The circulatory system is an organ system that passes nutrients gases, hormones, blood cells, etc. to and from cells in the body to help fight diseases and help stabilize body temperature. This system may be seen strictly as a blood distribution network, but some consider the circulatory system as composed of the cardiovascular system, which distributes blood.
The Heart is a muscular organ found in all animals with a circulatory system, that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions. The vertebrate heart is composed of cardiac muscle. The average human heart, beating at 72 beats per minute, will beat approximately 2.5 billion times during an average 66 year lifespan, and weighs approximately 250 to 300 grams in females and 300 to 350 grams in males.
Structure of Heart• The human heart has four chambers, two superior atria and two inferior ventricles. The atria are the receiving chambers and the ventricles are the discharging chambers. The right ventricle discharges into the lungs to oxygenate the blood. The left ventricle discharges its blood toward the rest of the body via the aorta.• Blood flows through the heart in one direction, from the atria to the ventricles, and out of the great arteries, or the aorta for example. This is done by four valves which are the tricuspid valve, the mitral valve, the aortic valve, and the pulmonary valve
Blood Blood is a specialized fluid that delivers necessary substances to the bodys cells such as nutrients and oxygen and transports waste products away from those same cells. Vertebrate blood is bright red when its hemoglobin is oxygenated. Blood has 3 parts – a)RBCs b)WBCs c)Platelets
RBCs – Red Blood Cells Red blood cells (erythrocytes) are the most common type of blood cell and the vertebrate organisms principal means of delivering oxygen (O2) to the body tissues via the blood flow through the circulatory system. They take up oxygen in the lungs or gills and release it while squeezing through the bodys capillaries. These cells cytoplasm is rich in haemoglobin, an iron-containing biomolecule that can bind oxygen and is responsible for the bloods red color.
White blood cells (leukocytes) are cells of the immune system involved in defending the body against both infectious disease and foreign materials.Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as a hematopoietic stem cell. Leukocytes are found throughout the body, including the blood and lymphatic system.
Platelets or thrombocytes are small, regularly-shaped clear cell fragments (i.e. cells that do not have a nucleus containing DNA), which are derived from fragmentation of precursor. The average lifespan of a platelet is normally just 5 to 9 days. Platelets play a fundamental role in hemostasis and are a natural source of growth factors. They circulate in the blood of mammals and are involved in hemostasis, leading to the formation of blood clots.
Blood Vessels The blood vessels are the part of the circulatory system that transport blood throughout the body. There are three major types of blood vessels: a)Arteries b)Capillaries c)Veins
Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary artery. The circulatory system is extremely important for sustaining life. Its proper functioning is responsible for the delivery of oxygen and nutrients to all cells, as well as the removal of carbon dioxide and waste products.
Capillaries Capillaries are the smallest of a bodys blood vessels and are parts of the microcirculation. They are only 1 cell thick. These micro vessels, measuring 5-10 in diameter, connect arterioles and venules, and enable the exchange of water, oxygen, carbon dioxide, and many other nutrient and waste chemical substances between blood and surrounding tissues.
In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart.
The heart beats around 3 billion times in the average persons life. About 8 million blood cells die in the human body every second, and the same number are born each second. Within a tiny droplet of blood, there are some 5 million red blood cells.