WRITTEN BY: Nisreen & Marwa

Transcription

1 NOTE 22 WRITTEN BY: Nisreen & Marwa

2 The lymphatic system plays a key role in controlling interstitial fluid protein concentration, volume, and pressure: It is already clear that the lymphatic system functions as an overflow mechanism to return excess proteins and excess fluid volume from the tissue spaces to the circulation. Therefore, the lymphatic system also plays a central role in controlling (1) The concentration of proteins in the interstitial fluids, (2) The volume of interstitial fluid, and (3) The interstitial fluid pressure. Let us explain how these factors interact. First, remember that small amounts of proteins leak continuously out of the blood capillaries into the interstitium. Only minute amounts, if any, of the leaked proteins return to the circulation by way of the venous ends of the blood capillaries. Therefore, these proteins tend to accumulate in the interstitial fluid, which in turn increases the colloid osmotic pressure of the interstitial fluids. Second, the increasing colloid osmotic pressure in the interstitial fluid shifts the balance of forces at the blood capillary membranes in favor of fluid filtration into the interstitium. Therefore, in effect, fluid is translocated osmotically outward through the capillary wall by the proteins and into the interstitium, thus increasing both interstitial fluid volume and interstitial fluid pressure. Third, the increasing interstitial fluid pressure greatly increases the rate of lymph flow, which carries away the excess interstitial fluid volume and excess protein that has accumulated in the spaces. Thus, once the interstitial fluid protein concentration reaches a certain level and causes comparable increases in interstitial fluid volume and pressure, the return of protein and fluid by way of the lymphatic system becomes great enough to balance the rate of leakage of these into the interstitium from the blood capillaries. Therefore, the quantitative values of all these factors reach a steady state, and they will remain balanced at these steady state levels until something changes the rate of leakage of proteins and fluid from the blood capillaries.

3 الؽظخ: ا ؾذ ٠ ش ػ ا ذ س ا ز ظ ١ lymph ؾب خ إسعبع ب رجم ا غ ائ ا جش ر ١ بد رؾب ي أ رشعغ ب مذاس )4-2( زش ١ ٠ ب. ف أص بء ش س م ا جش ر ١ بد داخ ا شؼ ١ شاد ٠ ؾص ب رغش ٠ ت ر زم إ interstitial fluid ال رغزط ١ غ ا ؼ دح ػ غش ٠ ك األ سدح ثغجت فشق ا عغػ ا ز مذاس 7 صئجم ثب زب ٠ ؾص ب رشاو داخ ٠ زجؼ interstitium ص ٠ بدح ف مذاس interstitial colloid osmotic pressure ثب زب ا زمبي ا غبئ ثؾغت ا خبص ١ خ األع ص ٠ خ ا شؼ ١ شاد إ داخ interstitium ثب زب ص ٠ بدح ؽغ ا غبئ ا ز ٠ زجؼ ص ٠ بدح ف ل ١ خ interstitial hydrostatic osmotic pressure ز ا ض ٠ بدح ا ىج ١ شح ف ا عغ غ رزغجت ف ص ٠ بدح رذفك ا غبئ ا ١ ف ا ز ٠ أخز ؼ ا غ ائ ا جش ر ١ بد ا ضائذح ػ ؽبعخ ا خال ٠ ب ز ا ؼ ١ خ غز شح دائ خ ؾفبظ ػ غز ا غ ائ ا جش ر ١ بد الؽظخ : ص ٠ بدح ا جش ر ١ بد...ص ٠ بpressure osmotic pressure hydrostatic osmotic pressure ص ٠ بدح ا غ ائ...ص ٠ بدح Effect of Interstitial Fluid Pressure on Lymph Flow. Note that normal lymph flow is very little at interstitial fluid pressures more negative than the normal value of 6 mm Hg. Then, as the pressure rises to 0 mm Hg (atmospheric pressure), flow increases more than 20-fold. Therefore, any factor that increases interstitial fluid pressure also increases lymph flow if the lymph vessels are functioning normally. Such factors include the following: Elevated capillary hydrostatic pressure Decreased plasma colloid osmotic pressure Increased interstitial fluid colloid osmotic pressure Increased permeability of the capillaries All of these factors cause a balance of fluid exchange at the blood capillary membrane to favor fluid.movement into the interstitium, thus increasing interstitial fluid volume, interstitial fluid pressure, and lymph flow all at the same time.

