Heart rate persons with coronary artery disease. The heart rate is rhythmically generated by the sinoatrial node. It is also influenced by central factors through sympathetic and parasympathetic nerves. Nervous influence over the heartrate is centralized within the two paired cardiovascular centres of the medulla oblongata. The cardioaccelerator regions stimulate activity via sympathetic stimulation of the cardioaccelerator nerves, and the cardioinhibitory centers decrease heart activity via parasympathetic stimulation as one component of the vagus nerve. During rest, both centers provide slight stimulation to the heart, contributing to autonomic tone. This is a similar concept to tone in skeletal muscles. Normally, vagal stimulation
Circulatory system of the horse septicemia, has experienced a great deal of blood loss, has advanced heart or lung disease, or is in shock. In these cases, the resting heart rate may be above 80 in an adult animal. When the heart rate is below 20 bpm, the horse may be hypothermic, or have pressure on the brain, heart disease, or collapsed circulation. Heart rate may be determined with a stethoscope, placed just behind the left elbow of the animal. The pulse may also be felt when taken on an artery close to the skin, most commonly the facial artery located on the lower jaw