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Questions and Answers
What is the primary function of the villi and microvilli in the small intestine?
What is the primary function of the villi and microvilli in the small intestine?
What is the role of peristalsis in the digestive system?
What is the role of peristalsis in the digestive system?
Which of the following describes a function of the large intestine?
Which of the following describes a function of the large intestine?
Which statement about the rectum is true?
Which statement about the rectum is true?
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What is the significance of microbial activity in the large intestine?
What is the significance of microbial activity in the large intestine?
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What is the primary function of the accessory organs associated with the alimentary canal?
What is the primary function of the accessory organs associated with the alimentary canal?
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What does mastication refer to in the digestive process?
What does mastication refer to in the digestive process?
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Which of the following processes occurs during chemical digestion?
Which of the following processes occurs during chemical digestion?
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Which term describes the elimination of undigested materials from the body?
Which term describes the elimination of undigested materials from the body?
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What is the end product of lipids during chemical digestion?
What is the end product of lipids during chemical digestion?
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Which activity is NOT part of the functions of the large intestine?
Which activity is NOT part of the functions of the large intestine?
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Which best describes digestion?
Which best describes digestion?
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What is egestion?
What is egestion?
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Which of the following is not considered a metabolic waste?
Which of the following is not considered a metabolic waste?
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Which organ is responsible for excreting carbon dioxide during exhalation?
Which organ is responsible for excreting carbon dioxide during exhalation?
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Which of the following processes involves the breakdown of amino acids to form urea?
Which of the following processes involves the breakdown of amino acids to form urea?
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What is the primary function of the kidneys?
What is the primary function of the kidneys?
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In what form are metabolic wastes primarily excreted from the body?
In what form are metabolic wastes primarily excreted from the body?
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Which part of the excretory system stores urine before it is excreted?
Which part of the excretory system stores urine before it is excreted?
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What substances do the sweat glands allow to diffuse from the blood?
What substances do the sweat glands allow to diffuse from the blood?
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What is the primary role of saliva in digestion?
What is the primary role of saliva in digestion?
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Which of the following structures is NOT part of the digestive tract?
Which of the following structures is NOT part of the digestive tract?
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What is the function of the tongue during digestion?
What is the function of the tongue during digestion?
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Which phase of digestion involves the movement of food through the digestive system?
Which phase of digestion involves the movement of food through the digestive system?
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What role do teeth play in digestion?
What role do teeth play in digestion?
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What is the primary function of the rectum in the digestive system?
What is the primary function of the rectum in the digestive system?
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Which accessory organ secretes enzymes that aid in the digestion of fats, proteins, and carbohydrates?
Which accessory organ secretes enzymes that aid in the digestion of fats, proteins, and carbohydrates?
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What coordinated activity is involved in swallowing?
What coordinated activity is involved in swallowing?
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What is the primary function of the liver related to blood glucose levels?
What is the primary function of the liver related to blood glucose levels?
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Which of the following statements accurately describes bile?
Which of the following statements accurately describes bile?
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What enzyme is NOT produced by the pancreas?
What enzyme is NOT produced by the pancreas?
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Which substance is primarily stored in the gall bladder?
Which substance is primarily stored in the gall bladder?
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What is the primary role of pancreatic juice?
What is the primary role of pancreatic juice?
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How does the liver contribute to hormone regulation?
How does the liver contribute to hormone regulation?
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Which of the following is considered an accessory organ of digestion?
Which of the following is considered an accessory organ of digestion?
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What process is primarily facilitated by the emulsifying action of bile?
What process is primarily facilitated by the emulsifying action of bile?
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What role does the soft palate play during swallowing?
What role does the soft palate play during swallowing?
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How long does food typically take to pass through the esophagus to the stomach?
How long does food typically take to pass through the esophagus to the stomach?
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What is the main function of hydrochloric acid in gastric juice?
What is the main function of hydrochloric acid in gastric juice?
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Which part of the small intestine is primarily responsible for receiving digestive juices from the pancreas and liver?
Which part of the small intestine is primarily responsible for receiving digestive juices from the pancreas and liver?
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What is the function of villi in the small intestine?
What is the function of villi in the small intestine?
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What is the process called that moves food through the digestive tract?
What is the process called that moves food through the digestive tract?
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What activates pepsinogen into its active form, pepsin?
What activates pepsinogen into its active form, pepsin?
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What prevents injury to the stomach wall during digestion?
What prevents injury to the stomach wall during digestion?
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Which phase of swallowing is controlled voluntarily?
Which phase of swallowing is controlled voluntarily?
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What is the main purpose of the cardiac sphincter in the digestive system?
What is the main purpose of the cardiac sphincter in the digestive system?
