Human Anatomy/Physiology Chp. 23

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Human Anatomy/Physiology Chp. 23
2013-03-28 16:11:55
Digestive System

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  1. What makes up the digestive system?
    The digestive track and accessory organs of digestion.
  2. What is the digestive tract?
    The digestive track is a hollow tube extending from the mouth to the anus.
  3. What are alternative names for the digestive track?
    Alimentary canal or gastrointestinal tract (GI Tract).
  4. What are the structures of the GI tract?
    Mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus.
  5. What are the accessory organs?
    Salivary glands, teeth, liver, gallbladder, and pancreas.
  6. What is the definition of digestion?
    Digestion is the process by which food is broken down into smaller particles suitable for absorption.
  7. Where does digestion take place?
    Digestion takes place within the digestive tract.
  8. What is the definition of absorption?
    Absorption is the process by which the end products of digestion move across the walls of the digestive tract into the blood for distribution throughout the body.
  9. What are the two forms of digestion?
    The two forms of digestion is mechanical digestion and chemical digestion.
  10. What is mechanical digestion?
    Mechanical digestion is the breakdown of large food particles into smaller pieces by physical means. This process is usually achieved by chewing and by the mashing, or squishing, actions of the muscles in the digestive tract.
  11. What is chemical digestion?
    Chemical digestion is the chemical alteration of food. For instance a protein changes chemically into amino acids chemical substances such as digestive enzymes, acid, and bile accomplish chemical digestion.
  12. What are the four layers of the digestive tract?
    The four layers of the digestive track is the mucosa, the submucosa, the muscle layer, and the serosa.
  13. What is the inner most layer of the digestive tract and what is it composed of?
    The inner most layer is the mucosa. It is composed of the mucous membrane.
  14. What do glands within the mucosa layer secrete?
    The glands secrete mucus, digestive enzymes, and hormones.
  15. What do the ducts from the exocrine glands empty into?
    Ducts from the exocrine glands empty into the lumen of the digestive tract.
  16. What layer lies next to the mucosa and is that layer thick or thin?
    The layer that lies next tk the mucosa is the submucosa. The submucosa layer is thick.
  17. What does the submucosa layer contain?
    The submucosa layer contains blood, vessels, nerves, glands, and lymphatic vessels.
  18. What is the third layer of the digestive tract?
    The third layer of the digestive tract is the muscle layer.
  19. What are the two types of muslces that make the muscle layer?
    Two layers of smooth muscle are an inner circle layer and an outer longitudinal layer.
  20. What nerve fibers lie between the circular muscle and the longitudinal muscle in the muscle layer?
    Autonomic nerve fibers also lie between the two layers of muscles in the muscle layer.
  21. What is the muscle layer in the digestive tract responsible for?
    The muscle layer is responsible for several types of movements in the digestive tract.
  22. What form of digestion does the muscle layer within the digestive tract use?
    It uses the mechanical digestion method by repeatedly contracting and relaxing.
  23. What is peristalsis?
    Peristalsis is a second type of muscle movement of the muscle layer. It is a rhythmic alternating contractikn and relaxation of the muscles. Peristalsis is stimjlated by the presence of food.
  24. What is the condition paralytic ileus?
    Parytic ileus is a medical condition where intestinal peristalsis is sluggish and might cease.
  25. What is the outermost layer of the digestive tract?
    The outermost layer of the digestive tract is the serosa. The serosa extends as the peritoneal membranes.
  26. What is the unique nervous system network of the digestive tract called?
    It is called the Enteral Nervous System (ENS).
  27. What nervous system is the Enteral Nervous System apart of?
    It is apart of the Paraympathetic Nervous System and responds to vagal nerve stimulation.
  28. What does the Enteral Nervous System of the digestive tract regulate?
    The ENS regulates gut motility and secretion.
  29. How does the peritoneal membrane involved with the digestive tract?
    The peritoneal membranes within the abdominal cavity are extensions of the serosa layer of the digestive tract.
  30. How does the peritoneal membrane assist the digestive tract?
    They help anchor the digestive system organs in place. They carry blood vessels, lymph vessels, and nerves. And they help restrict the spread of infection in the abdominal cavity.
  31. What are the peritoneal membranes called when located behind the digestive organs?
    They are called the Mesentery and Mesocolon.
  32. What are the peritoneal membranes called when located in front of the organs?
    They are called the Greater and Lesser omentum. The greater omentum is a double layer of peritoneum that contains a considerable amount of fat and resembles an apron draped over the abdominal organs.
  33. What does the digestive tract begin with?
    The mouth, also known as the oral cavity.
  34. What is the buccal cavity?
    The buccal cavity is part of the oral cavity. It refers to the area between the gums and the cheeks or lips.
  35. What is an alternative name for "chewing"?
  36. What makes food easily swallowed following the mastication process by the teeth in the oral cavity?
    The secretions by the glands render the food moistene hence easier to swallow.
  37. What is another name for baby teeth that exist between the age of 6 months to 2.5 years?
    It is Deciuous teeth. There are 20 and are pushed out between the ages of 6 and 12 years. Once pushed out they're replaced by permanent teeth.
  38. How many permanent teeth are there following the poo ush out of every deciduous tooth?
  39. How many parts does a tooth have?
    • A tooth has three parts which are the crown, the neck, and the root.
    • The crown of the tooth is above the level of the gum, or also known as gingiva, and is covered with hard, brittle enamel.