4 When the interstitial fluid pressure becomes 1 or 2 mm Hg greater than atmospheric pressure (>0 mm Hg), lymph flow fails to rise any further at still higher pressures. This results from the fact that the increasing tissue pressure not only increases entry of fluid into the lymphatic capillaries but also compresses the outside surfaces of the larger lymphatics, thus impeding lymph flow. At the higher pressures, these two factors balance each other almost exactly, so lymph flow reaches a maximum flow rate. This maximum flow rate is illustrated by the upper level plateau زا ا ؾ ا ج ١ ب ٠ ظؼ ا ؼاللخ ب ث ١ interstitial fluid&lymph flow ٠ غت ا ز ٠ إ أ ؾ رذفك ا غبئ ا ١ ف غج أ أ سل ١ ظ 01 مذاس ا زذفك إ ب ٠ ؼ أ ا زذفك اصداد 01 أظؼبف وز ه ا شل ٠ ؼ 21 ص ٠ بدح ا زذفك 21 شح. ٠ ى Interstitial fluid osmotic pressure مذاس ثب غب ت زا ا ز ٠ زغجت ثب زصبق ا غ ذ ثبأل غغخ زا األ ش ا ز ٠ غبػذ ا غشاؽ ١ خالي ػ ١ بد صساػخ ا غ ذ ص ٠ بدح ل ١ خ interstitial fluid )-6 إ 1( رغججذ ف ص ٠ بدح رذفك ا غبئ ا ١ ف 21 شح : و ب ٠ ضداد ا عغػ ٠ ضداد ا زذفك ػ ١ أ ػب ٠ ؤصش ػ ٠ ؤصش Interstitial fluid osmotic pressure ػ Lymphatic flow

5 األ ض خ ػ ز ا ؼ ا : 1) capillary hydrostatic pressure 2) Plasma colloid osmotic pressure 3) Interstitial fluid colloid osmotic pressure 4) Permeability of the capillaries ز ا ؼ ا فظ ا م ١ ف ؼبد خ عزبس ظ ثب غجخ ز ا م ١ إ وب ذ عب ج ؽص ب ص ٠ بدح فغزم ا ؾص خ إ وب ذ عجخ اصدادد فغزضداد ا ؾص خ ضبي : 2=3-5 إرا اصداد ا شل ا غب ت )3( ١ صجؼ ضال 4 ع ١ ى ا برظ 0 أل ا برظ األص ث ١ ب إرا اصداد ا شل )5( ١ صجؼ ضال 7 ع ١ ى ا برظ 4 أوجش ا برظ األص "و ش ء عت رض ٠ ذ ٠ ض ٠ ذ و ش ء عب ت رض ٠ ذ ٠ م " ص ٠ بدح ل ١ خ و ا ؼ ا )0 3 4( عزض ٠ ذ ا ؾص خ ث ١ ب ػب سل 2 ع ١ زظ ػ ب رم ١ ا م ١ خ ص ٠ بدر ػ ا شغ أ ػب 3 عب ت إال أ ص ٠ بدر عزغجت ص ٠ بدح ف ا م ١ خ ١ ظ مصب ب ر ه ػ ذ فه األل اط عشة ا غب ت ف عب ت ف ١ صجؼ عت إرا ص ٠ بدر ع ١ زظ ػ ب ص ٠ بدح ف ا م ١ خ ا ؾص خ صد ب ل ١ إرا ا ٢ ل ب ل ١ خ ا ؼب 2 ع ١ ؾذس ب ٠ : أ(رضداد فبر ٠ خ ا غبئ ة(ص ٠ بدح ا ؾغ ط(ص ٠ بدح ا عغػ د(ص ٠ بدح lymphatic flow ا ٢ زم إ ا غضء ا ٢ خش ا ؾ ص ٠ بدح ا عغػ ػ ا صفش الؽع ا ال رغجت أ ص ٠ بدح ف ل ١ خ lymphatic flow أ ٠ ؾص ب ٠ غ فف ا ش ٠ بظ ١ بد plateau رغ ١ ش ل ١ أؽذ ا ؾب س غ صجبد ل ١ خ ا ؾ س ا ٢ خش ثغجت:

6 رضا ٠ ذ ا عغػ ف داخ األ غغخ ثغجت ص ٠ بدح وج ١ شح ف lymphatic flow أ ٠ عب ٠ غجت ص ٠ بدح ظغػ ػ lymph vessels ػ ١ ب ٠ ؼ ا ال رمذس ػ اعز ١ ؼبة ظغػ أوضش رى لذ ص ذ إ ا ؾذ األلص flow Lymphatic Capillary Pump. The terminal lymphatic capillary is also capable of pumping lymph, in addition to the pumping by the larger lymph vessels. The walls of the lymphatic capillaries are tightly adherent to the surrounding tissue cells by means of their anchoring filaments. Therefore, each time excess fluid enters the tissue and causes the tissue to swell, the anchoring filaments pull on the wall of the lymphatic capillary and fluid flows into the terminal lymphatic capillary through the junctions between the endothelial cells. Then, when the tissue is compressed, the pressure inside the capillary increases and causes the overlapping edges of the endothelial cells to close like valves. Therefore, the pressure pushes the lymph forward into the collecting lymphatic instead of backward through the cell junctions. The lymphatic capillary endothelial cells also contain a few contractile actomyosin filaments. In some animal tissues (e.g., the bat s wing), these filaments have been observed to cause rhythmical contraction of the lymphatic capillaries in the same rhythmic way that many of the small blood vessels and larger lymphatic vessels contract. Therefore, it is probable that at least part of lymph pumping results from lymph capillary endothelial cell contraction in addition to contraction of the larger muscular lymphatics. ا ٢ ع ف ذسط آ ١ خ ػ lymph ا أ زج إ أ د سح ا غبئ ا ١ ف ال رشج ا ذ سح ا ذ ٠ خ فب ذ سح ا ذ ٠ خ د سح رب خ ال ٠ ى رؾذ ٠ ذ ثذا ٠ ز ب ب ٠ ز ب أ ب د سح ا غبئ ا ١ ف ف ب ثذا ٠ خ ب ٠ خ ا جذا ٠ خ terminal lymphatics ا ب ٠ خ غ مخ الؽع أ ٠ عذ خال ٠ ب endothelium أ ٠ عب ٠ عذ anchoring filaments ػجبسح ػ أ ١ بف رضجذ lymphatic ف داخ ا غ ١ ظ إرا رغ ؼذ ا غ ائ ؽ ي lymphatics رغؾت anchoring filaments ا ج اثبد فزفزؼ

