Lesson 4- Lung histology

What is the trachea

Incomplete rings of cartilage prevent trachea from collapsing and keeps it open. Lined with ciliated epithelium with goblet cells.

What is hyaline cartilage

C shaped rings in walls of trachea and bronchi, C shaped so can open out and allow food to pass down oesophagus. Prevents breathing tubes from collapsing

What is smooth muscle and its function

• It is found in wall of trachea and bronchi

• When smooth muscle contracts it narrows lumen of airways reducing airflow, important if harmful chemicals enter but can over constrict during asthma or allergic attack

• When they relax airways widen increasing airflow

What are elastic fibres and their function

• They are elastic tissue made of elastin

• In the alveoli they stretch as lungs fill with air and recoil during exhalation to push air out helping ventilation

• In the arteries they allow the walls to stretch as blood is pumped out of heart and recoil to help maintain high pressure

What are Goblet/ glandular tissue

• Found between ciliated cells. Secrete mucus ( a glycoprotein). Mucus traps bacteria and particles to prevent blocking alveoli and infection

• Found in trachea and bronchi

What is ciliated epithelium

Cilia ‘beat’ rhythmically in coordinated waves, moving mucus upwards and out of the airways to back of the throat. Mucus swallowed into stomach HCL, or coughed/sneezed out.

Order of tissue in bronchiole

-Smooth muscle

-Ciliated epithelium

-Loose tissue with elastic fibres

-Goblet cells

-Blood vessel

Lung microscope image