    The neck of the tooth conncects the crown with the root of the tooth.

    The root of the tooth is embedded in the jaw bone.
  40. What is the outer surface of the root of the tooth anchored to and by what?
    The outer surface of the root is anchored to the periodontal membrane by cementum. This holds the tooth in place.
  41. What does the bulk of the tooth consist of?
    The bulk of the tooth consists of a bonelike material called dentin.
  42. What penetrates the dentin of the tooth and how?
    Nerves, blood vessels, and connective tissue, called pulp, penetrate the dentin through the pulp cavity and supply the tooth with sensation and nutrients.
  43. What does the pulp caity of the tooth extend into?
    Root canal.
  44. What are gingivitis and stomatits?
    Gingivitis and stomatitis are mouth conditions that are often drug induced. Both cause considerable discomfort and intefere with nutrition. Gingivitis is the inflammation of the gums. Stomatitis refers to the inflammation or ulcers of the mouth area.
  45. What type of organ is the tongue and where is it positioned? (Pg. 400)
    The tongue is a muscular organ that occupies the floor of the mouth.
  46. What are the two major roles of the tongue? (Pg. 400)
    • 1.) It facilitates chewing and swallowing by continuously repositioning the food in the mouth. As swallowing begins, the tongue pushes the food, which it has molded into a ball-like mass called a bolus, toward the pharynx.
    • 2.) The tongue contains the taste buds and allows us to taste food.
  47. What prevents the tongue from being swallowed? (Pg. 400)
    A small piece of mucous membrane called the frenulum, is what anchors the tongue to the floor of the mouth and is the reason people cannot swallow their tongues.
  48. Why are medications absorbed so rapidly when administered sbulingually? (Pg. 400)
    The second structure of the tongue is an extensive capillary network that provides the sublingual (under the tongue) area with a rich supply of blood.
  49. What are the three pairs of salivary glands? (Pg. 400)
    The three pairs of salivary glands secrete their contents into the mouth:

    • 1.) the parotid glands.
    • 2.) the submandibular glands.
    • 3.) the sublingual glands.
  50. Which of the three salivary glands are the largest? (Pg. 400)
    The partoid glands are the largest of the three glands and lie below and anterior to the ears.
  51. Which of the three salivary glands are infected by the mumps virus? (Pg. 400)
    The partoid glands.
  52. Where are the submandibular glands (salivary glands) located? (Pg. 400)
    The submandibular glands are located on the floor of the mouth.
  53. Which salivary gland is the smallest and where is its location? (Pg. 400)
    The sublingual glands are located under the tongue and are the smallest of the salivary glands.
  54. What do the salivary glands secrete and what is it? (Pg. 400).
    The salivary glands secrete saliva, a watery fluid that contains mucus and one digestive enzyme called salivary amylase, or ptyalin.
  55. What is the most important function of saliva? (Pg. 400).
    The most important function of saliva is to soften and moisten food and thereby facilitate swallowing.
  56. What is the condition called where one of the salivary ducts becomes obstructed by a stone? (Pg. 400)
    The condition is called sialothiasis and is characterized by intense pain on eating when the salivary juices start to flow.
  57. What is the uvula and what creates it? (Pg. 400)
    The soft palate (located at the roof of the mouth) extends toward the back of the oral cavity. The uvula plays a role in swallowing.
  58. Where does the tongue push the bolus following the chewing process (mastication)? (Pg. 400)
    The tongue pushes the food from the mouth into the pharynx, also known as the throat.  The pharynx is involved in swallowing, also known as deglutition.
  59. What are the three parts of the pharynx? (Pg. 400)
    The three parts of the pharynx are the nasopharynx, the oropharynx, and the laryngopharynx.
  60. Which two parts of the pharynx are involved in the digestive system? (Pg. 400)
    Only the oropharynx and the laryngopharynx are part of the digestive system.
  61. Why doesn't food enter the nasal passageway when the tongue pushes the bolus into the oropharynx and laryngopharynx? (Pg. 400)
    Food does not normally enter the nasal or respiratory passages because swallowing temporarily closes off the opening to both.
  62. What is the purpose of the epiglottis? (Pg. 400)
    The laryngeal opening is closes when the trachea moves upward and allows the epiglottis to cover the entrance to the respiratory passages.
  63. What part of the digestive system is also known as the "food tube"? (Pg. 400)
    The esophagus is the "food tube"; it carries food from the pharynx to the stomach.
  64. Why are the glands within the mucosa of the esophagus important? (Pg. 400)
    Glands within the mucosa of the esophagus secrete mucus, which lubricates the bolus and facilitates its passage along the esophagus.
  65. The esophagus has two sphincters. What are they called and where are they located? (Pg. 400).
    The two esophageal sphincters are the pharyngoesophageal sphincter located at the top of the esophagus, and the gastroesophageal, or lower esophageal sphincter, a thickening at the base of the esophagus.
  66. What is gastroesophageal reflux disease (GERD)? (Pg. 401)
    In some persons a porrly functioning LES (gastroesophageal sphincter) allows for reflux of stomach contents into the esophagus. It is characterized by a burning sensation called heartburn or pyrosis. The burning sensation is a result of the high acidity of stomach contents. The word pyrosis is related to the word pyromaniac, a person who loves to set fires, and to the word pyretic, referring to fever.
  67. What are the five important digestive functions of the stomach? (Pg. 401)
    • 1.) Secretion of gastric (stomach) juice, which includes digestive enzymes and hydrochloric acid as its most important substances. 
    • 2.) Secretion of gastric hormones and intrinsic factor.
    • 3.) Regulation of the rate at which the partially digested food is delivered to the small intestine. 
    • 4.) Digestion of food. (Digestion within the stomach is limited).
    • 5.) Absorption of small quantities of water and dissolved substances. The stomach is not well suited for an absorptive role. It can, however, absorb alcohol efficiently. Therefore the consumption of alcoholic beverages on an empty stomach can quickly increase blood levels of alcohol.
  68. What are the three major regions of the stomach? (Pg. 401).
    The major regions of the stomach include the fundus, the body, and the pylorus.
  69. What region of the stomach regulates the rate at which gastric contents are delivered to the small intestine? (Pg. 401)
    The pylorus continues as the pyloric canal. A pyloric sphincter is located at the end of the pyloric canal and helps regulate the rate at which gastric contents are delivered to the small intestine.
  70. What are two landmarks within the stomach? (Pg. 401).
    Other landmarks of the stomach include the greater curvature and the lesser curvature.
  71. What gives the stomach the capability of expanding when necessary? (Pg. 401)
    How big can your stomach get? The empty stomach lies in thick accordion-like folds called rugae. The rugae allow the stomach to expand.
  72. What are the three muscle layers of the stomach and where are their locations? (pg. 402).
    The stomach has three layers of muscles that lie in three directions: longitudinal, oblique, and circular. The oblique muscle is the innermost layer; the circular muscle is the central layer; and the longitudinal muscle is the outer most layer.
  73. When the three layers of stomach muscles does its job of churning and mixing the food, what is the pastlike mixture it becomes called? (Pg. 402).
  74. What type of glands does the mucosa layer, mucus membranes of the stomach have and what does it do? (Pg. 402)
    The mucous membranes of the stomach contain gastric glands. These glands contain three types of secretory cells: the mucus cells, which secrete mucus; the chief cells, which secrete digestive enzymes; and the parietal cells, which secrete hydrochloric acid and intrinsic factor.
  75. What are the three types of secretory cells located within the stomach gastric glands? (Pg. 402)
    • 1.) Mucus cells: secrete mucus. 
    • 2.) Parietal cells: secrete hydrochloric acid & intrinsic factor.
    • 3.) Chief cells: secrete digestive enzymes.
  76. Is the stomach responsible for emesis (vomitting)? (Pg. 403)
    Not completely.
  77. Describe what an ucler is. (Pg. 403)
    Ucler is a lesion: A healthy digestive tract has an intact inner mucous membrane. The stomach lining may erode, or breakdown, thereby creating a lesion called an ucler. Some uclers are caused by the Helicobacter pylori microorganism and are painful and prone to bleeding. An antiucler drug plan for this type of ulcer includes an antibiotic in addition to drugs that decrease or neutralize acid.
  78. Describe what a Hiatal hernia is. (Pg. 403).
    The stomach is located in the upper abdominal cavity immediately below the diaphragm. The esophagus enters the abdominal cavity through an opening in the diaphragm. If that opening is weakened or enlarged, the stomach may protrude, or herniate, from the abdominal cavity into the thoracic cavity. This condition is called a hiatal hernia.
  79. Describe what Nasogastric tube is. (Pg. 403).
    Many conditions require that a nasogastric (NG) tube be inserted through the nasal passages into the stomach. Most often the NG tube is used to empty the stomach to prevent vomiting. When a person cannot eat normally, a tube may be surgically inserted through the abdominal wall into the stomach. Food is introduced directly into the stomach through this tube. This procedure is called a gastrostomy.
  80. Describe what Gastric resection is. (Pg. 403)
    An important function of the stomach is to regular the rate at which chyme is delivered to the duodenum. A person with cancer of the stomach may require a surgical procedure that removes the stomach or part of it. The procedure is called a gastric resection, or gastrectomy. A serious consequence of gastric resection is the inability to regulate the rate at which chyme is delivered to the duodenum. Because food (chyme) is literally dumped into the duodenum, since there is not stomach, a condition called dumping syndrome develops. The person experiencing dumping syndrome looks and acts "shocky" with severe nausea, perspiration, dizziness, and tachycardia.
  81. Describe what Pyloric stenosis is. (Pg. 403)
    The digestive tract is a hollow tube that must remain open. Occasionally during infancy, the pylorus is too narrow and impedes the movement of food out of the stomach. This condition is pyloric stenosis (narrowing). Pyloric stenosis is characterized by projectile vomiting immediately after feeding. Fortunately, a simple surgical procedure corrects the defect.
  82. Describe what Gastric hyperactivity is. (Pg. 403)
    Stimulation of the vagus nerve increases gastric secretion and motility. Certain drugs block the effects of the vagus nerve, thereby decreasing gastric secretion and motility. For instance, gastric hyperactivity, which occurs with some ulcers and a nervous stomach, may be treated with a drug that slows gastric motility and secretions. Atropine-like drugs are drugs that have a vaglytic effect and are used widely in the treatment of gastric hypermotility disordes. The adminstration of a vagolytic drug is like cutting the vagus nerve (vagotomy).
  83. Important gastric facts. (Pg. 403)
    Autonomic translation. Stimulation of the vagus nerve activates muscarinic receptors. Drugs that activate muscarinic receptors stimulate gut motility and secretion. Anticholinergic or antimuscarinic (atropine) drugs block muscarinic receptors, thus slowing gut motility and decreasing gastric secretions.
  84. What does the stomach inject into the small intestine? (Pg. 404).
    An acidic chyme is ejected by the stomach into the small intestine.
  85. What is the small intestine primarily concerned about? (Pg. 404)
    The small intestine is concerned primarily with chemical digestion and the absorption of food.
  86. What are the three parts of the small intestine? (Pg. 404)
    The small intestine consists of three parts: the duodenum, the jejunum, and the ileum. 

