The Digestive System 1 Flashcards
herbivores with large microbial fermentation chambers where plant materials are partially broken down before the food reaches the stomach
Ruminants
herbivores that have an extremely well developed and expansive fermentation chamber (cecum) at the junction of the small and large intestines that allows microbes to help break down plant materials
Nonruminants
animals with a GI tract that is responsible for converting consumed meals into nutrients and energy without the aid of a microbial fermentation chamber
Carnivores
the part of the breakdown process in which larger molecules are broken down into their smaller component parts
Digestion
List the 2 types of digestion
- Mechanical
- Chemical
Another name for the gastrointestinal tract
Alimentary Canal
referring to the stomach
Gastric
referring to the intestines
Enteric
List the 4 layers of the GI tract walls
- Mucosa
- Submucosa
- Muscular Layers
- Serosa or Adventitia
What are the 2 sublayers in the muscular layer of the GI tract wall?
- Inner Circular Layer
- Outer Longitudinal Layer
the name for the outermost layer of the GI tract walls if that part of the GI tract is suspended from the body cavity
Serosa
the name for the outermost layer of the GI tract walls if that part of the GI tract is surrounded by other tissue
Adventitia
controls both motor and secretory functions of the GI tract, contains its own “pacemaker” cells, and is influenced by the autonomic nervous system
Enteric Nervous System
In what 2 ways does the autonomic nervous system affect the enteric nervous system?
- Parasympathetic Nervous System > enhances digestive processes
- Sympathetic Nervous System > inhibits digestive processes
Give the 2 plexuses of the enteric nervous system
- Meissner’s Plexus (submucosal plexus)
- Auerbach’s Plexus (myenteric plexus)
the entrance to the GI tract
Buccal (Oral) Cavity
Give the 2 parts of the buccal cavity
- Vestibule
- Oral Cavity Proper
the space between the outer surface of the teeth and the surrounding lips and cheeks
Vestibule
the lateral walls of the oral cavity vestibule
Cheeks
the opening into the oral cavity whose boundary is marked by the lips
Oral Fissure
the process of bringing food into the oral cavity with the lips or teeth
Prehension
the mechanical grinding and breaking down of food into smaller pieces that can be easily swallowed and mixing the food with saliva in order to lubricate and soften the food
Mastication
the cleft dividing the 2 halves of the upper lip that can be deeper or shallower depending on the species
Philtrum
the space bordered by the inner surface of the teeth laterally and rostrally and by the hard and soft palate dorsally
Oral Cavity Proper
the dorsal border of the oral cavity
Palate
the part of the palate made up of the palatine, maxillary, and incisive bones which are covered in a mucous membrane
Hard Palate
the part of the palate made up of muscle and connective tissue and divides the pharynx into an oropharynx and the nasopharynx
Soft Palate
Which subdivisions of the palate are the hard vs soft palate?
Hard Palate > rostral part of the palate
Soft Palate > caudal part of the palate
the lower part of the pharynx that connects with the mouth
Oropharynx
the upper part of the pharynx that leads to the nasal passageway
Nasopharynx
sockets or cavities that house teeth
Alveoli
the structure that holds teeth in their sockets
Periodontal Ligament
the part of the tooth that projects above the gingiva
Crown
the gums
Gingiva
the part of the tooth embedded in the alveoli below the gingiva
Root
the tip of the root of a tooth where the blood vessels and nerves enter the tooth
Apex (pl. Apices)
the area of the tooth where the crown and the root meet
Neck
Why is it important to know what the different surfaces of the teeth are called?
