Breathing and Exchange of Gases Test 59

Emphysema is another chronic obstructive pulmonary disease. As in this condition, the inner walls of the air sac get ruptured creating larger air space. This reduces the surface area of the lungs and thus, reduces the amount of oxygen to reach the bloodstream. Patients initially experience bouts of breathlessness and coughing, and their ability to be active becomes very limited. Eventually, the alveoli become permanently damaged, and whole regions of the lung are unable to be engaged in the gas exchange with the blood. The most common cause of emphysema is cigarette smoking (80-90% of emphysema cases) and pollution. Thus, the correct answer is option A.

Total lung capacity (TLC) is the maximum amount of air the lungs can hold when they are fully inflated. The average total lung capacity of an adult human male is about 6 litres of air. It can be calculated by using the formula TLC = TV + IRV + ERV + RV where TV is tidal volume(500 ml), IRV is inspiratory reserve volume(3100 ml), ERV is expiratory reserve volume (1200 ml) and RV (1200  ml) stands for residual volume.

Most of the oxygen is transported bound to haemoglobin as oxyhemoglobin. The diffusion of gases depends on the partial pressure differences of the gases between two surfaces. In tissues, the partial pressure (tension) of oxygen is low as compared to the oxygenated blood. Hence, in tissues oxygen is liberated from oxyhemoglobin.

Pleurisy is a condition in which the layer covering the lungs, called the pleura, becomes inflamed. It is sometimes called pleuritis.

A specialized centre present in the medulla region of the brain called respiratory rhythm centre that primarily regulates the respiration. Another centre present in the pons region of the brain called pneumotaxic centre that moderates the functions of the respiratory rhythm centre. The neural signal from this centre can reduce the duration of inspiration and thereby alter the respiratory rate. Thus, the correct answer is option B.

The rima glottidis is the opening between the true vocal cords and the arytenoid cartilages. It is subdivided into two parts: that between the arytenoid cartilages is called the intercartilaginous part and that between the vocal folds the intramembranous part or glottis vocalis. It is closed by the lateral cricoarytenoid and arytenoid muscles.

The elevated carbon dioxide level in the blood stimulates the respiratory centre that responds to in order to signal the respiratory muscles to breathe. Chemoreceptors found in carotid bodies and aortic bodies are responsible for detecting the decrease in blood pH by carbon dioxide.

The respiratory system in human beings primarily works to obtain oxygen for the body cells and eliminate the carbon dioxide produced by them. Since the process of respiration results in the exchange of Oxygen and carbon dioxide with the body and environment, 98.5% of all oxygen carried in the blood is bound to hemoglobin and 1.5 % is dissolved in plasma.  However, the carbon dioxide which is transported from the body cells to the lungs are carried as bicarbonate -60%, carbaminohaemoglobin-30% and 10% is dissolved in plasma.

House fly has sponge-like organs called the labella. The labella is a complex structure having many grooves. These grooves are called pseudotrachea. This takes up liquids like sponges. Salivary secretions from the labella help to dissolve and collect food particles so that they may be more easily taken up by the pseudotrachea. The liquid food is then drawn up through the food channel into the esophagus. The labrum is located between the maxillary palps.

The amount of oxygen bound to the haemoglobin is related to the partial pressure of oxygen to which the haemoglobin is exposed. In the lungs, at the alveolar-capillary interface, the partial pressure of oxygen is typically high, and therefore the oxygen binds readily to haemoglobin that is present. As the blood circulates to other body tissue in which the partial pressure of oxygen is less, the haemoglobin releases the oxygen into the tissue because the haemoglobin cannot maintain its full bound capacity of oxygen in the presence of lower oxygen partial pressures. The effectiveness of haemoglobin-oxygen binding can be affected by several factors. The standard curve is shifted to the right by an increase in temperature, 2,3-DPG, or $$PCO_2$$, or a decrease in pH. The curve is shifted to the left by the opposite of these conditions. A rightward shift causes a decrease in the affinity of haemoglobin for oxygen. This makes it easier for the haemoglobin to release bound oxygen. Conversely, a leftward shift increases the affinity, making the oxygen easier for the haemoglobin to pick up but harder to release.