Bio171L P3:Digestive System Anatomy

  1. What is the function of the Digestive System?
    Provides the body with nutrients essential for growth and maintenance.
  2. Gastrointestinal tract
    Organs of the GI tract make up the hollow tube, composed of smooth muscle, which extends from mouth to anus and are involved in Prehension, Mastication, Swallowing, Digestion, Absorbtion, Elimination
  3. What activities is the GI tract involved in?
    • Prehension
    • Mastication
    • Swallowing
    • Digestion
    • Absorbtion
    • Elimination
  4. Prehension
    • Obtaining food materia from the outside world.
    • Accomplished by lips and teeth
  5. Mastication
    Chewing accomplished by the teeth
  6. Swallowing
    Pushing food into the esophagus so waves of Peristalsis may take the injesta further into the digestive tract
  7. Peristalsis
    Smooth muscle contractions moving food along digestive tract.
  8. Digestion
    • Chemical and Mechanical breakdown of food
    • Occurs in mouth, stomach, and small intestine
  9. Absorbtion
    • Moving digested material and water from the lumen of the digestive tract into the blood stream for use in the body
    • Occurs mainly in the stomach and small and large intestines
  10. Elimination
    • Removal of undigested ingesta
    • Occurs through rectum and anus
  11. Accessory Organs
    • Organs of the GI system through which food does not pass 
    • These structures release their products into the digestive tract to aid in digestion and absorption of materials
  12. What are the accessory organs
    • Salivary Glands
    • Liver
    • Gallbladder
    • Pancreas
  13. Salivary Glands
    • Three glands located inferior to the ear which work together to produce and release saliva. Saliva lubricates the food and begins the breakdown of starches using the enzyme amylase
    • Accessory organ of the digestive system.
  14. Parotid Salivary Gland
    The largest of the three, it lays adjacent to the Masseter muscle, its duct actually lays on top of the muscle.
  15. Submandibular Salivary Gland
    A smaller gland which lays inferior and caudal to the parotid gland
  16. Sublingual Salivary Gland
    The smallest of the three found just rostral to the submandibular, often quite difficult to find.
  17. Lips
    • Lips in some species aid in the prehension of food
    • These organisms can use their lips to grab food and pull it into the mouth
    • Paralysis of the lips could be determined for these organisms as they may no longer be able to adequately feed themselves
  18. Name a species that uses it's lips to obtain food.
    Horse
  19. Mouth
    Defined as the opening between the lips including the oral cavity and vestibule
  20. What are the three superficial parts of the tooth?
    • Crown 
    • Neck
    • Root
  21. Crown (tooth)
    • The portion of the tooth visible above the gum
    • The crown is covered with enamel which is the hardest substance in the body
  22. Neck (tooth)
    The portion of the tooth between the gum line and where the gum attaches to the tooth
  23. Root (tooth)
    • The portion of the tooth below the neck that extends into the bone
    • The root is covered with cementum which attaches the tooth to the periodontal ligament holding the tooth in the socket.
  24. What are the three deeper parts of the tooth?
    • Dentin
    • Pulp Cavity
    • Root Canal
  25. Dentin
    The layer of the tooth deep to the crown, neck, and root it makes up the bulk of the tooth and is similar in structure to bone.
  26. Pulp Cavity
    Deep to the dentin, in this cavity is the Pulp which is the blood, nervous, and lymphatic supply to the tooth.
  27. Root Canal
    An extension of the pulp cavity deep in the root of the tooth, this canal allows for blood, lymph, and nervous supply to enter the pulp cavity.
  28. How are teeth classified
    • Shape
    • Function
    • Time of Eruption
  29. What are the four major categories of teeth?
    • Incisor
    • Canine
    • Premolar
    • Molar
  30. Incisor
    Used for cutting
  31. Canine
    Used for grasping
  32. Premolar
    Used for chewing
  33. Molar
    Used for chewing and grinding
  34. What 2 types of teeth do mammals have during their life
    • Deciduous
    • Permanent
  35. Deciduous
    • milk or baby teeth
    • Only incisor, canines, and premolars are replaced by bigger adult teeth at certain times as the organisms mature
  36. Permanent
    • Adult teeth
    • All four types of teeth are seen in this set, the time of eruption of these teeth can be used to age young organisms
  37. Canine Dental Formula
    • 3-1-4-2
    • 3-1-4-3  x2
  38. Cat Dental Formula
    • 3-1-3-1
    • 3-1-2-1  x2
  39. Tongue
    A highly mobile, muscular structure that aids in taste, mastication, swallowing, and grooming
  40. What are the three types of papillae on the tongue of the cat?
    • Filiform
    • Fungiform
    • Circumvallate
    • Foliate
  41. Filiform
    • Spiny papillae used for grooming
    • Found on front half of the tongue
    • Have no taste buds
  42. Fungiform
    • Small rounded papillae found between the filiform papillae on the front half of the tongue and are also found more caudally
    • Received their name for the mushroom like appearance
  43. Circumvallate
    Difficult to locate on a preserved cat.  They would be found on the lateral aspects at the base of the tongue.
  44. Foliate
    Leaf shaped papillae found on the lateral aspects of the tongue and at the base
  45. Taste Buds
    • Small structures on the dorsal surface of the tongue (on the papillae) and on the soft palate
    • Provide information about the taste of food being eaten
    • It is known that their are 5 taste bud sensations
  46. What are 5 taste bud sensations?
    • Sweet, Bitter, and Umami/Savory (which signal through a G-protein coupled receptor)
    • Salty and Sour (which operate with ion channels)
  47. Vestibule
    Area between the teeth and cheek
  48. Hard Palate
    • "Roof of the Mouth"
    • Made up of the incisive, maxillae and palatine bones which are covered by Palatine Rugae or ridges
  49. Soft Palate
    Soft, muscular area behind the hard palate which separates the nasopharynx and the oral cavity
  50. Esophagus
    • Long muscular tube which is found dorsal to the trachea and connects the oral cavity to the stomach.
    • Proximal end near mouth
    • Distal end attached to stomach
  51. Why is the stomach a muscular tube while the trachea is a cartilaginous tube?
    Pushing food down into the stomach
  52. What is the function of the greater omentum?
    • Protect abdominal cavity
    • Vascular, shock absorber
  53. What is the function of the spleen?
    • Immunity 
    • Discard bad/dead RBC/WBC
  54. Liver
    A large dark reddish brown organ directly caudal to the diaphram, it is an accessory organ in the digestive system
  55. What are the five lobe that the liver is divided into?
    • Right Lateral lobe
    • Right Medial lobe
    • Left Medial lobe
    • Left Lateral lobe
    • Caudate Lobe
  56. Right Lateral Lobe
    • Divided into two sections by a deep cleft
    • Cups over the top of the right kidney
  57. Right Medial Lobe
    Contains a cleft housing the gallbladder
  58. Caudate Lobe
    Found Deep to the Lesser Omentum
  59. Lesser Omentum
    Similar to the greater omentum but is much smaller and found in the smaller curvature of the stomach
  60. Gallbladder
    Small green sac structure embedded in the right medial lobe of the liver, stores the bile created by the liver to emulysify fats
  61. Stomach
    • An enlargement of the gastrointestinal system which connects the esophagus to the small intestine.  It acts as a mixing and holding chamber for ingesta and is a site for partial digestion of protein
    • There are four main components of the stomach
  62. What are the four main components of the stomach?
    • Cardia
    • Fondus
    • Body
    • Pylorus
  63. Cardia (stomach)
    Area of the stomach which surrounds cranial opening of the stomach right below the esophageal sphincter
  64. Fondus (stomach)
    Rounded portion of the stomach which is cranial to the Cardia,blind sac which distends as the stomach fills
  65. Body (stomach)
    Main portion of the stomach which contains folds or rugae which allows the stomach to expand
  66. Pylorus (stomach)
    Area of th stomach which connects to the small intestine, end at the pyloric sphincter
  67. Lesser Curvature
    • The medial aspect of the stomach
    • The lesser omentum attaches here
  68. Greater Curvature
    The lateral aspect of the stomach
  69. What are the three parts of the small intestine?
    • Duodenum
    • Jejunum
    • Ileum
  70. Duodenum
    • Extends from the pyloric sphincter to the tiny curve at the base of the mesentery, the descending duodenum is found on the right of the abdominal cavity
    • The mesentery between the Duodenum and the stomach holds the small, granular pancreas
  71. Pancreas
    An accessory organ of the digestive system which releases digestive enzymes as well as insulin
  72. Jejunum
    The twisted, looped, longest section of the small intestine, there is no landmark separating this section of the small intestine from the next, much shorter ileum.
  73. Ileum
    The last part of the small intestine which leads  to the cecum and large intestine.
  74. Large Intestine
    • Begins at the Ileoceal Sphincter and extends to the rectum, this organ functions in water reabsorption and storage of feces until it can be expelled
    • This organ varies greatly between species, it is simple in carnivores and rather complex in nonruminant herbivores called hindgut fermenters. 
