Modern feeding in childhood.

This problem is very essential. “Complicated” character of child is often the result of uncorrect feeding. Children feeding organizational questions are well-distributed nowadays and may be highly-used by responsible parents.

It is known that in course of the first life year the most natural and essential child food must be female milk. This food is not changeable. It is especially significant in course of first days and weeks. It contains not only everything necessary for baby’s life but also immune bodies protecting him from different diseases.

Beginning from 3 months he begins his feeding up with berries, fruit and vegetable raw juices as well as their mixtures. Beginning from 5-6 months – one can train to porridge with breast feeding 2-3 times in course of twenty-four-hours. Beginning from 9-th month – parents can include meat products and curd cheeze. Although it would be better not to give meat to a child up to 3-5 years. It can increase his immunity and decrease the allergic reactions development possibility.

To organize proper feeding of a child elder than 1 year is rather complicated task if the regime of previous feeding was uncorrect and it was not different.

It’s necessary to follow all rules and conditions mentionned above in elder age groups.

It’s necessary to remember that ideal feeding regime is individual one. Food should be taken only when we are really hungry. Our feeding must be limited in its caloric equivalent due to moveless life style of many of us. And the most important thing – don’t do any cult from eating. Be closer to feeding culture!!! You have separate element of this culture in this lecture. Follow them in course of your life – and you will receive strong health and additional years of active, happy life! Make food medicine, not poison! Good luck in this deed!!!

Lecture 22 Digestion, its types and functions. Oral cavity role in digestion.

Digestion – is an integrity of food products physical and chemical processing, their transformation into components without species specificity and suitable for absorbtion and participation in substances exchange.

Digestion types have been formed in course of alive organisms development and nowadays we differentiate:

• Intracellular – food products hydrolysis realized inside cells (it is very limited in human being, the example of which is phagocytosis).

• Extracellular – is performed in special cavities (oral cavity, stomach, intestine); enzymes synthesized by secretory cells are released in extracellular environment (cavity).

• Membrane – has intermediate state between extra- and intracellular digestion and performed by enzymes localized on enterocytes membrane structures (in zone of enterocytes mucosa striggillate margin).

Alimentary tract main functions:

1. Secretory – alimentary juices (saliva, stomach, intestinal, bile) secretion and releasing by glandulocytes.

2. Motor-evacuational – food growing shallow, its mixturing with juices, passage through alimentary tract.

3. Absorbtional – transport of ending digestion products, water, salts, vitamins through alimentary tract epithelium in blood and lymph.

4. Excretory – excretion of non-assimilated food components, some metabolism products, hard metals salts, medicines (drugs) out off organism.

5. Incretory – releasing of hormones regulated digestion organs functions.

6. Protective – bacteriocide, bacteriostatic, detoxicative action.

7. Receptor – many receptive zones existance in alimentary tract for excretory, circulatory system reflexes and so on.

8. Erythropoietic – there exists iron depot in stomach, small intestine mucosa, liver participating in haemoglobine synthesis; there is so-called internal Kastl’s factor necessary for vitamine B₁₂ absorbtion responsible for erythropoiesis regulation.

Digestion process is originated from oral cavity. This part of alimentary tract performs 2 functional groups:

1. Specific functions – food suitability assessment performes by means of chemo-, mechano-, thermo-, nociceptors, gustatory receptors in oral cavty. Information comes in central nervous system from these receptors and then – to oral cavity organs (masticatory muscles, salivatory glands, tongue). Food gustatory features determining, food mechanic processing and swallowing are performed due to their action. Food chemical processing is also originated from oral cavity (mainly of carbohydrates). Absorbtion can also perform in oral cavity.

2. Non-specific -

• participation in behavioural reactions forming (hunger, thirst);

• thermoregulatory;

• protective;

• excretory;

• incretory;

• participation in articulation and speech forming.

Digestion in oral cavity is mainly realized due to salivary galnds secretory function. Salivary glands secretory function is provided by functionning of 3 pairs of large (parotid, sublingual and submandibular) and great amount of small glands disseminated in oral mucosa. Saliva is a secretes mixture. Saliva is a mixture of secretes. With the addition of epytheliocytes, food particles, mucus, lymphocytes, neutrophils and microorganisms (they are in oral cavity in large amounts) it formes oral liquid. Daily saliva secretion is 0,5-2,0 litres. Its pH fluctuates from 5,25 to 8,0.

Saliva contains up to 99,5% of water. There are many organic and inorganic substances in solid residue. One can say that almost all Mendeleev’s table is in saliva (even gold!). There are many organic substances in saliva. They are protheins – albumins, globulins, aminoacids. Nitrogen-containing substances – urea, ammonia, creatine. Bacteriocydic substances – lyzozyme; enzymes – alpha-amylase or ptyalin, maltase, proteases, peptidases, lipase, alkaline and acid phosphatase.

