Microbiology Final Micro.txt

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Microbiology Final Micro.txt
2010-10-01 00:45:46
micro claude

micro final
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  1. True or False.
    Mammals have the sharpest hearing of all of the animals. This is due to the fact that they have all evolutionarily developed very similar structures for auditory perception.
    True and False. Mammals have the sharpest sense of hearing but also display a wide variety and diversity in their hearing.
  2. This part of the ear helps to collect sound waves and delivers them to the middle ear.
    External ear
  3. Along with the external ear, two other structures contain elastic cartilage. What are these two other structures? (hint: all three start with the letter E)
    • External ear
    • Eustachian tube
    • Epiglottis
  4. Sound waves are alternating waves of air pressure with periods of ___________ and ___________.
    Compression and Rarefaction
  5. What characteristic of sound waves is a function of the frequency of sound waves? What units are used to measure this?
    Pitch. Pitch is measured in Hertz (cycles per second)
  6. What is the audible range for humans?
    20Hz to 20kHz.
  7. Our interpretation of sound intensity that is a function of the wave amplitude or the pressure difference between waves is called what? It is measured with what logarithmic scale?
    Loudness. Loudness is measured on the decible scale (dB)
  8. True or False.
    The chain of ossicles (small bones in the ear) have already reached full adult dimensions and rigidity at the time of birth.
    True. The external ear, middle ear, cochlea and outermost hair cells (auditory receptors) continue to develop for different amounts of time after birth. The ossicles, however, reach adult dimensions and rigidity at birth.
  9. True or False.
    All parts of the ear are derived from the same embryological germ layer.
    False. Various parts of the ear are developed from all three germ layers.
  10. The glands near the external ear whose name is derived from the Latin word for "wax" are called what? What is their secretory substance called?
    Ceruminous glands secrete cerumen.
  11. What are the names of the three ear bones and in which part of the ear are they located?
    • Malleus (hammer)
    • Incus (anvil)
    • Stapes (stirrup)
    • These three bones are located in the middle ear
  12. True or False.
    The eustachian tube lise flat and, if opened, allows for the equalization of pressure between the middle ear and the nose.
    False. The eustachian tube does allow for the equalization of pressure, but it does so between the middle ear and the throat (links middle ear to pharynx)
  13. Which tonsil surrounds the opening of the eustachian tubes?
    The pharyngeal tonsil.
  14. If you could taste the paper triangle that was handed out in class you are a(n):
    A. Stupid taster
    B. Sour taster
    C. Serious taster
    D. Super taster
    D. Super taster
    (this multiple choice question has been scrambled)
  15. True or false.
    Enamel is the second hardest material in the body. Second only to the bones of the inner ear.
    False. Enamel is the hardest substance in the body. It is about 95% inorganic content, 1% organic and 4% water.
  16. How many ameloblasts does it take to secrete one full key-hole enamel rod unit?
  17. What is the difference between the cribiform plate and the cortical plates?
    The cribiform plate faces the tooth and follows its general outline. The cortical plates face the cheek and lips(outer cortical plate) and the tongue(inner cortical plate).
  18. Where is an interradicular crest or septum found?
    This is the bone that is found in the furcation of a multi-rooted tooth.
  19. True or False.
    Interradicular crests are lined by cribiform plate.
  20. The holes found in cribiform plate where vasculature runs are known as ___________.
    Volkmann's canals.
  21. What are the types of fibers that can be found in the PDL?
    • Oxytalan fibers (appear in large numbers when PDL is subjected to increased stress)
    • Elaunin fibers
  22. There are two types of nerve endings in the PDL. What are the two types and what are they responsible for?
    • Free, unmyelenated nerve endings are responsible for pain sensation
    • Encapsulated nerve endings are responsible for sensing pressure changes during mastication.
  23. What is the name for inflammation of the middle ear? This inflammation can be caused by infections in the throat traveling up through the eustachian tube to the middle ear.
