The surface coating of the tooth is the hardest substance in the human body. This can be explained by the high degree of mineralization - the content of inorganics in the enamel reaches 97%, with a water content of up to 3%.
The liver with its duct system and gall bladder develop from the hepatic diverticulum of the ventral endoderm of the primary midgut. Liver development begins in the 4th week of the intrauterine period. The future bile ducts are formed from the proximal part of the diverticulum, and the hepatic beams from the distal part.
The liver lobule is a morphofunctional unit of the liver. In the center of the lobule is the central vein. The central veins, connecting with each other, eventually flow into the hepatic veins, which in turn flow into the inferior vena cava.
The liver is the largest organ in humans. The functions of the liver are varied. It is involved in the processes of digestion, hematopoiesis and performs numerous functions in metabolism.
Human saliva is a secretion that is secreted by the salivary glands (large and small). The total volume of saliva produced during the day ranges from 1,000 to 1,500 ml (pH 6.2-7.6).
The structure of the human salivary glands consists of their division into alveolar, tubular and alveolar-tubular. They represent a well-developed system of ducts that connect into a large excretory duct.
There are mucous, serous and mixed minor salivary glands, which are located singly and in groups in the submucosal layer, in the thickness of the mucous membrane and between muscle fibers in the oral cavity, oropharynx, and upper respiratory tract.
