Physiology Quiz: Heart and Muscle Function

Organ Function and Oxygen Difference

• The organ with the highest arteriovenous O2 difference under normal resting conditions is the heart.

Ventricular Muscle Action Potential

• The sodium permeability is the highest in phase 0 of the ventricular muscle action potential.

A-V Node and Heart Rate Regulation

• An increase in potassium permeability at the A-V node will cause a decrease in heart rate.

ECG and Heart Activity

• The "T wave" is due to ventricular repolarization within the heart.

Frank-Starling's Law of the Heart

• Frank-Starling's law of the heart explains the increase in cardiac output that occurs when venous return is increased.

Anemia Types

• Anemia caused by vitamin B12 and folate deficiency is megaloblastic anemia.

Blood Components and Plasma

• Serum is characterized by plasma with fibrinogen and some clotting factors removed.
• Plasma is whole blood with haemocytes removed.

Buffer Systems in Plasma

• The most abundant and buffering capacity buffer system in plasma is Bicarbonate buffer system (NaHCO3/H2CO3).

Cardiac Conduction and Action Potential

• The fastest rate of conduction of the cardiac action potential occurs in Purkinje fibers.

Organ Oxygen Demand

• Skeletal muscle has the highest arteriovenous O2 difference under normal resting conditions.

Ventricular Muscle Action Potential

• Sodium permeability is highest in phase 4 of the ventricular muscle action potential.

Heart Rate Regulation

• Decreased acetylcholine levels at the A-V node will cause an increase in heart rate.

ECG Waveforms

• The T wave is due to ventricular repolarization.

Cardiac Function

• Frank-Starling's law of the heart explains the increase in cardiac output when the ventricular end-diastolic volume increases, not when the sympathetic nerves supplying the heart are stimulated.

Anemia

• Vitamin B12 and folate deficiency causes megaloblastic anemia.

Blood Components

• Serum is characterized by plasma with fibrinogen and some clotting factors removed.

Blood Buffering Systems

• The KHCO3/H2CO3 buffer system has the highest buffering capacity in plasma.

Blood Transfusion

• ABO blood group system cannot be transfused without cross-matching.
• A person with blood group O is not always a "universal blood donor".
• A person with blood group AB is not always a "universal recipient".
• Rh-positive people should not receive Rh-negative blood.

Test your knowledge of human physiology with these questions about heart and muscle function, including arteriovenous O2 differences and ventricular muscle action potentials.