circulatory system: human anatomy biology

circulatory function

1. THE CIRCULATORY SYSTEM

2. The circulatory system is one of the mechanisms in the body that facilitates the nourishment of cells with the various nutrients and essential elements introduced into our body through the food that we eat and the air we breathe. It is comparable to a complex arrangement of Metropolitan highways that connect all destinations or cells in the body thus providing the cells the much-needed provisions for its sustainability. Together with the respiratory system, it circulates important materials vital to life to all cells and at the same time excretes metabolic wastes away from the body. This system is also known as the CARDIOVASCULAR SYSTEM.

3. THE HEART The heart is hollow muscle, as big as your fist which is located in the centre of your chest between the lungs. It is a double pump that pumps on both left and right sides. It has four distinct chambers, two chambers on each side the atrium and ventricle. What takes place when you inhale and exhale ? How do the heart and lungs work together ? What does blood deliver to the different parts of the body ?

4. The upper chambers are the atria and the lower chambers are the ventricles. The atria are the receiving chambers of the heart accepting blood from the body(right atrium) and from the lungs (left atrium). The ventricles are the pumping chambers, moving blood to the lungs (right ventricle), and to the different parts of the body (left ventricle). The heart has valves between its upper and lower chambers that serves as one-way door regulating the flow of the blood inside the heart thus preventing the blood from flowing backwards

5. THE BLOOD VESSEL The blood vessels carry the blood throughout the body. It has three main types. The Artery- carries oxygenated blood away from the heart to cells, tissues, and organs in the body. The Veins- carries deoxygenated blood or blood carrying CO2 from the body to heart to be expelled to the lungs. Capillaries- the smallest blood vessels in the body connecting the smallest arteries (arterioles) and veins (venule).

6. THE BLOOD The blood carries the essential materials throughout the body. It is primarily compose of blood cells (45%) and plasma (55%). Blood cells are classified as . Red Blood cells (erythrocytes) characterized by red pigmentation due to hemoglobin (site where oxygen attachment). White blood cells (leukocytes)- functions for body defense. They fight infections by engulfing bacteria and other microorganisms that enter the body, foreign proteins etc. Antibodies produced by lymphocytes a type of WBC act against foreign materials. Antigens are materials that cause the body to produce antibodies Platelets- a component of blood that functions (along with the coagulation factors ) to react to bleeding from blood vessel injury by clumping, thereby initiating a blood clot . Platelets have no nucleus. They are fragments of cytoplasm that are derived from the megakaryocytes.

7. CIRCULATIONS IN THE BODY Pulmonary circulation - deoxygenated blood moves away from the right ventricle, to the lungs via the pulmonary artery, and returns oxygenated blood to the left atrium and then to ventricle of the heart .

8. Systemic circulation Oxygen-rich blood from the lungs move passing through the pulmonary vein and enters the left atrium of the heart and goes to the left ventricle. From the left ventricle, it pumps the blood through the arteries via the aorta, to the capillaries in the tissues of the body and picks up waste materials like CO2.;Coronary arteries supply oxygenated blood to the heart muscle, and cardiac veins. It drains away the blood once it has been deoxygenated.

9. DID YOU KNOW: The heart beats in a rhythmic manner during the entire life of a person. This alternating contraction and relaxation of the heart defines the cardiac cycle. There are two phases in a cycle namely DIASTOLE, (when the heart relaxes and the blood flows into the four chambers) and SYSTOLE (refers to the period of contraction). The average heartbeat rate (PULSE) of an adult is 70 times/min.

10. THE BLOOD VESSELS