T. d. að labba upp stiga eða í stigvél T.d. að labba upp stiga eða í stigvél. Effects of muscle exercise on blood flow in the calf of a leg during strong rhythmical contraction. The blood flow was much less during constractions than between contractions ! Ástæðan er að vöðvar í áreynslu (ekki slakir) þrýsta á æðarnar og stoppa blóðflæðið næstum en það also causes rapid weakening of the contraction. Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

Hvaða áhrif hefur vöðvasamdráttur í hjarta á blóðflæði í kransæðum Hvaða áhrif hefur vöðvasamdráttur í hjarta á blóðflæði í kransæðum ? Við aukið erfiði slær hjarta hraðar og kröftugar og þá fá kransæðarnar minna blóð og þrengjast. The resting coronary blood flow in the human being averages about 225 ml/min sem er ca 4-5% af total cardiac output. Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

Phasic flow of blood through the coronary capillaries of the human left ventricle during cardiac systole and diastole. Minna blóðflæði er í kransæðum í systolu. Diastolan styttist við kröftugri og hraðari hjartslátt. Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

Vinstri hlutinn vinnur meira og hefur þörf fyrir meira blóðflæði. Figure 23-4 Coronary blood flow cycle. Downloaded from: StudentConsult (on 14 November 2007 04:21 PM) © 2005 Elsevier

Minute anastomoses in the normal cooronary arterial system Minute anastomoses in the normal cooronary arterial system. In a normal heart, almost no large communications exist among the larger coronary arteries but many anastomoses do exist among the smaller arteries. Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

Systolic stretch: when the normal portions og the ventricular muscle contract, the ischemic portion of the muscle whether this be dead or simply nonfunctional, instead of contraction is forced outward by the pressure that develops inside the ventricle. Therefore, much of the pumping force of the ventricle is d issipated by bulging of the area of nonfunctional cardiac muscle. Cardiac shock almost always occurs when more than 40% of the left centricle is infarcted og dauði þar með í 85% tilvika. Cardiac shock er þegar hjartavöðvinn er orðinn of veikburða út af þessu til að pumpa nægu blóði og peripheral vefir verða fyrir súrefnisskorti. Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

The tendency to develop fibrillation is especially great after a large infarction but fibrillation can sometimes occur after small occlusions as well. Indeed some patients with chronic coronary insufficiency die suddenly from firbrillation without any acute infarction. Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

Cardiac output minnkar og þrýstingur í hægra atrium eykst. Progressive changes in the cardiac output curve after acute myocardial infarction. Both the cardiac output and right atrial pressure change progressively from point A to point D over a period of seconds, minutes, days and weeks. Cardiac output minnkar og þrýstingur í hægra atrium eykst. Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

Cardiac reverse in different conditions showing less than zero reserve for two of the conditions ! Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

For this reason, major portions of the heart sounds cand be recorded electronically in phonocardiograms even though they cannot be heard with a stethoscope. Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

Chest areas from which sound from each valve is best heard. Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

Mitral regurgitation er bakflæði gegnum mítralloku. Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

Patent ductus arteriosus, showing by the intensity of the pink color that dark venous blood changes into oxygenated blood at different points in the circulation. The right hand diagram shows backflow of blood from the aorta into the pulmonary artery and the through the lungs for a second time. Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

Tetralogy of Fallot, showing by the intensity of the pink color that most of the dark venous blood is shunted from the right ventricle into the aorta without passing through the lungs. Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

About 10% of the total blood volume can be removed with almost no effect on either arterial pressure or cardiac output but greater blood loss usually diminishes the cardiac output first and later the arterial pressure, borth of which fall to zero when about 35-45% Menn þola að missa um 1 -1 ½ L eða 1/3 blóðs , annars verða menn að fá blóðgjöf. Sjokk/Lost: Fall í blóðþrýstingi sem líkaminn ræður ekki við. Ef ekkert er að gert leiðir þetta til dauða. Við þetta ástand víkka æðarnar og tónusinn frá sympatíska kerfinu lækkar eða hverfur. Láta fólk liggja með fætur upp , jafnvel láta höfuð halla niður ! Ekki er vitað af hverju þetta gerist! Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

Time course of arterial pressure in dogs after different degrees of acute hemorrhage. This experiment demonstrates that the circulatory sustem can recover as long as the degree of hemorrhage is no greater than a certain critical amount. Hemorrhage beyond a certain critical level causes shock to become progressive. That is, the shock itself causes still more shock and the condition becomes a vicious circle that ecentually leads to death. Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

Figure 22-8 Effect of blood volume on cardiac output Figure 22-8 Effect of blood volume on cardiac output. The investigators changed effective circulating volume (x axis) by altering blood volume. Downloaded from: StudentConsult (on 14 November 2007 04:05 PM) © 2005 Elsevier

Different types of positive feedback that can lead to progression of shock. Ef slagæðaþrýstingur fellur neðar en það sem þarf til að næra hjartavöðvann þá veikir það hjartað og veikir þar með útfall hjartans enn meir- keðjuverkandi áhrif til hins verra. Á fyrstu stigum losts eykst styrku sympatíska kerfisins sem hjálpar cardiac output og kemur í veg fyrir að þrýstingur falli en að lokum nægir blóðflæðið ekki, brain vasomotor center becomes depressed og sympatísk virkni hættir. After many hours of capillary hypoxia and lack of other nutrients the permeability of the capillaries gradually increases and large quantities of fluid begin to transude into the tissues. Talið er að lost valdi líka losun toxískra efna s.s. Histamín, serotonin og tissue sensíma. Einnig talað um endotoxin sem er frá dauðum gram negatívum bakteríum þarma. Minnkað blóðflæði til þarma veldur stundum aukinni upptöku og framleiðslu þessara efna. Veldur cardiac depression. Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier

Failure of transfusion to prevent death in irreversible shock Failure of transfusion to prevent death in irreversible shock. Eftir að lost hefur náð ákveðnu stigi þá er ekkert hægt að gera til að bjarga manneskjunni og blóðgjöf virkar ekki og dauði á mínútum eða klukkustundum. Eins og sést á mynd þá jafnvel næst að koma cardiac output í lag og arterial pressure en það ástand nær ekki að haldast. Á ákveðnum punkti hefur bara of mikið skemmst og of mikið af destructive ensímum verið losað útí blóði og of mikil acidosa ofl . Downloaded from: StudentConsult (on 8 January 2009 08:17 AM) © 2005 Elsevier