There are four main types of tissue: muscular, epithelial, connective and nervous. Each is made up of specialized cells grouped together based on structure and function. Muscle tissue varies depending on its function and location in the body. In mammals the three types are: skeletal or striated muscle; smooth or non-striated muscles; and the cardiac muscle, which is sometimes known as semi striatum. Smooth and cardiac muscles contract involuntarily, without conscious intervention. Epithelial tissue can have columnar, cuboidal or squamous cell shapes. Epithelial tissue has differently shaped building blocks, or cells, i.e. There are columnar cells, which means “column-like cells”; cuboidal cells, which are cube-like cells; and squamous cells, which are flattened, scale-like cells. Connective tissues include several types of fibrous tissue that vary only in their density and cellularity, as well as more specialized and recognizable variants: bones, ligaments, tendons, cartilage, and adipose (fat) tissue. Nervous tissue or nervous tissue is the main tissue component of the two parts of the nervous system; the brain and spinal cord of the central nervous system (CNS) and the branches of the peripheral nerves of the peripheral nervous system (PNS), which regulate and control bodily functions and activities. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original Essay To me, the “wave” of depolarization is defined as the contractions of the heart constantly going back and forth as a wave would. The pulmonary circulation is the circulation system that transports deoxygenated blood to the lungs and returns oxygenated blood from the lungs to the heart. The two blood vessels involved in the pulmonary circulation are the pulmonary artery and the pulmonary vein. Deoxygenated blood flows into the right ventricle from the right atrium. This blood is transported to the alveoli of the lungs for oxygenation by the pulmonary artery. The pulmonary artery, which arises immediately from the right ventricle, is called the pulmonary trunk. The pulmonary trunk divides into two; the left pulmonary artery and the right pulmonary artery. The left pulmonary artery carries blood to the left lung while the right pulmonary artery carries blood to the right lung. Carbon dioxide is removed from the blood while oxygen is brought into the blood by the alveolar capillaries. Oxygenated blood is transported into the left atrium of the heart by four pulmonary veins. A small amount of oxygenated blood is transported to the heart by bronchial veins. Please note: this is just a sample. Get a custom paper from our expert writers now. Get a Custom Essay Systemic circulation is the circulation system that transports oxygenated blood throughout the body and returns deoxygenated blood to the heart from the body's tissues. Oxygenated blood from the lungs returns to the left atrium of the heart through the pulmonary veins. This blood flows into the left ventricle and exits the heart through the aorta. The aorta branches into small arteries, which carry blood to different organs in the body. Within an organ or tissue, these arteries branch into arterioles, which form blood capillaries. The exchange of oxygen and nutrients with metabolizing cells occurs through blood capillaries. Carbon dioxide and other metabolic wastes are transported back into the blood. The deoxygenated blood drains into the venules and returns to the right atrium of the heart via the vena cava. Deoxygenated blood from the upper half of the body above the diaphragm drains through the superior vena cava while the.