Saliva role in digestion: it gives the beginning to food chemical processing. It occurs due to amylase acting on polysacharides (starch) while their destruction to maltose. Under other enzyme maltase influence maltose destruction to glucose can occur. But enzymes action is very limited because food is in oral cavity very little time. One of the most important digestion rules: careful (durable) food mastication due to which saliva can influence on food (in oral cavity) more effectively.

But saliva is not only restricted by food possible chemical processing. Saliva takes part in preparation of food portion to swallowing and further digestion. Food is mixed with saliva in course of mastication and is swallowed better. Saliva equally covers teeth in neutral environment forming special tunic on them. In acid environment releasing mucin covers teeth surface an encourages teeth coating and stones forming. That’s why after food taking it’s necessary either to brush teeth or to wash oral cavity. Teeth and mucosa state depends on saliva content and features. Saliva volume, chemical content and features change can underline many diseases of oral cavity. For example, saliva, while contact with dental enamel is the calcium, phosphorus, zinc and other microelements sourse for it. If saliva pH is 7,0-8,0 it oversaturated by calcium that creates ideal conditions for ions passage into enamel. At environment acidification (pH 6,5 and lower) oral liquid becomes deficient on calcium ions content that encourages its releasing form enamel and caries development.

According to saliva chemical analysis and even smell, colour one can tell about inner organs diseases. For instance, at nephritis, stomach and duodenum ulcer disease residual nitrogen amount is increased in saliva. At stroke on the injury (haemorrhagia) side salivary glands excrete great number of protein.

You know about oral mucosa increased regenerative ability. Quickly mucosa restoration after its wounding (it occurs practically every day) is connected not only with tissular immunity but also with saliva antibacterial features. Besides, there are substances in saliva influencing on blood coagulation and fibrinolysis. That’s why oral cavity protective function is also delt with this saliva ability to influence on local haemostasis and fibrinolysis.

Saliva formation mechanism. Saliva is formed both in acinuses and in salivary glands ducts. Secretory granules are in glandulocytes cytoplasm. Granules size, amount and localization are changed in course of secretion. They are moved to cellular apex from Golgi complex. Organic substances synthesis passed with water through cell on endoplasmic net is performed in granules. Saliva formation first stage is realized in acinuses – primary secrete forming containing amylase and mucin. Ions content in it insignificantly differs from their concentration in extracellular space. Secrete content changes significantly in salivary ducts: sodium ions are actively reabsorbed and potassium ions are actively secreted. As a result, sodium amount in saliva becomes less and potassium – bigger.

Salivary glands in new borns secrete little saliva – 0,4 ml per minute in course of sucking, less – out off sucking. It is in average in 8 times less than in adulthood. Salivation volume is increased from 4 months and reaches up to 150 ml per day to 1 year (it is 1/10 of adult secretion). Amylase activity in new-borned saliva is low and it is increased in second half-year, reaching adult level in course of 1-2 years after birth.

Salivation regulation is performed by complicated-reflectory and humoral ways. Special place in regulation has complicated-reflectory mechanism. It consistes of conditioned-reflectory and unconditioned-reflectory. Conditioned-reflectory salivation regulating way is connected with food appearence, its smell (in humans and animals), communication about it and other conditioned stimuli (pictures, writings, symbols) delt with alimentary motivation. Unconditioned-reflectory appears as an answer to oral cavity mechano-, chemo-, thermo- and gustatory receptors irritation. Nervous impulses flow comes from these receptors through V,VII,IX and X pairs of cranio-cerebral nerves to medulla oblongata in salivation center. Efferent fibres of given reflectory acts go from this center to salivatory glands. They can carry information to salivary glands through sympathetic and parasympathetic fibres that innervate salivary glands. Sublingual and submandibular salivary glands are innervated by preganglionar parasympathetic nervous fibres coming in composition of chorda tympani (facial nerve branch) to corresponding ganglions located in glands body. Postganglionar nervous fibres innervate glands secretory cells and vessels.

Parotid glands are innervated by preganglionar parasympathetic fibres of inferior salivatory nucleus of medulla oblongata coming in the composition of IX pair in auricular node. Postganglionar nervous fibres are directed to secretory cells and vessels. Sympathetic innervation is represented by preganglionar nervous fibres from lateral corns of spine II-IV thoracic segments and is finished in superior cervical node, then postganglionar fibres to salivary glands come.

At sympathetic nerve excitement small saliva amount containing mucin doing it viscous and dense is released. At parasympathetic nerve – on the contrary, saliva becomes fluid and its amount is big.

Hypothalamic anterior and posterior nuclear groups participate in salivation regulation. Salivation reflectory regulation is not unique though it is main.

Humoral mechanism is delt with hypophyseal, pancreatic, thyroid, sexual hormones action. Excessive salivation occurs due to salivatory center irritation by carbonic acid. Saliva releasing may be stimulated by vegetothropic pharmacologic substances – pilocarpine, proserine, atropine. Saliva production can decrease too. It may be connected with noceoceptive and emotional reactions, with fever states, at systematic sleeping pills usage, diabetes mellitus, anaemia, uraemia, salivary glands diseases.