    Otitis media
  24. The "foot plate" of the stapes is attached to the inner ear through which opening?
    The oval window
  25. Which structures in the inner ear are responsible for our sense of balance and equilibrium?
    The vestibular apparatus. This is composed of the 3 semicircular canals and 2 saclike otolith organs, the utricle and saccule.
  26. The inner ear is filled with what type of fluid?
    Lymph fluid
  27. True or False.
    The cochlea, vestibule and ossicles are the three regions of the inner ear.
    • False.
    • The three regions of the inner ear are:
    • Cochlea
    • Semicircular canals
    • Vestibule
  28. Comprising the inner ear are two "labrynths." What are their names, what fluid is each filled with and where are they found?
    The inner ear is comprised of the bony labyrinth and the membranous labyrinth. They are filled with perilymph and endolymph, respectively. The membranous labyrinth is found inside of the bony labyrinth. the bony labyrinth surrounds the membranous labyrinth.
  29. How are lymph waves initiated in the cochlear duct?
    By movements of the stapes against the oval window.
  30. The "ear drum" is know as the ___________.
    Tympanic membrane
  31. The Cochlea is divided into three fluid-filled compartments. These three parts are known as the ___________, __________ and ___________ ducts.
    Cochlear, Tympanic and vestibular ducts.
  32. The cochlear duct contains structures on the basilar membrane that are very sensitive, detecting pressure impulses and responding with electrical impulses that travel along the auditory (cochlear) nerve to the brain. This "microphone of the body" is called ____________________.
    The Organ of Corti.
  33. The cochlea is part of the inner ear. What is its function?
  34. The basilar membrane of the cochlear duct has receptor cells with hair that is imbedded in the rigid ________ membrane. Vibrations pull the hairs which synapse with sensory fibers of the cochlear nerve. These structures are all part of the Organ of Corti.
  35. Sound waves in the ear become vibrations when they strike the __________ membrane.
    Tympanic membrane. This is the "ear drum."
  36. Once sound waves strike the tympanic membrane, vibrations are transferred to the three bones of the middle ear (which are called?). These vibrations are then converted into fluid waves within the _________ duct as the smallest bone in the human body vibrates against the oval window.
    The Malleus, Incus and Stapes are the names of the ossicles. The stapes is the smallest bone in the body and rests on the oval window. The oval window "looks into" the Vestibular duct. The vestibular duct is where sound waves, converted to vibrations and finally to fluid waves, enter the inner ear.
  37. True or False.
    Fluid waves push on the membranes of the cochlear duct, thereby activating the sensory hair receptors in the organ of corti.
    True. This is how it happens.
  38. The energy from fluid waves enters the vestibular duct through the oval window, transfers across the cochlear duct and then into the ________ duct where it is finally dissipated at the _________ window.
    • Tympanic
    • Round
  39. The two ends of the coiled cochlea are called the _____ and the _____.
    Base and the apex.
  40. The vestibular and tympanic ducts are continuous and are filled with __________ , a fluid similar to plasma. Hint: this is the fluid that fills the bony labyrinth.
  41. The cochlear duct is a dead-end tube filled with ________, a fluid similar to intracellular fluid. This fluid is high in ____. Hint: This is the fluid that fills the membranous labyrinth.
    Endolymph is high in K+
  42. Excess vibration and pressure are dissipated at the _______.
    Round window
  43. The organ of Corti rests on the basilar membrane and contains hair cells that are covered with _______.
    stereocilia. The longest stereocilia of hair cells are embedded in the overlying tectorial membrane.
  44. While the ______ is known as the "seat of the soul" the _______ is known as the "temple of hearing."
    • pineal gland (remember this one?)
    • organ of Corti
  45. The cochlea is spatially arranged in a way that allows different frequencies (pitch) of sound to stimulate hair cells in in different places along the cochlear duct. This is called _________ organization.
    tonotopic. The cochlea is tonotopically arranged.
  46. Sound waves cause deformation of the cochlear duct that then move the tectorial membrane. This motion bends the stereocilia of the hair cells and activates channels that let positive ________ ions into the cells.