    • Dow = Duodenum
    • Jones = Jejunum
    • Industrials = Ileum.
  87. What is the first segment of the small intestine and what is it responsible for? (Pg. 404).
    The duodenum is the first segment of the small intestine. In addition to receiving chyme from the stomach, the duodenum also receives secretions from several accessory organs of digestion such as the liver, gallbladder, and pancreas. These secretions, in addition to those from the mouth, stomach, and duodenum, are responsible for the digestion of all food. Most digestion and absorption occur in the duodenum.
  88. What is the second segment of the small intestine and what is it responsible for? (Pg. 404)
    The jejunum is the second segment of the small intestine. Some digestion and absorption of food occurs in the first part of the jejunum.
  89. What is the third segment of the small intestine and what is it responsible for? (Pg. 404)
    The ileum is the third segment of the small intestine. It extends from the jejunum to the ileocecal valve. The lining of the ileum contains numerous patches of lymphoid tissue called Peyer's patches which diminish the bacterial content in the digestive system.
  90. The ileum extends from the jejunum to the ileocecal valve. What is the purpose of the ileocecal valve? (Pg. 404)
    The ileocecal valve prevents the refluxd of contents from the cecum (part of the large intestine) back into the ileum.
  91. Why are villi and microvilli, which lie on the wall of the small intestine, so important? (Pg. 405).
    The wall of the small intestine forms circular folds with fingerlike projections called villi. The epithelial cells of each villus form extensions called microvilli. The large number of villi and microvilli increases the amount of digested food that can be absorbed.
  92. What is a villus and its job? (Pg. 405)
    Each villus consists of a layer of epithelial tissue that surrounds a network of blood capillaries and a lymphatic capillary called a lacteal. The villus absorbs the end products of digestion from the duodenum into either the blood capillaries or the lacteal. The capillary blood within the villus drains into the hepatic portal vein and then into the liver. Thus the end products of carbohydrate and protein digestion first go to the liver for processing before being distributed throughout the body. The end products of fat digestion enter the lacteal, forming a milk-white lymph called chyle. The chyle empties directly into the lymphatic system. (Do not confuse the words chyle and chyme).
  93. What are the parts of the large intestine and where does the large intestine lie? (Pg. 405)
    The large intestine extends from the ileocecal valve to the anus. The parts of the large intestine are the cecum, colon, rectum, and anal canal. 
  94. What is the first part of the large intestine and where is its location? (Pg. 405).
    The first part of the large intestine is teh cecum. The cecum is located in the LRQ and ascends on the right side as the asccending colon.
  95. What is an important piece connect to the first part of the large intestine? (Pg. 405).
    The important piece is the appendix, which is a worm like structure that contains lymphocytes and is a source of immune cells. The appendix is very important because occasionally, the appendix becomes inflamed, causing appendicities, and must be surgically removed through an appendectomy.
  96. What are the four parts of the colon and where are they located? (Pg. 405).
    The four parts of the colon is the ascending colon (located on the right side of the patient), the transverse colon (located beneath the stomach and liver), the descending colon (located on the left side of the patient), and the sigmoid colon which is an S-shaped segment which is at the end of the colon.
  97. What three structures are distal to the sigmoid colon? (Pg. 406).
    The three structures are,

