Advanced Physiology Challenge

Which ion is primarily responsible for the depolarization phase of an action potential in neurons?

• Chloride ion (Cl-)

• Potassium ion (K+)

• Calcium ion (Ca2+)

• Sodium ion (Na+)

What is the primary function of the sinoatrial (SA) node in the heart?

• To control the contraction of the ventricles.

• To regulate blood flow to the lungs.

• To store electrical impulses for later use.

• The primary function of the sinoatrial (SA) node is to generate electrical impulses that initiate the heartbeat.

During which phase of the respiratory cycle does the diaphragm contract and move downward?

• Inhalation

• Breathing pause

• Resting phase

• Exhalation

Which type of muscle fibers are primarily involved in endurance activities?

• Fast-twitch muscle fibers (Type II fibers)

• Cardiac muscle fibers

• Smooth muscle fibers

• Slow-twitch muscle fibers (Type I fibers)

What hormone is primarily responsible for regulating blood glucose levels?

• Cortisol

• Insulin

• Glucagon

• Adrenaline