Pericardium in the context of "Pericarditis"

The heart is a muscular organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make up the circulatory system. The pumped blood carries oxygen and nutrients to the tissue, while carrying metabolic waste such as carbon dioxide to the lungs. In humans, the heart is approximately the size of a closed fist and is located between the lungs, in the middle compartment of the chest, called the mediastinum.

In humans, the heart is divided into four chambers: upper left and right atria and lower left and right ventricles. Commonly, the right atrium and ventricle are referred together as the right heart and their left counterparts as the left heart. In a healthy heart, blood flows one way through the heart due to heart valves, which prevent backflow. The heart is enclosed in a protective sac, the pericardium, which also contains a small amount of fluid. The wall of the heart is made up of three layers: epicardium, myocardium, and endocardium.

The serous membrane (or serosa) is a smooth epithelial membrane of mesothelium lining the contents and inner walls of body cavities, which secrete serous fluid to allow lubricated sliding movements between opposing surfaces. The serous membrane that covers internal organs (viscera) is called visceral, while the one that covers the cavity wall is called parietal. For instance the parietal peritoneum is attached to the abdominal wall and the pelvic walls. The visceral peritoneum is wrapped around the visceral organs. For the heart, the layers of the serous membrane are called parietal and visceral pericardium. For the lungs they are called parietal and visceral pleura. The visceral serosa of the uterus is called the perimetrium. The potential space between two opposing serosal surfaces is mostly empty except for the small amount of serous fluid.

The Latin anatomical name is tunica serosa. Serous membranes line and enclose several body cavities, also known as serous cavities, where they secrete a lubricating fluid which reduces friction from movements. Serosa is entirely different from the adventitia, a connective tissue layer which binds together structures rather than reducing friction between them. The serous membrane covering the heart and lining the mediastinum is referred to as the pericardium, the serous membrane lining the thoracic cavity and surrounding the lungs is referred to as the pleura, and that lining the abdominopelvic cavity and the viscera is referred to as the peritoneum.

Pericardial fluid is the serous fluid secreted by the serous layer of the pericardium into the pericardial cavity. The pericardium consists of two layers, an outer fibrous layer and the inner serous layer. This serous layer has two membranes which enclose the pericardial cavity into which is secreted the pericardial fluid. The fluid is similar to the cerebrospinal fluid of the brain which also serves to cushion and allow some movement of the organ.

Cardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate muscle tissues, the others 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. It is composed of individual cardiac muscle cells joined by intercalated discs, and encased by collagen fibers and other substances that form the extracellular matrix.

Cardiac muscle contracts in a similar manner to skeletal muscle, although with some important differences. Electrical stimulation in the form of a cardiac action potential triggers the release of calcium from the cell's internal calcium store, the sarcoplasmic reticulum. The rise in calcium causes the cell's myofilaments to slide past each other in a process called excitation-contraction coupling.Diseases of the heart muscle known as cardiomyopathies are of major importance. These include ischemic conditions caused by a restricted blood supply to the muscle such as angina, and myocardial infarction.

The endocardium (pl.: endocardia) is the innermost layer of tissue that lines the chambers of the heart. Its cells are embryologically and biologically similar to the endothelial cells that line blood vessels. The endocardium also provides protection to the valves and heart chambers.

The endocardium underlies the much more voluminous myocardium, the muscular tissue responsible for the contraction of the heart. The outer layer of the heart is termed epicardium and the heart is surrounded by a small amount of fluid enclosed by a fibrous sac called the pericardium.

The Anopheles gambiae complex consists of at least seven morphologically indistinguishable species of mosquitoes in the genus Anopheles. The complex was recognised in the 1960s and includes the most important vectors of malaria in sub-Saharan Africa, particularly of the most dangerous malaria parasite, Plasmodium falciparum. It is one of the most efficient malaria vectors known. The An. gambiae mosquito additionally transmits Wuchereria bancrofti which causes lymphatic filariasis, a symptom of which is elephantiasis.