Histology of glands of a gastrointestinal tract at children
Morphological and functional characteristics and especially of the salivary glands in the newborn. Stages of formation of the segments of the liver in the fetus. The functionality of the liver in young children, the histology of the pancreas in infants.
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Department of Histology, Cytology and Embryology
IWS (individual student's work)
The theme: «Histology of glands of a gastrointestinal tract at children»
- Features of a structure and functioning of salivary glands at children
- Features of the structure and functioning of the liver in children
- Pancreas histology at newborns
Digestive bodies of the child have several morphological and physiological features. These features are most brightly expressed at children of early age at whom the digestive device is adapted mainly for digestion of breast milk which digestion demands the smallest amount of enzymes.
Children of early age (especially newborn) have a number of morphological features, the general for all departments of digestive tract:
· thin, gentle, dry, vulnerable mucous membrane;
· richly vaskulyarizirovanny submucous layer consisting mainly of friable cellulose;
· insufficiently developed elastichesky and muscular fabrics;
· low sekretorny function of the ferruterous fabric separating small amount of digestive juice with the low content of enzymes.
These features of a gastrointestinal tract complicate digestion of food if the last doesn't correspond to age of the child, reduce barrier function of digestive tract and lead to frequent diseases, create prerequisites to the general system reaction to any pathological influence and demand very attentive and careful care of mucous membranes.
Features of a structure and functioning of salivary glands at children
General morfofunktsionalny characteristic. In a mouth output channels of three couples of big salivary glands open: parotid, submaxillary and hypoglossal. Besides, in the thickness of a mucous membrane of a mouth there are numerous small salivary glands: lip, shchechny, lingual, palatal.
Epitelialny structures of all salivary glands develop from an ektoderma, as well as the multilayered flat epithelium covering a mouth. Therefore multiple layers are characteristic of a structure of their output channels and the sekretornykh of departments.
Trailer departments (portio terminalis) of a structure and character of the allocated secret happen three types: proteinaceous (serous), mucous and mixed (i.e. proteinaceous and mucous).
Output channels of salivary glands are subdivided into vnutridolkovy (ductus interlobularis), output channels and channels of gland (ductus excretorius seu glandulae) including inserted (ductus intercalates) and ischerchenny (ductus striatus), mezhdolkovy (ductus interlobularis).
Proteinaceous glands allocate the liquid secret rich with enzymes. Mucous glands form more dense, viscous secret with high content of a mutsin - substance which part glycoproteins are. On the mechanism of office of a secret from cages all salivary glands merokrinovy (ekkrinovy).
Salivary glands perform ekzokrinny and endocrine functions. Ekzokrinny function consists in regular office in a saliva mouth. Water (about 99%), albumens, including enzymes, inorganic substances, and also cellular elements (cages of an epithelium and leukocytes) are its part.
Features of salivary glands of the newborn:
· low sekretorny activity
· allocation of a small amount of dense viscous saliva (sealing of a mouth during sucking)
· saliva reaction neutral or subacidic
· concentration of amylase low.
Functional activity of salivary glands increases in 1,5 - 2 months; at children at the age of 3-4 months saliva quite often follows from a mouth. It is connected with immaturity of regulation of salivation and swallowing saliva (physiological salivation). Acidity of saliva increases with age. From the first days of life are a part of saliva and - the amylase and other enzymes necessary for splitting of starch and a glycogen. At newborns, within the first year of life contents and activity of these enzymes considerably increase.
morphological newborn liver pancreas
Features of the structure and functioning of the liver in children
The liver by the time of the birth is one of the largest bodies and occupies 1/3-1/2 volumes of an abdominal cavity, her bottom edge considerably acts from under a podreberye, and the right share can even concern a crest of a podvzdoshny bone. At newborns the mass of a liver makes more than 4% of body weight, and adults have 2%. The liver continues to grow in the post-natal period, but more slowly, than body weight: the initial mass of a liver doubles by 8-10 months and trebles by 2-3 years.
Formation of segments of a liver begins at a fruit, but by the time of the birth of a segment of a liver are delimited indistinctly. Their final differentiation comes to the end in the post-natal period. The lobular structure comes to light only by the end of the first year of life.
Branches of hepatic veins are located by compact groups and don't alternate with branches of a vorotny vein. The liver is full-blooded owing to what it quickly increases at infections and intoxications, disorders of blood circulation. Fibrous capsule of a liver thin.
About 5% of volume of a liver at newborns fall to the share of the haematogenic cages, in the subsequent their quantity quickly decreases.
