Tissues in the lungs

• which gas enters the blood at the lungs?

  oxygen
• which gas exits the blood at the lungs?

  carbon dioxide
• label the diagram

  A) nasal cavity

  B) pharynx

  C) larynx (voice box)

  D) mouth

  E) trachea

  F) lung (left)

  G) right bronchus

  H) right bronchiole

  I) alveoli

  J) diaphragm

  
• label diagram

  A) cavity of alveolus

  B) alveolar duct

  C) epithelial cell of alveoli

  D) moist alveolar surface

  E) blood plasma

  F) pulmonary capillary

  G) red blood cell compressed against capillary wall

  H) low carbon dioxide concentartion

  I) high oxygen concentration

  
• what is the diameter of an alveolus?

  200-300 um
• why do alveoli have a moist lining?

  • oxygen dissolves in the water before diffusing into the blood - carbon dioxide dissolves before evaporating into the air in the alveoli
• what is the purpose of surfactants?

  allows alveoli to remain inflated and prevents them collapsing during breathing
• what is the role of cartilage?

  • found in trachea, bronchi and bronchioles
  • is flexible to allow movement of head an neck
  • strong/tough to support airways and prevent collapse due to low pressure when breathing in
  • arranged in c-shapes to allow flexibility (open part of c is where oesophagus is found)
  • inside surface is smooth to reduce when air flows passed
• what is the role of smooth muscle?

  • surrounds trachea, bronchi and bronchioles
  • muscle can contract for long periods without fatigue
  • contractions are involuntary
  • contracts to constrict the airways, therefore reducing airflow into lungs - prevent dust etc, from getting into alveoli
• what is the role of elastic fibres?

  • found in lung tissue and around alveoli and airways
  • also help to return airways to original shape when smooth muscle relaxes
  • can stretch during inhalation (inspiration) which prevents alveoli bursting and during exhalation (expiration) they recoil therefore helping force air out of lungs - helps maintain bigger diffusion gradient
• what is the role of epithelial tissue?

  • contains goblet cells which produce and secrete mucus
  • mucus is stick so traps bacteria, pollen and dust
  • found in lining of trachea, bronchi and larger bronchioles (not in small bronchioles as mucus might block them)
  • cilia move in a synchronised pattern and waft the mucus up the airways to back of the throat
  • most mucus is swallowed and stomach acid kills bacteria
• what is the role of the nasal cavity in the functioning of the lungs?

  • to humidify and warm the inspired air - larger surface area with a good blood supply
  • removes some airborne particles and other debris before the air reaches lower airways - hairy lining which secretes mucus
  • mucus and hair prevents lungs from irritation and infection
• what is the importance of cartilage found in the trachea and bronchi?

  • supports them so that they don't collapse and keeps them open
• what are the two cells found in the epithelium of airways?

  • goblet cells - produce mucus
  • ciliated epithelium - waft mucus up
• what are the functions of macrophages?

  • type of phagocyte that destroys bacteria in the lungs
• what is the function and adaptions of smooth muscle?

  • contracts to constrict airways, reducing diameter of lumen
  • lots of mitochondria to produce lots of ATP from respiration