    • In its most simple for the large intestine can be divided into the cecum, ascending colon, transverse colon, descending colon, rectum, and anus
  75. What are the divisions of the large intestine?
    • Cecum 
    • Ascending Colon
    • Transverse Colon
    • Descending Colon
    • Rectum and Anus
  76. Cecum
    Small vestige in the cat which will be discussed further with the hindgut fermenters
  77. Ascending Colon
    Located on the right side of the cat, area of the large intestine which extends cranially then turns forming the Transverse Colon
  78. Transverse Colon
    Portion of the colon which extends from the right side of the body to the left, when the structure turns caudally the structure becomes the Descending Colon
  79. Descending Colon
    Section of the large intestine which continues caudally to the rectum
  80. Rectum and Anus
    The terminal portion of the large intestine which allows for elimination of fecal matter in a process called defecation
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  83. What are the two systems utilized by herbivores to obtain nutrients from their food?
    • Ruminant Stomach
    • Hindgut Fermentation
  84. Carnivore
    Eat Meat
  85. Omnivore
    Eats plant and meat
  86. Herbivore
    Eats plants
  87. Ruminant
    • Rumination or chewing cud is a process carried out by cattle, sheep, and goats
    • This process involves swallowing and regurgitating food to chew it more before swallowing it again.  Ruminants have four chambered stomach, the first three chambers are the components of the "forestomach" or fermenting stomach while the last chamber is the true stomach.  
    • The reticulum, rumen, and omasum are the chambers of the forestomach and the abomasum is the true stomach.
  88. What are the chambers of the forestomach?
    • reticulum
    • rumen
    • omasum
  89. WHat is the true stomach called?
    Abomasum
  90. Reticulum
    • The smallest, most cranial compartment of the ruminant stomach
    • The walls of this chamber have a honeycomb appearance - these structures increase the surface area for absorption
    • Also known as tripe
    • Walls of this chamber are continuous with the rumen, they generally work together so their contractions are called reticulorumen contractions
    • Magnets are inserted into this chamber to prevent hardware disease
  91. Hardware Disease
    This disease is caused by the ingestion of metal which lodges in the reticulum and punctures the diaphragm and heart if not contained
  92. Rumen
    • Large fermentation vat which allows for generally unusable cellulose to be broken down for energy.
    • This structure is divided by muscular folds called pillars into four parts
    • Dorsal Sac, Dorsal Blind Sac, Ventral Sac, Ventral Blind Sac
    • The muscular contraction of this vat allows for
    • 1. mixing rumen contents
    • 2. Partially digested food to be regurgitated, chewed, and reswallowed
    • 3. This increases the surface area of the ingesta so that the microbes in the rumen can more efficiently break it down into its components
    • 4. Expulsion of carbon dioxide and methane built up during fermentation.  The bacteria and protozoa found in the rumen are able to break down the cellulose that animal systems are unable to utilize thus providing the ruminant with nutrients which would not be able to be obtained otherwise
  93. What structure is divided by muscular folds called pillars into four parts?
    • Dorsal Sac
    • Dorsal Blind Sac
    • Ventral Sac
    • Ventral Blind Sac
  94. Omasum
    • The opening for this compartment is off the reticulum
    • Contractions of the rumen and reticulum send partially digested food ingesta into the omasum
    • This compartment is comprised of muscular folds which function in
    • 1. Breaking the food particles down further
    • 2. Absorbing more nutrients and water from ingesta
    • Removing the bicarbonate ions that would neutralize the pH of the abomasum
  95. Abomasum
    True or enzymatic stomach, much like the monogastric stomach studied in the previous section that connects the pylorus of the small intestine
  96. Hindgut Fermentation
    • An alternative to the ruminant plan is the system used by the horse.  Hindgut fermentation means that the fermentation or breakdown of cellulose into unusable carbohydrates occurs after the small intestine. In this plan the organism has a monogastric stomach and typical small intestine which allows for the digestion and absorption of easily digestible grains and the breakdown of the grasses consumed  doesn't occur until the large intestine
    • Organisms utilizing hindgut fermentation have an incredibly large cecum, this organ, which is usually a vestige, acts as the fermentation vat for these animals absorbing the nutrients released so they also have an extensive and elaborate large intestine commonly called the great colon
  97. Cecum
    • Large comma shaped extending from the pelvis to the diaphragm 
    • Environment comparable to the rumen as it is filled with bacteria and protozoans which produce enzymes that will digest cellulose into absorbable material
    • Filled by the ileum
  98. Great Colon
    • Food moves through the great colon which consists of several sections connected together by sharply bending pieces of colon called flexures
    • It is these flexures that food and foreign bodies can become lodged and cause many difficulties for the animal
    • Once food has traveled through the great colon it enters the small colon and the rectum and anus
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dg527
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Bio171L P3:Digestive System Anatomy
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Bio171L P3:Digestive System Anatomy
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