Digestive system - teeth, Biology

TEETH -

2398_tooth structure.png

  1. Study of teeth is odontology.
  2. Accumulation of oral bacteria & their products on teeth is plaque.
  3. Some acids are secreted by bacteria causing carries.
  4. Pyrrohea is caused by Entamoeba gingivalis. It' s transmission is possible by kissing only because encystment is absent.
  5. Teeth present in upper and lower jaw. Upper jaw is made up of premaxilla and maxilla.
  6. Lower jaw is made up of only one bone i.e. Dentany (total two bones).
  7. On jaw bones, thick mucosal folds and submusocal folds present to form gums or gingiva.
  8. Inflamation of gums is periodental disease. Teeth are partially ectodermal & partially mesodermal.
  9. True teeth is mesodermal. Teeth are partially living and partially dead. Ca contents are more.
  10. Teeth are thecodent i.e. situated in sucket or alveoli. Teeth are heteordont i.e. of different types.
  11. In Heterodont teeth are of following types -

(i) Incissor -

  1. Root less or small root i.e. Hypsodont. For cutting or gripping food.
  2. In elephant 1 pair upper incisors are modified in to tusk (In Indian elephant in male only, in African elephant in both sexes). They yield ivary. In rabbit, these are of unlimited growth.

(ii) Canine

  1. Pointed teeth. For tearing flesh. Generally well developed in carnivorous animals.
  2. Minimum changes occur in life time. In wild pig canines are of unlimited growth.
  3. In walrus upper canine (one pair) are modified into tusk & helpful in locomotion.
  4. In rabbit absent so diastema present between incisor and pre molar.

(iii) Pre molar -

  1. For chewing. 1-2 roots present.

(iv) Molars -

  1. For chewing. 2-3 roots present.
  2. Pre molar and molar collectively known as cheeck teeth.
  3. Their crown is flat and serrate so known as lophodont.
  4. In cheeak buccinator muscle present.
  5. Last molars are wisdom teeth.
  6. If crown is small teeth are brachydont.
  7. Teeth are diphyodont i.e. comes 2 times in life span. First as temporary set or deciduous second as a permanent set.
  8. In rabbit incisors are polyphyodont.
  9. In rat, mole, shrew and squirell monophyodont.
  10. In rabbit, molars are teeth are monophyodont.
  11. Osteoclast cells damage their roots so milk teeth are shed off.
  12. In man 32 teeth present.
  13.  Dental formula -
  14. 1211_dental formula.png
  15. A 17 years old boy - 2122/2122 = 28
  16. In milk teeth = 2102/2102 = 20
  17. In rabbit 28 = 2033/1023 .                               
  18. In rabbit milk teeth are 16 = 203/102 .
  19. In Dog = 3142/3143  = 42.                              
  20. In Cow = 0033/3133  = 32.
  21. In Elephant = 1003/0003  = 14.                        
  22. In Horse = 3143/3143  = 42.
  23. In oposum 50 teeth present (maximum in mammals).
  24. In each tooth there are three parts - Crown, neck and root.
  25. Crown part is present out side gum. Root present in sucket.
  26. Neck between these two parts. Cusps are square type i.e. Solenodont.
  27. If root small - Hypsodont e.g. Horse. If root large - Brachydont e.g. sheep.
  28. Cusps are pointed - Secodont e.g. lion.
  29. Crown part is covered by enemal which is dead, ectodermal, hardest part of body (5-6% H O only), made up of calcium carbonate and calcium sulphate formed by ameloblast cells. (Enemal absent in armadillows & sloth)
  30. Floride gives it strength. Inside enemel, dentine is main part having canaliculi.
  31. Tooth is hollow, having pulp cavity filled with pulp, rich in nerve & blood supply.
  32. Pulp cavity opens outside by apical foramen.
  33. If opening is wide, growth of tooth is unlimited. If opening is narrow, growth of tooth is limited.
  34. Root of pulp cavity is made up of odontoblast cells (unit of teeth, power of division present.)
  35. Tooth is fixed in gum by cement layer (formed by cementocyte cells) outside it a layer of periodontoblast cells present.
  36. Sharpen's fibres (Collagen) passes from this layer to gums & helpful in fixing.
  37. Tartar is hard deposite of calcium phosphate on tooth from saliva.
Posted Date: 10/1/2012 7:23:27 AM | Location : United States







Related Discussions:- Digestive system - teeth, Assignment Help, Ask Question on Digestive system - teeth, Get Answer, Expert's Help, Digestive system - teeth Discussions

Write discussion on Digestive system - teeth
Your posts are moderated
Related Questions
Q. Which are the target tissues and target organs of the neurohypophysis? The target organs of oxytocin are the mammary glands and the uterus and target organs of ADH are the k

Define the Role of Vitamin D in the immune system? Immune responses that are, mediated by T-cells can be inhibited by tile large doses of calcitriol i.e. 1, 25 dihydroxycholec

What evidence did Charles Elton collect that suggested that fluctuations in hare and lynx populations were related? What other evidence shows that these fluctuations ma

NAILS - Cover terminal segment of fingers & toes. Highly vascular dermis under lying the nail is called nail bed . It gives pinkish colour to nail. The small part

When a human donor gives a pint of blood, it generally requires how many weeks for body RESERVE of red corpuscles to be replaced? Is it: a) 7 week b) 3 weeks c) 1 weeks

Q. Explain about Oxidation reduction potential? The tendency of a substrate to accept or donate electrons is termed its redox potential (Eh). When a substrate loses electrons,

In eukaryotes possibly the most rapid and complex signaling is mediated through nerve impulses.  The Nerve  cells  (neurons)  consist  of  a cell  body  with  numerous projections

Q. What is the cell division process directly related to the embryonic growth? The embryonic growth depends directly on mitosis Through this kind of cell division the zygote di

Explain Procedure for the test of Presence of Coliform Bacteria? This test procedure is in continuation to the presumptive test procedure followed on last experiment. Now carry

M i croinjection method: In another approach fertilised eggs are microinjected by DNA. Microinjection requires excess of fertilized eggs. Gene transfer by microinjection is