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85 Cards in this Set
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- Back
- 3rd side (hint)
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Digestion |
The process of breaking down food into individual molecules small enough to be absorbed through the intestinal wall |
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Absorption |
The process of moving nutrients from the GI tract into the circulatory system |
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Transport |
The process of moving absorbed nutrients throughout the body through the circulatory and lymph systems |
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What are the accessory organs of digestion?
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Liver, pancreas, gallbladder
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List the five components of the GI tract: |
Mouth |
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Mechanical digestion
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Breaking down food through grinding, chewing, squeezing. |
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Chemical digestion |
Breaking down food through enzymatic reactions |
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Lower esophageal sphincter aka: cardiac sphincter
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Allows a bolus of food to enter the stomach, prevents stomach contents from returning to the esophagus. |
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Pepsin |
Enzyme that begins breakdown of proteins in stomach |
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Goblet Cells
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Secrete musin to create mucus to avoid ulcers; protective |
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Gastric glands
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Secrete gastric juice which contains chief and parietal cells |
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Chief Cells |
Secrete pepsinogens |
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Parietal Cells
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Release HCl & intrinsic factor (absorpstion of B12) |
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Four regions of the stomach |
Fundus |
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Cardia |
Area of cell change |
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Body (of the stomach) |
Food reservoir (1c-1gal) |
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Pylorus |
Part of the stomach that connects to the duodenum |
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Fundus
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Gas chamber
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What is the function of HCl? |
-Activate the zymogen pepsinogen to form pepsin (chief cells) |
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Gastrin
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Hormone secreted by stomach into blood in response to a meal, it returns to the stomach, stimulating muscle contraction and parietal cells to release HCl. |
Secreted from: gastric cells |
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What stimulates the secretion of CCK and secretin into the blood? |
The movement of chyme into the small intestine |
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What do secretin and CCK stimulate? |
The secretion of digestive enzymes and bicarbonate ions from the pancreas into the small intestine. |
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What stimulates the secretion of CCK and secretin into the blood? |
The movement of chyme into the small intestine |
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What does CCK specifically stimulate? |
Contraction of gallbladder, which releases bile into the small intestine |
Secreted from: intestinal wall |
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Salivary amylase |
Secreted by salivary glands, digests starch |
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Pancreatic amylase |
Secreted by the pancreas, digests starch |
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Sucrase
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Enzyme secreted by the small intestine to digest sucrose |
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Maltase |
Secreted by small intestine, digests maltose |
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Lactase |
Secreted by the small intestine, digests lactose |
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Pepsinogen |
Secreted by the stomach, turns to pepsin, begins breakdown of proteins |
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HCl |
Secreted by parietal cells into stomach |
Denatures protein; activates pepsinogen->pepsin
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Intrinsic factor |
Secreted by parietal cells into stomach |
Needed for Vitamin B12 absorption |
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Mucus |
Secreted by gastric glands |
Lubricates and coats mucosa for protection |
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Bile |
Secreted by liver into gallbladder for storage; released from gallbladder into small intestine via common bile duct |
Emulsifies large globules of lipid into smaller droplets |
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Bicarbonate ions |
Secreted by the pancreas through the pancreatic duct into the small intestine |
Raise pH and neutralize stomach acid |
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Intestinal juice |
Secreted by the crypts into small intestine |
Contains enzymes that digest carbohydrate, protein, and lipid |
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Layers of the small intestine from outer to inner |
Serosa Muscularis externa Submucosa Mucosa Lumen |
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Muscularis Externa |
Two layers of smooth muscle: Longitudinal Circular Responsible for GI motility |
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Circular folds |
Folds in the small intestine, resulting in increased surface area |
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Villi |
Fingerlike projections that increase surface area of small intestine even further Each villi contains capillaries and a lacteal for picking up nutrients |
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Microvilli |
cells on the surface of the villi, enterocytes, end in hair-like projections called microvilli |
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How is the large intestine different from the small intestine? |
-Shorter -No villi or microvilli -Does not produce digestive enzymes -Not tightly coiled |
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What is absorbed in the large intestine? |
-water -Electrolytes-Na, K, Cl -biotin and vitamin K |
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What are the parts of the large intestine? |
ascending colon, transverse colon, sigmoid colon, rectum |
