Excretion (separate organs and systems role). Oral cavity as excretory organ.

Excretion -is metabolism part realized by ending and intermediate metabolism products, side and excessive substances excretion out off organism for optimal environment content and normal viability providing. Excretion is closely connected with water exchange because main part of substances to be excreted from organism is released in a state soluble in water. Kidneys are main excretory organ secreting and releasing urine and substances necessary for excretion out off organism. Also kidneys are main organ of water-salty metabolism providing.

Excretory organs are following:

· kidneys;

· alimentary tract;

· lungs;

· skin;

· mucosae;

· salivary glands;

· lacrimal glands;

· sweat and sebaceous glands;

· milky glands (during lactation).

Excretory skin function – is mainly provided by means of sweat, sebaceous and milky glands. Sweat glands are essential for destruction products having been formed in course of metabolism, in heat regulation (sweat evaporation from skin surface enforces heat emission), in osmotic regulation (by means of water and salts excretion). Sweat contains up to 98-99 per cent of water, inorganic substances (sodium and potassium chloride), organic - urea, urinary acid, creatinine, flying fat acids. Up to 300-1000 ml of sweat is excreted in average for 24 hours. Sebaceous glands have less importance as for excretion than sweat (up to 20 gramms per day). Sebum cutaneum softens skin and lumbricates hairs. It consists of neutral fats. Sebum cutaneum is destructed under sweat acids with fat acids formation possessing special smell. Milky glands excrete milk, essential feeding product for new-borns. It contains proteins, fats, carbohydrates, vitamines, mineral substances, water. There are bacteriocydic substances, antibodies for chidren passive immunity in milk. Milky hormones are essential for growing organism. Good mother’s mood helps normal milk secretion. Hard psychical emotions, fear, inhibited mood decrease milky secretion or even may lead to its complete stoppage. Particularly, rock-music has such influence.

Liver and alimentary tract excretory function is the following: these organs excrete some metabolism products with alimentary juices under normal conditions. Liver excretes haemoglobine and other porphyrines ending metabolism products with bile as bile; ending cholesterine products - as biliary acids. Thyroxine, urea, calcium, phoshorus, medicines, poisons are excreted with bile out off organism. Stomach provides metabolism products excretion as juice components (urea and urinary acid), medicines and poisones (mercury, iod, salicylates). Intestine excretes food metabolism excessive and harmful products; alimentary juices and bile components, hard metals salts, proteins, water.

Lungs and respiratory ways excretory function is in flying metabolites and exogenic substances - carbonic dioxide, ammonium, acetone, ethanole and others – excretion from organism internal environment. Bronchi ciliate epithelium excretes lung tissue metabolism products as well as surfactant degradation products. Water is partially excreted through lungs as steam (from 400 ml under rest to 1 l at increased breathing).

Kidneys functions are various; but excretory function is dominant. Kidneys participate in organism water and ions equillibrium, osmotic constant level, acid-alkaline balance support; proteins, lipids and carbohydrates metabolism, erythropoiesis and haemostasis regulation thus performing excretory and non-excretory functions.

Uropoiesis is main kidneys function. Urine produces in kidneys from blood. Uropoiesis in kidneys is originated from blood plasma ultrafiltration in kidney glomeruli. 2 mechanisms are esseentIal in this process: filtrating membrane and pressure gradient. Filter providing uropoiesis consists of 3 layers:

· capillary endothelium – it has foramens with diameter up to 100 nm, through which water with substances dissolved in them comes free;

· basal membrane – it has very small pores through which formed elements and large molecules don’t pass;

· layer consisting of podocytes between which fissure-like diaphragms with diameter about 10 nm are remained. These podocytes processes are contracted and relaxed due to myofibrilles and pump filtrate in capsule cavity as micropumps.

Filtrational pressure is created due to blood hydrostatic pressure difference in glomerular capillaries (it is equal to 70 mm of mercury column) and pressures sum impeding filtration (oncotic pressure - 30 mm merc. col. and ultraphyltrate capsular pressure –20 mm merc col). As a result, filtration pressure under norma is equal to 20 mm merc col. Filtration process is stopped when blood hydrostatic pressure in glomerule capillaries is reduced up to 40 mm merc col. Filtration level depends on afferent and efferent vessel cavity namely: efferent vessel constriction leads to filtration increasing, afferent vessel constriction – to its decreasing. Primary urins daily amount is about 180 l per day. It is identical to blood plasma only with protheins exception.