7 الؽع ا ٠ عذ فشاؽ ث ١ ا خال ٠ ب ا زغب سح رى أ ١ ز ف أ ػ ذ عؾت lymphatics أل ب زا ا فشاؽ ٠ ىجش رؼجش ا غ ائ خال ر ز ئ lymphatics ثب غ ائ Lymphatic Capillary Pump. The terminal lymphatic capillary is also capable of pumping lymph, in addition to the pumping by the larger lymph vessels. The walls of the lymphatic capillaries are tightly adherent to the surrounding tissue cells by means of their anchoring filaments. Therefore, each time excess fluid enters the tissue and causes the tissue to swell, the anchoring filaments pull on the wall of the lymphatic capillary and fluid flows into the terminal lymphatic capillary through the junctions between the endothelial cells. Then, when the tissue is compressed, the pressure inside the capillary increases and causes the overlapping edges of the endothelial cells to close like valves. Therefore, the pressure pushes the lymph forward into the collecting lymphatic instead of backward through the cell junctions. The lymphatic capillary endothelial cells also contain a few contractile actomyosin filaments. In some animal tissues (e.g., the bat s wing), these filaments have been observed to cause rhythmical contraction of the lymphatic capillaries in the same rhythmic way that many of the small blood vessels and larger lymphatic vessels contract. Therefore, it is probable that at least part of lymph pumping results from lymph capillary endothelial cell contraction in addition to contraction of the larger muscular lymphatics. ػ ذ دساعخ رشو ١ جخ lymphatic fluid الؽع أ ب شج ١ خ ر ب ب ثزشو ١ جخ interstitial fluid ف ا جذا ٠ خ أ ب غ رمذ داخ lymphatic فغززغ ١ ش ز ا زشو ١ جخ ثغجت إظبفخ ا جش ر ١ بد ا ذ زا ب ٠ ؾذس ف ا ؾب خ ا طج ١ ؼ ١ خ أ ب ػ ذ ص ٠ بدح غجخ ا غ ائ وض ١ شا فغ ١ زظ ػ ب إغالق ج اثبد ثب زب ٠ ز لف دخ ي ا غ ائ إ lymphatics ز ا ؾب خ ا ز ػجش ب ػ ب عبثمب ة plateau

8 ص ٠ بدح ؽغ ا غبئ ع ١ عغػ ػ ١ ب ٠ ؼصش ب ثب زب رمذ lymphatics إ األ ب ز رؼزجش أ ي ١ ىب ١ ى ١ خ خبصخ ؽز رذفغ ا غ ائ ف lymphatics ثب زب إسعبػ إ circulation أ ب ا ١ ىب ١ ى ١ خ ا ضب ١ خ ف ع دح ػ ذ ثؼط أ اع ا ؾ ١ ا بد ض ا غ اغ ١ غذ ع دح ػ ذ اإل غب ؽ ١ ش أ ٠ مف ؼبوغب ؽ ١ ش ٠ ى سأع ألعف لذ ب ألػ ٠ غز ش ػ ز ا ظؼ ١ خ فزشاد غ ٠ خ عذا طم ١ ب ز ا ظؼ ١ خ عزغجت رغ غ غ ائ ف طمخ ا شأط ثغجت ا غبرث ١ خ األسظ ١ خ إال أ ػ ذ ؽ ١ ا ا غ اغ ال ٠ ؾذس زا ثغجت ر اعذ actomyosin filaments داخ ا خال ٠ ب ا طالئ ١ خ endothelium رؼ وأ ب ػعالد ؽ ١ ش رغجت ػصش lymphatic رؾش ٠ ى ثب زب غ رغ غ ا غ ائ ف ا شأط terminal lymphatics ثب ١ ٢ ز ١ ا غبثمز ١ ػ ب ػ إسعبع ا غ ائ large lymphatics إ Lymphatic Pump Increases Lymph Flow. Valves exist in all lymph channels. When a collecting lymphatic or larger lymph vessel becomes stretched with fluid, the smooth muscle in the wall of the vessel automatically contracts. Furthermore, each segment of the lymph vessel between successive valves functions as a separate automatic pump. That is, even slight filling of a segment causes it to contract, and the fluid is pumped through the next valve into the next lymphatic segment. This fluid fills subsequent segment and a few seconds later it, too, contracts, the process continuing all along the lymph vessel until the fluid is finally emptied into the blood circulation. In a very large lymph vessel such as the thoracic duct, this lymphatic pump can generate pressures as great as 50 to 100 mm Hg

