Reparatory System (1) Learning Objectives

What are the 5 major functions of the respiratory system?

1. Air passageway

2. Gas exchange

3. Odor detection

4. Sound production

5. pH regulation

What happens during gas exchange?

O₂ moves from the alveoli → blood, while CO₂ moves from the blood → alveoli.

How does breathing help regulate blood pH?

Breathing changes CO₂ levels, which affects blood pH.

What is included in the upper respiratory tract?

Nose, nasal cavity, pharynx, and larynx.

What is included in the lower respiratory tract?

Trachea, bronchi, bronchioles, alveolar ducts, and alveoli.

What does the conducting zone do?

It transports/ conducts air.

What does the respiratory zone do?

It participates in gas exchange with the blood.

What happens to the epithelium as you move toward the alveoli?

It becomes progressively thinner.

What do goblet cells produce?

Mucin and a protective mucus layer.

What does mucus do?

It traps dust, particles, and microorganisms.

What do cilia do?

They move mucus and trapped debris toward the pharynx so it can be swallowed or expelled.

What happens when smoking damages cilia?

Mucus builds up, chronic coughing can occur, and infection risk increases.

What keeps the trachea open?

C-shaped hyaline cartilage rings

What is the bronchial tree pathway?

Trachea → primary bronchi → lobar bronchi → segmental bronchi → bronchioles

Do bronchioles have cartilage?

No

What controls the diameter of bronchioles?

Smooth mucle

What is the last part of the conducting zone?

Terminal bronchioles.

What is the first part of the respiratory zone?

Respiratory bronchioles

What is the respiratory zone pathway?

Respiratory bronchioles → alveolar ducts → alveolar sacs → alveoli.

What happens during bronchoconstriction?

Smooth muscle contracts → airway gets narrower → resistance increases → airflow decreases.

What happens during bronchodilation?

Smooth muscle relaxes → airway gets wider → resistance decreases → airflow increases.

What happens during asthma?

Airway inflammation and bronchoconstriction cause narrowed airways and decreased airflow. The narrowing is generally reversible.

What is COPD?

A chronic, progressive condition that causes airflow limitation.

What is chronic bronchitis?

Inflammation + excess mucus → narrowed airways.

What is emphysema?

Destruction of alveolar walls → decreased gas-exchange surface area.

Is COPD reversible?

No.

What are alveoli surrounded by?

A dense network of pulmonary capillaries.

What is the main job of Type I alveolar cells?

Gas exchange. They are thin and cover about 95% of the alveolar surface.

What do Type II alveolar cells produce?

Pulmonary surfactant.

What does surfactant do?

Reduces surface tension and helps prevent alveoli from collapsing.

What do elastic fibers do?

Allow the lungs to stretch during inspiration and recoil during expiration.

What are alveolar pores?

Small openings between alveoli that allow air to circulate between them.

What are alveolar macrophages?

Cells that patrol the alveolar surface and eat particles and microorganisms.

Why are macrophages important in the alveoli?

Alveoli do not have cilia, so macrophages help remove particles and microorganisms that reach the alveoli.