Uropoiesis second stage – is channel reabsorbtion and secretion. Water reabsorbtion and substances having filtrated in glomeruli occurs in nephron channels. One can tell about proximal and dystal reabsorbtion.

· Proximal reabsorbtion determines complete glucose reabsorbtion (that’s why sugar glucose is absent in ending urine), protheins, aminoacids (that’s why there is no prothein in secondary urine), water and sodium biggest part, potassium, chlorum, urinary acid, urea reabsorbtion. 1/3 ultrafiltrate volume is remained to proximal channel end. Glucose and aminoacids proximal reabsorbtion is performed by special transporters and is tightly connected with sodium transfer. Such transfer is called active. Water absorbtion is realized passively and depends on sodium and chloridum reabsorbtion.

· Distal reabsorbtion – ions absorbtion (about 10 per cents of sodium and chlorum ions) and water. Water is reabsorbed alongside all the channel. Reabsorbtion velocity is increased twice in dystal channel part. Henle loop descendant part epithelium passes water good, and ascendant – actively transports sodium ions from primary urine to tissular liquid due to kidneys outflowing-turning system. Urine concentrating and dissolving occurs in this system because substance transport processes in one knee of system are enforced (multiplied) by means of other knee activity. Ascendant knee performs dominant role in outflowing mechanism mechanism. Its wall actively reabsorbs sodium ions in surrounding intersticial spaces. Ascendant knee wall is permeable for water which comes passively from cavity in intersticial hypertonic environment. Urine becomes more and more hyperosmotic alongside descendant knee. Urine becomes less and less osmotic in descendant knee because of absorbtion and hypotonic urine comes in dystal channel cortex. Collecting tube formes outflowing system with ascendant knee. At vasopressine (antidiuretic hormone) presence collecting tube wall is permeable for water. With urine passage through collecting tubules into the depth of medulla water passes passively in intersticium hypertonic content and urine becomes more and more concentrated. There is also vascular outflowing system.

Outflowing systems action result – is ending (secondary) urine forming. Its character, finally, depends on blood osmotic pressure. Osmotic pressure increasing leads to hypothalamic osmoreceptors excitement, then information moves into neurohypophysis, releasing antidiuretic hormone. This hormone enforces dystal channel wall permeability for water and as the result of this urine becomes hypertonic. If osmotic pressure is reduced mentioned reactions will be weakened and urine will be hypotonic. Children on mother milk excrete hypotonic urine, on caw milk or artificial feeding mixture – more often are released hypertonic urine.

In ending uropoiesis definite place takes channel secretion. This is channel epithelium active transport in urine substances containing in blood or forming in channel epithelium cells. Channel secretion determines potassium, hydrogenium ions, organic acids, ammonium and other substances passage into urine.

Secondary or ending urine is about 65-80 per cent of used water, this is daily diuresis for 24 hours which is equal to 0,7-2,0 l. Urine reaction is usually light acid, but everything depends on food character. At primarily plant food urine becomes more alkaline, and at animal or prothein – more acid. It has definite colour, transparity, sediment.

Uroreleasing is performed in the following order. First, urine comes into renal pelves. Renal pelvis and ureter smooth muscles possess automatism. With pelves filling by urine mechanoreceptors irritation occurs that causes pelvis musculature reflectory contraction and ureters opening. Urine passes into urinary vesicle due to their smooth musculature contractions like peristaltic. It stretches walls while its filling. But this stretching doesn’t cause reflectory reactions directed to urine releasing till definite vesicle volume (it is approximately equal to 250-400 ml). But when urine volume predominates these ziphras urinary vesicle wall mechanoreceptors irritation begins right after this that results in urine releasing. This process is under control of spine sacral parts. Impulses from this part cause urinary vesicle wall smooth muscle contraction and sphincter relaxation through parasympathetic fibres. In the adult day diuresis predominates night one in 2-3 times.