  47. Signals from the primary sensory neurons travel through the cochlear nerve to the ___________ in the brain stem.
    cochlear nucleus
  48. Once signals reach the cochlear nucleus in the brain stem, they are relayed to the _________ and then to the primary auditory cortex in the __________ lobe of the brain.
    • thalamus
    • temporal
  49. True or False.
    The spatial coding of pitch found in the cochlea is preserved in the primary auditory cortex in the temporal lobe.
    True. The tonotopic arrangement found in the cochlea is preserved in the primary auditory cortex.
  50. True or False.
    The base of the cochlea is where higher frequency sounds are perceived and the apex of the cochlea is where lower frequency sounds are perceived.
    True. High pitch = base, Low pitch = apex
  51. Auditory data from the auditory cortex and pontine nucleus is received in the ________.
    cerebellum. Possible roles for the cerebellum include coordinate transformation, motor timing, and localization.
  52. What are the four types of hearing loss that we covered?
    • 1. Sensorineural hearing loss (nerve-related deafness)
    • 2. Conductive hearing loss
    • 3. Mixed hearing loss
    • 4. Central hearing loss
  53. What is the most common type of hearing loss and what causes it?
    Sensorineural hearing loss is the most common. This type of hearing loss involves damage to the inner ear caused by aging, pre-natal and birth-related problems, viral and bacterial infections, heredity, trauma and exposure to loud noise, fluid backup or a benign tumor in the ear. Exposure to loud noise is the most common cause of hearing loss in young people.
  54. One out of every _____ Americans have hearing loss.
    One in every ten
  55. True or False.
    Hearing loss is the second most common birth defect in America, behind congenital heart disease.
    False. (don't take this one to the bank) She claims that hearing loss is the most common birth defect in America so know that for the test.
  56. The vestibular apparatus includes which of the following inner ear structures?
    A) Semicircular canals
    B) Utricle
    C) Saccule
    D) All of the above
    E) None of the above
    F) Some, but not all of the above
    G) A, B and C plus the cristae within the ampula and the maculae.
    G is the correct, and totally ridiculous answer.
  57. The vestibular apparatus responds to both _______ and _______ changes in the body's position relative to space.
    Rotational and linear
  58. True or False.
    The 3 semicircular canals and 2 saclike otolith organs of the vestibular apparatus are filled with perilymph.
    False. These structures are filled with endolymph.
  59. Vertigo, tinnitis and progressive hearing loss are all symptoms of what disease? What causes this disease?
    Meniere's Disease. This is caused by a buildup of endolymph (endolymph hydrops) - an increased pressure within the inner ear's endolymph system.
  60. The sensory receptors for rotational acceleration are called ________ and are located at the _______ of each semicircular canal.
    • Cristae , Base
  61. The chambers where the cristae are located are called what?
  62. Each crista consists of a cupula that, when pushed by the endolymph, bends the kinocilium of each hair receptor. What are the culpa and kinocilium?
    A culpa is a gelatinous mass and kinocilium are embedded cilia.
  63. True or False.
    The semicircular canals can sense all three degrees of rotation.
    True. Since the three semicircular canals are oriented at right angles to each other, they can sense all three degrees of rotation.
  64. The sensory receptors for linear acceleration are called __________ and are found in the ________ and _______.
    The sensory receptors are called maculea and are found within the utricle and saccule.
  65. The small crystals of calcium carbonate inside of macula are called _______. These, along with the cilia of hair cell receptors are embedded in a gelatinous mass known as the _______ .
    Otoliths. Otolith membrane.
  66. The maculae of the saccule are oriented ________ when the head is in its upright position.
  67. The maculae that are oriented horizontally when the head is in its upright position are found in the _______.
    utricle. The maculae in the utricle are sensitive to horizontal forces.
  68. Benign Paroxymal Positional Vertigo is caused by what?
    Debris (otoliths) from the utricle finding its way into the semi-circular canals.
