Tag: lymph and its function

Majority of mammals including human being forms two sets of teeth during their life, a set of temporary, milk or deciduous teeth replaced by a set of permanent or adult teeth. This type of dentition is called diphyodont. An adult human has 32 permanent teeth, which are of four different types, namely, incisors (I), canine (C), premolars (PM) and molars(M). Arrangement of teeth in each half of the upper and lower jaw in the order I, C, PM, M is represented by a dental formula which in human is 2123/ 2123. The premolars and last molars are absent in children. Thus the teeth which grow twice are incisors, canines and two molars i.e., a total of 20 teeth.

Enamel is the hardest material of animal kingdom. Enamel is ectodermal. It is secreted by Ameloblast cells of the ectoderm. lt has maximum amount of inorganic salt (96%) in It. Inorganic salt are mainly found in the form of phosphate and carbonate of Ca, Mg, Na and K. 3% of water is found in the enamel. Along with it Keratin and  ossein are also found in teeth. Ossein is a protein of bones, remaining part of tooth develops from mesoderm of embryo.

Cheek teeth or post canines comprise the molar and premolar teeth in mammals. Cheek teeth are multicuspidate (having many cusps or tubercles). Mammals have multicuspidate molars.

Stomach - Foveolar cells are mucus-producing cells, which cover the inside of the stomach, protecting it from the corrosive nature of gastric acid. The mucus produced by these cells is extremely important, as it prevents the stomach from digesting itself.
Duodenum - Brunner's glands (or duodenal glands) are compound tubular submucosal glands present in the duodenum. The main function of these glands is to produce a mucus-rich alkaline secretion (containing bicarbonate) in order to: protect the duodenum from the acidic content of chyme (which is introduced into the duodenum from the stomach); provide an alkaline condition for the intestinal enzymes to be active, thus enabling absorption to take place and lubricate the intestinal walls.
Large intestine - Goblet cells reside throughout the length of the small and large intestine and are responsible for the production and maintenance of the protective mucus blanket by synthesizing and secreting high-molecular-weight glycoproteins, known as mucins. 

Teeth appear to have first evolved in sharks, and are not found in the more primitive jawless fish. Lampreys do have tooth-like structures on the tongue, these are in fact, composed of keratin, not of dentine or enamel, and bear no relationship to true teeth. 

• The premaxilla is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. 
• In humans, they are fused with the maxilla and usually termed as the incisive bone (the portion of the maxilla adjacent to the incisors). Hence,  Incisor is present in premaxilla of the human jaw.