Kidney excretory function is essential for nitrogen metabolism products releasing - urea, urinary acid, creatinine and others. These substances accumulation in blood may cause toxic phenomenon development called uraemia. Uraemia leads to nervous system excitability reducing up to unconscious state (coma), external and tissular breathing, blood circulation disorders, body temperature decreasing and even to exitus letalis. If one kidney works normally uraemia won’t occur. In uraemia case haemodyalisis is performed – kidneys artificial clearence from accumulating metabolites. One differentiates extra- and intracorporal haemodyalisis. The first one is artificial kidney, the second one – abdominal cavity washing.

Kidney metabolic function is provided by substrates and metabolites excretion. Kidneys metabolize small-sized peptides, denaturated peptides filtrating with urine and return them into blood. Kidney tissue possess the ability to perform gluconeogenesis. Such ability is higher in kidney than in liver if to count on mass unit. For example, almost 50 per cent of glucose is produced by kidneys in course of durable fasting.

Kidneys role in blood arterial pressure supporting is realized by following way: several substances the function of which is connected with vascular vessels cavity regulation are formed in kidneys. One of them is produced in juxtaglomerular apparatus and is called renin. Renin itself doesn’t influence on vessels. It is the essential component of so-called renin-angiotensine-aldosterone system that regulates vascular vessels tone, sodium equillibrium in organism, circulating blood volume. Renin passing into blood circulation transforms angiotensine into angiotensine I. Further, in lungs (under special converting enzyme action) it transforms into angiotensine II. Blood pressure level depends on this substance concentration and activity. Renin secretion is increased at blood pressure decreasing (for instance, as a result of blood loss, hypotension of medical origin and other reasons), intrachannel pressure increasing (it can be found at ureter constriction, stones in kidney and ureter), at blood pressure reducing in afferent glomerular arteriole; at hypersympathicotony, sodium concentration increasing into dystal urine (urine of dystal channel).

Arterial pressure level in blood depends not only on renin synthesis in kidneys. Kidneys possess antihypertensive function due to depressors production - neutral medullar lipid, prostaglandines, kinines. Kidneys excrete water and electrolytes and their content in blood, extra- and intracellular environments is essential for arterial pressure support. Kidneys may also regulate arterial pressure on mechanism “pressure-diuresis”. Arterial pressure increasing accelerates blood circulation through kidney medulla direct vessels. It leads to sodium and urea osmotic gradient washing (reducing) that decreases water reabsorbtion and, thus, weakenes kidney concentrational ability. Diuresis increasing decreases blood circulating volume and makes blood pressure normal. At moderate (physiological) water consumption saliva and chimus osmotic pressure is reduced, that is percepted by oral cavity, alimentary tract osmoreceptors and liver osmo- and sodium-dependent receptors. Sygnals from these receptors with reflectory way usage before sodium and osmotic pressure level change in systemic blood circulation decrease vasopressine (antidiuretic hormone) neurosecretion and enforces uropoiesis right after drinking. Blood volume is restricted because of drunk water absorbtion as a result of sodium and water excretion by kidneys. It also can influence on blood pressure level and reflects kidneys homeostatic function. Excessive water consumption leads to hyperhydratation, osmotic pressure and plasmic sodium content reducing that also inhibits vasopressine neurosecretion. Water surplus is excreted out off blood as water reabsorbtion decreasing in dystal channels and collecting tubules. This process is triggered by urea absorbtion absence in collecting tubules that decreases kidney medulla intersticium osmolarity and restrictes water reabsorbtion in more extent. At described mechanisms insufficiency water is remained in organism. From one side, it may influence on blood pressure level, from another - it causes water exit in tissues and oedemas (swelling). Excessive hydratation leads to water poisoning and, finally, to brain haemorrhagias. On the contrary, water fasting or water excessive loss leading to circulating blood volume decreasing, causes renin secretion enforcement. Angiotensine-II appearence as a result of this, causes thirst development while drinking center stimulation. Angiotensine-II may be produced in brain tissue itself leading to thirst forming. Water fasting or excessive water loss cause cellular dehydratation and potassium ions exit with water that leads to strong disorders especially of central nervous system.