  69. What is the equilibrium pathway?
    The equilibrium pathway starts as signals travel along the vestibulocochlear nerve and are transmitted to the vestibular nuclei in the brain stem and cerebellum.
  70. What are the three types of oral mucosa?
    • 1. Lining - found under tongue, floor of mouth, cheeks, inner lip and soft palate
    • 2. Masticatory - found in the hard palate and gingiva
    • 3. Specialized - found on upper surface of tongue.
  71. These structures help to keep the basal lamina and the lamina propria from shearing apart from one another. They are called ____________.
  72. The general structure of oral mucosa tissue consists of what layers?
    • 1. Epithelial layer
    • 2. Basal lamina
    • 3. Lamina propria (connective tissue)
    • 4. Submucosal layer (not present in some mucosa)
    • Beneath these layers may be striated muscle or bone, depending on the tissue.
  73. The epithelial layer of oral mucosa is divided into three major regions which are:
    • 1. Basal layer (where mitosis occurs)
    • 2. Prickle cell layer (cells moving toward luminal surface)
    • 3. Outer layer (may or may not be keratinized)
  74. The epithelial layer contains which of the following types of cells?
    A) Epithelial cells
    B) Melanocytes (for pigmentation)
    C) Langerhann cells (immune cells)
    D) Merkel cells (associated with nerve terminals)
    E) Inflammatory cells (lymphocytes, monocytes and neutrophils)
    F) All of the above
    G) None of the above
    F - all of the above! The epithelial layer contains both epithelial and non-epithelial cells.
  75. What are the two layers of the basal lamina?
    • 1. Lamina lucida (immediately below basal cell layer)
    • 2. Lamina densa (next to the lamina propria layer)
  76. The lamina propria also has 2 layers. What are these layers?
    • 1. Upper papillary layer
    • 2. Lower reticular layer (contains numerous fibers)
  77. The interlocking portions of the epithelial tissue into the lamina propria are known as ____________.
    • Rete's ridges (or Rete's pegs) - These are the extensions of epithelial tissue into the lamina propria.
    • Papillae are the extensions of lamina propria into the epithelial tissue.
  78. The sub-cellular anchoring system that holds the epithelial layer to the lamina propria is comprised of hemidesmosomes. The _______ fibrils extend into the epithelial layer and _______ fibrils extend into the lamina propria to bind the collagen fibers of this layer.
    • tonofibrils
    • anchoring
  79. True or False.
    Lining mucosa is keratinized stratified squamous epithelium.
    False. Lining mucosa is non-keratinized stratified squamous epithelium. The other two types of oral mucosa are generally keratinized but lining is not!
  80. At the corners of the mouth are specialized ________ glands which are unique because they are not associated with hair follicles.
    Sebaceous - these glands lend lubrication and flexibility to this area of the mouth.
  81. True or False.
    The vermilion border gives way to the lining mucosa of the inner lip. The epithelial layer on the lining mucosa is much thicker than that on the lip or facial skin.
    • True. The epithelial layer of the lining Oral mucosa is much thicker than the epithelium of the Vermilion border or facial skin. Minor salivary gland also appear in the oral mucosa.
  82. True or False.
    the lining oral mucosa of the soft palate is very thick with a thin lamina propria layer that has few papillae.
    • False.
    • The lining oral mucosa of the soft palate is thin with a very thick lamina propria which has numerous papillae.
    • The submucosal layer is loose connective tissue and contains numerous salivary glands.
  83. The ventral (bottom) surface of the tongue has a unique feature which is the absence of ___________.
  84. Why is the lining mucosa is often called "mucus membrane."
    Because it usually contains salivary glands.
  85. Where is lining mucosa found?
    • Inner lip
    • Cheeks
    • Ventral surface of tongue
    • Floor of mouth
    • Soft palate
  86. Masticatory Mucosa is found where? Like the lining of the ventral surface of the tongue, masticatory mucosa generally lacks a submucosal layer except in this area: ________.