9 داخ رشو ١ جخ ٠ عذ lymphatics valves ا ز رفزؼ رغ ؼ غ ائ أ رزمذ ر غ سع ػ ب ا ٢ دفغ ا غ ائ ٠ ؤد إي ر عغ عذسا ب ا ز ٠ عذ ث ػعالد غبء ز ١ ىب ١ ى ١ خ ا زمبي lymph داخ large lymphatics ٠ غت اال زجب إ أ ا طمخ ا ؾص سح ث ١ ص ب ١ رؼ وأ ب لطؼخ اؽذح ع ١ خ ذفغ ا غبئ إ األ ب إ أ رص إ thoracic duct أوجش ل بح ١ ف ع دح ف ا غغ ا ز رؼ ١ ذ إ circulation ف ز ا م بح ٠ ى ا عغػ شرفغ عذا عذا ؽ ١ ش رزشا ػ ل ١ ز ب ث ١ صئجم Pumping causes by external intermittent compression of lymphatics In addition to the pumping caused by intrinsic intermittent contraction of the lymph vessel walls, any external factor that intermittently compresses the lymph vessel also can cause pumping. In order of their importance, such factors are as follows: Contraction of surrounding skeletal muscles Movement of the parts of the body Pulsations of arteries adjacent to the lymphatics Compression of the tissues by objects outside the body The lymphatic pump becomes very active during exercise, often increasing lymph flow 10- to 30-fold. Conversely, during periods of rest, lymph flow is sluggish (almost zero). آ ١ بد إسعبع ا غبئ ا ١ ف ف terminal & large lymphatics ب د س ثغ ١ ػ عذا ف ػ ١ خ إسعبع lymphatic االػز بد األوجش ػ ا ١ ىب ١ ى ١ خ ا ع دح ؽ ي األ غغخ ا ١ فب ٠ خ ز األ رش : أ(رم ص ا مجبض ا ؼعالد ا غبء ا ؾ ١ طخ ؽ ١ ش أ ا مجبظ ب ٠ غجت ظغػ ػ األ غغخ ا ١ فب ٠ خ ف ١ ؼصش ب ٠ ذفؼ ب أل ب ضبي 0:

10 ػ ذ ا غفش فزشاد غ ٠ خ ػذ اعزخذا ا ؼعالد ٠ ؾص ب اسرخبء أ ا جغبغ ثب زب رغ غ ا غ ائ ػذ رؾش ٠ ه lymphatics ؽذ س ر س ف ا شع ١ ضبي 2: ػ ذ بسعخ ا ش ٠ بظخ ٠ ؾذس اعزخذا ؼعالد ثشى وج ١ ش عذا زا ٠ ؼ ػ ص ٠ بدح رذفك ا غبئ ا ١ ف ث مذاس وج ١ ش عذا ٠ ص إ 31 ظؼف ة( رؾش ٠ ه أعضاء ا غغ ط(رم ص عذسا ا ششا ١٠ ا م ت د( ا عغػ ػ أ غغخ ا غغ خالي ػ ا خبسع ١ خ lymphatics الؽظخ : ز ا ؼ ا األسثؼخ أ ا ١ ىب ١ ى ١ خ ا زار ١ خ شرجخ ؽغت األ ١ خ Edema Edema refers to the presence of excess fluid in the body tissues. Intracellular Edema Two conditions are especially prone to cause intracellular swelling: (1) Lack of adequate nutrition to the cells and Depression of the metabolic systems of the tissues: For example, when blood flow to tissues decreased, the delivery of oxygen and nutrients is reduced. If the blood flow becomes too low to maintain normal tissue metabolism, the cell membrane ionic pumps become depressed. When this occurs, sodium ions that normally leak into the interior of the cell can no longer be pumped out of the cells, and the excess sodium ions inside the cells cause osmosis of water into the cells.