Kidneys participate in erythropoiesis regulation. Hormone-like substance erythropoietin is secreted in juxtaglomerular apparatus. It is as it is well-known is the only specific erythropoiesis regulator. Its concentration increases in blood at blood losses, oxygen low partial pressure (it is essential both for mountain regions residents and for those rising into highlands), at heart and lungs diseases. Erythropoietin action way: it accelerates and enforces stem cells transformation in erythroblasts, increases cellular mitosis amount, accelerates normoblasts and reticulocytes maturation.

Kidneys are delt with blood coagulation and fibrinolysis. They synthesize substances influencing on all haemostasis links: vessel-thrombocytic, blood coagulation and fibrinolysis. First of all, kidneys are vessel-thrombocytic haemostasis regulators. Probably, it is necessary for activity of kidneys themselves. They contain (and can release into circulation) different prostaglandines (particularly prostacycline), influencing directly on platelets aggregation activating and inhibiting. They either produce coagulational factors (for instance, thromboplastine) or release coagulation factors surplus accumulating in them (for example, fibrin degradation products and others).

Kidneys are essential for fibrinolysis regulation. Urokinase – natural plasminogen activator – is excreted from kidneys. This plasminogen activator receives from urine for thrombosis, thromboembolic diseases, thrombotic disease treatment. In organism there exists very interesting dependence of urokinase producing on sodium chloridum concentration. The more sodium chloridum in organism the worse urokinase is produced. It should be taken into account by all lovers of salty products. In many aspects urine antiinflammational effect is connected with urokinase. People have been using urine for ages at inflammations on skin for example, burns, combustions, traumas. It is not occasional. Active fibrinolytic system is necessary for reparation, regeneration, restoration. Urine is natural product containing plasminogen activators. That’s why urinotherapy is considered to be very widely spread nowadays in “folk medicine”. Having detemined urine coagulational and fibrinolytic activity one can tell about kidneys functions and their disorders.

Oral cavity as excretional organ. Salivary glands are necessary for excretion together with other organs mentioned above. They excrete different substances form blood: iod, bromium, hard metals salts – mercury, vismute, gold, lead and others. Salivary glands are especially active as for their excretory function at kidneys insufficiency (compensatory principle of organism activity). Salivary glans excrete much urea which is transformed into ammonium under saliva influence. That’s why patients are smelly from their mouth. Urinary acid is excreted in saliva at podagra (gut) while bile compounds - at jaundice.

 

In conclusion, telling “Good-bye” to you we would like to wish you following:

1. Stop to moan, to complaint on smth, to search for guilty every time – because these are main reasons of all your problems.

2. Don’t ignore physical loadings, don’t do physical trainings the company. Having started to do any physical exercises – continue all your life according to your genetical possibilities.

3. Don’t forget that it’s necessary to eat for live, not on the contrary. Remember: each 2,5 cm of waist circle as for breast are equal to 2 years of life.

4. Stop smoking, taking drugs and medicines and achieve this from other people.

5. Don’t afraid any risk, life difficulties, go forward to them and learn to overcome them. Life is too short to loose it for triviality. Truth and politeness are the most valuable in this life. Smile, clever joke, truly word will help you and your relatives more than all medicines in the world.

6. Take in your Way your knowledge, love to work, because the of sweet “doing nothing” is over and world – is not a hall for loafers but great workshop! Create in it! Have a good journey through the country the of which is Your Life!

 

 

Content

 

Lecture 1. General physiology of excitable tissues. Physiology of muscles and nerves. Features of functionning of muscles of maxillo-facial area.

Lecture 2. Central nervous system and endocrine glands role in oral cavity physiological functions regulation.

Lecture 3. Analizators. Oral cavity role in purposeful behaviour.

Lecture 4. Blood circulation and its regulation. Blood circulation and its regulation peculiarities in maxillar-facial region.

Lecture 5. Blood and its defence functions. The oral cavity role in the blood defence function regulation.

Lecture 6. Respiration physiology. Oral cavity importance for speech respiration and speech-forming.

Lecture 7. Digestion, its types and functions. Oral cavity role in digestion.

Lecture 8. Hunger, appetite and satiation state. Substance and energy exchange, thermoregulation. Oral cavity role in these reactions.

Lecture 9. Excretion (separate organs and systems role). Oral cavity as excretory organ.