    • Gingiva
    • Hard Palate
    • The lamina propria is usually bound directly to bone . Submucosa is present, however at the sides of the hard palate in the premolar area.
  87. Masticatory mucosa is found in areas where abrasion is high. In order to prevent damage to the deeper layers of tissue, this mucosa is marked by the presence of _______.
  88. Gingival tissue is divided into three major types. What are these?
    • 1. Attached - attached to alveolar bone and has striped appearance due to Rete's ridges
    • 2. Free gingiva (marginal gingiva) which forms a collar around base of tooth
    • 3. Sulcar or junctional gingiva. This is the inner surface of free gingiva which faces the tooth enamel and is non-keratinized.
  89. A thickening of the keratin layer that occurs with continued irritation of keratinized epithelium is known as ___________.
  90. The collagenous fibers of connective tissue that anchor the lamina propria directly to bone in the hard palate are called ______ bands.
  91. What are rugae and what is the median raphe?
    • The median raphe is the midline of the hard palate that is produced by the merging of the 2 palatine shelves during development. a.k.a. palatine raphe.
    • Rugae are the ridges that are manifested as the lamina propria is thrown into deep folds on either side of the median raphe.
  92. The soft palate has different types of epithelium on the oral and nasal sides. What type of epithelium is on each side?
    • Oral side: lining oral mucosa (stratified squamous epi)
    • Nasal side: respiratory epi (pseudostratified, ciliated columnar)
  93. True or False.
    The soft palate has a thick mucosa containing minor salivary glands and muscle. It also separates the oral and nasal pharynges.
  94. The dorsal side of the tongue is covered by _________ mucosa.
  95. There are four types of mucosa on the tongue, all of which lack a submucosal layer. What are the four types?
    • 1. Filiform (keratinized, no taste buds)
    • 2. Fungiform (non-keratinized, contain taste buds)
    • 3. Foliate (non-keratinized, taste buds, folds along side of tongue)
    • 4. Circumvalate (non-keratinized, many taste buds, set deep into tongue surface, Von Ebner's glands)
  96. True or False.
    Rete's ridges and papillae are present in the tongue.
  97. vonEbner's glands are found around what type of lingual papilla? What are their function?
    vonEbner's glands are found at the base of the cleft of circumvallate papillae. They are specialized serous salivary glands and serve to flush out the cleft so that new taste chemicals can reach the taste buds.
  98. Clusters of 50-100 cells which appear as a clear ball in the epithelial layer and act as the gustatory sensory organ are known as ___________.
    Taste buds
  99. How many types of cells are found in taste buds? What is the function of each type of cell?
    There are four types of cells. The first three are sensory cells and the fourth (called basal cells) is the origin of new cells.
  100. Where are taste buds found?
    They are associated primarily with folate, fungiform and circumvallate papillae. Some are also found on the soft palate, epiglottis, larynx and pharynx.
  101. Tonsils! These wonderful lymphoid tissues form a ring around the oropharynx called ____________.
    Waldeyer's ring
  102. Tonsils are:
    A) Not encapsulated
    B) Partially encapsulated
    C) Fully encapsulated
    B. Tonsils are partially encapsulated.
  103. How many tonsils are there, where are they found and what is the name of each one?
    • There are three tonsils.
    • 1. Pharyngeal tonsil (adenoid) is a single tonsil located at the midline in the posterior wall of the superior portion of nasopharynx.
    • 2. The palatine tonsils are located adjacent to the posterior molars.
    • 3. The sublingual tonsils are located below the base of the tongue.
  104. Which tonsil is the largest and why is it particularly prone to inflammation/infection?
    The palatine tonsil is the largest and is particularly prone to inflammation/infection because it has deep blind crypts. These crypts easily collect bacteria and lack glands to flush them out.
  105. The palatine tonsil is covered with what kind of epithelium?
    Stratified squamous epithelium covers the palatine tonsil on the oral surfice (lining mucosa)
  106. What kind of epithelium covers the pharyngeal tonsil? Is the lymphatic tissue in this tonsil mor or less well defined than in other tonsils?
