Nutrition Test 2 (Chapter 3) - Shannon Crosby

how food travels through GI tract

- Food moves from one organ to the next by propulsion. Various sphincters along the way allow food to pass 1) begins in mouth 2) once chewed (mastication), the tongue rolls it into a bolus 3)tongue thrusts it into the pharynx to be swallowed, it then enters the esophagus through the upper esophageal sphincter 4) it then enters the stomach through the lower esophageal sphincter by peristaltic movements 5) LES keeps food in stomach

gastric juice

- HCL: destroy active proteins & harmful bacteria & viruses, and converts pepsinogen to pepsin - Protease: protein digesting enzyme that attacks bonds and breaks them into shorter chains - Pepsin: digests protein - Gastric lipase: digests fats - GIP: slows down emptying of stomach

diarrhea

abnormally frequent passage of watery stools

amylase

an enzyme that converts starch and glycogen into simple sugars

sphincter

circular rings of muscle that open and close in response to nerve input

where FAT is digested and absorbed

gastric lipase (stomach), pancreatic lipase (pancreas), lipase

Where does digestion and absorption occur?

gastrointestinal tract

constipation

infrequent passage of dry, hardened stools

accessory organs

liver, gallbladder, pancreas, salivary glands

pH of stomach

lower than that of other organs because of HCL; acidity is higher

organs of GI tract

mouth, pharynx, esophagus, stomach, and small/large intestines

passive diffusion (absorption in SI)

movement from high to low concentration

where PRO is digested and absorbed

pepsin (stomach), pancreas, di/tripeptidase

absorption

process of moving nutrients from GI tract into circulatory system

active absorption (in SI)

protein carrier & energy is used to move nutrients against a concentration gradient

facilitated diffusion (absorption in SI)

protein carriers move nutrients

where CHO is digested and absorbed

salivary amylase (saliva), maltase, lactose

role of mucus

secretion produced throughout the GI tract that moistens and lubricates food and protects membranes

Chyme

semiliquid, partially digested food mass that leaves the stomach and enters the small intestine

Bolus

soft mass of chewed food

ulcer

sore or erosion of the stomach or intestinal lining

ileocecal valve

sphincter that separates the small intestine from large intestine

Feces (stool)

- waste produced in the large intestine - consists of the undigested food residue, as well as sloughed-off cells from the GI tract and a large quantity of bacteria - 75% water, 25% solids

segmentation v. peristalsis

- Segmentation: muscular contractions of the small intestine that move food back and forth, combining it with digestive juices - circular muscles - Peristalsis: forward, rhythmic motion that moves food; mechanical digestion- longitudinal muscles

Endocytosis (absorption in SI)

- absorptive cell engulfs particles or fluid to form a vesicle which is taken in by the cell - 2 types 1) phagocytosis (solid) 2) pinocytosis (liquid)

pepsin

- active form of pepsinogen - begins the digestion of proteins in the stomach

colon

- another name for large intestine - subdivided into ascending, transverse, descending, sigmoid

cecum

- beginning of large intestine - receives waste from small intestine

heartburn

- burning sensation in the middle of the chest; involves esophagus - occurs in lower esophageal sphincter - acidic gastric juice from stomach flows back into esophagus (GERD - 2x or more a week) - 50% US adults

liver

- carbohydrate metabolism, produces proteins, and manufactures a yellow-green bile to break down fat (bile makes the feces a color) - removes and degrades toxins

protease

- classification of enzymes that catalyze the hydrolysis of proteins - protein-digesting enzymes

lipase

- digests fat - secreted by chief cells

nutrients in lymph system

- fat soluble nutrients and long chain fatty acids - later enter blood stream via lymph to thoracic duct which connects to the blood; then to liver/body tissues

rectum

- final 8 inch portion of large intestine - mass is pushed into rectum by peristaltic waves

celiac disease - treatments and symptoms

- genetic disease in which a hyperimmune response damages the villi of the small intestine when gluten is consumed - treatment: gluten-free diet symtoms: reoccurring abdominal bloating, cramping, diarrhea, gas, fatty and foul-smelling stools, weight loss, anemia, fatigue, bone or joint pain, and even a painful skin rash called dermatitis herpetiformis

Bile

- helps digest dietary fat - made in liver - absorbs A, D, E, K

gastrin

- hormone triggered by thoughts and presence of food - Prepares body for protein digestion - Increase HCl and pepsin to act upon the protein - released from stomach and upper duodenum

GIP (Gastric Inhibitory Peptide)

- inhibits the secretion of stomach acid and enzymes - slows down gastric emptying (1tsp. at a time) to prevent ulcers - realize in small intestine

small intestine - 3 parts & functions

- long, coiled chamber that is the major site of food digestion and nutrient absorption - 3 parts: duodenum (most digestion - 10in), jejunum (most absorption - 8ft), ileum (prepare food to be waste; bile reabsorbed here - 12 ft) - extends from pyloric splinter to valve at the beginning of the large intestine

large intestine - parts

- lowest portion of the GI tract, where water and electrolytes are absorbed and waste is eliminated; forms fecal matter; houses beneficial bacteria - parts: cecum, ileocecal valve, colon (ascending, transverse, descending, sigmoid), rectum

pancreas

- makes bicarbonate (neutralizes acidity), digestive enzymes (lipase, protease) - pancreatic amylase digests starch - pancreatic lipase digests fat - proteases digest protein

stomach - functions & layers

- mix food with various gastric juices to chemically break it down into smaller and smaller pieces - 4 layers: goblet cells and gastric pits, parietal cells, chief cells, and mucus - gallon size when full, cup size when empty

Digestive System

- movement, secretion, digestion, absorption, transportation, storage, elimination -role in immunity - 23 ft long muscular tube with primary and accessory organs

upper esophageal sphincter

- muscular ring located at the top of the esophagus - opens once food passes through the pharynx; allows bolus to enter into the esophagus

lower esophageal sphincter

- muscular ring located between the base of the esophagus and the stomach - where the esophagus ends - relaxes to allow the bolus to enter into the stomach

bacterial functions

- produces vitamins, ferments undigested and unabsorbed carbs (causes gas), breaks down undigested fiber into amino acids, lubricant for fecal matter, controls pathogens

Gastriontestinal tract

- purpose: digestion (breaking down foods into a form the body can use - mechanical and chemical) - mouth > anus

digestive enzymes

- recreated along GI tract, but most are produced in pancreas

secretin

- release in small intestine - act upon bicarbonate and digestive enzymes

enzymes

- speed of chemical reactions - most important role: accelerate hydrolysis (water breaks the bonds of digestible carbs, fats, proteins, and alcohol) - can be used over and over again - conditions for it to be present 1) compatible enzyme and nutrient must both be present 2) the pH of the environment must fall in the appropriate range 3) the temp of the environment must fall within the appropriate range (98.6)

CCK (cholecystokinin)

- stimulates the release of pancreatic enzymes and bile from the gallbladder - slows GI motility to give digestive enzymes time to aid absorption of nutrients - released in small intestine

gallbladder

- storage center for bile

Villi

- tiny folds and small, fingerlike projections that line the lumen of the small intestine - increase surface area to maximize absorption and help mix the partially digested chyme with intestinal secretions - lined with goblet cells that make mucus

Microvilli

- tiny projections on the villi in the small intestine - "brush border" - trap nutrients and absorb them into the enterocyte interior

nutrients in CV system

- water soluble nutrients (CHO, PRO, Vitamin B, Vitamin C) - short and medium chain fatty acids - absorbed directly into bloodstream - taken to liver via portal vein; leftovers from liver is transported to cells via blood