Proper documentation where a lesion has occurred on the tooth
referencing the outer surfaces of the teeth that face the cheeks
Buccal
referencing the outer surfaces of the teeth that face the lips
Labial
references in the inner surfaces of the teeth that face the tongue
Lingual
references the inner surfaces of the teeth that face the soft palate
Palatal
references the surface between teeth that faces the midline or center of the dental arch
Mesial
references the surface between teeth that faces away from the midline or center of the dental arch
Distal
references the surfaces on the upper and lower teeth that come together when the mouth is closed
Occlusal (Masticatory)
referencing something toward the crown of the tooth
Coronal
referencing something toward the root of the tooth
Apical
Give the 5 layers of the tooth
- Enamel
- Dentin
- Pulp Cavity
- Cementum
- Periodontal Membrane
the thin layer of hard white material that covers the crown of the tooth and is the hardest substance in the body
Enamel
the layer the forms the bulk of the tooth
Dentin
the inner layer of the tooth that contains the blood supply and nerves which supply the tooth
Pulp Cavity
a thin bonelike covering over the roots of brachyodont teeth and most of the entire tooth superficial to the enamel in hypsodont teeth
Cementum
the dense fibrous connective tissue that links the cementum with the alveolar wall, anchoring the tooth into the jaw
Periodontal Membrane
What are the 2 classifications of teeth?
- Brachyodont Teeth
- Hypsodont Teeth
teeth that have relatively small crowns and well developed roots and do not continually grow
Brachyodont Teeth
teeth that grow continuously during most of the life of the animal due to a large reserve of crown beneath the gingiva
Hypsodont Teeth
List the 2 types of hypsodont teeth
- Radicular Hypsodont
- Aradicular Hypsodont
teeth whose apices of their roots remain open for a significant portion of the animal’s life but do eventually close and stop growing
Radicular Hypsodont Teeth
teeth that lack a true root and grow continuously throughout the life of the animal
Aradicular Hypsodont Teeth
the filing down of sharp points and hooks on teeth to create a level occlusal surface
Floating the Teeth
the process of recontouring a tooth surface
Odontoplasty
the set of teeth present in the jaw at birth but erupt through the gums at different times in different species and tend to be smaller and whiter
Deciduous Dentition
the set of adult teeth
Permanent Dentition
refers to teeth of differing shapes and sizes
Heterodont Dentition
Give the 4 types of teeth
- Incisors
- Canines
- Premolars
- Molars
teeth that are small and often used to cut and nibble food
Incisors
What bone are the incisors in?
Premaxilla (Incisive Bone)
a thickened region found in ruminants that lower incisors can grind and crush food upon
Dental Pad
teeth that are sharp and pointed and are used to tear flesh and hold prey
Canines
What bones are the canines found in?
- Maxilla (upper)
- Mandible (lower)
teeth that act like shears, cutting and grinding food into smaller pieces for swallowing
Premolars
What bones are the premolars in?
- Maxilla (upper)
- Mandible (lower)
teeth that assist in grinding food into smaller particles but are only found in adult dentition
Molars
What bones are the molars in?
- Maxilla (upper)
- Mandible (lower)
the largest cutting teeth in the jaw of carnivores
Carnassial Teeth
indicates how many of each type of tooth are present on ONE side of the oral cavity and is used to help document any diseased or missing teeth
Dental Formula
List the tooth abbreviations for each type of tooth
I = incisors
C = canines
P = premolars
M = molars
Uppercase = permanent teeth
Lowercase = deciduous teeth
What is the dental formula equation?
Dental Formula = 2[tooth abbreviation][# of teeth of that type in upper jaw/#teeth of that type in lower jaw]
the consistent system across species used to chart and locate specific teeth by numbering teeth beginning at the midline of the upper arch and continuing caudally
Triadan System
Triadan System: 100 series
Right Maxillary Arch (Permanent Teeth)
Triadan System: 200 series
Left Maxillary Arch (Permanent Teeth)
Triadan System: 300 series
Left Mandibular Arch (Permanent Teeth)
Triadan System: 400 series
Right Mandibular Arch (Permanent Teeth)
Triadan System: 500 series
Right Maxillary Arch (Deciduous Teeth)
Triadan System: 600 series
Left Maxillary Arch (Deciduous Teeth)
Triadan System: 700 series
Left Mandibular Arch (Deciduous Teeth)
Triadan System: 800 series
Right Mandibular Arch (Deciduous Teeth)
the arrangement of teeth into 2 arches, one on the upper jaw and one on the lower jaw
Dental Arcade
Give the 2 types of muscles in the tongue
- Extrinsic Muscles
- Intrinsic Muscles
muscles in the tongue that anchor it in place
Extrinsic Muscles
muscles in the tongue that originate and insert on the tongue itself and make up the majority of the mass of the tongue
Intrinsic Muscles
What are the 3 parts of the tongue?