    The pharyngeal tonsil is covered with pseudostratified columnar cilia (respiratory epithelium). The lymphatic tissue in the pharyngeal tonsil is less well defined than that of the other tonsils. NO crypts. Surrounds the opening of eustachian tubes.
  107. Which tonsil is located in the posterior 1/3 of the tongue and covered with stratified squamous epithelium? Why does this tonsil rarely become inflamed or infected?
    The lingual tonsils are located at the posterior 1/3 of the tongue. They rarely become inflamed because the crypts in this tonsil are not blind and are washed out by the salivary glands that empty into them, keeping them free of bacteria and foreign debris.
  108. Which three tissues are collectively called the "supporting tissues?"
    The alveolar bone, periodontal ligament and the dentogingival junction.
  109. This is the part of the maxilla and mandible that supports the roots of the teeth. It consists of the alveolar bone proper and supporting bone. What is this part called?
    The alveolar process.
  110. Clinically, the alveolar bone is defined as the ________ on a radiological basis. Hint: Radiographically, it is more radiopaque than the surrounding bone and connective tissue.
    Lamina dura
  111. The presence of alveolar bone is dependent on the presence of ___________.
    dental roots
  112. Alveolar bone forms the socket (alveolus) that the tooth rests in and serves as an anchor for the PDL that holds the tooth in place. The part of the alveolar bone that directly faces the root of the tooth and follows its outline is called the __________ plate.
  113. Alveolar bone that is between the roots of a multi-rooted tooth is called ___________ alveolar bone. The bone between the roots of two different teeth is called __________ alveolar bone.
    • interradicular (interradicular septum)
    • interdental (interdental septum)
  114. The compact lamellar bone surfaces that faces the cheek on one side and the tongue on the other are known as the inner and outer ____________ plates.
  115. The small holes in cribiform plate that allow for the passage of vasculature to the PDL and the pulp of the tooth are called _____________.
    Volkmann's canals.
  116. True or False.
    Orthodontic forces as well as mesial drift can provide the stress that will cause bone to recontour, undergoing both resorption and deposition to accommodate the movement of a tooth.
  117. The new bone laid down when a tooth moves away from the cribiform plate is called _______ bone.
    woven bundle
  118. This is a sheet of tendon-like tissue that ties the tooth to the alveolar bone, to neighboring teeth and to the gingiva. What is it called?
    The Periodontal Ligament (PDL)
  119. The PDL is a product of the cells (fibroblasts) of what developmental part of the tooth?
    The dental sac.
  120. The PDL is made up of groups of fiber bundles called _________ and _______________. The bulk of the fibers are mad up of type ___ collagen.
    • gingival fibers and principal fiber bundles.
    • type I
  121. The areas of loose connective tissue between the fiber bundles of the PDL are called _________ spaces.
  122. What are the four types of fibers that are classified as gingival fibers?
    • 1. Dentogingival fibers - extend from cervical cementum to the free gingiva and to the lamina propria of the gingiva, over the alveolar crest.
    • 2. Dentoperiosteal fibers - extend form cervical cementum over alveolar crest to cortical plates of bone.
    • 3. Transseptal fibers - extend from cementum of the tooth to adjacent tooth, over the alveolar crest.
    • 4. Circular fibers - extend horizontally around the most cervical part of root and insert into cementum, lamina propria of gingiva and the alveolar crest.
  123. What are the different groups of principle fibers?
    • 1. Free gingival fibers
    • 2. Alveolar crest fibers
    • 3. Horizontal fibers
    • 4. Oblique fibers
    • 5. Apical fibers
    • 6. Inter-radicular fibers
  124. What are free gingival fibers?
    In the cervical portion of the root they extend from cementus into the gingiva surrounding the neck of the tooth. They hold gingiva to the tooth surface.
  125. What are Alveolar crest fibers?
    These extend from the cervical cementum and insert into the alveolar crest. These fibers resist horizontal movement of the teeth.
