SOBBING

What is the function of the pulmonary circuit?

• Moves deoxygenated blood from the right side of the heart to the lungs for gas exchange.

• Returns oxygenated blood to the left side of the heart.

What is the function of the systemic circuit?

• Moves oxygenated blood from the left side of the heart to the body.

• Returns deoxygenated blood to the right side of the heart.

What are the four chambers of the heart and their functions?

• Right Atrium: Receives deoxygenated blood from body (via vena cava)

• Right Ventricle: Pumps deoxygenated blood to lungs

• Left Atrium: Receives oxygenated blood from lungs

• Left Ventricle: Pumps oxygenated blood to the body

What is the pericardium and what does it do?

• A protective sac that surrounds the heart.

• Anchors the heart and prevents overfilling of the chambers.

What is the significance of the plateau phase in cardiac action potentials?

• Prolongs depolarization for strong, sustained contraction

• Prevents tetany by ensuring a longer refractory period

What is the sequence of events in the action potential of pacemaker cells in the heart?

1. Slow Na⁺ Influx:
   

   • Na⁺ channels open

   • Membrane potential rises from -60 mV to -40 mV (threshold)

2. Depolarization:
   

   • At threshold, Ca²⁺ channels open

   • Ca²⁺ influx causes membrane potential to become positive

4. Repolarization:
   

   • K⁺ channels open

   • K⁺ exits the cell, returning membrane potential to -60 mV