Question

Question 46 1 pts Blood flow to a capillary bed can be controlled by: O precapillary sphincter regulation of blood flow between arterioles and venules. the peptide endothelin, which causes arteriole vasoconstriction None of the choices listed can control blood flow to the capillary All of the choices listed can control blood flow to a capilary. contraction of arterioles leading to the capillary, D Question 47 1 pts During normal inhalation of air in humans: the diaphragm contracts and chest cavity volume decreases, which increases the pressure inside the lungs to cause air to enter the lungs, the diaphragm contracts and chest cavity volume increases, which decreases the pressure inside the lungs to cause air to enter the lungs, the diaphragm contracts and chest cavity volume increases, which increases the pressure inside the lungs to cause air to enter the lungs, the diaphragm relaxes and chest cavity volume increases, which increases the pressure inside the lungs to cause air to enter the lungs. O the diaphragm relaxes and chest cavity volume decreases, which decreases the pressure inside the lungs to cause air to enter the lungs.

Answer 1

QUESTION 47 -  During inhalation of air in human-

Answer - The diaphragm contracts and chest cavity volume increase ,which decrease the pressure inside the lungs to cause air to enter the lungs.

Explanation -

Breathing involves two stages : Inspiration during which atmospheric air is in and Expiration by which the alveolar air is released out.

INSPIRATION -

• At the time of inspiration, contraction in diaphragm and external Intercoastal muscles takes place.
• Diaphragm becomes flat and is pushed towards abdominal cavity.
• Sternum moves towards ventral and anterior direction.
• Ribs move towards outside and ventral side.
• As a result of all these reactions, the volume of thoracic cavity (chest cavity) is increased. So the pressure of coelomic fluid over lungs is decreased.
• As a result of this, air pressure in the lungs decreased as compared to atmospheric pressure.
• Now air rushes from outside through respiratory track and fills the lungs .
• Inspiration is an active process.
• Normally it takes around 2 seconds.