As a part of a liver the newborn has more water, but it is less than protein, fat and glycogen. By 8 years the morphological and histologic structure of a liver becomes same, as at adults.
Formation of bile begins already in the pre-natal period, however the bile production at early age is slowed down. With age ability of a gall bladder to concentrate bile increases. Concentration of bilious acids in hepatic bile at children of the first year of life high, especially in the first days after the birth that causes frequent development of a subhepatic holestaz (a bile condensation syndrome) in newborns. By 4-10 years concentration of bilious acids decreases, and at adults increases again.
The fermental systems of a liver providing adequate metabolism of various substances by the birth there isn't enough zrela. Artificial feeding stimulates their earlier development, but leads to their disproportion.
After the birth at the child synthesis of albumine decreases that leads to decrease in an albuminoglobulinovy ratio in крови. кислот decreases, and at adults increases again.
Mochevinoobrazovatelny function of a liver is formed by 3-4 months of life, before at children note a high excretion with ammonia urine at low concentration of urea.
The liver carries out barrier function, neutralizes endogenous and exogenous harmful substances, including the toxins arriving from intestines and takes part in metabolism of medicinal substances. At children of early age the neutralizing function of a liver is developed insufficiently.
Functionality of a liver at small children rather low. Her enzymatic system at newborns is especially insolvent. In particular, metabolism of the indirect bilirubin which is released at a gemoliza of erythrocytes is carried out not completely what physiological jaundice is result of.
Pancreas histology at newborns
The pancreas - parenchymatous body of external and internal secretion - at newborns has the small sizes: weight makes her about 23 g, and length - 4-5 cm. By 6 months the mass of gland doubles, by 1 year increases by 4 times, and by 10 years - by 10 times.
At the newborn the pancreas settles down deeply in an abdominal cavity at the level of Tkh, i.e. above, than at the adult. Owing to weak fixing to a back wall of an abdominal cavity at the newborn she is more mobile. At children of early and senior age the pancreas is at the level of Ln. Most intensively gland grows in the first 3 years and in the pubertal period.
By the birth and in the first months of life the pancreas is differentiated insufficiently. At early age the surface of a pancreas smooth, and by 10-12 years appears the bugristost caused by allocation of borders of segments. Shares and segments of a pancreas at children less by the sizes are also small. An endocrine part of a pancreas by the birth is more developed, than ekzokrine part.
Juice of a pancreas contains the enzymes providing hydrolysis of proteins, fats and carbohydrates, and also the bicarbonates creating alkaline reaction of the environment, necessary for their activation. At newborns the small volume of pancreatic juice after stimulation, activity of amylase and bicarbonate capacity low is allocated. Activity of amylase from the birth till 1 year increases several times. Upon transition to usual food upon which more than a half of need for calories becomes covered at the expense of carbohydrates activity of amylase quickly increases and reaches the maximum values by 6-9 years. Activity of a pancreatic lipase at newborns low that defines a big role of a lipase of salivary glands, gastric juice and a lipase of breast milk in fat hydrolysis.
The type of feeding has significant effect on activity of a pancreas: at artificial feeding activity of enzymes in duodenal juice is 4-5 times higher, than at natural.
The pancreas at children, as well as at adults, possesses externally - and vnutrisekretorny functions. Albumine, globulins, minerals and electrolytes, and also a big set of the enzymes necessary for digestion of food, including proteolytic (trypsin, an elastaza, etc.), the lipoliticheskikh and the amiloliticheskikh are its part (alpha and beta amylase, a maltose, lactase, etc.). The rhythm of secretion of a pancreas is regulated by neuroreflex and humoral mechanisms.
For children of the first months of life have defining a zncheny nutrients which arrive with milk ма Teri and are digested at the expense of the substances which are contained in the most women's milk. With introduction of a feeding up furs nizm of fermental systems of the child are stimulated. Absorption of food ingredients at children of early age has the features. Casein at first clot in a stomach under influence сы chuzhny enzyme. In a small intestine it begins to be split to amino acids which become more active and soaked up.
Digestion of fat depends on a type of feeding. Fats of cow's milk contain fats which are split at the expense of a pancreatic lipase in the presence of fatty acids.
Absorption of fat happens in final and average to an otda the lakh of a small intestine. Splitting of dairy sugar at children about proceeds in a border of an intestinal epithelium. In women's milk with the laktoza, in cow -- a laktoza keeps. In this regard at artificial feeding carbohydrate structure of food a-ism of not N. Vitamins are also soaked up in a small intestine.
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