    • 1.) rectum.
    • 2.) anal canal.
    • 3.) anus.
  98. What are the four functions of the large intestine? (Pg. 406)
    The four functions of the large intestine are:

    • 1.) Absorption of water and certain electrolytes.
    • 2.) Synthesis of certain vitamins by the intestinal bacteria (especially vitamin K and some B vitamins).
    • 3.) Temporary storage site of waste (feces).
    • 4.) Elimination of waste from the body (defecation).
  99. What moves the feces (fecal matter) from the cecum through the colon? (Pg. 406)
    Intermittent and well-spaced peristaltic waves move the fecal material from the cecum through the colon.
  100. Why do people sometimes feel constipation? (Pg. 406)
    Feces that remain in the large intestine for an extended period of time lose excess water, and the person experiences constipation.
  101. What causes diarrhea? (Pg. 407)
    Rapid movement through the intestine allows insufficient time for water reabsorption, hence causing diarrhea).
  102. What is expelled gas from the digestive tract called? (Pg. 409)
  103. What do the liver, gallbladder, and pancreas all have in common? (Pg. 410)
    They all empty their secretions into the duodenum. These secretions are necessary for the digestion of food.
  104. Where is the liver located? (Pg. 410)
    The liver is a large, reddish-brown organ located in the mid and right upper abdominal cavity. It lies immediately below the diaphragm; much of the liver is tucked up under the right rib cage.
  105. What is the largest gland in the body? (Pg. 410)
    The liver is the largest gland in the body and has two main lobes, a large right lobe and a smaller left lobe separated by a ligament.
  106. What is the purpose of the ligament that separates the liver into a right lobe and a left lobe? (Pg. 410)
    The ligament secures the liver to surrounding structures.
  107. What is the liver surround by? (Pg. 410)
    The liver is surrounded by a fibrous membrane called a capsule. The word hepatic refers/means liver.
  108. Name and explain the nine main functions of the liver? (Pg. 410)
    1.) Synthesis of bile salts and secretion of bile. Bile salts play an important role in fat digestion and in the absorption of fat-soluble vitamins. Bile secretion is the main digestive function of the liver. 