- Apex
- Body
- Root
the free unattached mobile tip of the tongue
Apex
the long and slender part of the tongue that links the two ends together
Body
the part of the tongue that anchors it to the hyoid bone and the sides of the mandible
Root
structures that deposit saliva into the oral cavity via ducts
Salivary Glands
a substance important to digestion, lubrication, antibacterial action, pH regulation, and thermoregulation that is made up of water, proteins, electrolytes, IgA, glycoproteins, salivary bicarbonate and enzymes
Saliva
an enzyme that breaks down proteins
Protease
an enzyme that breaks down fat molecules
Lipase
an enzyme that breaks down carbohydrates but is only found in pigs and rats and is minimal in horses
Amylase
an enzyme found in the saliva, along with immunoglobulins, that helps control the bacterial population in the oral cavity
Lysozyme
List the 3 main salivary glands
- Parotid salivary gland
- Mandibular salivary gland
- Sublingual salivary gland
a condylar joint that forms the connection between the mandibular condyle and the mandibular fossa of the temporal bone
Temporomandibular Joint (TMJ)
What are the 3 allowable movement by the TMJ?
- Extension
- Flexion
- Translation
the movement of the mandible laterally and rostrally
Translation
What influences the amount of possible translation of the TMJ?
Dietary preferences between species
Carnivores vs Herbivores - which has a higher degree of TMJ translation? why?
Carnivores - lower degree > barely chew
Herbivores - higher degree > grind food
where food is directed into the esophagus through the act of swallowing but prevented from entering trachea
Pharynx
the part of the laryngeal cartilage that covers the glottis during the act of swallowing and prevents food from being aspirated into the trachea
Epiglottis
the structure that helps equalize the atmospheric pressure with pressure in the middle ear
Eustachian Tube
lymphoid tissue in the pharynx that protects the animal against some diseases
Tonsils
a muscular tube that connects the pharynx to the stomach
Esophagus
a thickening at the gastric end of the esophagus that prevents the highly acidic contents of the stomach from refluxing into the esophagus and damaging its mucosa
Cardiac Sphincter
What types of salivary secretions are produced by each subdivision of the autonomic nervous system?
- Parasympathetic nervous system > produces serous saliva
- Sympathetic nervous system > produces mucoid saliva
formed from a mix of macerated food and saliva
Bolus
the process by which food from the oral cavity is transported to the stomach (in monogastric animals) or reticulorumen (in ruminants)
Deglutition (Swallowing)
What are the 3 phases of deglutition?
- Voluntary Stage
- Pharyngeal Stage
- Esophageal Stage
the stage of deglutition in which the tongue pushes the bolus toward the pharynx and the animal must be conscious for
Voluntary Stage
the stage of deglutition in which the food bolus stimulates pressure receptors in the pharyngeal wall, the epiglottis temporarily covers the glottis, and a wave of muscle contraction moves across the pharynx to push the bolus into the esophagus
Pharyngeal Stage
the stage of deglutition in which the presence of food in the esophagus stimulates the swallowing center in the brainstem to initiate peristalsis in the esophagus
Esophageal Stage
the pattern of muscle contraction that propels food through the gastrointestinal tract
Peristalsis
the membrane that covers the surfaces of organs in the abdominal cavity
Visceral Peritoneum
the membrane that lines the wall of the abdominal cavity
Parietal Peritoneum
folds that connect the organs to the parietal peritoneum
Connecting Peritoneum
What are the 3 types of connecting peritoneum in the abdominal cavity?
- Mesentery
- Omentum
- Ligaments
a double-layered connecting peritoneum that attaches the intestines to the abdominal wall
Mesentery
a double-layered connecting peritoneum that attaches the stomach to the abdominal wall or other organs and functions to store fat and assist in insulating the abdomen
Omentum
the mesentery that suspends the duodenum
Mesoduodenum
What are the 2 divisions of the omentum?
