Functions of the Blood and Cardiovascular System
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Functions of the Blood
Transports nutrients and oxygen to all the cells and collects waste products produced by cell metabolism. Contributes to the regulation of body temperature. Plays a role in the fight against infections.
Cardiovascular System
Shares nutrients and oxygen between cells and collects waste products that cells produce during metabolism.
Blood Vessels
Are responsible for carrying blood around the body.
Arteries
Carry blood from the heart to the other organs. Have wide and elastic muscular walls. As arteries get further away from the heart, they branch out and become thinner (arterioles).
Veins
Carry blood from tissues to the heart. Have thinner walls than arteries and have valves to stop blood from going backwards. Are formed where many venules join together.
Capillaries
Are microscopic vessels located in all the tissues. Are formed by walls that only have one layer of flat cells (endothelia). Connect arterioles and venules.
The Heart
Is a hollow muscular organ divided into two parts, the left (oxygenated blood) and right (deoxygenated blood). The heart is formed by a thick wall of muscle tissue called myocardium and it is covered by a double membrane named pericardium. It has a thin layer of cells, endocardium.
Heartbeat
Is a constant movement performed by the heart that pumps blood from the veins into the atriums, and from there it goes into the ventricles and is finally released into the arteries.
1. Heart Rate - is the number of times the heart beats per unit of time.
2. Cardiac Output - is the volume of blood the heart pumps in one minute.
Phases of Heartbeat
Atrial systole - atriums contract. Ventricular systole - ventricles contract. Diastole - heart relaxes and sucks blood.
Blood pressure - pressure applied by blood on the artery walls.
Blood Circuits
Circulation is closed - blood never leaves the blood vessels. Circulation is complete - oxygenated blood proceeding from the lungs never mixes with deoxygenated blood coming from the rest of the body. Circulation is double - blood has to travel twice through the heart in order to complete the whole circuit.