Chapter – 14
Breathing And Exchaneg Of Glass
Question 1. It is known that exposure to carbon monoxide is harmful to animals becauseIt destroys haemoglobin
.It reduces CO2 transport.
It increases O2 transport.
It increases CO2 transport.
Answer
1: The correct option is BEx planation of the correct option:Carbon monoxide destroys haemoglobin.
Carbon monoxide is known to combine more readily with haemoglobin than with oxygen.It forms the stable compound carboxyhemoglobin.
Thus, fewer molecules of free haemoglobin become available for oxygen transport.
Question 2. Define vital capacity. What is its significance?
Answer
Vital capacity is the maximum volume of air that can be exhaled after a maximum inspiration. It is around 3.5 – 4.5 litres in the human body. It allows the intake of maximum fresh air and removes the foul air within a single stroke of respiration. Hence, it causes an increase in gaseous exchange between the various tissues of the body, which leads to increased energy available for body functioning.
Question 3. Write a note on the mechanism of breathing.
Answer
The breathing process is carried out through different respiratory organs such as the nose, pharynx, larynx, trachea, bronchi, and lungs. The action of breathing in and out is because of the pressure changes within the thorax compared to the pressure in the outside environment. This action is also called external respiration. When we inhale, our diaphragm muscles contract downward, and rib muscles pull upward. This action causes an increase in the thoracic cavity. The pulmonary volume of the lungs also increases. Due to the increase in the size of the thoracic cavity, the internal air pressure decreases. As a result, air from the outside rushes into the lungs to equalise the pressures on both sides. This is known as inspiration.While exhaling, the diaphragm and intercostal muscles relax and return to their resting positions. The diaphragm regains its dome shape. Due to this relaxation, the size of the thoracic cavity reduces. This reduction increases the pressure in the lungs, and the air is pushed from the lungs to the outside through the nose. This is called expiration. Inspiration and expiration are the two main mechanisms of breathing
Question 4. What are the major transport mechanisms for CO2? Explain.
Answer
Carbon dioxide is said to be liberated by a vigorously active tissue in the blood. On average, 100ml of blood accepts approximately 3.7ml of carbon dioxide from tissues. In blood, CO2 is carried in three forms:Carbon dioxide as a simple solution:Nearly 5-10% of carbon dioxide in the total volume of blood is dissolved in plasma. Carbon dioxide is transported as a simple physical solution.Carbon dioxide as a bicarbonate ion:The partial pressure of carbon dioxide at the tissue site is high due to catabolism. Carbon dioxide diffuses in the blood and forms carbonic acid after reacting with water. This reaction occurs in the presence of the carbonic anhydrase enzyme. The reaction is as follows:
Question 5. The incidence of emphysema, a respiratory disorder, is high in cigarette smokers.
In such cases:the bronchioles are found damaged.
the alveolar walls are found damaged.
the plasma membrane is found damaged.
the respiratory muscles are found damaged.
Answer:
The correct option is BEx planation of the correct option:Emphysema is a chronic disorder. The alveolar walls are damaged in emphysema due to infection or abnormal dispersion.
It is a respiratory disorder caused primarily by cigarette smoking. It can also be caused by inhalation of other smoke or toxic substances over a while.
Explanation of the incorrect option:Options A, C and D did not satisfy the appropriate explanation of the given question.
Question 6. What happens to the respiratory process in someone going uphill?
Answer
When a man goes uphill, the altitude keeps increasing. As there is an increase in altitude, the oxygen level in the atmosphere decreases. Therefore, as a man goes uphill, he gets less oxygen with each breath. This uphill movement causes the amount of oxygen in the blood to decline—the respiratory rate increases in response to the decrease in blood oxygen content. Simultaneously, the heartbeat rate increases the supply of oxygen to the blood.
Question 7. What is the role of the neural system in controlling respiration?
Answer
The neural system plays an important role in regulating respiration. The neural system helps maintain and moderate the respiratory rhythm as per the demands of the body tissues. Regulation of respiration depends on various intrinsic and extrinsic factors. The respiratory rhythm centre is located in the medulla region. This is a specialised centre and is primarily responsible for the regulation of respiration. The pneumatic centre is located in the pons region of the brain. It can moderate the functions of the respiratory rhythm centre. Nerve signals from the pneumatic centre can reduce the duration of inspiration and can thus alter the respiratory rate. A chemosensitive section adjacent to the rhythm centre is very sensitive to hydrogen ions and CO2, which activates this centre by increasing these substances. Then, the chemosensitive area can signal the rhythm centre to make necessary adjustments to eliminate these substances. There are receptors associated with the aortic arch and carotid artery. These receptors can also recognise changes in CO2 and H+ concentration. After that, they send necessary signals to the rhythm centre to take corrective actions. The presence of oxygen is quite insignificant in regulating the respiratory rhythm centre.
Question 8. Explain the transport of O2 and CO2 between alveoli and tissue with a diagram.
Answer
Exchange of gases between alveoli and tissues:The primary site for the process of exchange between gases is alveoli. The exchange of gases between alveoli and tissue takes place through simple diffusion, which depends upon the following factors:A partial pressure gradient of gases across alveoli and tissues Solubility of the gases Diffusion membrane Diffusion of O2 across alveo The partial pressure of O2 is higher in the alveoli, i.e., 104 mmHg, compared to the deoxygenated blood (40 mHg). Therefore, O2 diffuses into the blood through the diffusion membrane. Transport of O2 to various body parts: O2 is transported by blood in the following ways:Transport via RBCs (in the form of oxyhaemoglobin): About 97% of O2.Transport via plasma (in the dissolved state): Remaining 3% of oxygen-rich blood reaches the left atrium from the lungs via the pulmonary veins. The left ventricle is carried by the systemic arteries, reaching the body tissues.Diffusion of O2 across tissue pO2 is more in the oxygenated blood (95 mmHg) than in the tissues (40 mmHg). Hence, O2 diffuses into the tissues from the blood