Oral cavity motor activity. Essence:

• food biting;

• getting small;

• grinding;

• mixturing with saliva;

• alimentary piece forming;

• swallowing.

Oral cavity motor function main part is realized in course of mastication.

Mastication – is a complicated act. Its essence is in consequent contractions of masticatory muscles, mandibule, tongue and soft palate movements. Masticatory muscles are fixated to moveless skull part by their one end, by other end – to unique movable skull bone – mandibule. They provide mandibule status change as for maxilla while their contraction. Mimic muscles are close to masticatory muscles on their functions. They participate in food catching, its supporing in oral cavity vestibule, oral cavity closure at mastication. They are essential at sucking in new-borns and at liquid food taking. Tongue has definite role in mastication. It takes active part in food mixture, definition of its place for getting smaller on teeth.

Mastication act by its mechanism is partially arbitrary, partially – reflectory. Human being can free inhibit or enforce masticative movements, change their character. Food biting and mastication is performed at superior jaw teeth occlusion (contact) with inferior jaw teeth. Mandibule performes rhythmic movements in 3 main directions: vertical, sagittal, transversal. Mastication is originated from assessment of received food after which food piece irritates located in oral cavity touch, temperature, gustatory, nociceptive receptors. Besides, due to sense of smell impulses occuring in these receptors come into mentionned above nervous stems in medulla oblongata in mastication center. Then they on trygeminal nerve second and third rami, facial, glosso-pharyngeal and hypoglossal nerve come to masticatory muscles. In parallel with food getting smaller its washing with saliva occurs for better swallowing. Food getting smaller degree is under oral mucosa receptors control. Non-food elements are pushed at this by tongue (bones, stones, paper et al.). One should remember about necessity of careful food processing in oral cavity. It’s an essential preventive measure for many diseases not only of alimentary tract. In babies sucking corresponds to mastication which is provided by mouth and tongue muscles reflectory contractions.

Swallowing – is a complicated reflectory act due to which food is transported from oral cavity into stomach. Phases:

• Oral arbitrary – from food common mass in oral cavity small piece is separated which by tongue movements is pressed to hard palate. Jaws are closed, soft palate is rised closing entrance into choanes. Simultaneousely with this palato-pharyngeal muscles are contracted. Septum is formed which closes passage between oral and nasal cavity in the result of these processes. Tongue moving ahead pressses onto palate and pushes food piece into pharynx. Because of this food piece is pushed down into pharynx. Entrance into larynx is closed by epiglottis, vocal cord is closed to prevent food coming into trachea. As food piece comes into pharynx, soft palate anterior arch are contracted and together with tongue root prevent food returning into oral cavity.

• Pharyngeal-inarbitrary – is originated when food piece is pushed ahead and pharyngeal-oesophageal sphincter, closing under rest state the entrance to oesophageus, is opened. Sphincter’s muscles are relaxed and pressure is decreased in it, food piece passes into oesophageus and sphincter is closed again because of pressure increasing in it. Such reaction prevents food piece passage from oesophageus into pharynx.

• Oesophageal inarbitrary: food piece transmits from oesophageus oral part to cardial.

Swallowing process as reflectory act is performed due to irritation receptor endings of trygeminal, superior and inferior laryngeal, glosso-pharyngeal nerves located in soft palate and pharynx mucosa. Swallowing center is located in medulla oblongata near respiratory center and is in reciproqual (antagonist) interrelations. At swallowing center excitement respiratory center activity is inhibited; respiration is stopped in this moment that prevents food particles passage into respiratory ways. Swallowing act afferent ways – superior and inferior pharyngeal, recurrens nerve and vagus fibres. They direct nervous impulses to muscles participating in swallowing.

Oral cavity is an initial link of reflectory reactions influencing on digestion in stomach and intestine. Oral cavity receptors irritation stimulates stomach juice forming, stomach motor function. Stomach and pancreas secretion depends on mastication act duration. The mastication is less the stomach juice is less. Oral mucosa and tongue is alimentary tract mirror. One can see problems which may occur in stomach and other alimentary tract parts in it. Pathological processes in oral cavity organs can encourage some inner organs diseases occurence, cause or support different complications. In particularly, teeth pathological agility and loss leads to incomplete food processing in oral cavity that in first turn influences on stomach and intestine motor and secretory activity. But digestion disorders in oral cavity caused by mastication change at teeth loss don’t always lead to one or another pathology in alimentary tract other parts. Alimentary tract initial link (oral tract) periodically undergo to action of removable substances (solid subjects, acids, alkalins, excessively warm or cold bodies, strong mechanical actions) that causes hypersalivation occurence as mean of oral cavity and alimentary channel tissues integrity providing. Rich microbe flora containing pathogenic microorganisms comes into oral cavity with alimentary substances. It was the reason of forming tissular and cellular barriers as well as oral cavity specific and non-specific resistance in course of evolution.