Heart Chambers and Blood Vessels

• The heart has four chambers: two atria (right and left) and two ventricles (right and left)

Heart Chambers

• The right atrium receives unoxygenated blood from the body via the superior and inferior vena cava and pumps it to the right ventricle
• The right ventricle receives blood from the right atrium and pumps it to the lungs for oxygenation via the pulmonary trunk and right and left pulmonary arteries
• The left atrium receives oxygenated blood from the lungs via the right and left pulmonary veins and pumps it to the left ventricle
• The left ventricle receives blood from the left atrium and pumps it to the aorta for distribution to the entire body

Blood Vessels

• Blood vessels conduct blood away from the heart

Arteries

• Arteries carry oxygenated blood except for the pulmonary artery.
• Arteries are usually deeply located in the body, pulsate strongly, and spurt blood when injured

Major Arteries

• The pulmonary artery brings blood from the right ventricle to the lungs for oxygenation
• The aorta transports blood from the left ventricle for distribution to arteries:
• The coronary artery brings blood to the heart
• The carotid artery brings blood to the head and neck
• The subclavian artery brings blood to the upper limb
• The bronchial artery brings oxygenated blood to the lung
• The posterior intercostal artery brings blood to the chest wall
• The celiac artery brings blood to the liver, gallbladder, spleen, and stomach
• The superior mesenteric artery brings blood to most of the small intestine and part of the large intestine
• The inferior mesenteric artery brings blood to most of the large intestine
• The iliac artery brings blood to the lower limb and internal organs of the pelvic cavity, such as the urinary bladder and uterus
• Arterioles are small arteries within the organs of the body
• Capillaries are the narrowest part of the blood vascular system, located within the tissues of the body for the exchange of oxygen and carbon dioxide.
• Venules are small veins within the organs of the body that receive blood from the capillaries
• Veins transport blood from the venules back to the heart and carry unoxygenated blood (except from the lungs to the left atrium); they are usually superficially located and blood flows smoothly when injured

Major Veins

• The superior vena cava transports blood from the heart, neck, upper limbs, and thorax to the right atrium
• The inferior vena cava transports blood from the abdomen, pelvic cavity, and lower limbs to the right atrium
• The coronary sinus returns blood from the heart tissue to the right atrium

Pulmonary Circulation

• Pulmonary circulation involves blood flow from the heart to the lungs and back to the heart:
• Blood from the body enters the superior and inferior vena cava and flows to the right atrium, then the right ventricle through the tricuspid valve
• Blood is pumped into the pulmonary artery to the lungs to release carbon dioxide and absorb oxygen, then it returns to the left atrium

Systemic Circulation

• Systemic circulation involves blood flow from the heart to all parts of the body and back to the heart:
• Oxygenated blood from the left atrium passes to the left ventricle and then to the aorta
• Blood is distributed through the coronary, carotid, and subclavian arteries to the heart, head, and arms/legs
• Blood distributes nutrients and oxygen to body tissues and collects CO2, eventually returning to the right atrium for pulmonary circulation