Problem 25 - Objective Biology for NEET

Question

The part starting with the external nostrils up to the terminal bronchioles constitute the (a) Respiratory part of respiratory system (b) Exchange part of respiratory system (c) Expiratory part (d) Conducting part of respiratory system

Step-by-Step Solution

Answer

The part of the respiratory system described in the problem is the (d) Conducting part of respiratory system.

Step 1: Identify the Given Part

Identify the part of the respiratory system mentioned in the problem. Here, it talks about the part stretching from the external nostrils to the terminal bronchioles.

Step 2: Understand the Function of the Given Part

Notice that this part of the system is primarily responsible for conducting air from outside the body into the lungs. It does not participate directly in gaseous exchange, but rather aids in carrying the air to the parts where actual gaseous exchange happens.

Step 3: Match the Function with the Options

Now it's time to match the function of the given part of the respiratory system with the correct option among the provided ones. Among the options, (d) Conducting part of respiratory system is the one that precisely describes this function.

Key Concepts

Conducting Part

The conducting part of the respiratory system plays a crucial role in enabling air to move into and out of the lungs. Its primary function is not to participate directly in gas exchange but to ensure that air reaches the lungs safely. This part includes several structures, including the nasal cavity, pharynx, larynx, trachea, bronchi, and terminal bronchioles.

These structures help in:

• Filtering: Removing debris and particles from the air.
• Humidifying: Adding moisture to the air.
• Warming: Adjusting the air's temperature to match the body's internal conditions.

By performing these functions, the conducting part prepares the air appropriately before it arrives at the parts of the respiratory system where gas exchange occurs.

External Nostrils

External nostrils, often known simply as nostrils, are the entry points into the human respiratory system. They serve as the initial passageway for incoming air. These passages are equipped with hairs and mucus membranes that function as a first line of defense against dust, pollen, and other particles.

The nostrils also contribute to:

• Smelling: Part of the olfactory system which aids in detecting odors.
• Conditioning the air: Enhancing the air's quality by warming and humidifying it.
• Providing a pathway: Channeling air into the nasal cavity and onward to the rest of the system.

Due to their critical role, keeping nostrils clear is important in maintaining an efficient respiratory process.

Terminal Bronchioles

Terminal bronchioles are the final passages in the conducting part of the respiratory system. They mark the transition from the conducting zone to the respiratory zone, where gaseous exchange begins. Terminal bronchioles lead into the respiratory bronchioles and eventually the alveolar ducts where the exchange of gases takes place.

Key characteristics of terminal bronchioles include:

• No gas exchange: Terminal bronchioles themselves do not participate in the exchange of gases.
• Smooth muscle walls: Allowing for dilation and constriction, helping control airflow.
• Branching: Extensively into numerous smaller pathways to maximize air distribution.

Understanding terminal bronchioles helps in grasping their pivotal role in transitioning air towards the regions involved in gas exchange.

Gaseous Exchange

Gaseous exchange is the core of respiratory function, occurring in the alveoli of the lungs. This process involves the transfer of oxygen from inhaled air to the blood and the removal of carbon dioxide from the blood to be exhaled.

Here’s how gaseous exchange works:

• Oxygen Diffusion: Oxygen from the air diffuses through the alveoli walls into the blood.
• Carbon Dioxide Diffusion: Carbon dioxide in the blood diffuses into the alveoli to be exhaled.
• Pressure Gradient: This exchange is driven by the difference in partial pressures of gases across the alveolar membrane.

This exchange is essential for maintaining blood pH and providing oxygen to organs and tissues throughout the body.