1.1 Respiratory and Circulatory Systems working

• The air we breathe goes through the nose, nasal passages, and then through the trachea or windpipe, which separates into two branches, called bronchial tubes or bronchi, one entering each lung
• The bronchi subdivide many times inside the lungs

  1. Analogous to the branching pattern of grapes

  2. Finally becoming hair-like tubes called bronchioles

  3. In the last part of the terminal bronchioles are tiny bubble-like bunch of structures called alveoli or air sacs
• The human breathing system is a fascinating creation that can carry out incredible tasks and activities
• The human body is composed of different systems, which are collections of cells, tissues, and organs, each of which has a special job that keeps you alive
• The respiratory and circulatory systems work together to transport oxygen-rich blood and nutrients to the different parts of the body
• The respiratory system is made up of the organs in the body that help us to breathe
• Breathing in and out is always linked to respiration
• The circulatory system is responsible for distributing materials throughout the body
• Circulation means transportation or movement in circles
• The respiratory and circulatory systems are essentially meant for each other, their common purpose could not be attained without the other system
• The respiratory system helps us to breathe
• The circulatory system transports nutrients, gases, and other molecules to and from the body
• The lungs supply the oxygen through the blood that passes to the heart while the heart pumps oxygenated blood throughout the body and pumps back deoxygenated blood towards the lungs for oxygenation
• The air molecules are compressed in the lungs when we inhale, and they expand when we exhale
• Air flow in the respiratory system

  1. Air enters through nose, nasal passages

  2. Through trachea

  3. Divides into bronchial tubes/bronchi

  4. Bronchi subdivide into bronchioles

  5. Bronchioles end in alveoli/air sacs
• Breathing mechanism


  1. Diaphragm muscle contracts during inhalation

  2. Diaphragm muscle relaxes during exhalation
• Blood flow in the circulatory system

  1. Air enters lungs

  2. Into left side of heart

  3. Pumped by heart into bloodstream

  4. Oxygen processes nutrients in cells

  5. Carbon dioxide delivered to right side of heart

  6. Pumped to lungs

  7. Carbon dioxide exhaled
• Heart


  Hollow muscular organ about the size of a fist, located between the lungs, a double pump with left and right sides
• Heart chambers


  • Atrium (top)
  • Ventricle (bottom)
• Heart valves


  • Act as one-way doors allowing blood to flow forward into next chamber or out of heart
• The circulatory system distributes nutrients, oxygen and other materials throughout the body
• If the heart fails to pump blood properly, it can have negative effects on the body
• One-way door


  Allowing blood to flow either forward into the next chamber, or out of the heart
• The blood delivers carbon dioxide into the right portion of your heart, from which it is pumped to the lungs. Carbon dioxide leaves your body through the lungs when you exhale.
• Heart


  • Hollow muscular organ, about the size of your fist, located in the center of your chest between the lungs
  • Double pump that pumps on the left and the right sides
  • Each side is divided across into two chambers
  • Top chamber is called the atrium
  • Bottom chamber is called the ventricle
• Valve


  Acts as one-way door, allowing blood to flow either forward into the next chamber, or out of the heart
• The key parts of the human breathing system are the trachea, bronchi, bronchioles, alveoli.
• The movement of oxygen in the human breathing system starts from the nose, nasal passages, trachea, bronchi, bronchioles, and alveoli.
• Circulatory and respiratory systems work together to circulate blood and oxygen throughout the body.
• The chambers of the heart are the atria and the ventricles. Atria are the receiving chambers of the heart while ventricles are the pumping chambers of the heart.
• The main function of the heart is to pump blood.
• If your heart fails to pump blood properly, blood often backs up and causes fluid to build up in your lungs and in your legs, causing your legs to swell and turn blue from lack of oxygenated blood flow.