Question

Mammalian lungs have an enormous number of minute alveoli (air \(\mathrm{sacs}\) ). This is to allow (a) more surface area for diffusion of gases (b) more space for increasing the volume of inspired ar (c) more nerve supply to keep the lungs working (d) more spongy texture for keeping lung in proper thape.

Short answer

The enormous number of minute alveoli in mammalian lungs provides (a) more surface area for diffusion of gases, which is the primary purpose of alveoli for efficient gas exchange.

Step-by-step solution

Identify the Function of Alveoli

The primary function of alveoli is to facilitate gas exchange between the air and the blood. By providing a large surface area, they efficiently allow oxygen to be absorbed into the blood and carbon dioxide to be expelled from the blood into the exhaled air.

Exclude Incorrect Options

Options (b), (c), and (d) do not directly relate to the primary function of gas exchange in the alveoli. More space for increasing the volume of inspired air would be related to the overall size of the lungs, not the number of alveoli. Nerve supply is important for the control of respiration, but an increased number of alveoli does not necessarily mean more nerve supply. The spongy texture of the lungs assists in their expansion and elasticity, not directly in the gas exchange process.

Select the Correct Answer

Given that the primary function of alveoli is to provide surface area for gas exchange, the correct answer is the one that mentions this function. This leads us to conclude that the correct answer is option (a) more surface area for diffusion of gases.

Key concepts

Diffusion of Gases

Understanding how gases move in and out of our lungs is crucial to grasping the function of the alveoli. Diffusion of gases is a passive process by which molecules spread from areas of higher concentration to areas of lower concentration. In the human lungs, this means oxygen in the air we inhale diffuses through the alveolar walls into the blood where the concentration of oxygen is lower. Conversely, carbon dioxide, which is at a higher concentration in the blood, diffuses into the alveoli to be exhaled. It's the large surface area of the alveoli, as mentioned in the exercise, that facilitates this efficient gas transfer.

The wall of each alveolus and the adjacent capillary is very thin, allowing for a short diffusion path. Furthermore, both oxygen and carbon dioxide are soluble in the liquid lining the alveoli, which speeds up the exchange. This gas exchange process is vital for maintaining proper blood pH, cellular respiration, and overall metabolic processes within the body.

Mammalian Respiratory System

Diving deeper into the mammalian respiratory system, we find it to be a complex network designed specifically for efficient gas exchange. Starting from the nasal cavity, where the air is warmed and moistened, all the way down to the tiny alveoli in the lungs, each part plays a significant role. The system includes structures such as the trachea, bronchi, and bronchioles, which act as conduits directing the air to the alveoli.

It's important to note that the respiratory system works in conjunction with the circulatory system to ensure that oxygen reaches every cell and carbon dioxide is removed. The lungs themselves are not just spongy bags of air but are meticulously structured to maximize the area for diffusion and optimize the exchange process. Hence, while the lungs do increase in volume when we inhale, as stated in option (b), it's the alveoli's surface area increase that is directly correlating to their primary function.

Gas Exchange in Lungs

When it comes to gas exchange in the lungs, each alveolus is a hub of activity. The gas exchange occurs where the alveoli and the capillaries meet. Oxygen and carbon dioxide are exchanged across their membranes via diffusion, as the exercise suggested.

The efficiency of this exchange is not just due to the number of alveoli but also their design and the surrounding structure. High vascularity, meaning many capillaries surround each alveolus, ensures that blood passes by these air sacs continually, allowing for an unceasing exchange of gases. Furthermore, the partial pressure gradient between the alveolar air and blood drives the diffusion process. This matching of ventilation (air flow) and perfusion (blood flow) is another example of the delicate balance maintained in the respiratory system.