Respiratory system - Quiz

The spleen is an organ that only receives oxygenated blood. It is a small, fist-shaped organ located in the left upper quadrant of the abdomen. The spleen plays an important role in the immune system by filtering out old or damaged red blood cells and producing white blood cells to fight infection. The oxygenated blood supply to the spleen comes from the splenic artery, which branches off from the celiac artery, a major blood vessel that supplies blood to the abdominal organs. Options A and B are incorrect because both the lungs and gills are involved in the exchange of gases between the respiratory surface and the bloodstream, and thus receive both oxygenated and deoxygenated blood. Option C is incorrect because the liver receives both oxygenated and deoxygenated blood from the hepatic artery and hepatic portal vein, respectively.

The alveoli are the tiny air sacs in the lungs where gas exchange occurs between the air in the lungs and the blood. The alveolar epithelium is the thin layer of cells that makes up the walls of the alveoli. This epithelium is composed of nonciliated squamous cells, which are very thin and flat, allowing for efficient gas exchange. These cells are also very delicate and are susceptible to damage from various factors such as pollution and smoking. Damage to the alveolar epithelium can lead to various lung diseases, such as emphysema.

The pleura is a membrane that surrounds the lungs and lines the thoracic cavity. It is a double-layered membrane, consisting of an outer parietal layer and an inner visceral layer. The parietal pleura lines the inner surface of the thoracic cavity, while the visceral pleura covers the outer surface of the lungs. The two layers are separated by a thin layer of fluid called pleural fluid, which reduces friction and allows the lungs to expand and contract smoothly during breathing. Therefore, option C is the correct answer.

During normal expiration, the muscles involved in breathing, including the diaphragm and external intercostal muscles, relax without any active contraction. This relaxation results in the decrease of the thoracic cavity volume and the consequent expulsion of air from the lungs. As no muscle contraction occurs during normal expiration, it is considered a passive process. On the other hand, inspiration, forceful inspiration, and forceful expiration all require active muscle contractions, which require the expenditure of energy.

Inspiration is the process of breathing in air, and it occurs when the pressure in the lungs is lower than the atmospheric pressure. This is because the air flows from the region of high pressure (atmosphere) to the region of low pressure (lungs). Thus, a negative pressure gradient is needed to pull the air into the lungs during inspiration. The contraction of the diaphragm and external intercostal muscles increase the volume of the thoracic cavity, which in turn reduces the pressure within the lungs, allowing air to rush in. Therefore, the correct option is B.

In addition to the respiratory muscles such as diaphragm and external intercostal muscles, the abdominal muscles can help in increasing the strength of breathing. During forceful breathing, the abdominal muscles contract to help increase the intra-abdominal pressure, which in turn pushes the diaphragm upwards and helps in forceful expiration. This can be observed in activities such as coughing, sneezing, and laughing. Hence, option C is the correct answer.

The process of breathing involves inspiration and expiration. In normal conditions, inspiration takes about 2 seconds and expiration takes about 3 seconds. On average, an adult human breathes about 16 times in a minute. During inspiration, the diaphragm and external intercostal muscles contract to increase the volume of the thoracic cavity, which causes air to flow into the lungs. During expiration, the diaphragm and external intercostal muscles relax, which decreases the volume of the thoracic cavity and causes air to flow out of the lungs. Therefore, the correct option is A) Inspiration 2 sec and expiration 3 sec.

During normal inspiration, the diaphragm and external intercostal muscles contract, which increases the volume of the thoracic cavity. This expansion of the thoracic cavity causes the ribs to move outward and the sternum to move upward. However, the internal intercostal muscles are involved in forced expiration, not normal inspiration. These muscles contract during forced expiration to decrease the volume of the thoracic cavity and expel air from the lungs.

The concentration of oxygen in inspired air is 19.6% while the concentration of oxygen in expired air is 15.7%. Therefore, approximately 4% of the oxygen is transferred from air to the blood. Similarly, the concentration of carbon dioxide in inspired air is 0.04% and the concentration of carbon dioxide in expired air is 3.6%, so approximately 3.56% of the carbon dioxide is transferred from the blood to air.

The process of diffusion is affected by various factors including solubility of gases, thickness of the respiratory membrane, and partial pressure difference. However, molecular weight of gases does not affect diffusion as all gases diffuse from high partial pressure to low partial pressure irrespective of their molecular weight. Therefore, option D is the correct answer.