11 Sometimes this can increase intracellular volume of a tissue area (even of an entire ischemic leg, for example)to two to three times normal. When this occurs, it is usually a prelude to death of the tissue. Importance of the Na+-K+ Pump for Controlling Cell Volume. One of the most important functions of the Na+-K+ pump is to control the volume of each cell. Without function of this pump, most cells of the body would swell until they burst. The mechanism for controlling the volume is as follows: Inside the cell are large numbers of proteins and other organic molecules that cannot escape from the cell. Most of these are negatively charged and therefore attract large numbers of potassium,sodium,and other positive ions as well. All these molecules and ions then cause osmosis of water to the interior of the cell. Unless this is checked, the cell will swell indefinitely until it bursts. The normal mechanism for preventing this is the Na+-K+ pump. Note again that this device pumps three Na+ ions to the outside of the cell for every two K+ ions pumped to the interior.also, the membrane is far less permeable to sodium ions than to potassium ions, so that once the sodium ions are on the outside, they have a strong tendency to stay there. Thus, this represents a net loss of ions out of the cell, which initiates osmosis of water out of the cell as well. If a cell begins to swell for any reason, this automatically activates the Na+-K+ pump,moving still more ions to the exterior and carrying water with them. Therefore, the Na+-K+ pump performs a continual surveillance role in maintaining normal cell volume. (2)Intracellular edema can occur in inflamed tissues: Inflammation usually has a direct effect on the cell membranes to increase their permeability, allowing sodium and other ions to diffuse

12 into the interior of the cell, with subsequent osmosis of water into the cells. (3)Hyponatrimia meaning there is less sodium or more water in extracellular fluid. When there is this condition, the water moves from compartment of low concentration of solute to the compartment with high concentration of solute that is inside the cell causing swelling of the cell. Example brain edemas. ا ٢ ع زى ػ ا ظ ع األ edema ا ز رؼ : رغ غ ا غ ائ داخ ا غغ ث مذاس أوجش ا ؾذ ا طج ١ ؼ الؽظ ب أ ٠ عذ اص خ دل ١ مخ عذا رؼ ػ غ رغ غ ا غ ائ داخ interstitium ى أ رى ف داخ ا خال ٠ ب ى أ رى خبسع ب ثذا ٠ خ ع ذسط edema داخ ا خال ٠ ب ص ا ع ا ٢ خش ب عجت ؽذ س edema داخ ا خال ٠ ب! 0 ( مصب ا ذ ا زغز ٠ خ إ األ غغخ ischemia) (tissue 2 (اال ز بثبد 3 ( مص رشو ١ ض أ ٠ بد ا ص د ٠

13 0 ( مصب ا ذ ا زغز ٠ خ إ األ غغخ ischemia) (tissue مص و ١ خ ا ذ ا اص خ غ ١ ظ ٠ ؼ مص األوغغ ١ ا اد ا غزائ ١ خ ا ٢ ا غ ١ ظ رؼشض إ ischemia ثب زب مصب لذسح ا خ ١ خ ػ إ زبط عض ٠ ئبد ) ATP ا صذس األعبع طبلخ ف ا خ ١ خ( مصب ز ا غض ٠ ئبد ٠ ؤد إ رؼط عخخ ص د ٠ - ث ربع ١ ػ ا ؼ ظ ١ فخ ز ا عخخ إخشاط أ ٠ بد ا ص د ٠ إدخبي أ ٠ بد ا ج ربع ١ ا ٢ رؼط ز ا عخخ ٠ ؤد إ دخ ي ا ص د ٠ ا ز ٠ زجؼ دخ ي بء أ ؽذ س edema ب غز زظ أ عخخ ص د ٠ ث ربع ١ ال رى أ ١ ز ب فمػ ف غشد أ ٠ بد ا ص د ٠ إ ب أ ٠ عب ف غ دخ فب ذف إثمبء أ ٠ بد ا ص د ٠ ف ا خبسط ؽز ال ٠ ؾذس ا زمبي بء إ داخ ا خال ٠ ب ضبي: ااال ز بثبد: ٠ خ ػجبسح ػ ا غذاد ا غالق ششا ١٠ ثب زب مصب و ١ خ ا ذ ا اسدح إ ا ؼع خ ا م ج ١ خ ٠ مبي ischemia of the cardiac muscle 2 (ؽذ س اال ز بثبد : ف ؽب خ ؽذ س اال ز بة ضال رصجؼ ا ١ ذ ؽ شاء زفخخ ثغجت edema 3 ( مصب رشو ١ ض ا ص د ٠ ف ا ذ ثؾغت ا خبص ١ خ األع ص ٠ خ فأ ا بء ٠ زم طمخ رشو ١ ض ا ص د ٠ ف ١ ب ل ١ طمخ رشو ١ ض ا ص د ٠ ف ١ ب أػ إ ثب زب ػ ذ ب ٠ ؾذس مصب زشو ١ ض ا ص د ٠ ف ا ذ ع ١ صجؼ رشو ١ ض داخ ا خال ٠ ب أػ ثب زب رؾشن ا بء ثبرغب ا خال ٠ ب ؽذ س edema ٠ شع ا ز ١١ ض ث ١ ا صط ؾبد ا زب ١ خ : مص ف غجخ األوغغ ١ فمػ hypoxemia مص ف غجخ األوغغ ١ ا اد ا غزائ ١ خ ؼب tissue ischemia مص ف رشو ١ ض أ ٠ بد ا ص د ٠ hyponatrimia

