Introduction to Cardiovascular System
Heart
Pumps blood into the circulation.
Chambers
Four
Two atria: A left atrium and a right atrium.
Two ventricles: A left ventricle and a right ventricle.
Dual Pump
Four chambers make two pumps in series.
Right Heart
= Right atrium + Right ventricle.
Receives deoxygenated blood from vena cava.
Pumps blood into the lungs for oxygenation.
Left Heart
= Left atrium + Left ventricle.
Receives oxygenated blood from lungs.
Pumps blood into the systemic circulation.
Valves
Maintains flow of blood in a specific direction.
Atrioventricular valves
Between atria and ventricles
Tricuspid valve: Between right atria and ventricle.
Made up of three cusps.
Bicuspid valve/Mitral valve: Between left atria and ventricle.
Made up of two cusps.
Semilunar Valves
Between ventricles and major arteries.
Made up of three flaps
Half moon-like shape (hence the name)
Pulmonary valve: between right ventricle and pulmonary artery.
Aortic valve: between left ventricle and aorta.
Blood Vessels
Circulate the blood throughout the body.
Arranged in series as well as parallelly.
Arterial System
Starting from heart, it includes the aorta, arteries, and arterioles in this order.
As we go from the aorta to arterioles:
Lumen gets smaller
Resistance increases. Arterioles have maximum resistance ⟶ Called resistance vessels.
Constriction and dilatation of arterioles and small arteries ⟶ :
Controls local blood flow.
Helps control arterial blood pressure.
Capillaries
Large in numbers ⟶ Total cross-section area is very large ⟶ blood flow is slow.
Wall is only one cell thin.
Slow blood flow and one cell thin wall provide a favorable situation for the exchange of diffusible substances.
Venous System
Includes venules, veins, and vena cava in this order.
As we go from capillaries to vena cava, the diameter increases.
Hold a large quantity of blood ⟶ called capacitance vessels.
Systemic vs Pulmonary Division
System Circulation
Also called greater circulation.
From left ventricle to right atrium.
Oxygenated blood is supplied to the tissues through arteries.
Deoxygenated blood returns to the heart through veins.
Pulmonary Circulation
Also called lesser circulation.
From right ventricle to left atrium.
Deoxygenated blood goes to lungs through arteries.
Blood gets oxygenated in the lungs.
Oxygenated blood returns to the heart through veins.
Functions
Supply nutrients and remove waste products from peripheral tissues.
Regulation of body temperature.
Fluid balance.
Adjustment of oxygen and nutrient supply.