Digestion in the mouth and Dental formula of a human

The mouth  comprises of two jaws, the fixed in the mouth lower  jaw. They bear teeth, used    for  mastication­­, There lies a muscular tongue between the two halves of the lower jaw. It assist during mastication, food tasting and speech .

The roof of the bucal cavity is called the hard palate. The front portion is softer, called the soft palate.

 

Digestion in the mouth

It is both physical (mechanical) and chemical (enzymatic). The teeth masticate (chew) the food, reducing it into smaller sizes. This increases the surface area for enzymatic digestion of the food. Physical digestion occurs on every food type, irrespective of the class.

Chemical digestion is done by the enzyme ptyalin (salivary amylase).it acts on cooked starch, hydrolyzing it first into dextrin, then to maltase(a disaccharide).this chemical digestion in the mouth occurs on carbohydrates only.

Salivary amylase (ptyalin) is one of the constituent of saliva. The on the components are lysosymes; NaCl;NaHCo3, , , SCN and mucus.

The lysosymes help in the catalyzing the lysis of bacterial walls while the mucus helps stick food together after chewing, forming toil (singular: tolus) for easy swallowing

 

Human Dentition and  Dental formula

Humans have two sets of teeth; milk or deciduous teeth and permanent teeth. The milk teeth appears  first. Then , progressively, they are replaced by the permanent teeth.this conditions i.e termed diplohyodont.

In terms of shapes and seizes(or types), humans(and their mammals) four types of teeth. they are incisors, canines, premolar and molars. This condition is termed heterodont dentition (as opposed to hemodent dentition in fishes, amphibians and reptiles)

A tooth is typically structured as follows

 

Vertical section of a premolar

Dental formula: this a summary of the number of each kind of teeth in one half of the upper and
lower jaws. The dental formula of as adult human is

dental formula of as adult huma

letters I, C, pm and m  stand for    incisors, canines, predons and molar respectively. this formular is interpreted thus: in each half of the mouth, there  are two outside the trackets should be used tomultiply ll the figures within the baskets  to come up with the total number of teeth.

 

Swallowing

This is the process by which food in the bucal cavity is moved into the esophagus. Initially, it is a voluntary action, but once begun it is involuntary. It proceeds as follows

  1. The epiglottis is in a raised position while the nassal passages are open
  2. The tongue passes the idus against the soft palate, the nasal passage is closed while the epiglottis closes on the glottis (opening into the larynx)

 

 

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