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Questions and Answers
What is the primary function of the digestive system?
What is the primary function of the digestive system?
During digestion, into what are carbohydrates ultimately broken down?
During digestion, into what are carbohydrates ultimately broken down?
The breakdown of fats (lipids), results in which smaller components?
The breakdown of fats (lipids), results in which smaller components?
During digestion, proteins are broken down into which basic molecules?
During digestion, proteins are broken down into which basic molecules?
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Which of the following is NOT specifically mentioned as a result of the digestive process in the provided content?
Which of the following is NOT specifically mentioned as a result of the digestive process in the provided content?
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What is the primary role of the epiglottis during digestion?
What is the primary role of the epiglottis during digestion?
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Which process is NOT considered part of mechanical digestion?
Which process is NOT considered part of mechanical digestion?
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What is the function of the muscular ring located at the end of the esophagus?
What is the function of the muscular ring located at the end of the esophagus?
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In the context of digestion, what does 'lumen' refer to?
In the context of digestion, what does 'lumen' refer to?
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Which of the following best describes the primary function of the liver in relation to blood?
Which of the following best describes the primary function of the liver in relation to blood?
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What is the main purpose of the GI tract?
What is the main purpose of the GI tract?
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What is the main role of the lymphatic system regarding fluid in tissues?
What is the main role of the lymphatic system regarding fluid in tissues?
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Which of the following best describes the role of saliva?
Which of the following best describes the role of saliva?
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What is the purpose of hydrochloric acid in the stomach?
What is the purpose of hydrochloric acid in the stomach?
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Besides the kidneys, which organs plays a role in the removal of metabolic waste?
Besides the kidneys, which organs plays a role in the removal of metabolic waste?
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What process is best described by nutrients entering the body by crossing the gastrointestinal wall and going into the circulatory system?
What process is best described by nutrients entering the body by crossing the gastrointestinal wall and going into the circulatory system?
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Which term best describes the muscular contractions that move food along the esophagus?
Which term best describes the muscular contractions that move food along the esophagus?
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What is the inactive form of the protein-digesting enzyme produced by the stomach?
What is the inactive form of the protein-digesting enzyme produced by the stomach?
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The process of breaking down larger structures into smaller ones is known as what, and does it require or create energy?
The process of breaking down larger structures into smaller ones is known as what, and does it require or create energy?
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Which of these occurs in the mouth as part of the digestive process?
Which of these occurs in the mouth as part of the digestive process?
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What is the main role of the mucosal cells lining the GI tract?
What is the main role of the mucosal cells lining the GI tract?
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After leaving the heart, deoxygenated blood heading to the lungs has come from what major organ?
After leaving the heart, deoxygenated blood heading to the lungs has come from what major organ?
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Which of the following best describes the role of bile in the digestive process?
Which of the following best describes the role of bile in the digestive process?
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What is the function of the epiglottis during digestion?
What is the function of the epiglottis during digestion?
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What is the immediate product of digestion in the stomach before it is moved to the small intestine?
What is the immediate product of digestion in the stomach before it is moved to the small intestine?
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Which substance is responsible for protecting the stomach lining from the effects of pepsin and hydrochloric acid?
Which substance is responsible for protecting the stomach lining from the effects of pepsin and hydrochloric acid?
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What is the semi-liquid mixture of food and gastric secretions called?
What is the semi-liquid mixture of food and gastric secretions called?
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What is the primary function of bile in digestion?
What is the primary function of bile in digestion?
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Which of the following is NOT a method by which nutrients are absorbed in the small intestine?
Which of the following is NOT a method by which nutrients are absorbed in the small intestine?
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How does the presence of fat in a meal typically affect the rate of stomach emptying?
How does the presence of fat in a meal typically affect the rate of stomach emptying?
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Which organ is responsible for producing bicarbonate, pancreatic amylase, protease, and lipase?
Which organ is responsible for producing bicarbonate, pancreatic amylase, protease, and lipase?