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Study Notes
Digestive System Overview
- The digestive system is a long muscular tube, starting at the mouth and ending at the anus
- It has multiple sections, including the mouth, esophagus, small intestine, large intestine, rectum, and anal canal
- The system involves both mechanical (physical) and chemical breakdown of food
Digestive System Learning Outcomes
- Identify structures of the alimentary canal
- Identify accessory organs associated with the alimentary canal
- State the activities of the alimentary canal
- Explain mastication and deglutition
- Explain chemical digestion within the alimentary canal
- Describe functions of the large intestine
- Describe functions of accessory organs associated with the alimentary canal
Glossary of Terms
- Ingestion: Taking food into the alimentary canal
- Digestion: Mechanical (chewing, tearing, grinding, mixing) and chemical breakdown of food by enzymes
- Absorption: Digested food substances entering the blood and lymph
- Elimination: Undigested substances exiting the body as feces
- Mastication: The act of chewing
- Deglutition: The act of swallowing
- Peristalsis: Rhythmical muscular contractions that move food through the intestines
Digestion
- Breaks down complex biological molecules into component parts: lipids to fatty acids, proteins to amino acids, carbohydrates to simple sugars
- Filters out harmful substances
- Removes solid wastes
Mechanical Digestion
- Changes the physical form of food
- Involves chewing, tearing, grinding, and mixing
Chemical Digestion
- Changes the chemical composition of food
- Uses digestive enzymes as specialized proteins, breaking large food molecules into smaller ones for absorption
Phases of Digestion
- Ingestion
- Movement
- Digestion
- Absorption
- Further digestion
Mouth
- Food enters the mouth/oral cavity; tasting occurs
- Mechanical breakdown of food through chewing
- Secretion of salivary glands (salivary amylase) to begin starch digestion
Mouth - Tongue
- Mixes and rolls food into a bolus
- Pushes bolus toward the pharynx and into the esophagus during swallowing
Mouth - Teeth
- Cut, tear, crush, and grind food
Swallowing Mechanics
- Coordinated activity of tongue, soft palate, pharynx, and esophagus
- Food to pharynx (voluntary)
- Tongue blocks mouth
- Soft palate closes off nose
- Larynx and epiglottis to prevent food from entering the windpipe
- Phases: Buccal, Pharyngeal, Esophageal
Mastication & Deglutition
- Saliva moistens food
- Bolus formation
- Voluntary tongue/cheek muscles move bolus to pharynx
- Pharynx muscles push bolus to esophagus
- Bolus in pharynx initiates peristalsis
- Other routes closed to bolus
- Soft palate occludes nasal part of pharynx
Esophagus
- Straight muscular tube connecting the mouth to the stomach
- Food passage takes 4-8 seconds.
- Peristaltic waves propel food downward
Stomach
- J-shaped muscular sac
- Inner folds (rugae) increase surface area
- Churns and grinds bolus into smaller pieces
- Mixes with gastric juices (HCl and enzymes)
- HCl helps break down food and kill bacteria
- Creates chyme
Gastric Juice Components
- Water
- Hydrochloric acid
- Pepsinogen (activated to pepsin)
- Intrinsic factor (for Vit B12 absorption)
- Mucus
Small Intestine
- Long, coiled tube beneath the stomach
- Has three parts: duodenum, jejunum, ileum
- Duodenum receives digestive juices from pancreas and liver
- Chyme is mixed with secretions, becoming thin and watery
- Digestion and nutrient absorption occur
Small Intestine - Absorption
- Mucosa (inner wall) secretes enzymes
- Digested nutrients absorbed through intestinal walls
- Absorbed materials cross mucosa into bloodstream for storage or further chemical change
- Folded inner walls covered with villi (finger-like projections) and microvilli (tiny projections on villi)
- Increases surface area for greater absorption
- Peristalsis moves undigested food to large intestine
Small Intestine - Movement
- Mixing: Segmental contractions
- Secretion: Lubrication, liquefaction, digestion
- Digestion: Mechanical and chemical
- Absorption: Movement into circulation or lymph
- Elimination: Waste products removed from body
Large Intestine (Colon)
- Larger diameter, but shorter than small intestine (5 ft.)
- Water is absorbed from undigested food, making waste harder (solid)
- Waste stays for 10-12 hours.
- Waste is pushed into the rectum
- Solid waste excreted as feces through anus
- Appendix hangs on the right side
Large Intestine - Functions
- Absorption of water, mineral salts, and some drugs
- Microbial activity (synthesis of Vit K and folic acid)
- Defecation (elimination of feces)
Accessory Organs - Liver
- Produces or stores enzymes for digestion
- Largest gland
- Stores Vitamins A,D,E,K
- Produce bile (watery, greenish substance)
- Stores glycogen / sugar
- Secretes bile -> gallbladder -> hepatic duct -> cystic duct
- Converts glucose to glycogen with insulin , changes glycogen back to glucose with glucagon
- Desaturates fats
Accessory Organs - Gall Bladder
- Stores bile between meals
- Secretes bile to duodenum during mealtimes
- Bile contains bile salts, pigments, cholesterol & phospholipids
- Bile is an emulsifier (not enzyme, dissolves fat to watery contents)
Accessory Organs - Pancreas
- Produces juice with enzymes (amylase, lipase) to break down carbs, fats, and proteins
- Secretes juice into duodenum via pancreatic duct
- ~12-15cm long
- Head in duodenum curve
- Tail near left kidney
- Body behind stomach
- Pancreatic duct joins common bile duct -> ampulla
- Islets of Langerhans (endocrine function)
Pancreatic Juice
- Water
- Mineral salts
- Enzymes (pancreatic amylase, lipase, and peptidases)
Excretory System
- Gets rid of wastes the body doesn't need
- Digestive waste (egestion): feces
- Metabolic waste: water, carbon dioxide, salts, urea
Excretory Organs - Skin
- Allows water, salt, and urea to diffuse from blood into sweat glands
- Releases sweat through pores
Excretory Organs - Lungs
- Excretes carbon dioxide and water vapor during exhalation
Excretory Organs - Liver
- Removes excess amino acids
- Breaks down amino acids into urea (excrete in urine)
Excretory Organs - Kidneys
- Major excretory organs
- Purify blood by filtering out water, salts, digested food particles, and urea.
- Urine passes through urinary tract (ureter -> bladder -> urethra)
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Description
This quiz covers the components of the digestive system, including the structures of the alimentary canal and the functions of accessory organs. Learn key terms related to digestion, absorption, and the mechanical and chemical processes involved in breaking down food.