14 Extracellular Edema Extracellular fluid edema occurs when there is excessfluid accumulation in the extracellular spaces. Thereare two general causes of extracellular edema: (1) Abnormal leakage of fluid from the plasma to the interstitial spaces across the capillaries, and The most common clinical cause of interstitial fluid accumulation is excessive capillary fluid filtration. (2) Failure of the lymphatic to return fluid from the interstitium back into the blood. النوع الثان هو االتتفاخ الذي كون سببه تراكم الماء ف السائل ب ن الخلوي له سببان :االول : ز ادة نفاذ ة السوائل الى داخل االنسجة الثان :عدم لدرة السائل الل مفاوي على اعادة هذه السوائل الزائدة Lymphatic Blockage Causes Edema When lymphatic blockage occurs, edema can become especially severe because plasma proteins that leak into the interstitium have no other way to be removed. The rise in protein concentration raises the colloid osmotic pressure of the interstitial fluid, which draws even more fluid out of the capillaries. (1) Blockage of lymph flow can be especially severe with infections of the lymph nodes, such as occurs with infection by filaria nematodes. (2)Blockage of the lymph vessels can occur in certain types of cancer or after surgery in which lymph vessels are removed or obstructed. For

15 example, large numbers of lymph vessels are removed during radical mastectomy متى حصل السبب الثان ف حالت ن: األولى««ممكن أن حدث انسداد المنوات الل مفاو ة بواسطة دودة الف الر ا ح ث تنتمل عن طر ك البعوض وتضع ب وضها ف المنوات ثم تنمو داخل المنوات وتسبب انسدادها وتسبب خلل ف إعادة وحركة السائل الل مفاوي الثان ة««أثناء العمل ات الجراح ة الت تتسبب ف تلف الغدد الل مفاو ة أو ف حالة التعرض لإلشعاع أو أثناء عمل ة إزالة الثدي بسبب سرطان الثدي تم إزالة الغدد والمنوات الل مفاو ة الموجودة تحت اإلبط والت تكون مهمتها جمع السوائل من ال د...عند إزالتها تتجمع السوائل ف ال د مما ؤدي إلى انتفاخها.

16 Safety Factors That Normally Prevent Edema The reason the abnormality must be severe is that three major safety factors prevent excessive fluid accumulation in the interstitial spaces: (1) Low compliance of the interstitium when interstitial fluid pressure is in the negative pressure range, (2) The ability of lymph flow to increase 10-to 50-fold, and (3) Wash-down of interstitial fluid protein concentration, which reduces interstitial fluid colloid osmotic pressure as capillary filtration increases. Importance of interstitial gel in preventing fluid accumulation in the interstitium In normal tissues with negative interstitial fluid pressure, virtually all the fluid in the interstitium is in gel form. That is, the fluid is bound in a proteoglycan meshwork so that there are virtually no free fluid spaces larger than a few hundredths of a micrometer in diameter. The importance of the gel is that it prevents fluid from flowing easily through the tissues because of impediment from the brush pile of trillions of proteoglycan filaments. Also, when the interstitial fluid pressure falls to very negative values, the gel does not contract greatly because the meshwork of proteoglycan filaments offers an elastic resistance to compression. In the negative fluid pressure range, the interstitial fluid volume does not change greatly, regardless of whether the degree of suction is only a few millimeters of mercury negative pressure or 10 to 20 mm Hg negative pressure. In other words, the compliance of the tissues is very low in the negative pressure range.

17 By contrast, when interstitial fluid pressure rises to the positive pressure range, there is a tremendous accumulation of free fluid in the tissues. In this pressure range, the tissues are compliant, allowing large amounts of fluid to accumulate with relatively small additional increases in interstitial fluid hydrostatic pressure. Most of the extra fluid that accumulates is free fluid because it pushes the brush pile of proteoglycan filaments apart. Therefore, the fluid can flow freely through the tissue spaces because it is not in gel form. When this free flow of fluid occurs, the edema is said to be pitting edema(such as heart renal, and liver failure) because one can press the thumb against the tissue area and push the fluid out of the area. When the thumb is removed, a pit is left in the skin for a few seconds until the fluid flows back from the surrounding tissues. :Safety factor ه العوامل الت تمنع تجمع السوائل داخل األنسجة compliance)1 low النسبة الطب ع ة للضغط أن كون )-3 0( اآلن إذا زاد الضغط عن الصفر حتى لو كان تغ ر بس ط س ؤدي إلى حدوث ز ادة كب رة جدا ف الحجم و جب االنتباه إلى أنه ف الحالة المعاكسة أي نمصان الضغط من )-10 _ -20( مثال ال حدث انكماش بسبب وجود البروتوجال كان الذي منع انتمال السوائل باإلضافة إلى أنه جزء من ترك بة الجل

