cigarettes has many impacts on the respiratory system. Describe the normal histo

Question

cigarettes has many impacts on the respiratory system. Describe the normal histology and functions of the conducting portion and respiratory portions and then describe the changes in structure and function that may result from smoking leading to smoker's symptoms. (12) Type of epithelial tissue lining Functions Nose/mouth pharynx larynx Trachea main-primary bronchi lobar bronchi-secondary bronchi- segmental bronchi = tertiary bronchi- interlobular bronchi Branching bronchioles of various sizes terminal bronchioles Alveoli Relate the major histological changes between normal and smoker's respiratory zone

Explanation / Answer

Normal histology and functions of the conducting portions and respiratory portions:

1. Nose/ mouth _pharynx_larynx:

Type of tissue lining : pseudo stratified ciliated columnar epithelium

Function: the cilliated epithelium helps in moving the secretions and foreign particles to move out of the body ( as a protective mechanism) in the form of sneezing, coughing,etc.

2. Trachea to interlobular bronchi:

Type of epithelial tissue lining: pseudo stratified columnar epithelium

Function: they help to clear inhaled pathogens and allergens, help in mucus secretion and regulation and in expectoration without causing inflammation.

3.branching bronchioles of various sizes to terminal bronchioles:

Type of epithelial lining :

Simple ciliated columnar and simple ciliated cuboidal epithelium

Functions: they also help in clearing the airway by expectorating the foreign particles

4.respiratory bronchioles:

Type of epithelium lining: simple nonciliated cuboidal epithelium

Function: this epithelial lining helps in composition of surfactants and in detoxyfying the harmful substances.

5. Alveoli:

Type of epithelial lining: simple squamous epithelium

Functions : this epithelial lining is extremely thin and it facilitates gaseous exchange ( diffusion of oxygen and co2) and it also helps in regulation of surfactant.

After smoking:

In a non smoking individual the epithelial lining from nose to the alveoli helps in protecting the respiratory system by expectoration or detoxyfying the harmful substances.

In smokers, the harmful toxic substances partially paralyze the cilia and eventually reduce the mucocilliary movement and further they may undergo metaplasia. Due to this the foreign particles cannot be thrown out of the body by protective mechanism. In smokers the mucous production is increased but it cannot swept away and it gets accumulated, causes inflammation and leads to smoker's cough. Such patients are more prone to infections as the airway protective mechanism is not working properly.

The airway becomes narrow and airflow if reduced. And such patients experience shortness of breath. Due to the reduced surfactants gaseous exchange is also reduced.

Due to the long term smoking, the harmful chemicals can lead to normals cells to undergo neoplasia in which abnormal cells or cancerous cells can be produced which invades the surrounding area.

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