What is the primary function of alveoli in the lungs?

RRB Nsg. Superintendent-2026 (Shift -2nd)

Applied Physiology

Easy

Appeared in: RRB Nsg. Superintendent-2026 (Shift -2nd)

Explanation

The primary and essential function of the alveoli is to serve as the site for gas exchange in the lungs, a process known as external respiration.
Alveoli are tiny, thin-walled air sacs surrounded by a dense network of capillaries. This structure creates a large surface area and a very short diffusion path, maximizing the efficiency of gas transfer.
During gas exchange, oxygen from the inhaled air moves from the alveoli into the blood within the capillaries, while carbon dioxide moves from the blood into the alveoli to be exhaled.

Option A: Mucus production is the function of goblet cells, which are found in the lining of the larger airways (trachea and bronchi) to trap inhaled particles. Mucus in the alveoli would impair gas exchange.
Option B: Filtering the blood to remove waste products is the primary function of the kidneys. The lungs' role is gas exchange, not blood filtration.
Option C: The movement of the rib cage is controlled by the intercostal muscles, working in coordination with the diaphragm, to change the volume of the thoracic cavity during breathing.

Visual 1: Diagram - An illustration of a single alveolus with its surrounding capillary network. Arrows should clearly show oxygen (O₂) diffusing from the alveolus into a red blood cell and carbon dioxide (CO₂) diffusing from the capillary into the alveolus. This visualizes the core concept of gas exchange.
Visual 2: Flowchart - A simplified diagram of the respiratory tract, starting from the trachea, branching into bronchi, then bronchioles, and ending in the alveolar sacs. This helps to contextualize the location of the alveoli at the terminal end of the airways.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Function of Alveoli in the Respiratory System as background academic context rather than a clinical decision trigger.
Understanding alveolar function is fundamental for nurses managing patients with respiratory conditions like pneumonia, COPD, or Acute Respiratory Distress Syndrome (ARDS), where gas exchange is compromised.
Nurses monitor for signs of impaired gas exchange, such as low oxygen saturation (SpO₂), altered mental status, cyanosis, and shortness of breath, which directly reflect problems at the alveolar-capillary level.
What if? If a patient develops pulmonary edema, fluid fills the alveoli, increasing the diffusion distance for gases. This leads to severe hypoxemia. The nursing priority becomes supporting oxygenation (e.g., with positive pressure ventilation) and administering medications like diuretics to remove the excess fluid.

How to Approach the Question

First, identify the key term in the question: 'alveoli'.
This is a direct recall question testing your knowledge of basic respiratory anatomy and physiology.
Recall the primary purpose of the lungs and their functional units. The main job of the respiratory system is to get oxygen in and carbon dioxide out.
Evaluate each option against this primary purpose. 'Exchanging gases' directly describes this core function.
Systematically eliminate the other options by assigning their functions to the correct anatomical structures: mucus production (goblet cells), blood filtering (kidneys), and rib cage movement (intercostal muscles).

Concept Tested & Keywords

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