    2.) Synthesis of plasma proteins. The plasma proteins play an important role in maintaining blood volume and controlling blood coagulation. 

    3.) Storage. The liver stores many substances: glucose in the form of glycogen, the fat-soluble vitamins (A,D,E, and K), and Vitamin B12. 

    4.) Detoxification. The liver plays an important role in the detoxification of drugs and other harmful substances. The liver changes these toxic substances into substances that can be more easily eliminated from the body by the kidneys. 

    5.) Excretion. The liver excretes many substances, including bilirubin, cholesterol, and drugs. 

    6.) Metabolism of carbohydrates. The liver plays an important role in the regulation of blood glucose levels. If blood glucose levels rise above normal, the liver takes the glucose out of the blood, converts it to glycogen, and then stores it for future use. If the blood glucose levels decline below normal, the liver makes glucose from glycogen and non-glucose substances (gluconeogenesis) and releases it into the blood. 

    7.) Metabolism of protein. The liver can make variety of different amino acids. Also, because only the liver contains the urea cycle enzymes, nitrogen (from ammonia) is converted to urea in the liver for eventual excretion by the kidneys. Free ammonia is toxic to humans.

    8.) Metabolism of fats. The liver can break down fatty acids, synthesize cholesterol and phopholipids, and convert excess dietary protein and carbohydrates to fat. 

    9.) Phagocytosis. The kupffer cells are heptaic macrophages and can phagocytose bacteria and other substances.
  109. What is the unique arrangement of blood vessels within the liver called? (Pg. 410)
    The liver has a unique arrangement of blood vessels called the heptaic portal system.
  110. Where does the liver receive blood from? (Pg. 410)
    The liver receives a lot of blood, approximately 1.5L/min, from two sources: the portal vein (which provides most of the blood) and the hepatic artery.
  111. Which vessels delivers blood rich in digestive end products to the liver? (Pg. 410)
    The portal vein brings blood rich in digestive end products to the liver. Blood leaves the liver through the hepatic veins and empties  into the vena cava, where it is returned to the heart for recirculation.
  112. What is the functional unit of the liver? (Pg. 410)
    The functional unit of the liver are the liver lobules.
  113. Where does the blood from the vessels hepatic artery and portal vein mix? (Pg. 410)
    Blood from those two blood vessels mixes in the liver in spaces called sinusoids.
  114. Important information regarding the liver lobule. (Pg. 410)
    The hepatic cells extract water and dissolved substances from the sinusoidal blood. Hepatic cells then secrete a greenish yellow substance called bile into tiny canals called canaliculi. These tiny bile canals merge with canals from other lobules to form larger hepatic bile ducts. Bile exits from the liver through the hepatic bile ducts.
  115. Where does bile from the liver exit? (Pg. 410)
    Bile exits from the liver through the hepatic bile ducts.
  116. What is bile? (Pg. 410)
    Bile is a greenish yellow secretion produced by the liver and stored in the gallbladder.
  117. What is bile composed of? (Pg. 410)
    Bile is composed primarily of water, electrolytes, cholesterol, bile pigments (bilirubin & biliverdin), and bile salts.
  118. How are the bile pigments bilirubin and biliverdin formed? (Pg. 410)
    The bile pigments are formed from the hemoglobin of won-out red blood cells. The bile salts are the most abundant constituents of the bile.
  119. What is the most abundant constituent of bile and what's unique about them? (Pg. 410)
    The bile salts are the most abundant constituents of the bile and only the bile salts ahve a digestive function; they play an important role in fat digestion and in the absorption of fat-soluble vitamins.
  120. What gives stool its brownish color? (Pg. 410)
    The bile pigment urobilinogen (a breakdown product of bilirubin) is what gives the stool a brownish color.
  121. What are bile salts made from? (Pg. 412)
    Bile salts are made from cholesterol by the liver. If the liver is stimulated to make additional bile salts, more cholesterol is used up, thereby lowering the amount of cholesterol in the blood. The "statins," popular cholesterol-lowering drugs, stimulate the hepatic synthesis of bile salts and are therefore useful in the prevention of coronary artery disease.
  122. What are the ducts that connect the liver, gallbladder, and duodenum called? (Pg. 412)
    They are called the biliary tree.
  123. What are the three different types of ducts within the network of ducts (biliary tree)? (Pg. 412)
    The three types of ducts are,

