Excitation conduction and contraction The electrical excitation of the heart muscle is effected by a cardiac conduction system, which, as with smooth muscles, is based on the presence of spontaneously discharging (depolarizing) pacemaker cells. The first instance of this system is the so-called sinus node, the primary pacemaker. Here, the heart rate is set at … Excitation conduction and contraction | Myocardium
Properties of the heart muscle With humans a heart muscle cell is on the average about 50 to 100 μm long and 10 to 25 μm broad. The left ventricle is the chamber from which blood is ejected into the body’s circulation.This must therefore provide a much higher pumping capacity than the right ventricle, which … Properties of the heart muscle | Myocardium
Synonyms in a broader sense Coronary arteries Angina pectoris General information When we speak of vascular supply (vascular supply of coronary arteries), we must first distinguish between arteries, veins and lymph vessels. While arteries carry the oxygen-rich blood to the respective target organ, the oxygen-poor blood is transported back to the heart via veins after … Vascularization of the heart
Vascularization of the heart The heart (Cor) is a hollow muscular organ that plays a central role in the vascular supply of the body (vascular supply heart). As a pump, it transports oxygen-depleted blood to the lungs (pulmo), where the blood is enriched with oxygen. The heart then pumps the oxygen-rich blood back into the … Vascularization of the heart | Vascularization of the heart
Definition The sinus node (also: sinuatrial node, SA node) is the primary electrical pacemaker of the heart and is largely responsible for heart rate and excitation. Function of the sinus node The heart is a muscle that pumps on its own, which means it is not dependent on nerves like most muscles. This is because … Sinus node
Sinus node defect If the sinus node fails as the primary pacemaker and stimulation center of the heart, a secondary pacemaker must step in for it (sick sinus syndrome). This is called the atrioventricular node (AV node) and can take over the function of the sinus node to a certain extent. It generates a rhythm … Sinus node defect | Sinus node
Definition and function The pericardium, also called pericardium in medicine, is a bag made of connective tissue that surrounds the heart, except for the outgoing vessels. The pericardium serves as a protective cover and prevents the heart from expanding excessively. Anatomy and position The pericardium consists of two layers: the layer that lies directly on … Pericardium
Synonym: Atrium Definition The heart has two atria, the right atrium and the left atrium. The atria are located in front of the respective ventricle and can be assigned to different blood circulations: The right atrium is part of the “small” circulation (pulmonary circulation) The left atrium is part of the “big” circulation (body circulation) … Left atrium
Synonym: Valvae cordis Definition The heart consists of four cavities, which are separated from each other and from the respective blood vessels by a total of four heart valves. This allows blood to flow in only one direction and only when it is appropriate within the scope of the heart action (systole or diastole). The … Heart valves
Clinical aspects of heart valves If the function of a heart valve is restricted, this is called heart valve vitium. Such a vitamin can be congenital or acquired. There are two types of functional limitations: Mild valve defects can go unnoticed, while more severe ones usually become symptomatic sooner or later. Common to all valve … Clinical aspects of heart valves | Heart valves
The heart consists of different layers. The outermost layer of the heart wall is the epicardium (outer skin of the heart). The epicardium is firmly attached to the underlying myocardium (heart muscle tissue). Structure/Histology To understand the entire structure of the layers, it is best to take another look at the entire heart. On the … Epicardium
The heart consists of different layers. The innermost layer is the endocardium. As the innermost layer, it comes into direct contact with the blood that flows through the heart. The endocardium (from inside to outside) contains the myocardium (the layer of the heart muscle) and the epicardium (the outer skin of the heart). The pericardium, … Endocardium
