Human/mammal breathing system

• Label this diagram of the human breathing system

  A) larynx

  B) C-shaped cartilage

  C) trachea

  D) lung

  E) ribs

  F) bronchus

  G) bronchiole

  H) alveolus

  I) diaphragm

  J) intercostal muscles

  K) pleural cavity

  
• Why are the rings of cartilage surrounding the trachea C-shaped?

  Allows flexibility in shape

  • so the trachea can change shape with ventilation
  • and so it can accommodate change in shape of oesophagus when food moves down it
• Why is the trachea surrounded by rings of cartilage?

  To prevent collapse during pressure changes in ventilation
• Label this diagram with the types of cells

  A) goblet cell

  B) ciliated columnar epithelium

  
• How do the ciliated cells and the mucus in the trachea work together to defend the body against disease?

  Mucus traps pathogen/dust/dirt, and the ciliated cells move the mucus and trapped pathogen to the back of the throat to be swallowed
• What is the pleural cavity made from?

  2 pleural membranes:

  • Inner -> next to lung
  • Outer -> next to ribs
• What does pleural fluid in the pleural cavity do?

  Reduces friction between the lungs and ribs during breathing
• What is the gas exchange surface in mammals?

  Alveoli
• How are alveoli adapted for gas exchange?

  -large surface area: lots of small alveoli

  -short diffusion pathway: alveolar walls are 1 cell thick and flat (squamous epithelium), and capillary walls are also 1 cell thick

  -good blood supply: surrounded by lots of capillaries, maintains the concentration gradient

  -they are moist so that gases can dissolve
• What are the alveoli coated in and why?

  Surfactant: this is a liquid that reduces surface tension and so prevents them collapsing
• How is the breathing system in mammals kept ventilated by negative pressure ventilation?

  -diaphragm contracts and flattens

  -the external intercostal muscles contract, pulling the ribs up and out

  -this increases the volume of the thorax, decreasing the pressure

  -air moves into the lungs from an area of high to low pressure
• What do the pleural membranes do during negative pressure ventilation?

  -when the ribs move up and out, this pulls the outer pleural membrane outwards

  -the outer membrane pulls the inner membrane outwards

  -the inner membrane pulls the lungs out, causing the alveoli to expand
• What is the function of the intercostal muscles?

  When they contract, they raise the rib cage in ventilation
• How does negative pressure ventilation in mammals work?

  Ventilation movements bring oxygenated air to the lungs and remove carbon dioxide rich air from the lungs.

  This maintains a concentration gradient between the blood and alveoli
• How does ventilation work during inspiration (breathing in)?

  -intercostal muscles contract, pulling the rib cage up and out

  -diaphragm contracts, pulling the diaphragm down and flattening it

  -the external pleural membrane is pulled out

  -pressure decreases in the pleural cavity

  -the inner pleural membrane moves out, pulling on the lungs and expanding the alveoli

  -volume of the lungs increases, and pressure decreases

  -alveolar pressure falls below that of the atmosphere and air flows in through the trachea and passes into the alveoli
• Briefly describe and explain the process of inspiration in a mammal.?


  • intercostal muscles contract
  • ribs move up and out
  • diaphragm contracts and flattens
  • volume of thorax increases
  • pressure in lungs/thorax decreases
  • pressure in the lungs is higher than pressure of outside, so air is forced into the lungs and the alveoli