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Which of these best describes the transit time from mouth to the small intestine?
Which of these best describes the transit time from mouth to the small intestine?
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Where does the majority of absorption of nutrients occur in the digestive system?
Where does the majority of absorption of nutrients occur in the digestive system?
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Once absorbed, how do water-soluble nutrients travel to the liver?
Once absorbed, how do water-soluble nutrients travel to the liver?
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How do fat soluble vitamins get transported to the blood?
How do fat soluble vitamins get transported to the blood?
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Study Notes
Course Information
- Course title: Eating and Human Digestion
- Course code: NUTR 1100
- Instructor: Stephanie Gladman, MHSc, RD
- Institution: Langara College
Learning Outcomes
- Recall the anatomy and function of the gastrointestinal tract, including major structures and their roles.
- Describe nutrition-related physiological processes, including digestion, absorption, transport, and elimination, and their roles in delivering and using energy and nutrients in the body.
- Differentiate between water-soluble and fat-soluble absorption, including which system is used and the rationale.
- Describe metabolism processes and the role of using energy and nutrients in the body.
Digestion
- This is the breaking-down of nutrients into their smallest parts.
- Brightspace contains relevant videos and links.
Digestive System - Where Does Food Travel?
- Diagram of the digestive system, labeling the different parts involved in the pathway of food.
Digestive System - Accessory Organs
- Diagram of the digestive system, labeling the accessory organs.
Human Digestion
- The act of breaking down nutrients into their smallest components involves several nutrients. Some examples are: carbohydrates, fats (lipids), proteins, vitamins, minerals, and water.
Human Digestion - Mechanical Digestion
- Involves physically breaking down food into smaller parts using: teeth (chewing), stomach (muscular contractions), and muscular contractions (peristalsis).
Human Digestion - Chemical Digestion
- Enzymes speed up chemical breakdown.
- Acids (hydrochloric acid—gastric juice) break down chemical bonds in food.
Digestive System
- The gastrointestinal (GI) tract is a 30-foot-long hollow tube.
- The lumen is lined by mucosal cells.
- The GI tract supplies the body with constant water and nutrients by secretion of digestive juices and enzymes, digestion of food, absorption of water and nutrients, and the distribution of these absorbed nutrients to circulating blood.
Digestive System Functions
- Each part of the digestive tract has specific functions that are essential for its process, these include:
- Passage of food, temporary storage, digestion of food, absorption of food, and waste elimination.
Mouth-Structure, Enzymes, and Secretions
- Teeth
- Taste buds
- Saliva (1-1.5 liters produced daily), moistens, containing enzymes (salivary amylase).
- Saliva carries taste to taste buds.
- Saliva protects teeth and forms a protective coating over them
Throat (Pharynx) - Structure, Enzymes, and Secretions
- Trachea → lungs
- Esophagus → stomach
- Epiglottis, prevents food from going down the wrong tube.
Esophagus
- Connects the pharynx to the stomach.
- Rhythmic muscle contractions (peristalsis) move food bolus.
- Food passes through a muscular ring to enter the stomach.
- No digestion occurs in the esophagus.
Stomach - Structures, Enzymes, and Secretions
- Temporary storage until processing.
- Mechanical and chemical digestion.
- Gastric glands produce gastric juice containing water.
- Pepsin (inactive form) is a protein-digesting enzyme.
- Kills microorganisms, unfolds proteins, activates pepsinogen to pepsin.
Stomach
- Stomach acid protects the stomach lining from pepsin and hydrochloric acid.
- Chyme is a semi-liquid blend of foods and gastric secretions.
- Chyme leaves the stomach through the pyloric sphincter and enters the small intestine.
Stomach Emptying
- Regulated by chyme and signals from different parts, small intestine, and even the brain.
- Affected by meal size (large meal > small meal > liquid meal), meal composition (fat > fiber and protein > carbohydrates and sugars), and affects satiety.
