Hyperventilation or hyperpnoea causes
A) Increased carbon dioxide concentration of blood
B) Decreased blood carbon dioxide concentration
C) Temporary stoppage of respiration
D) Both B and C

Hint: People may start deep breathing when they are running, walking, or doing some other physical activities. In these conditions, the heart beats faster and the blood pump gets faster this results in the increase in the oxygen requirement.

Complete Answer:
- Hyperpnea is a condition that occurs while we are doing exercise, when we were at a high altitude, and ill. In this condition our body demands more oxygen than we need normally. As we all know, breathing is a process of bringing oxygen from the air to the body through respiration. The blood that passes through the lungs distributes the oxygen to every cell of the body. Breathing is an automatic process that is controlled by the nervous system when we need oxygen.
- Now, in hyperpnea we require deeper breathing and may be faster breathing. This is our body response to signals from the brain and blood vessels to control our breathing. Deep breathing results in the increase in the requirement of oxygen. As mentioned above, hyperpnea mostly occurs when we are doing some physical activity and people in high altitude also have hyperpnea as in high altitude the oxygen level is lower in compared to plain area therefore, our body requires more oxygen to make up the oxygen demand of the body.
- There are many other medical conditions that cause hyperpnea, like in anemia, the blood has lowered the ability of the oxygen transportation that causes hyperpnea. In asthma, the person suffers from short breathing, therefore, the oxygen demand of the body increases. In chronic obstructive pulmonary disease, the oxygen is not able to distribute throughout the body, hence the oxygen demand increases and it causes hyperpnea.

Thus, the correct answer is ‘D’. Both B and C.

Note: Hyperpnea is not itself dangerous but if a person is suffering from some chronic respiratory diseases like Asthma, Chronic obstructive pulmonary disease, and panic disorders then this condition may become fetal, therefore immediate consultation of doctor is advisable.