Question

39. Oxygen diffuses from lungs to blood and carbon dioxide diffuses from blood to lungs 

a) pulmonary ventilation b) external respiration c) transport d) internal respiration 

40. Which of the ekg waves represents ventricular depolarization (contraction) 

a) QRS complex b) P wave c) T wave d) S wave 

41. Which of the ekg waves represents ventricular repolarization (recharging) 

a) QRS complex b) P wave c)T wave d) S wave

Answer 1

39. External respiration or pulmonary gas exchange is the process of diffusion of oxygen in the lungs and diffusion of carbon dioxide in the alveolar air. It occurs in the lungs. Internal respiration takes place in the tissues. Here, oxygen diffuses from the lungs to metabolizing tissues and carbon dioxide diffuses out of the tissues.

The flow of oxygen from lungs to blood and flow of carbon dioxide from blood to lungs will be external respiration. It is the gas exchange across the alveolar membrane in the lungs. This gas exchange occurs by diffusion from a region of high concentration to a region of low concentration. Oxygen concentration is higher in lungs than blood and carbon dioxide concentration is higher in the blood than lungs.

Pulmonary ventilation is the process of breathing wherein air flows in and out of the lungs. Inhalation is the movement of air (gases) into the lungs while exhalation is the movement of air (gases) out of the lungs. The alveolar pressure of the lungs should be lower than the atmospheric pressure to cause inhalation. Reversely, the alveolar pressure should be higher than atmospheric pressure to cause exhalation. These pressure gradients are created by pulmonary ventilation. Oxygen transport is the movement of oxygen from the lungs to peripheral tissues by haemoglobin. Carbon dioxide transport is movement of carbon dioxide from peripheral tissues to the lungs.

Hence, right choice is b. External respiration.

40. Electrocardiography or ECG or EKG is the process by which electrical activities of heart are recorded. The waves of EKG represent the atrial and ventricular depolarization and repolarization. The P wave follows the QRS complex and the T wave. The P wave is associated with atrial depolarization and is the first wave. The QRS complex indicates depolarization of the ventricles. The QRS complex indicates the ventricular depolarization or contraction. It has three waves: Q-wave: Indicates the depolarization of the ventricular septum. The R-wave: indicates the ventricle activation while the S-wave indicates the end stage of ventricular depolarization. Ventricular repolarization is represented by the T wave, observed as a small wave after the QRS complex.

Right choice is the a) QRS complex.

41. ECG indentifies the electrical activities of the heart. There are three waves: The P wave, QRS complex and the T wave. The QRS complex has three waves- Q, R, and S waves. The waves identify the follows: The P wave- atrial depolarization, QRS complex- ventricular depolarization, (and atrial repolarization), T wave- ventricular repolarization.

The T wave identifies the repolarization of the ventricles. This repolarization allows the ventricles to recharge for the next impulse.

Right choice is the c) T wave.