BIO-0014 Lecture Notes - Lecture 26: Atrioventricular Node, Pulmonary Circulation, Heart Valve
20 Apr 2017
School
Department
Course
Document Summary
Higher pressure in systemic circuit than pulmonary circuit. Larger distance: systemic- left ventricle through aorta back to right atrium. Blood vessels contract to increase resistance and reduce flow where not needed. Blood vessels dilate to reduce resistance and increase flow where needed. Blood can be distributed to many parts of body. Slowest velocity so that diffusion can occur to maximum extent. All blood vessels have equal flow rate, but different velocity based on area. Pacemaker cells: in sa node, in right atrium. Spontaneously electrically discharge and set pace/rhythm of heart rate. Modified muscle cells that rapidly conduct electrical charge. Allows ventricular and atrial muscles to be contracted at different times- increases ventricular filling time. Sa node- conducting cells- heart muscle cells contract. Contracts every muscle cell of ventricle at same time. Av valves open when atrial pressure exceeds ventricular pressure. Left ventricle has higher pressure because it is in the systemic circulation,
