where are the cardiac and vasomotor centers found
medulla oblongata the medulla oblongata
title: Cardiac physiology text: the four pulmonary veins. The two atrioventricular valves, the tricuspid and mitral valves, are both open, so blood flows unimpeded from the atria and into the ventricles. Approximately 70–80 percent of ventricular filling occurs by this method. The two semilunar valves, the pulmonary and aortic valves, are closed, preventing backflow of blood into the right and left ventricles from the pulmonary trunk on the right and the aorta on the left. Contraction of the atria follows depolarization, represented by the P wave of the ECG. As the atrial muscles contract from the superior portion of the atria toward the atrioventricular title: Respiratory center text: Respiratory center The respiratory center is located in the medulla oblongata and pons, in the brainstem. The respiratory center is made up of three major respiratory groups of neurons, two in the medulla and one in the pons. In the medulla they are the dorsal respiratory group, and the ventral respiratory group. In the pons, the pontine respiratory group includes two areas known as the pneumotaxic centre and the apneustic centre. The respiratory centre is responsible for generating and maintaining the rhythm of respiration, and also of adjusting this in homeostatic response to physiological changes. The respiratory center receives input title: Brainstem text: The pons houses the respiratory pneumotaxic center and apneustic center that make up the pontine respiratory group in the respiratory center. The pons co-ordinates activities of the cerebellar hemispheres. The pons and medulla oblongata are parts of the hindbrain that form much of the brainstem. The medulla oblongata often just referred to as the medulla, is the lower half of the brainstem continuous with the spinal cord. Its upper part is continuous with the pons. The medulla contains the cardiac, dorsal and ventral respiratory groups, and vasomotor centres, dealing with heart rate, breathing and blood pressure. Another important medullary structure title: Vasomotor center text: Vasomotor center The vasomotor center (VMC) is a portion of the medulla oblongata that, together with the cardiovascular center and respiratory center, regulates blood pressure and other homeostatic processes. Vasomotor center is a fairly archaic term since this function relies not on a single brain structure ("center") but rather represents a presympathetic network of interacting neurons. Upon increase in carbon dioxide level at central chemoreceptors, it stimulates the sympathetic system to constrict vessels. This is opposite to carbon dioxide in tissues causing vasodilatation, especially in the brain. Cranial nerves IX (Glossopharyngeal nerve) and X Vagus nerve both feed into the title: Systole text: into the ventricles through the open atrioventricular valves. At the start of atrial systole, during ventricular diastole, the ventricles are normally filled to about 70 – 80 percent of capacity by inflow from the atria. Atrial contraction, also referred to as the "atrial kick," contributes the remaining 20–30 percent of ventricular filling. Atrial systole lasts approximately 100 ms and ends prior to ventricular systole, as the atrial muscle returns to diastole. The two ventricles are isolated electrically and histologically (tissue-wise) from the two atrial chambers by electrically impermeable collagen layers of connective tissue known as the cardiac skeleton. The cardiac