Which of the following substances are transported by the blood?

• All of the above
• O₂
• Glucose
• Urea

Which of the following vessels always carries blood away from the heart?

• Artery
• Vein
• Capillary
• Both arteries and capillaries

Which of the following vessels always returns blood to the heart?

• Veins
• Capillaries
• Arteries
• Both veins and capillaries

Where is the site of nutrient/waste exchange in the tissues?

• Capillaries
• Arterioles
• Venules
• Arteries

Which of the following carries blood at the highest pressure?

• Arteries
• Veins
• Capillaries
• Arterioles

Which of the following has the greatest diameter?

• Veins
• Arteries
• Venules
• Capillaries

Which of the following has the thickest tunica media (middle layer) of muscle tissue?

• Pulmonary artery
• Pulmonary vein
• Superior vena cava
• Inferior vena cava

Which of the following arterial layers is full of elastin protein?

• Tunica media 
• Tunica intima
• Tunica externa
• Epithelial layer

What happens in the arteries during systole?

• Elastic fibres stretch and store potential energy
• Elastic fibres recoil and propel blood forward

Which of the following cell types is found in the tunica intima (inner layer of the artery)?

• Endothelial cells
• Smooth muscle cells
• Red blood cells
• Elastin cells