is understood now, this syndrome it not uncommon. Sick sinus syndrome: (SSS') is charictenzed by some ECG changtt and is due lo some damage in the sinu atnal node (SAN) it may be symptom free The ECG findings reveal that, there is often a gross bradycardra. The P waves in ECG might be periodically missing. Pace makers Pace makers have revolutionized the treatment of heart blocks. In heart block patients, pace makers are introduced with an aim to supply to the heart the proper stimuli, so that lack (due to block) Of natuial impulse (coming from the SAN) will not result in cardiac standstill. A pace maker is an electronic device, placed suitably, (so that its tip is positioned in the night ventricle) which supplies stimuli lo the heart: Various types of pace makers are used but perhaps the most papular type is 'demand ventncular pace maker' In this type of instrument .the naturally occurring impulses do their job but if there be missed natural impulses, the pace maker delects them (= missing impulses) and supplies artificial stimult. FIBRILLATION Atrial fibnllaiion. In this
condition, the coordinated and effective contraction of the atria is lost. At any given instant, some parts of the atria are contacting while other pans are quiascent so that it looks like the movements of a worm (vermiform movements) Numerous independent action potentials develop in the atria, many of which are blocked at the AVN. These impulses develop at irregular intervals. As a result the ventricles receive rtregulariy irregular impulses so that the outstanding clinical feature is irregularly irregular pulse which is usually also very rapid. Persisient atrinal fibrillation may lead to embolism and heart failure Ventricular fibrillation. The same vermiform (worm like) movements may, also develop in the ventricle leading to circulatory standstill. Ventricular fibrittalion usually kills the paiieni instantaneously or rarely the patient develops Stokes Adam's syndrome t
like condition and recovers without medical aid. Medical aid consists of giving external electncal shock (counter shock) or (if the instrument is not available) xylocaine may be injected. SUMMARY & HIGHLIGHTS (i) In CVS shock. Ihe cardiac output is not sufficient to meet the demands. Nature's compensatory mechanisms consist mainly of neural (baroieceptor reflex eic), fluid shift and rerun angiotensm mechanism. (ii) Heart failure may be seen as pump failure and the cardiac output is insufficient to the need. Compensatory mechanisms include (a) Frank Starling's law (b) sympathetic overac. twty (due to baroreceptor and olher reflexes). Pump failure is aggravated because of the operaton of Laplace's law(iiii) The murmurs of valvular disease, logically, can occur even if the critical value of Reynold's number is not exceeded, although exercising the patient increases the propensity of turbulence and murmur (iv) Common sites of heart blocks are AVN, bundle branch (right/left). Sick sinus syndrome affects the SAN. (v) Atrial fibrillation is a chronic condition whereas ventricular fibrillation usually kills instantaneously. Functional anatomy The lymphatic channels are present in every tissue, excepting the central nervous system and cornea. The lymph channels start as blind capillanes lined by single layer of end othehum but no basement membrane In these blind capillanes tissue fluid and some protein molecules enter from the tissue But these fluid and protein molecules. Once they enter these channels, cannot leave them. These vessels then dram into bigger vessels which are fewer in number, which in tum, open into still bigger (and still fewer in number) vessels. Ultimately all lymphatic fluid opens into right and left subclawen veins respectively. Thus the fluid and the protein of the tissue fluid are relumed to the bood. On its way the lymphatic channels are interupted by lymph nodes. On approaching a lymph node, a lymph channel breaks up into several afferent channels, all of which enter the lymph nodes From the lymph node one (or sometimes more) single channel, called efferent channel, draining the lymph node, emerges and continues onward .The lymph node adds lymphocytes and antibodies to the flowing lymph. Theietore. these lymphocytes and antibodies eventually enter the blood in the subclavian veins. The lymphatic channels contain valves which ensure a unidirectional flow. Formation of the lymph From the capillaries of the arterial system, the fluid tries to come out but is opposed by the proteins of plasma, as discussed earlier, in connection with the Starling's hypothesis (fig 1.1.9). There. it was presumed that no protein can come out of me capillary blood vessel to the tissues. But the statement was not fully accurate A little plasma proterns can and do leave the blood capillaries. These form Ihe proteins of Ihe lymph (for details, see "movements of large molecules', in micmcirculation, chap. 10. sec V) Question anees if this be the truth, the concentration of lymph fluid prolein should have been low. But the lymph fluid sometimes contain good amount of proitm How? The answer may be that because of the fad that during the return of tissue fluid to the venous end of the capillaries, these proteins are debarred to enter the blood capillaries (because of the relative impermaabilny of the capillary wall to the proteins). Thus, although the exit of proteins from the capillaries is only in traces, these proteins tend to accumulate in the tissues Therefore, the concentialion of protein in the tissue fluid nses and the concentrated protein ultimately returns to the lymph vessels. Functions of the lymph 1. Plasm:
condition, the coordinated and effective contraction of the atria is lost. At any given instant, some parts of the atria are contacting while other pans are quiascent so that it looks like the movements of a worm (vermiform movements) Numerous independent action potentials develop in the atria, many of which are blocked at the AVN. These impulses develop at irregular intervals. As a result the ventricles receive rtregulariy irregular impulses so that the outstanding clinical feature is irregularly irregular pulse which is usually also very rapid. Persisient atrinal fibrillation may lead to embolism and heart failure Ventricular fibrillation. The same vermiform (worm like) movements may, also develop in the ventricle leading to circulatory standstill. Ventricular fibrittalion usually kills the paiieni instantaneously or rarely the patient develops Stokes Adam's syndrome t
like condition and recovers without medical aid. Medical aid consists of giving external electncal shock (counter shock) or (if the instrument is not available) xylocaine may be injected. SUMMARY & HIGHLIGHTS (i) In CVS shock. Ihe cardiac output is not sufficient to meet the demands. Nature's compensatory mechanisms consist mainly of neural (baroieceptor reflex eic), fluid shift and rerun angiotensm mechanism. (ii) Heart failure may be seen as pump failure and the cardiac output is insufficient to the need. Compensatory mechanisms include (a) Frank Starling's law (b) sympathetic overac. twty (due to baroreceptor and olher reflexes). Pump failure is aggravated because of the operaton of Laplace's law(iiii) The murmurs of valvular disease, logically, can occur even if the critical value of Reynold's number is not exceeded, although exercising the patient increases the propensity of turbulence and murmur (iv) Common sites of heart blocks are AVN, bundle branch (right/left). Sick sinus syndrome affects the SAN. (v) Atrial fibrillation is a chronic condition whereas ventricular fibrillation usually kills instantaneously. Functional anatomy The lymphatic channels are present in every tissue, excepting the central nervous system and cornea. The lymph channels start as blind capillanes lined by single layer of end othehum but no basement membrane In these blind capillanes tissue fluid and some protein molecules enter from the tissue But these fluid and protein molecules. Once they enter these channels, cannot leave them. These vessels then dram into bigger vessels which are fewer in number, which in tum, open into still bigger (and still fewer in number) vessels. Ultimately all lymphatic fluid opens into right and left subclawen veins respectively. Thus the fluid and the protein of the tissue fluid are relumed to the bood. On its way the lymphatic channels are interupted by lymph nodes. On approaching a lymph node, a lymph channel breaks up into several afferent channels, all of which enter the lymph nodes From the lymph node one (or sometimes more) single channel, called efferent channel, draining the lymph node, emerges and continues onward .The lymph node adds lymphocytes and antibodies to the flowing lymph. Theietore. these lymphocytes and antibodies eventually enter the blood in the subclavian veins. The lymphatic channels contain valves which ensure a unidirectional flow. Formation of the lymph From the capillaries of the arterial system, the fluid tries to come out but is opposed by the proteins of plasma, as discussed earlier, in connection with the Starling's hypothesis (fig 1.1.9). There. it was presumed that no protein can come out of me capillary blood vessel to the tissues. But the statement was not fully accurate A little plasma proterns can and do leave the blood capillaries. These form Ihe proteins of Ihe lymph (for details, see "movements of large molecules', in micmcirculation, chap. 10. sec V) Question anees if this be the truth, the concentration of lymph fluid prolein should have been low. But the lymph fluid sometimes contain good amount of proitm How? The answer may be that because of the fad that during the return of tissue fluid to the venous end of the capillaries, these proteins are debarred to enter the blood capillaries (because of the relative impermaabilny of the capillary wall to the proteins). Thus, although the exit of proteins from the capillaries is only in traces, these proteins tend to accumulate in the tissues Therefore, the concentialion of protein in the tissue fluid nses and the concentrated protein ultimately returns to the lymph vessels. Functions of the lymph 1. Plasm:
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