Respiration and Gas Exchange

A cough can expel air at speeds up to 60 mph (approximately 96 km/h). The force of a cough is generated by the diaphragm and respiratory muscles suddenly contracting to expel irritants. This high velocity helps clear the airways effectively.

Passive smoking refers to involuntary inhalation of tobacco smoke by non-smokers who are exposed to smoke exhaled by smokers or released from burning tobacco products. It is also called secondhand smoke and poses serious health risks similar to active smoking. Active smoking is voluntary smoking by the smoker themselves.

During smoking, nicotine and other active substances are absorbed through the alveoli in the lungs, which have a massive surface area for gas exchange. From the lungs, these substances rapidly enter the bloodstream and reach the brain within seconds. The lungs are the primary absorption site, not the heart, pancreas, or liver.

The left lung is smaller than the right lung because the heart is located on the left side of the chest cavity and occupies space that would otherwise be taken by lung tissue. The left lung has only two lobes while the right lung has three lobes. The right lung is larger and shorter to accommodate the liver underneath the diaphragm.

Amphibians like frogs can breathe through both their lungs and their skin. Their skin is highly vascularized and stays moist, allowing direct gas exchange with the environment (cutaneous respiration), which is especially useful when underwater.

Insects have a tracheal respiratory system where air enters through external openings called spiracles located along the sides of their body. These spiracles connect to a network of tracheal tubes that deliver oxygen directly to tissues. Birds use lungs, fish use gills, and frogs use a combination of lungs and skin.

The lungs never completely empty. Even after maximum exhalation, about 1 liter of residual air remains (residual volume). Each breath only exchanges a portion of the lung's air capacity, which is why we need multiple breaths to affect air quality changes. The answer is correctly False.

With each breath, only about 10-15% of the air in the lungs is exchanged with fresh air. The lungs contain residual volume that never gets completely replaced. This is why breathing techniques work and why we can hold our breath - the lungs don't empty completely.

The lungs are situated in the thoracic cavity, which is the chamber of the body located above the diaphragm. The thoracic cavity is bounded by the rib cage and contains the lungs, heart, and other organs. The abdominal cavity contains digestive organs, pericardial cavity surrounds the heart, and buccal cavity is the mouth cavity.

Hiccups are involuntary contractions of the diaphragm - the large muscle separating your chest cavity from your abdominal cavity that helps you breathe. The spasm causes a sudden intake of breath followed by quick closure of the vocal cords, creating the 'hic' sound.

Coughs can expel air at very high speeds, with 60 mph being the maximum recorded velocity. This is why coughs can propel droplets significant distances.

Pneumonia is an inflammatory condition of the lung primarily affecting the alveoli. It causes the air sacs to fill with fluid or pus. The lungs (option C) are the correct answer - liver, spine, and abdomen are not affected in pneumonia.

Tuberculosis (TB) most commonly affects the lungs (pulmonary TB), but the bacteria can spread to other organs including the intestines (extra-pulmonary TB). Option B correctly identifies that TB can affect both lungs and intestines, though pulmonary TB is more common.

Hyperventilation is the condition of excessive breathing rate and depth, leading to reduced carbon dioxide levels in blood. This causes tingling, dizziness, and potential fainting. Hypoxia (A) is insufficient oxygen, aerosinusitis (B) is sinus inflammation, and aerotitis (D) is ear inflammation - all different conditions.