Circulatory systemThe blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, that consists of the heart and blood vessels (from Greek kardia meaning heart, and from Latin vascula meaning vessels). The circulatory system has two divisions, a systemic circulation or circuit, and a pulmonary circulation or circuit.
Cardiac muscleCardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate muscle tissues, with the other two being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that constitutes the main tissue of the wall of the heart. The cardiac muscle (myocardium) forms a thick middle layer between the outer layer of the heart wall (the pericardium) and the inner layer (the endocardium), with blood supplied via the coronary circulation.
Purkinje fibersThe Purkinje fibers (pɜːrˈkɪndʒi ; ˈpurkɪɲɛ; Purkinje tissue or subendocardial branches) are located in the inner ventricular walls of the heart, just beneath the endocardium in a space called the subendocardium. The Purkinje fibers are specialized conducting fibers composed of electrically excitable cells. They are larger than cardiomyocytes with fewer myofibrils and many mitochondria. They conduct cardiac action potentials more quickly and efficiently than any of the other cells in the heart's electrical conduction system.
Sinoatrial nodeThe sinoatrial node (also known as the sinuatrial node, SA node or sinus node) is an oval shaped region of special cardiac muscle in the upper back wall of the right atrium made up of cells known as pacemaker cells. The sinus node is approximately 15 mm long, 3 mm wide, and 1 mm thick, located directly below and to the side of the superior vena cava. These cells can produce an electrical impulse known as a cardiac action potential that travels through the electrical conduction system of the heart, causing it to contract.
Pulmonary arteryA pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The largest pulmonary artery is the main pulmonary artery or pulmonary trunk from the heart, and the smallest ones are the arterioles, which lead to the capillaries that surround the pulmonary alveoli. The pulmonary arteries are blood vessels that carry systemic venous blood from the right ventricle of the heart to the microcirculation of the lungs.
SphygmomanometerA sphygmomanometer (ˌsfɪɡməʊməˈnɒmɪtər ), a blood pressure monitor, or blood pressure gauge, is a device used to measure blood pressure, composed of an inflatable cuff to collapse and then release the artery under the cuff in a controlled manner, and a mercury or aneroid manometer to measure the pressure. Manual sphygmomanometers are used with a stethoscope when using the auscultatory technique. A sphygmomanometer consists of an inflatable cuff, a measuring unit (the mercury manometer, or aneroid gauge), and a mechanism for inflation which may be a manually operated bulb and valve or a pump operated electrically.
Cardiac outputIn cardiac physiology, cardiac output (CO), also known as heart output and often denoted by the symbols , , or , is the volumetric flow rate of the heart's pumping output: that is, the volume of blood being pumped by a single ventricle of the heart, per unit time (usually measured per minute). Cardiac output (CO) is the product of the heart rate (HR), i.e. the number of heartbeats per minute (bpm), and the stroke volume (SV), which is the volume of blood pumped from the left ventricle per beat; thus giving the formula: Values for cardiac output are usually denoted as L/min.
Wiggers diagramA Wiggers diagram, named after its developer, Carl Wiggers, is a unique diagram that has been used in teaching cardiac physiology for more than a century. In the Wiggers diagram, the X-axis is used to plot time subdivided into the cardiac phases, while the Y-axis typically contains the following on a single grid: Blood pressure Aortic pressure Ventricular pressure Atrial pressure Ventricular volume Electrocardiogram Arterial flow (optional) Heart sounds (optional) The Wiggers diagram clearly illustrates the coordinated variation of these values as the heart beats, assisting one in understanding the entire cardiac cycle.
Heart blockHeart block (HB) is a disorder in the heart's rhythm due to a fault in the natural pacemaker. This is caused by an obstruction – a block – in the electrical conduction system of the heart. Sometimes a disorder can be inherited. Despite the severe-sounding name, heart block may cause no symptoms at all in some cases, or occasional missed heartbeats in other cases (which can cause light-headedness, syncope (fainting), and palpitations), or may require the implantation of an artificial pacemaker, depending upon exactly where in the heart conduction is being impaired and how significantly it is affected.
Interventricular septumThe interventricular septum (IVS, or ventricular septum, or during development septum inferius) is the stout wall separating the ventricles, the lower chambers of the heart, from one another. The ventricular septum is directed obliquely backward to the right and curved with the convexity toward the right ventricle; its margins correspond with the anterior and posterior interventricular sulci. The lower part of the septum, which is the major part, is thick and muscular, and its much smaller upper part is thin and membraneous.
