digestive system part 3

are accessory digestive organs located in sockets of the alveolar processes of the mandible and maxillae.  The alveolar processes are covered by gingivae or gums which extend slightly into each socket

lines the sockets and consists of dense fibrous connective tissue that anchors the teeth to the socket walls

is the visible portion above the level of the gums

embedded in the socket

is the constricted junction of the crown and root near the gum line.

forms the majority of the tooth.  It consists of a calcified connective tissue that gives the tooth its basic shape and rigidity.  It is harder than bone because of its calcium content.

this covers the dentin of the crown and consists primarily of calcium phosphate and calcium carbonate. Harder than bone it is the hardest substance in the body.  It protects the tooth from wear and tear and acids that can easily dissolve dentin

the dentin of the root is covered by this a bone like substance, which attaches the root to the periodontal ligament.

the dentin of a tooth encloses a space.  The enlarged part of the space called this lies within the crown and is filled with pulp, a connective tissue containing blood vessels, nerves and lymphatic vessels.

narrow extensions of the pulp cavity.  They run through the root of the tooth.

humans have two of these, or sets of teeth: deciduous and permanent

begin to erupt at about 6 months of age and approx 2 teeth per month thereafter until all 20 are present

are closest to the midline, are chisel-shaped and adapted for cutting into food.

next to the incisors moving posteriorly thay have a pointed surface and are used to tear and shred food

posterior to the cuspids, which have four cusps. They crush and grind food to prepare it for swallowing.

replace the deciduous teeth by age 12. They contain 32 teeth and resemble deciduous teeth with a few exceptions

replace the deciduous molars. They have two cusps and one root and are used for crushing and grinding

erupt into the mouth posteriorly to the premolars.  They do not replace any deciduous teeth and erupt as the jaw grows. first ones at age 6 second at age 12 and the last at 17

chewing.  seen in mechanical digestion.  food is manipulated by the tongue, ground by the teeth and mixed with saliva.

a soft, flexible easily swallowed mass

initiates the breakdown of starch.  Seen in chemical digestion. It breaks down carbs into monosaccharides.

contained in saliva, this enzyme becomes activated in the acidic environment of the stomach and thus starts to work after food is swallowed.  It breaks down dietary triglycerides into fatty acids

the muscularis becomes slightly more prominent at each end of the esophagus. This one consists of skeletal muscle and regulates the movement of food from the pharynx into the esophagus

which consists of smooth muscle tissue.  It regulates the movement of food from the esophagus into the stomach.

the superficial layer of the esophagus, rather than the serosa in the stomach and intestines, It attaches the esophagus to surrounding structures

it secretes mucous and transports food into the stomach.  It does not produce enzymes and it does not carry on absorbtion