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What are the potential benefits of probiotics? |
-Enhance immune system -Decrease bad bacteria -Acidify the colonic pH -Promote excretion of toxic substances -Enhance fecal bulk production |
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How long is food in the small intestine? |
3-10 hours |
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How long is food in the large intestine? |
12-70 hours |
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How is the liver an important accessory organ? |
-Essential in carb metabolism -Produces proteins -Makes bile salts used to digest fats -EtOH metabolism -Removes and degrades toxins and excess hormones |
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What is the importance of the gallbladder? |
-Receives bile from the liver via the common hepatic duct -Concentrates bile -Releases bile into small intestine via common bile duct |
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What is the importance of the pancreas? |
Endocrine: releases hormones to maintain BGL Exocrine: secretes digestive enzymes into small intestine |
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What is peristalsis? |
Mechanical digestion that squeezes food forward through the GI tract |
Uses longitudinal, circular, and diagonal muscles |
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What is segmentation? |
-Shifts food back and forth along the GI tract in the intestines and adds chemical secretions -Allows contact with the surface of the small and large intestine and increases absorption |
Uses longitudinal and circular muscles of the small and large intestine |
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What three conditions must be present for an enzyme to work? |
-Compatible enzyme and nutrient must both be present. -pH of the surrounding environment must fall within the correct range -The temperature of the environment must be optimal |
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What are the four ways nutrients are absorbed? |
-Passive diffusion -Facilitated diffusion - need a carrier protein -Active transport - moving from low to high concentration, need a carrier protein and energy -Endocytosis
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How is water absorbed from the large intestine? |
Passive diffusion |
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How is Na absorbed from the large intestine? |
Active transport |
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What is the enteric nervous system? |
-Meshwork of nerve fibers that innervate the GI tract, pancreas, gallbladder -Monitors stomach contractions after eating and the secretions of the cells in the GI tract |
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Gastric Inhibitory Peptide (GIP) |
Inhibits gastric motility and stomach secretions |
Secreted from: duodenum |
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Peptide YY |
Slows stomach motility |
Secreted from: Ileum |
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Secretin |
Stimulates the pancreas to release bicarbonate ions |
Secreted from: duodenum |
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Ghrelin |
Stimulates gastric motility, stimulates hunger |
Secreted from: gastric cells |
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How are water soluble nutrients absorbed into the body? |
Through GI tract capillaries through the hepatic portal vein to the liver into the cardiovascular system |
E.G. Carbs, amino acids, and water-soluble vitamins |
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How are fat-soluble nutrients absorbed into the body? |
Through the lymph capillaries, into the lymphatic vessels, through the thoracic duct, into the lymphatic system |
E.G. Fat-soluble vitamins, long-chain fatty acids, and proteins |
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What happens when you digest food? |
You go poo poo. |
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Fermentation |
Partial breakdown of sugars that occurs without oxygen |
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Aerobic Respiration |
consumes organic molecules and O2 and yeilds ATP (cellular respiration) |
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Anaerobic Respiration |
Consumes compounds other than O2 |
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Anabolic Reactions |
-Building things up -Requires energy (ATP) |
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Catabolic Reactions |
-Breaking things down -Releases energy (ATP) |
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Insulin |
-Produced by the pancreas -Stimulates protein and glycogen synthesis -Anabolic |
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Glucagon |
-Produced by the pancreas -Stimulates protein degredation, glycogenolysis, and lipolysis -Catabolic |
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Epinephrine |
-Hormone produced by the adrenal glands -Stimulates glycogenolysis and lipolysis -Catabolic |
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Cortisol |
-Hormone produced by the adrenal glands -Stimulates protein degredation and gluconeogenesis |
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What is the first stage of Cellular Respiration? |
Glycolysis - breaks down glucose into two molecules of pyruvate |
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What is the second stage of Cellular Respiration? |
Citric Acid or Krebs Cycle - completes the breakdown of glucose |
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What is the third stage of Cellular Respiration? |
Electron transport and oxidative phosphorylation - accounts for most of the ATP synthesis |
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How do the electrons travel through Cellular Respiration? |
Glucose->NADH->ETC->Products of H2O and CO2 |
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Oxidative phosphorylation |
Accounts for 90% of ATP generated by cellular respiration E.G. Electron transport chain |
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Substrate level phosphorylation |
Produces a smaller amount of ATP E.G. glycolysis and Krebs Cycle |
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What is phosphorylation? |
Addition of a phosphate to a molecule or protein
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Substrate Level Posphorylation |
Synthesis of ATP by the direct transfer of phosphate group from a substrate ADP --> ATP |
-Reaction is catazlyed by kinases -Occurs in glycolysis and Krebs cycle |
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Kinases |
Enzymes that phosphorylate molecules |
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How many ATP does glycolysis produce? |
2 |
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How many ATP does the Krebs Cycle produce |
2 |
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How many ATP does ETC produce? |
up to 34 |
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