Chapter 4 Flashcards
4 main tissue types in the human body
epithelial, connective, nervous, muscular
What tissue lines the digestive tract?
epithelial
Digestion
Mechanical or chemical breakdown of large ingested molecules into small absorbable molecules
Absorption
The passage of digested molecules across the digestive tract into the inside of the body
Why does the GI tract play an important role in immunity?
Everything inside this tube is external to the human body until it is absorbed
No pathogens inside
Pre-Ingestion Digestive Processes
cutting, mashing, marinades, tenderizing
Mouth
-Mastication increases SA
-Bolus forms
-saliva (lubrication)
Saliva digestion
Salivary Amylase (carbs->starches)
Lingual Lipase (lipids)
Esophagus
-no chemical digestion
-peristalsis (rhythmical, wave-like)
Sphincter btw esophagus and stomach
cardiac sphincter/lower esophageal
Inactive form of pepsin?
pepsinogen
Stomach
-proteins get denatured (digestion)
-not much lipid digestion “Fats Float”
-mixing and churning
-bolus-> chyme
-gastric acid
-secretes intrinsic factor
What activates pepsinogen?
HCL pepsinogen into pepsin
-helps with immunity
-denatures protein
What is in gastric acid?
HCL, H2O, Enzymes
Sphincter btw stomach and small intestine?
pyloric sphincter
Small Intestine
-primary site of digestion and absorption
-pancreas, liver, gallbladder
-3 sections: duodenum, jejunum, ileum
-poly & disaccharides -> monosaccharides
Pancreas
secretes pancreatic juice containing digestive enzymes and bicarbonate into small intestine
Liver
produces bile to aid fat digestion and absorption
Gallbladder
Stores bile which aids in absorption
Sphincter btw Small and Large Intestine?
Ileocecal valve
Large Intestine
-reabsorbing water & electrolytes (Na+ & K+)
-forms & stores feces
-houses most gut microbiota
Where do we see mechanical digestion?
Pre-ingestion digestive processes (mashing)
Mouth (chewing)
Esophagus, Small and Large Intestine (peristalsis)
Stomach (mixing)
Where do we see Chemical Digestion?
Pre-Ingestion Digestive Processes (marinade)
Mouth (salivary enzymes)
Stomach (stomach enzymes)
Accessory organs (enzymes)
Where is a bolus formed?
mouth
Where is chyme formed?
stomach
Why are intestinal secretions, like HCL and different enzymes, tightly regulated/controlled?
-HCL will digest the stomach lining
-protein digesting enzymes could target body proteins
Sphincter of Oddi (Hepatopancreatic Sphincter)
controls where accessory organs dump into the SI
Gastroesophageal Reflux Disease (GERD)
Heartburn
lower esophageal sphincter relaxes or malfunctions contents of stomach flow back into esophagus
Segmentation
-takes place in SI
-back n forth “kneading”
Mass Movements
large peristaltic waves
Olfactory
stimulates salivary glands and other digestive processes
Saliva
contains lubricants, enzymes, and lysozymes
Bile
emulsifies fat (breaks apart into tiny pieces)
Sodium Bicarbonate
-pancreas, small intestine
-neutralizes stomach acid when it reaches SI
Hormones
-stomach, SI, pancreas
-regulate food intake, digestion, and absorption
Flavor =
taste + smell + texture
5 sensations
salty, sour, sweet, bitter, umami
Umami
savory or meaty taste, MSG
What is Intrinsic Factor and why do we need it?
Needed to absorb vitamin B12 in the SI
What foods naturally contain vitamin B12?
animal products
What do villi and microvilli do in SI?
increase surface area
Enterocytes
-special absorption cells in the villi
-live 2-5 days
Protases
Trypsin, Chymotrypsin, Carboxypeptidase
Gastrin
stimulates HCL and pepsinogen production
stimulates gastric and intestinal motility
Secretin
-from SI
-stimulates release of pancreatic bicarbonate in response to acidic chyme in the small intestine
Cholecystokinin (CCK)
-from SI
-stimulates release of pancreatic enzymes and bile from the gallbladder in response to fat in the chyme
Somatostatin
inhibits release of GI hormones, slows gastric emptying, GI motility, and blood flow to the intestine
Enterohepatic Circulation
liver-> gallbladder->small intestine->hepatic portal vein-> liver
bile reused
Where do pancreatic enzymes and bile enter the small intestine?
Alimentary canal at the entrance of the duodenum
What is bile produced from?
water, electrolytes, bile acids, cholesterol, phospholipids and bilirubin
What gets absorbed in the stomach?
mostly drugs, alcohol, some water, some vitamins or minerals
What gets absorbed in the large intestine?
water and electrolytes
How does the gut microbiome impact health?
-crowds out pathogens
-produces antimicrobial substances
-modulates inflammation
-don’t know what optimal gut microbiome looks like
What are some things that can impact the composition of the gut microbiome?
-genetics, aging, stress
-exercise
-geographic location of residence
-medical treatments
-smoking and alcohol decrease microbial diversity
What are probiotics?
bacteria
found in fermented foods like yogurt, kombucha
People shouldn’t take probiotics
What are prebiotics?
food for probiotics
non-digestible carbohydrates (dietary fibers)
apples, bananas, garlic
Heartburn
occasional reflux from fried/fatty foods… relaxes sphincter
too large a meal puts pressure on tube
Contributing factors to heartburn and GERD
obesity, smoking, and alcohol use
How to treat GERD and heartburn?
lifestyle modifications and medicine
What are the 2 most common causes of ulcer formation?
- infection with H. pylori (a bacteria)
- Heavy use of NSAID medications such as aspirin and ibuprofen
What are gallstones?
when cholesterol and bile pigments form crystal-like particles
What are some factors associated with gallstone formation?
overweight, prolonged fasting, rapid weight loss, high-cal low-fiber diet, sedentary lifestyle
Food intolerances
inability to digest a food
lactose and gluten common
Food allergy
cause an immune response
8 most common food allergens
milk, wheat, soy, eggs, fish, shellfish, peanuts, tree nuts
What is gluten?
a protein found in wheat, barley, rye, and possibly oats
Celiac Disease
consumption of gluten causes damage to the intestinal villi
What are some causes of constipation?
-poor fluid intake, poor fiber intake
-excessive fiber consumption
-ignoring the urge to defecate
-medications, laxative abuse
-pregnancy, eating disorders like anorexia nervosa
FODMAPS?
fermentable oligosaccharides, disaccharides, monosaccharides and polyols
When might people avoid FODMAPS?
when they are poorly digested and absorbed and there is gas formation
What is IBS?
Irritable bowel syndrome
more common in women
What is IBD?
group of serious, chronic, intestinal diseases like ulcerative colitis and Crohn’s disease
Crohn’s Disease
-can affect any part of the GI tract
Crohn’s is full-blown
Ulcerative Colitis
only impact the colon