Small Intestine (Structure, Enzymes, and Secretions)
- The primary site for chemical digestion and absorption.
- Comprised of three parts.
- Accessory organs play a crucial role in this process.
Accessory Organs
- Organs like the pancreas, liver, and gallbladder.
- Pancreas produces bicarbonate, Pancreatic amylase, Protease and Lipase.
- The liver creates bile and stores it in the gallbladder.
Bile's Role
- Emulsifies lipids (mechanical digestion).
- Makes fat particles smaller for enzyme action.
- Lipases break bonds to release glycerol and fatty acids (chemical digestion).
Large Intestine
- Absorbs water and some vitamins.
- Fibre takes action and prebiotics and probiotics are involved in the function of the large intestine.
Rectum
- Storage area for wastes.
- Expels wastes through the anus.
Transit Time
- The time it takes for food to travel from mouth to anus varies depending on multiple factors, including the diet, physical activity level, health status, and use of laxatives.
- Mouth to small intestine (6-8 hours)
- Mouth to large intestine (~40 hours).
Transit Time Impacts
- Diet composition (meat takes longer than fiber/water)
- Physical activity level, Emotional state
- Health status (diarrhea = very fast)
- Use of laxatives
Absorption
- Most happens in the small intestine.
- Once nutrients are digested into their smallest molecules (nutrients), they cross the gastrointestinal wall into the circulatory system.
- Folds, villi, and microvilli in small intestines increase surface area for maximum absorption of nutrients.
Methods of Absorption
- Passive/Simple diffusion
- Facilitated diffusion
- Active transport
Passive Diffusion
- Nutrients absorbed due to a concentration gradient.
- No energy required if the concentration of the substance is higher on one side of the membrane than the other.
Facilitated Diffusion
- Similar to passive diffusion, from high to low concentration.
- No energy required. A special protein carrier is for nutrients across.
Active Transport
- Nutrients absorbed from a low to high concentration by requiring energy and a carrier.
Post-Absorption
- Circulatory/cardiovascular system.
- Urinary system (Waste removal)
Movement of Nutrients
- Water soluble nutrients enter the capillaries in the villi>hepatic portal vein (bloodstream)>liver.
- Fat soluble nutrients enter the lymphatic system > blood.
Circulatory / Cardiovascular System
- Transports nutrients to cells and waste away from cells.
- Consists of heart, blood, and blood vessels.
- Nutrients are absorbed in the small intestine, travel to the liver via the hepatic portal vein, then to the heart through the inferior vena cava, then to the lungs to get oxygen. The oxygenated blood travels to all body cells.
Liver
- Collects absorbed nutrients.
- Stores nutrients.
- Converts nutrients into usable substances.
- Filters and removes harmful substances.
Lymphatic System
- Removes fluid and impurities from tissues into the blood.
- Involved in the immune system, containing immune cells that fight antigens.
- Transports fat-soluble nutrients and waste products.
Waste Removal
- Undigested/unabsorbed materials (feces) exit via the GI tract.
- Kidneys filter excess water and waste, excreting excess as urine.
- Lungs exhale carbon dioxide and water vapor.
- Skin excretes waste through sweat.
Excretion and Waste
- Urine color chart and Bristol Stool Chart are provided as a reference.
Review Differences
- Digestion: food breakdown.
- Absorption: nutrients enter the body.
- Metabolism: what happens to nutrients inside the body.
Metabolism
- The use of absorbed nutrients for energy production and larger structure building.
- Breaking down larger structures to create energy.
Digestive System Summary
- Summary chart of the digestive system with important factors.
Student Independent Activity
- Review the Allergies and Intolerances section.
Outcome Reviews
- Summarizing the key outcomes covered in the presentation.
Participation Activity
- Instructions to participate in a Kahoot!.
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Description
Test your knowledge about the digestive system with this quiz. Explore questions on the primary functions of digestion and the breakdown of carbohydrates, fats, and proteins. Ideal for students looking to reinforce their understanding of digestive processes.
