Which of the following is the primary function of the respiratory system?

• To supply oxygen to tissues

• To remove carbon dioxide from the blood

• To regulate body temperature

• To synthesize hemoglobin

The main muscle responsible for inspiration is:

• Diaphragm

• External intercostals

• Sternocleidomastoid

• Internal intercostals

The volume of air left in the lungs at the end of maximal expiratory effort is called:

• Tidal volume

• Residual volume

• Expiratory Reserve volume

• Inspiratory Reserve volume

Assertion: Tuberculosis occurs more commonly at the base of lungs. Reason: The higher oxygen level facilitates the growth of tubercular bacilli.

• Both assertion and reason are true and reason is the correct explanation.

• Both assertion and reason are true but reason is not the correct explanation.

• Assertion is true but reason is false

• Assertion is false but reason is true.

The anatomical dead space refers to:

• Areas of the lung where no air enters

• The volume of the respiratory tract that does not participate in gas exchange

• Alveolar regions where oxygen is not absorbed

• The volume of air in the trachea

What is the normal pacemaker of the heart?

• AU node

• SA node

• Purkinje fibers

• Bundle of His

Which of the following is the main determinant of preload?

• Heart rate

• End-diastolic volume

• Stroke volume

• Peripheral resistance

What is the major ion responsible for the plateau phase of the cardiac action potential?

• Sodium

• Calcium

• Potassium

• Chloride

In a healthy individual, which vessel has the highest total cross-sectional area?

• Arteries

• Arterioles

• Capillaries

• Veins

Which of the following structures has the fastest conduction velocity in the heart?

• SA node

• AU node

• Bundle of His

• Purkinje fibers