  126. What are horizontal fibers?
    Horizontal fibers extend at right angles to the long axis of the tooth in a horizontal plane from the alveolar bone to the cementum. Found in the cervical 1/3 of the root. These fibers also resist horizontal movement of teeth.
  127. What are Oblique fibers?
    Oblique fibers slant occlusally from the cementum to the alveolar bone. Most abundant of the fiber bundles. They begin at the apical 2/3 of root, apical to the horizontal fibers. These suspend the tooth in the socket and resist compressing the apex of the tooth into the base of the tooth socket.
  128. What are apical fibers?
    Apical fibers radiate out from the apical cememtum into the alveolar bone. These fibers stabilize the tooth against tilting movements.
  129. What are Inter-radicular fibers?
    These are only seen in multi-rooted teeth. They extend from the cementum in the furcation to the interradicular alveolar bone. They stabilize the tooth in the socket.
  130. The terminal ends of all principle fibers that are embedded in bone or cementum are called __________ fibers.
  131. True or False.
    When a tooth is functional and in occlusion, the PDL becomes narrower and less organized in order to accommodate the load on the tooth.
    False. A functional tooth has a thicker and more organized PDL. Like most tissues, it stays strong by using it. When there is no load on a tooth the PDL narrows and loses organization of fiber bundles.
  132. ________ fibers are one of the two types of fibers in the PDL. These fibers are related to elastic fibers and appear in larger numbers when the PDL is subject to increased stress. What are these fibers?
    Oxytalan. The other type of fibers are elaunin fibers.
  133. True or False.
    The blood supply to the PDL is very rich and highly developed - more than in any other connective tissue.
    True. Blood vessels are found throughout the interstitial spaces of the ligament.
  134. Each tooth, its PDL and the alveolar bone of the tooth share a common blood supply through an artery that enters through the __________ to supply the pulp of the tooth, enters the PDL, which supplies areas all around the tooth and enters the alveolar bone of the tooth.
    The artery enters through the apical foramen to supply these tissues with blood.
  135. Innervation of the PDL: Which two types of nerves innervate the PDL?
    • 1. Autonomic - sympathetic fibers that travel with blood vessels to regulate blood flow.
    • 2. Afferent sensory fibers - mostly myelenated nerves from branches of the 2nd and 3rd divisions of the trigeminal nerve.
  136. There are also two types of nerve endings in the PDL. They are...
    • 1. Free, unmeyelenated for pain sensation.
    • 2. Encapsulated for sensing pressure changes during mastication.
  137. What is Junctional epithelium and how does it attach to the tooth?
    Junctional epithelium forms a junction between the sulcular epithilium and the tooth. It is attached to the tooth by hemidesmosomes connected to the cementum or enamel. It is located between two basil lamina - one lamina faces the enamel of the tooth, the other faces the connective tissue of the gingiva. Junctional epithelium thickens with age.
  138. True or False.
    Enamel is the hardest substance in the body.
  139. Enamel is composed mainly of inorganic calcium salts and hydroxyapatite. The total inorganic composition of enamel is ____% with ____% organic compounds and ____% water.
    • 95% inorganic content
    • 1% organic content
    • 4% water
  140. The protein ______ is the main organic component of enamel.
  141. True or False.
    Enamel fully mineralizes before both dentin and bone.
    False. Enamel takes years to fully mineralize.
  142. Ameloblasts are tall, columnar cells that have _____ sides, allowing them to pack in close together in an interlocking type pattern.
    Ameloblasts are six sided.
  143. The secretory process on an ameloblast is called _______ process. It is shorter than odontoblastic processes and is shovel-shaped.
    Tome's process
  144. Hydroxyapatite crystals increase in size in all dimensions as water and organic material is removed from enamel by the resorptive ameloblasts. Because of this, hydroxyapatite crystals in enamel are ____ times larger than those in dentin or cementum.
  145. Ameloblasts have two phases or stages. What are they?
    • 1. The secretory phase when they deposit enamelin containing enamel matrix through the Tome's process.
    • 2. Resorbing phase. After deposition of enamel, ameloblasts remove most of the water and organic material from the matrix. Tome's process is not visible and the border takes on a ruffled appearance.
  146. The tightly packed masses of hydroxyapatite crystals that form enamel are called _____ or ______.
    Rods or Prisms. These structures run from the DEJ to the outer edge of the enamel surface.
  147. Enamel rods are stacked in interlocking rows and have a key-hole shape when viewed in cross-section. How many individual ameloblasts must function together to form one keyhole?
  148. Deposition of enamel happens in a manner that is perpendicular from the DEJ to the tangent of the enamel surface. In areas where this structure is not possible, enamel rods become bent, creating _______ enamel.
    Gnarled. Gnarled enamel has a higher organic content and the space between rods is greater. Because of this, gnarled enamel is more susceptible to decay.
  149. Lines in enamel that are the result of rhythmic recurrent deposition of the enamel are called ________ or Stripes of ________.
    Incremental lines or stripes of Retzius.
  150. These lines, with absolutely no clinical importance, are only able to be seen when enamel is illuminated by polarized light. What are these lines called?
    Hunter-Schreger Bands
  151. The end points for incremental lines that are manifested on the outer surface of enamel are called ______.
  152. Enamel lamellae are what?
    Enamel lamellae are cracks in the enamel that can be caused many ways. Lamellae are enamel defects.
  153. Another enamel defect that fills with organic material and is found near the DEJ between groups of enamel rods that are oriented slightly apart from each other are called __________.
    Enamel tufts
  154. Overly ambitious odontoblast processes that extend across the DEJ and into the enamel are called ________.
    Enamel spindles
  155. Why is fluoride application helpful in the prevention of tooth decay?
    Because fluorapatite is more resistant to bacterial acids that are secreted onto the enamel surface.
  156. Which part of the key-hole shaped enamel rod is the most easily acid etched?
    The top, rounded portion of the key-hole shaped enamel rod is most easily acid etched. Because of this, acid etched enamel shows horse shoe shaped indentations.
  157. ____________ is a broad spectrum antibiotic that was commonly used in the 50s and 60s that caused staining in dentin
  158. Enamel pits and fissures are more susceptible to decay because breaks in the enamel often occur there and crowding of ameloblasts cause incomplete maturation of the enamel

    in these areas. Using __________ is a good preventative treatment in these areas.
    Pit and fissure sealants
  159. Cementum is consists of:
    ___% inorganic components
    ___% organic components
    ___% water
    • 65% inorganic
    • 23% organic
    • 12% water
  160. The first layer of dentin that is laid down on the entire root surface of the tooth is called _______ cementum and is deposited by __________________.
    Intermediate cementum is deposited by Hertwig's root sheath. This first layer of cementum calcifies to a greater extent than the next layer of cementum to be deposited.
  161. After the deposition of intermediate cementum, mesenchymal cells migrate and differentiate into cementoblasts. They then begin to deposit a secondary layer of cementum that is acellular at the ______ 1/3 of the root and cellular at the _______ 2/3 of the root.
    • Acellular cementum is deposited at the cervical 1/3 of the root.
    • Cellular cementum is deposited at the apical 2/3 of the root.
  162. True or false.
    Cementum functions to form one half of the anchor for the PDL.
  163. What are some common cementum abnormalities?
    • 1. Reversal lines - reflect areas of resrption that typically occurs with extreme movement of the teeth.
    • 2. Cementicles - sounds like cementum testicles. Maybe looks like them too?
    • 3. Arrest or resting lines - banding pattern from periods of deposition and non-deposition
    • 4. Hypercementosis - abnormal thickening of parts of the cementum, generally in apical region.
  164. CEJ does not always have a consistent abutment.
    ____% of the time cementum and enamel overlap
    ____% they meet
    ____% there is a gap
    • 60% overlap
    • 30% meet
    • 10% gap