18 * الجل: مجموعة السوائل غ ر حرة الحركة واألل اف)الكوالج ن & البروتوجال كان( 2 (ز ادة التدفك الل مفاوي 3 (تمل ل البروت نات داخل الخال ا By contrast, when interstitial fluid pressure rises to the positive pressure range, there is a tremendous accumulation of free fluid in the tissues. In this pressure range, the tissues are compliant, allowing large amounts of fluid to accumulate with relatively small additional increases in interstitial fluid hydrostatic pressure. Most of the extra fluid that accumulates is free fluid because it pushes the brush pile of proteoglycan filaments apart. Therefore, the fluid can flow freely through the tissue spaces because it is not in gel form. When this free flow of fluid occurs, the edema is said to be pitting edema(such as heart renal, and liver failure) because one can press the thumb against the tissue area and push the fluid out of the area. When the thumb is removed, a pit is left in the skin for a few seconds until the fluid flows back from the surrounding tissues.

19 اآلن عند ز ادة الضغط باالتجاه الموجب فمد الجل ترك بة ل صبح أكثر س ولة وتتجمع السوائل فتحصل edema تم اختبار (edema) عن طر ك الضغط على الجلد لمدة 30 ث وتكون حفرة وأحسن مكان هو المكان الذي كون تحته مباشرة عظم مثل الجلد أعلى عظمة tibia : ه العالمة السر ر ة الت تم بها اختبار the interstitial Pitting edema fluid edema This type of edema is distinguished from non-pitting edema, which occurs when the tissue cells swell instead of the interstitium or when the fluid in the interstitium becomes clotted with fibrinogen so that it cannot move freely within the tissue spaces. Such as Mxyoedema, elphantisis, and angioneurotic pitting edema ل س كل interstitial fluid edema ه Non-pitting edema تحصل ف حالت ن هما: 3 1 (تواجد السوائل داخل الخال ا 2( وف حاالت مرض ة كون سببها عوامل التخثر وهذه تحدث ف مرض ة : أ(انتفاخ الوجه بسبب تعطل الغدة الدرل ة حاالت

20 ب(تجمع السوائل بسبب انسداد المنوات ج(ف.حاالت الحساس ة تجمع السوائل ف الوجه خاصة حول الجفون والشفاه Importance of the proteoglycan filaments as a Spacer forيفسح the cells and in preventing rapid المجاح أا ماجفسح flow of fluid in the tissues. The proteoglycan filaments, along with much larger collagen fibrils in the interstitial spaces, act as a spacer between the cells. Nutrients and ions do not diffuse readily through cell membranes; therefore, without adequate spacing between the cells, these nutrients, electrolytes, and cell waste products could not be rapidly exchanged between the blood capillaries and cells located at a distance from one another. The proteoglycan filaments also prevent fluid from flowing too easily through the tissue spaces. If it were not for the proteoglycan filaments, the simple act of a person standing up would cause large amounts of interstitial fluid to flow from the upper body to the lower body. When too

21 much fluid accumulates in the interstitium, as occurs in edema, this extra fluid creates large channels that allow the fluid to flow readily through the interstitium. Therefore, when severe edema occurs in the legs, the edema fluid often can be decreased by simply elevating the legs. Even though fluid does not flow easily through the tissues in the presence of the compacted proteoglycan filaments, different substances within the fluid can diffuse through the tissues at least 95 percent as easily as they normally diffuse. Therefore, the usual diffusion of nutrients to the cells and the removal of waste products from the cells are not compromised by the proteoglycan filaments of the interstitium. **وجود السائل ب ن الخلوي منع تجمع الخال ا ح ث عند استخدام المجهر الضوئ ال نرى الفراغات ب ن الخال ا بكن عند استخدام االلكترون تكون الفراغات واضحة بسبب وجود البروتوجال كان أي أنها تفرق الخال ا عن بعضها البعض حتى تصل إل ها السوائل الت انتملت من الدم **عدم انتمال السوائل بسبب وجود الجل ال عن بالضرورة عدم انتمال المواد الغذائ ة الذائبة ف ه ألنها تعتمد على االنتشار البس ط وفرق الترك ز **المواد الغذائ ة تنتمل عن طر ك االنتشار البس ط بسبب فرق الترك ز من الدم إ ىل األنسجة ومن األنسجة)السائل ) إلى الخال ا وفضالت الخل ة تنتمل باالتجاه المعاكس إذا الجل ل د من حركة السائل فمط أما بالنسبة للمواد الغذائ ة فه تتحرن بنسبة %09-00 (1)Safety Factor Caused by Low Compliance of the Interstitium in the Negative Pressure Range(Low compliance of the interstitium when interstitial fluid pressure is in the negative pressure range) In most loose subcutaneous tissues of the body is slightly less than atmospheric pressure, averaging about 3 mm Hg. This slight suction in the tissues helps hold the tissues together. In the negative pressure range (less than 0 mmhg), the compliance of the tissues is low.

