Lungs and heart

• The main organ of the respiratory system are the lungs.
• The respiratory system works to provide oxygen into the blood stream from the air that we inhale and releases carbon dioxide when we exhale.
• The trachea splits into tubes and extend into each lung through the bronchi
• the bronchi (bronchus) which distribute the air throughout the lungs until reaching the respiratory bronchioles
• The bronchioles, carry air to small sacs in your lungs called alveoli
• The alveoli(alveolus) perform your body's gas exchange.
• other term of alveoli is alveolar sacs
• The heart is a muscular organ that pumps blood containing oxygen and nutrients that the body needs.
• The 4 chambers of heart are

  Right atrium

  Right ventricle

  Left atrium

  Left ventricle
• The right atrium receives deoxygenated blood from the body and pumps it to the right ventricle.
• The right ventricle pumps the deoxygenated blood to the lungs.
• The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle.
• The left ventricle pumps the oxygen-rich blood to the body.
• The heart has 4 valves.

  Tricuspid valve

  Pulmonary valve

  Mitral valve

  Aortic valve
• The valves are like little doors which open one-way and prevent the backward flow of the blood.
• Veins carry blood to the heart.
• Arteries carry blood away from the heart.
• The superior and inferior vena cava are large veins that deliver deoxygenated blood to the heart.
• Systole is when the heart contracts and pumps blood.
• Diastole is when the heart relaxes and fills with blood