Which of the following describes the reflex increase in hea rate with on atrial distension?
Bainbridge reflex: When the hea rate is slow, intravenous infusions of blood or electrolyte solutions usually accelerate the hea. Both atria have receptors that are affected by changes in blood volume and that influence the hea rate. These receptors are located principally in the venoatrial junctions: in the right atrium at its junctions with the venae cavae and in the left atrium at its junctions with the pulmonary veins. Distention of these atrial receptors sends afferent impulses to the brainstem in the vagus nerves. The efferent impulses are carried from the brainstem to the SA node by fibers from both autonomic divisions. Bezold-Jarisch reflex or the coronary chemoreflex: Activation of chemosensitive vagal C fibers in the cardiopulmonary region (eg, juxtacapillary region of alveoli, ventricles, atria, great veins, and pulmonary aery) causes profound bradycardia, hypotension, and a brief period of apnea followed by rapid shallow breathing. It can be elicited by a variety of substances including capsaicin, histamine, serotonin, phenylbiguanide, and veratridine. In human this reflex may be activated: During myocardial ischemia or, reperfusion (thrombolytic therapy) as a result of increased production of oxygen radicals. By agents used as radiocontrast for coronary angiography. It is cardioprotective by producing bradycardia, thus reduce the amount substances get absorbed into the blood Vasovagal syncope has been attributed to activation of the Bezold-Jarisch reflex J reflex or pulmonary chemoreflex: Because the C fiber endings are close to pulmonary vessels, they have been called J (juxtacapillary) receptors. They are stimulated by hyperinflation of the lung, but they respond as well to intravenous or intracardiac administration of chemicals such as capsaicin. The reflex response that is produced is apnea followed by rapid breathing, bradycardia, and hypotension Oculocardiac reflex: Traction on the extraocular muscles (especially the medial rectus), conjunctiva, or orbital structures causes hypotension and a reflex slowing of the HR, as well as arrhythmias Cushing's reflex: Increased CSF pressure (intracranial pressure) - cerebral aery compressed - CNS ischemia that causes hypoxia and hypercapnia in medulla, which directly stimulates the vasomotor centre - increased BP - baroreceptor mechanisms causes reflex Bradycardia. Cushing reflex causes the symptoms of Cushing triad: Bradycardia Hypeension (with widened pulse pressure) Irregular respiration (bradypnea)
J reflex
Bainbridge reflex
Cushing reflex
Bezold Jarisch reflex
Cardiovascular System