    • 1.) Heptaic bile ducts.
    • 2.) Cystic duct.
    • 3.) Common bile duct.
  124. What do the ducts within the biliary tree (network of ducts) do? (Pg. 412)
    The hepatic bile ducts receive bile from the canaliculi within the liver lobules. The hepatic drugs merge with the cystic duct to form the common bile duct, which carries bile from the both the hepatic ducts (liver) and the cystic duct (gallbladder) to the duodenum.
  125. What forms the hepatopancreatic ampulla (ampulla of Vater)? (Pg. 412)
    The base of the common bile duct swells to form it.
  126. What is the hepatopancreatic sphincter (sphincter of Oddi)? (Pg. 412)
    The hepatopancreatic sphincter (sphincter of Oddi) encircles the base of the ampulla, where it enters the duodenum. This sphincter helps regulate the delivery of bile to the duodenum and is sensitive to nervous, hormonal, and pharmacologic control.
  127. What is the gallbladder? (Pg. 412)
    The gallbladder is a pear-shaped sac attached to the underside of the liver.
  128. What connects the gallbladder with common bile duct? (Pg. 412)
    The cystic duct connects the gallbladder with the common bile duct.
  129. Where is bile produced? (Pg. 412)
    In the liver.
  130. Once bile is produced in the liver, where does it go? (Pg. 412)
    Bile, produced in the liver, flows through the hepatic ducts and into the cystic duct and gallbladder. The gallbladder concentrates about 1200 ml of bile per day.
  131. What does the fat in the duodenum stimulate the release of and what does it do and go? (Pg. 412)
    The fat in the duodenum stimulates the release of a hormone, cholescystokinin (CCK). This hormone enters the bloodstream and circulates back to the gallbaldder, where it causes the smooth muscle of the gallbladder to contract. When the gallbladder contracts, the bile is ejected into the cystic duct and then into the common bile duct and duodenum.
  132. What is a pancreas? (Pg. 412)
    The pancreas is an accessory organ of digestion located just below the stomach. The head of the pancreas rests in the curve of the duodenum, and the tail lies near the spleen in the upper left quadrant of the abdominal cavity.
  133. What does the main pancreatic duct do? (Pg. 412)
    The main pancreatic duct, which travels the length of the pancreas, joins with the common bile duct at the ampulla of Vater. The pancreatic duct carries digestive enzymes from the pancreas to the duodenum, the meeting point for digestion.
  134. What is the main function of the pancreas? (Pg. 412)
    The pancreas secretes both endocrine and exocrine substances. The exocrine secretions include digestive enzymes and an alkaline secretion. These secretions form the pancreatic juice: the pancreas secretes about 1400 ml/day.
  135. What is the most important digestive enzyme? (Pg. 412)
    The pancreatic enzymes are the most important of all the digestive enzymes. Acinar cells secrete the pancreatic enzymes in their inactive form. The enzymes travel through the main pancreatic duct to the duodenum and are activated in the duodenum.
  136. In addition to the digestive enzymes, what else does the pancreas secrete? (Pg. 412)
    In addition to the digestive enzymes, the pancreas also secretes an alkaline juice rich in bicarbonate. The bicarbonate neutralizes the highly acidic chyme coming from the stomach into the duodenum. This neutralization is important because the digestive enzymes in the duodenum work best in an alkaline environment.
  137. What controls, or stimulates, the secretion of digestive enzymes and bicarbonate? (Pg. 412)
    The nervous system (vagus nerve) and hormones control the secretions. The presence of food in the stomach and duodenum is the stimulus for the nervous and hormonal responses. For instance, the presence of chyme in the duodenum stimulates the release of the hormone CCk from the duodenal walls. CCK travels by way of the blood to the pancreas, stimulating the release of pancratic digestive enzymes. Note that CCK affects both the gallbladder and the pancreas.
  138. What stimulates the release of a second hormone within the pancreas/duodenum? (Pg. 413)
    The acid in the duodenum stimulates the release of a second hormone, secretin, from the duodenal walls. Secretin travels by way of the blood to the pancreas, stimulating release of the bicarbonate-rich juice.