aminopeptidase |
Digests PROTEINS secreted from BRUSH BORDER of small intestine secreted into SMALL INTESTINE |
| Dipeptidase |
Digests PROTEINS secreted from the BRUSH BORDER and secreted into the SMALL INTESTINE |
| Enteropeptidase |
Trypsinogen is secreted by the BRUSH BORDER into the SMALL INTESTINE |
| Sucrase |
Digests CARBS secreted from the BRUSH BORDER and into the SMALL INTESTINE |
| Maltase |
Degiests CARBS secreted from the BRUSH BORDER and into the SMALL INTESTINE |
| Lactase |
Digests CARBS secreted from the BRUSH BORDER into the SMALL INTESTINE |
| Dextrinase |
Digests CARBS secreted from the BRUSH BORDER into the SMALL INTESTINE |
| Salivary amylase |
Digests STARCH secreted from the SALIVARY GLANDS into the MOUTH |
| Lingual Lipase |
Digests LIPIDS secreted from the SALIVARY GLANDS into the MOUTH |
| Pepsin |
Digests PROTEINS secreted from the GASTRIC GLANDS into the STOMAC |
| Gastric Lipase |
Digests LIPIDS secreted from the GASTRIC GLANDS into the STOMAC |
| Pancreatic Lipase and Colipase |
Digests LIPIDS secreted from the PANCREAS and into the SMALL INTESTINE |
| Cholesterol Esterase |
Digest LIPIDS secreted from the PANCREAS and into the SMALL INTESTINE |
| Phospholipase A2 |
Digests LIPIDS secreted from the PANCREAS and into the SMALL INTESTINE |
| Pancreatic Amylase |
Digests CARBS secreted from the PANCREAS and into the SMALL INTESTINE |
| Carboxypeptidase |
Digests PROTEINS secreted from the PANCREAS and into the SMALL INTESTINE |
| Elastase |
Digests PROTEINS secreted from the PANCREAS and into the SMALL INTESTINE |
| Collagenase |
Digest PROTEIN secreted from the PANCREAS and into the SMALL INTESTINE |
| Gastroesophageal sphincter |
junction of the stomach and the esophagus; prevents gastric juice from flowing back into the esophagus |
| Pyloric Sphincter |
The sphincter by which chyme is released into the small intestine |
| Hormone Regulation of the Stomac |
1. Gastrin 2. Motilin |
| Gastrin |
Starts to be secreted by the site, smell or thought of food. The presence of partially digested food causes gastrin to be released by the G cells |
| Functions of Gastrin |
Stimulates the HCl and Pepsinogen secretion. Increases gastric motility. Gastrin is released until pH is sufficiently low. |
| Motilin |
Secreted in response to bile and pancreatic juice in duodenum |
| Function of Motilin |
Increases gastric motility (gastric emptying) in stomac and increases motility in the small intestine to produce peristaltis |
| Secretin and CCK |
Secreted by the pancreas in response to the acidic chyme in the duodenum. Cause pancreas to secrete pancreatic juice containing bicarbonate. Opposes the action of gastrin. |
| Pancreatic Juice |
Secreted from pancreas through pancreatic duct to duodenum |
| Endocrine cells secrete what? |
Insoline and Glucagon |
| Exocrine cells secrete what? |
Pancreatic juice - Bicarbonate, Electrolytes, digestive enzymes |
| What percent of nutrients are digested by pancreatic enzymes? |
Allot! 80% |
| Main function of the LIVER |
Produces bile which is made from cholesterol |
| Function of GALLBLADDER |
Concentrates and stores bile |
| Gallstones |
Over concetrated bile that precipitate |
| How does CCK effect the gallbladder? |
Stimulated it to contract |
| Why do we need bile? |
To absorb lipids; acts as a detergent to emulsify the lipids |
| 95% of the secreted bile acids and bile salts are reabsorbed where? |
Small Intestin - ileum |
| How many diffrent types of bacteria in the large intestin |
Over 400 |
| Pancreatic Juice |
Secreted from pancreas through pancreatic duct to duodenum |
| Endocrine cells secrete what? |
Insoline and Glucagon |
| Exocrine cells secrete what? |
Pancreatic juice - Bicarbonate, Electrolytes, digestive enzymes |
| What percent of nutrients are digested by pancreatic enzymes? |
Allot! 80% |
| Main function of the LIVER |
Produces bile which is made from cholesterol |
| Function of GALLBLADDER |
Concentrates and stores bile |
| Gallstones |
Over concetrated bile that precipitate |
| How does CCK effect the gallbladder? |
Stimulated it to contract |
| Why do we need bile? |
To absorb lipids; acts as a detergent to emulsify the lipids |
| 95% of the secreted bile acids and bile salts are reabsorbed where? |
Small Intestin - ileum |
| How many diffrent types of bacteria in the large intestin |
Over 400 |
| Does the large intestin take part in digestion? |
No! Fermentation |
| How many hours does it take to pass material through the large intestin? |
12-70 |
| What does the large intestin ferment? |
Carbohydrates and proteins |
| What is the result of this fermentation? |
Short chain fatty acids and gas (colonic salvage) |
| LI fermentation may occur due to what? |
Lactase or other enzyme deficientcy, consomption of soluble fiber, sugar alcohol, olestra or large quantities of sucrose or fructose, pancreatitis, IBS, Celiacs, Cystic fibrosis (over production of mucus) |
| What happens when the fat is not absorbed and excreated in our stools? |
They float |
| What is a common sign of pancreatitis? |
Floating stools |
| Absorption mechanisms |
1. Passive diffusion 2. Facilitated diffusion 3. Active transport 4. Pingocytosis |
| Passive Diffusion |
Crosses the membrane freely, moving from higher concentration to lower concentration |
| Facilitated Diffusion |
Able to cross cell membrane using a carrier (transport protein) |
| Active Transport |
Requires a carrier and energy expenditure (from ATP) |
| Pinocytosis |
Cell membrane engulfs large molecule to move into cells |
Beef Production