22 Low compliance (small change in volume large increase in interstitial fluid hydrostatic Pressure (or interstitial free fluid pressure) opposes further capillary filtration In the positive pressure range (above 0 mmhg), the compliance of the tissues is high. High compliance (large change in volume small increase in interstitial fluid hydrostatic Pressure (or interstitial free fluid pressure) no further opposes capillary filtration edema Because the normal interstitial fluid hydrostatic pressure is 3 mm Hg, the interstitial fluid hydrostatic pressure must increase by about 3 mm Hg before large amounts of fluid will begin to accumulate in the tissues. Therefore, the safety factor against edema is a change of interstitial fluid pressure of about 3 mm Hg. (2) Increased Lymph Flow as a Safety Factor against Edema

23 The lymphatics act as a safety factor against edema because lymph flow can increase 10- to 50-fold when fluid begins to accumulate in the tissues. This allows the lymphatics to carry away large amounts of fluid and proteins in response to increased capillary filtration, preventing the interstitial pressure from rising into the positive pressure range. The safety factor caused by increased lymph flow has been calculated tobe about 7 mm Hg. (3) Washdown of the Interstitial Fluid Protein as a Safety Factor against Edema As increased amounts of fluid are filtered into the interstitium, The interstitial fluid pressure increases, Causing increased lymph flow. The protein concentration of the interstitium decreases Interstitial fluid colloid osmotic pressure decrease Decrease net filtration pressure Decrease edema The safety factor from this effect has been calculated to be about 7 mm Hg.

24 اآلن مراجعة سر عة ل : safety factor 1( compliance low الذي عن ضغط عال وحجم لل ل وهذا حدث عند الضغط المحصور ب ن -3 و 0 أما عند صعود الضغط عن ل مة 0 فتحدث ز ادة عال ة ف الحجم وهو ما مال له high compliance 2( ز ادة التدفك الل مفاوي ح ث أنه عند ز ادة السوائل زداد الضغط ف زداد التدفك ح ث أن التدفك زداد من ضعف 3 (تمل ل البروت نات أمر ز ادة التدفك الل مفاوي ف الحم مة مهم جدا ح ث أنه عط safety factor 7 مم زئبم أ أنه أي تغ ر ألل من 7 لن سبب حالة مرض ة ب نما أكثر منها س فعل ز ادة السوائل >> ز ادة الضغط>>ز ادة التدفك الل مفاوي) (>> ملل نسبة البروت ن>> ملل << interstitial fluid colloid osmotic pressure مل edema بالتال ال تحدث << filtration pressure Factors That Can Increase Capillary Filtration To understand the causes of excessive capillary filtration, it is useful to review the determinants of capillary filtration Q w = K. [(P c P i ) σ (π c π i )] From this equation, one can see that any one of the following changes can increase the capillary filtration rate: a. Increased capillary filtration coefficient. b. Increased capillary hydrostatic pressure. c. Decreased plasma colloid osmotic pressure.

25 Causes of increase interstitial fluid and edema: 1. Increase filtration pressure (due to increase capillary hydrostatic pressure): Arterial dilation. )a Venular constriction. )b Increase venous pressure: heart failure )c incompetent valves venous obstruction increase total ECF volume effect of gravity 2. Decrease osmotic pressure gradient across the capillary: a) Decrease plasma protein level (decrease production of albumin as in liver failure or increase loss of albumin by kidney as in Glomerulonephritis) b) Accumulation of osmotically active substances in interstitium (as albumin and Na) 3. Increase capillary permeability: by any substance cause vasodilatation like: substance P, histamine, 4. Inadequate lymphatic flow: like in elephantiasis هذه الجزئ ة مطلوبة بالكامل الدكتور لام بتعداد النماط فمط ولذلن ال وجد لها شرح *************************

26 Significance of negative interstitial fluid pressure as a means for holding the body tissues together Traditionally, it has been assumed that the different tissues of the body are held together entirely by connective tissue fibers. However, connective tissue fibers are very weak or even absent at many places in the body, particularly at points where tissues slide over one another (e.g., skin sliding over the back of the hand or over the face). Yet, even at these places, the tissues are held together by the negative interstitial fluid pressure, which is actually a partial vacuum. When the tissues lose their negative pressure, fluid accumulates in the spaces and the condition known as edema occurs. هذه الفمرة موجودة ببدا ة صفحة 19 موجودة على النسخة المعدلة إال أن الدكتور لم مم بشرحها ح ث أنها ل ست ******************* Study study ا فتى فإن examination لد أتى!!!