Cardiovascular Physiology Lecture Notes PDF

**[Lec8]** **[Objective ]** Splanchnic Circulation Blood and lymph in the lung Heart failure **Splanchnic circulation** The splanchnic circulation is composed of gastric, small intestinal, colonic, pancreatic, hepatic, and splenic circulations, arranged in parallel with one another. The three...

**[Lec8]** **[Objective ]** Splanchnic Circulation Blood and lymph in the lung Heart failure **Splanchnic circulation** The splanchnic circulation is composed of gastric, small intestinal, colonic, pancreatic, hepatic, and splenic circulations, arranged in parallel with one another. The three major arteries that supply the splanchnic organs, celiac and superior and inferior mesenteric, give rise to smaller arteries that anastomose extensively. The circulation of some splanchnic organs is complicated by the existence of an intramural circulation. Numerous extrinsic and intrinsic factors influence the splanchnic circulation. Extrinsic factors include general hemodynamic conditions of the cardiovascular system, autonomic nervous system, and circulating neurohumoral agents. Intrinsic mechanisms include special properties of the vasculature, local metabolites, intrinsic nerves, paracrine substances, and local hormones. Anatomy of the splanchnic, portal and hepatic venous circulation. (With permission: Gelman S, Mushlin PS. Catecholamine-induced changes in the splanchnic circulation affecting systemic hemodynamics. Anesthesiology 2004, 100: 434-439).   **Fig. 1 Splanchnic circulation** Splanchnic circulation receives 25% of the cardiac output and up to 35%.Splanchnic perfusion is controlled through **autoregulation, neurogenic, and humoral regulation**. Pressure-flow autoregulation ensures that splanchnic flow is modulated to meet metabolic demand. **Blood & Lymph in the Lungs\ **Both the **pulmonary circulation** and the **bronchial circulation** contribute to blood flow in the lungs. In the pulmonary\ circulation, almost all the blood in the body\ passes via the pulmonary artery to the pulmonary capillary\ bed, where it is oxygenated and returned to the left atrium via\ the pulmonary veins. The pulmonary arteries strictly follow\ the branching of the bronchi down to the respiratory bronchioles. The pulmonary veins, however, are spaced between\ the bronchi on their return to the heart. The separate and\ much smaller bronchial circulation includes the bronchial arteries that come from systemic arteries. They form capillaries, which drain into bronchial veins or anastomose with\ pulmonary capillaries or veins. The bronchial veins drain into\ the azygos vein. The bronchial circulation nourishes the trachea down to the terminal bronchioles and also supplies the\ pleura and hilar lymph nodes. It should be noted that lymphatic channels are more abundant in the lungs than in any\ other organ. Lymph nodes are arranged along the bronchial\ tree and extend down until the bronchi are ∼5 mm in diameter. Lymph node sizes can range from 1 mm at the bronchial\ periphery to 10 mm along the trachea. The nodes are connected by lymph vessels and allow for unidirectional flow of\ lymph to the subclavian veins. **Heart failure:** Heart failure is a condition where the heart fails to pump and circulate an adequate supply of blood to meet the requirements of the body. The muscles of the heart become less efficient and damaged, leading to overload on the heart.The failure may involve primarily the right ventricle (corpulmonale), but much more commonly it involves the left ventricle or both ventricles. Pathogenesis :HF can be caused from: -**[Coronary artery disease:]** If blood clot block blood flow to an area of the heart muscle cause weakening the heart\'s pumping ability and often leaving permanent damages. \- [**Cardiomyopathy**](http://www.webmd.com/content/pages/9/1675_57821.htm): Damage to the heart muscle from infections or alcohol or drug abuse and others. -**Conditions that overwork the heart:** including high blood pressure, [valve disease](http://www.webmd.com/content/pages/9/1675_57850.htm), thyroid disease, kidney disease, or congenital heart disease. heart has to work harder than it should to circulate blood throughout your body. All these condition over a time lead to heart failure by weakening of heart muscle. If a heart suddenly becomes severely damaged, such as by myocardial infarction, the pumping ability of the heart is immediately depressed. As a result, two main effects occur: (1) reduced cardiac output and (2) damming of blood in the veins, resulting in increased venous pressure. **[Compensatory mechanisms : ]** \\ **Causes of peripheral edema in heart failure** 1. Decrease glomerular filtration 2. Activation of Renin- angiotensin system 3. Increase aldosterone secretion 4. the heart muscle weakens and can no longer pump enough blood to meet the body's needs **Left sided heart failure**: failure of left ventricle causes increased pulmonary venous pressure, pulmonary venous distention and transudation of fluid into air spaces leading to pulmonary congestion. A person with left-sided heart failure may have shortness of breath and coughing caused by the fluid buildup in the lungs. Pulmonary edema may cause the person to [cough](http://medical-dictionary.thefreedictionary.com/Cough) mucous contains blood. **Right sided heart failure:** failure of right ventricle causes increased venous pressure, increased fluid transudation so ankle and sacral edema, ascitis and hepatomegaly because increased venous pressure causes increased resistance to portal flow. right ventricular heart failure usually occurs as a result of left-sided failure. When the left ventricle fails, increased fluid pressure is, in effect, transferred back through the lungs, ultimately damaging the heart\'s right side. **Sign and symptom of HF:** - shortness of breath with activity or when lying down. - Fatigue and weakness. - Swelling in the legs, ankles and feet. - Rapid or irregular heartbeat. - Reduced ability to exercise. - Wheezing. - A cough that doesn\'t go away or a cough that brings up white or pink mucus with spots of blood. - Swelling of the belly area. - Sudden death References : 2020 International Society of Hypertension Global Hypertension Guyton and Hall textbook of pysio. Principle of physiology Ganongs review of medical physoplogy