- Lesser Omentum
- Greater Omentum
the connecting peritoneum that connects the smaller inner curve of the stomach to the first part of the duodenum and the liver
Lesser Omentum
the smaller inner curve of the stomach
Lesser Curvature
the connecting peritoneum that connects the larger outer curve of the stomach to the dorsal abdominal wall
Greater Omentum
the larger outer curve of the stomach
Greater Curvature
the pulpy acidic fluid which passes from the stomach to the small intestine, consisting of gastric juices and partly digested food
Chyme
a C-shaped, single chambered organ located just behind the diaphragm in the left cranial abdomen
Monogastric Stomach
the first branch of the abdominal aorta and is the stomach’s main blood supply vessel
Celiac Artery
transient folds of gastric mucosa which allow the stomach to expand when it is filled with food and increase the surface area for absorption
Rugae
lesions that develop in the stomach if the surface mucous cells do not produce adequate mucus
Gastric Ulcers
monogastric stomach with wall that contains both glandular and nonglandular tissue
Composite Stomach
the clear line of demarcation dividing the upper nonglandular half and lower glandular portion of the horse’s stomach
Margo plicatus
List the 4 divisions of the glandular region of the stomach
- Cardia
- Fundus
- Corpus
- Pylorus
the part of the stomach where the esophagus enters and contains mucus gland that secrete a thick layer of alkaline mucus to protect the mucosa against damage from gastric acids
Cardia
the expanded, dome-shaped, blind-ended sac of the stomach where the rugae are prominent
Fundus
the largest section of the stomach
Corpus
the distal part of the stomach
Pylorus
the circular muscle that helps determine the rate of gastric emptying
Pyloric Sphincter
the rate at which the stomach empties chyme into the duodenum
Rate of Gastric Emptying
shallow depressions that dot the mucosal surface of the stomach and are the opening of ducts lined by glandular cells
Gastric Pits
What are the 4 types of glandular cells in the stomach?
- Mucous Neck Cells
- Parietal Cells
- Chief Cells
- G Cells
progenitor cells of gastric glands that are close to the opening of the duct and secrete a thinner, less viscous mucus
Mucous Neck Cells
cells capable of dividing and creating new cells
Progenitor Cells
cells of gastric glands that secrete hydrogen and chloride in order to form hydrochloric acid (HCl) in the lumen of the stomach and secrete intrinsic factor
Parietal Cells
a substance secreted by parietal cells in the stomach that is necessary for absorption of vitamin B12 in the small intestine
Intrinsic Factor
cells of gastric glands that secrete pepsinogen and are located in the fundus
Chief Cells
an inactive precursor form of the enzyme pepsin and is converted into pepsin by the acidic environment of the stomach created by HCl
Pepsinogen
a proteolytic enzyme that begins the chemical digestion of proteins
Pepsin
endocrine cells found in the pyloric region of the stomach that secrete the hormone gastrin into the bloodstream
G Cells
What 3 substances stimulate secretions by glandular cells in the stomach?
- Acetylcholine
- Gastrin
- Histamine
the substance released by cholinergic neurons that stimulate secretions by chief cells and parietal cells in the stomach
Acetylcholine
the substance released by G cells that stimulate secretions by stomach parietal cells
Gastrin
the substance released by enterochromaffin-like cells that stimulate secretions by parietal cells in the stomach
Histamine
What are the 2 phases of secretion?
- Cephalic Phase
- Gastric Phase
the phase of digestive secretion that begins when an animal anticipates or is preparing to eat a meal
Cephalic Phase
the phase of digestive secretion that begins when food enters the stomach
Gastric Phase
the process that forces larger food particles back into the corpus so they can be remixed and grinded into small enough particles that will allow them to pass through the pyloric sphincter
Retropulsion
controlled by neurotransmitters and hormones
Neurohumeral Control
What controls gastric motility?
Neurohumeral Control
Give the 2 phases of chemical digestion
- Luminal Chemical Digestion
- Membranous Chemical Digestion
the phase of chemical digestion in which large macromolecules are broken down into short chain polymers via hydrolysis and occurs in the stomach and small intestine
Luminal Chemical Digestion
the phase of chemical digestion in which short chain polymers are broken down into their basic component parts via hydrolysis and occurs only in the small intestine
Membranous Chemical Digestion
