2) The Respiratory Pump
This is based upon alternating compression and decompression of veins. During inhalation, the diaphragm moves caudally increasing the pressure in the abdominal cavity and conversely reducing pressure in the thoracic cavity. This results in abdominal veins being compressed and a greater volume of blood moving from the compressed abdominal veins into the decompressed thoracic veins and then into the right atrium.
Control of Blood Pressure
Several negative feedback systems adjust heart rate, stroke volume, systemic vascular resistance and blood volume.
A) Cardiovascular (CV) Centre
Located in the medulla oblongata
Helps regulate heart rate and stroke volume Controls neural, hormonal, and local negative feedback systems that regulate blood pressure and blood flow to specific tissues Receives input both from higher regions of the brain and from sensory receptors Output flows along sympathetic and parasympathetic neurons of the ANS. Increased sympathetic stimulation increases heart rate and contractility. Parasympathetic stimulation does the opposite.
261
Made with FlippingBook Publishing Software