Take The Quiz To Know About Structure and function of the alveoli

Explanation
The tiny sacs of air present in the human lungs are known as alveoli. These small structures are responsible for the exchange of oxygen and carbon dioxide between the lungs and the bloodstream. They have thin walls and a large surface area, allowing for efficient gas exchange. Bronchus and bronchioles are parts of the respiratory system, but they do not refer specifically to the sacs of air in the lungs. Therefore, the correct answer is alveoli.

Explanation
The bronchi enter the lungs at the hilus. The hilus is a depression on the medial surface of each lung where the bronchi, blood vessels, lymphatic vessels, and nerves enter and exit the lungs. It is the point of entry and exit for various structures that are essential for the functioning of the lungs.

Explanation
Type II pneumocytes are the cells responsible for producing surfactants in the lungs. Surfactants are essential for reducing surface tension in the alveoli, preventing their collapse and maintaining their shape. Type I pneumocytes, on the other hand, are involved in gas exchange. Macrophages are immune cells that remove debris and pathogens, while bronchioles are small air passages in the lungs.

Explanation
The correct answer is Mediastinum. The mediastinum is located between the two pleural sacs and is considered the central compartment of the thoracic cavity. It contains various structures such as the heart, major blood vessels, esophagus, trachea, thymus, and lymph nodes. It plays a crucial role in providing support and protection to these structures within the thoracic cavity.

Explanation
Alveoli are tiny air sacs in the lungs responsible for gas exchange. Epithelial cells line the alveoli and play a crucial role in this process. They are thin and flat, allowing for efficient diffusion of oxygen and carbon dioxide between the lungs and bloodstream. Epithelial cells also produce a surfactant that helps prevent the alveoli from collapsing. Muscle cells, connective cells, and nervous cells are not present in the alveoli and do not have a direct role in gas exchange.

Explanation
Human lungs contain approximately 300 million alveoli. Alveoli are tiny air sacs located at the end of the bronchioles in the lungs, and they are responsible for the exchange of oxygen and carbon dioxide between the lungs and the bloodstream. The large number of alveoli allows for a large surface area, maximizing the efficiency of gas exchange.

Explanation
All of the options listed, namely pneumonia, tuberculosis, and emphysema, are considered alveolar lung diseases. Pneumonia is an infection that causes inflammation in the alveoli, the tiny air sacs in the lungs. Tuberculosis is a bacterial infection that primarily affects the lungs, causing inflammation and damage to the alveoli. Emphysema is a chronic lung condition where the alveoli become damaged and lose their elasticity, leading to difficulty in breathing. Therefore, all of these conditions fall under the category of alveolar lung diseases.

Explanation
Cilia are small, hair-like structures that line the respiratory tract. They work by constantly beating in a coordinated manner to move mucus and trapped particles away from the lungs towards the throat, where they can be coughed out or swallowed. This helps to keep the airways clear and prevent the accumulation of mucus and dirt in the lungs, thus aiding in the proper functioning of the respiratory system.

Explanation
Total lung capacity refers to the maximum volume of air that can be contained in the lungs after a full forced inhalation. It represents the sum of all the lung volumes, including tidal volume, inspiratory reserve volume, and expiratory reserve volume. This measurement is important in assessing lung function and can be used to diagnose respiratory conditions such as chronic obstructive pulmonary disease (COPD) or restrictive lung diseases.

Explanation
Mycobacterium tuberculosis is the correct answer because it is the specific microorganism that causes tuberculosis. Bacillus anthracis causes anthrax, Vibrio cholerae causes cholera, and Bacillus thuringiensis is a common soil bacterium used as a biological pesticide.