Epithelial tissue

What is epithelial tissue?

  • lines any surface in contact with the external environment

  • could line the outer surface of internal organs and blood vessels

Types of epithelial tissue in the lungs

  • columnar epithelium- tall and rectangular

  • squamous epithelium- flattened

Goblet cells (columnar epithelial)

  • found in the trachea and the bronchi

  • contain a plentiful supply of mitochondria

  • cilia beat dust/ debris continuously in the opposite direction of incoming air back towards the mouth away from the lungs

  • produce mucus- traps dust, debris and pathogens to prevent them from entering further towards the lungs

  • walls are reinforced with c-shaped hyaline cartilage- helps to keep airway open

Alveoli (squamous epithelial)

  • flattened and one cell thick

  • contain an egg-shaped nuclei

  • large surface area

  • short diffusion pathway

Importance of being one cell thick

  • maintains high concentration gradient

  • prevents collapsing of alveoli

  • short diffusion pathway- allows rapid diffusion of O2 into the lungs and blood

  • large surface area

Chronic Obstructive Pulmonary Disease (COPD)

  • combined diseases- asthma, emphysema and chronic bronchitis

  • caused by air pollution, dust, smoking and biomass exposure

Symptoms of COPD

  • excessive & chronic coughing

  • limited airflow

  • bronchiole airway inflammation

  • smooth muscle constriction

  • shortness of breath

  • wheezing

  • chest tightness

Effects of COPD on the body

  • aveoli can break open- causing them to merge together and decrease the surface area, making gas exchange less effective and decreasing the amount of oxygen the body receives due to getting stuck

  • goblet cells increase mucus- causes cilia to struggle and mucus moves towards the lungs & alveoli

  • less mitochondria due to smoking- less atp for cilia to beat away debris