The average life span of human red blood cells is:

 

1.	10 days	2.	120 days
3.	21 days	4.	three months

A chest pain or pressure, usually due to not enough blood flow to the heart muscle, is known as:

What is the percentage of atrial blood that flows into the ventricles without atrial systole?

QRS complexes on the ECG tracings show that:
1. The atria are depolarizing.
2. The ventricles are depolarizing.
3. The ventricles are repolarizing.
4. The heart is at rest.

Pulmonary veins return the oxygenated blood from the lungs to:

Erythrocytes in humans are destroyed mainly in:

The most common WBC under normal physiological conditions are:

The chamber with the thickest musculature in the human heart would be:

Sympathetic stimulation would lead to:
1. increased heart rate.
2. increased stroke volume.
3. vasoconstriction in visceral blood vessels.
4. all of the above.

The innermost layer of blood vessel walls made up of one layer of endothelium and in direct contact with the blood is: