Understanding the Respiratory System

What is the primary role of haemoglobin in oxygen transport during exercise?

• To dissolve oxygen in the blood plasma

• To bind oxygen and transport it to tissues

• To convert oxygen into carbon dioxide

• To store oxygen in the muscles

Answer explanation

The primary role of haemoglobin is to bind oxygen in the lungs and transport it to tissues throughout the body, especially during exercise when oxygen demand increases.

How does the oxygen dissociation curve shift during intense exercise?

• To the left

• To the right

• It remains unchanged

• It becomes a straight line

Answer explanation

During intense exercise, the body produces more carbon dioxide and lactic acid, which lowers pH and increases temperature. This causes the oxygen dissociation curve to shift to the right, enhancing oxygen release to tissues.

What is the effect of high altitude on respiration?

• Decreased breathing rate

• Increased oxygen availability

• Increased breathing rate

• Decreased carbon dioxide levels

Answer explanation

At high altitudes, oxygen levels decrease, prompting the body to increase the breathing rate to enhance oxygen intake. This compensatory mechanism helps maintain adequate oxygen supply despite lower atmospheric pressure.

Which muscle is primarily responsible for inspiration during normal breathing?

• Intercostal muscles

• Abdominal muscles

• Diaphragm

• Pectoral muscles

Answer explanation

The diaphragm is the primary muscle responsible for inspiration during normal breathing. It contracts and moves downward, increasing the thoracic cavity volume and allowing air to flow into the lungs.

What happens to the ventilation rate during exercise?

• It decreases

• It remains constant

• It increases

• It stops

Answer explanation

During exercise, the body's demand for oxygen increases, leading to an increase in ventilation rate to supply more oxygen and remove carbon dioxide. Therefore, the correct answer is that the ventilation rate increases.

Where does gaseous exchange occur in the lungs?

• Bronchi

• Alveoli

• Trachea

• Larynx

Answer explanation

Gaseous exchange occurs in the alveoli, which are tiny air sacs in the lungs. They provide a large surface area for oxygen and carbon dioxide to diffuse between the air and the blood, making them essential for respiration.

What is a key cardiorespiratory adaptation to regular exercise?

• Decreased lung capacity

• Increased resting heart rate

• Increased stroke volume

• Decreased blood volume

Answer explanation

Increased stroke volume is a key adaptation to regular exercise, as it enhances the heart's efficiency by pumping more blood per beat, improving oxygen delivery to muscles. This contrasts with the incorrect options.

How does the oxygen dissociation curve change at high altitudes?

• Shifts to the left

• Shifts to the right

• Becomes steeper

• Becomes flatter

Answer explanation

At high altitudes, the oxygen dissociation curve shifts to the left due to lower partial pressure of oxygen, enhancing hemoglobin's affinity for oxygen. This allows for more efficient oxygen uptake in low-oxygen environments.

What is the role of the diaphragm during exhalation?

• It contracts

• It relaxes

• It remains tense

• It expands

Answer explanation

During exhalation, the diaphragm relaxes, allowing the thoracic cavity to decrease in volume. This reduction in volume increases pressure in the lungs, pushing air out. Therefore, the correct answer is that the diaphragm relaxes.

Which factor increases the affinity of haemoglobin for oxygen?

• High temperature

• Low pH

• High carbon dioxide levels

• Low carbon dioxide levels

Answer explanation

Low carbon dioxide levels increase hemoglobin's affinity for oxygen by shifting the oxygen-hemoglobin dissociation curve to the left, promoting oxygen binding. In contrast, high temperature, low pH, and high CO2 decrease this affinity.