Many veins of the limbs contain valves that keep blood flowing toward the heart.
Correct Answer
True
True. Venous pressure is low, so valves in limb veins prevent backflow when blood is moving against gravity. When these valves weaken, blood pools and can produce varicose veins.
Category: Vessel Structure
Question 2
Elastic arteries are located farther from the heart than muscular arteries.
Correct Answer
False
False. Elastic arteries, such as the aorta, are closest to the heart, where their elastic fibers absorb and recoil from each surge of pressure. Muscular arteries lie farther out and distribute blood to organs.
Category: Vessel Structure
Question 3
The vasa vasorum are small vessels that supply blood to the walls of large arteries and veins.
Correct Answer
True
True. The walls of large vessels are too thick to be nourished by diffusion from the lumen alone, so the vasa vasorum deliver oxygen and nutrients to the outer layers.
Category: Vessel Structure
Question 4
Capillaries of the brain are fenestrated, which allows most solutes to pass freely into brain tissue.
Correct Answer
False
False. Brain capillaries are continuous capillaries sealed by tight junctions, and they form the blood-brain barrier that restricts what enters brain tissue. Fenestrated capillaries are found in places such as the kidneys and small intestine.
Category: Vessel Structure
Question 5
At any given moment, the systemic veins hold a larger share of the total blood volume than the systemic arteries.
Correct Answer
True
True. Veins have thin walls and large lumens that let them hold large volumes at low pressure, and the systemic veins contain the majority of the blood volume at rest.
Category: Vessel Structure
Question 6
Blood flow to the brain falls sharply during strenuous exercise.
Correct Answer
False
False. During exercise, flow increases to skeletal muscle, the heart and the skin, while flow to digestive organs and kidneys decreases. Blood flow to the brain stays largely constant.
Category: Vascular Regulation
Question 7
Diastolic pressure is the arterial pressure measured while the ventricles contract.
Correct Answer
False
False. Diastolic pressure is the lower arterial pressure measured while the ventricles relax. The higher pressure recorded during ventricular contraction is systolic pressure.
Category: Blood Pressure and Flow
Question 8
Blood viscosity increases when the number of red blood cells rises.
Correct Answer
True
True. Red blood cells are the main formed elements in blood, so more of them makes blood thicker. Higher viscosity raises resistance and makes the heart work harder to move blood.
Category: Blood Pressure and Flow
Question 9
Increasing a blood vessel's length decreases its resistance to blood flow.
Correct Answer
False
False. Resistance is directly proportional to vessel length, so a longer vessel has more resistance. This is one reason extra body mass, which requires more vessels, can raise blood pressure.
Category: Blood Pressure and Flow
Question 10
The first Korotkoff sound heard as a blood pressure cuff deflates corresponds to the systolic pressure.
Correct Answer
True
True. When cuff pressure drops just below systolic pressure, blood begins to spurt through the compressed artery and makes a tapping sound. The point at which the sounds disappear marks the diastolic pressure.
Category: Blood Pressure and Flow
Question 11
Under normal conditions, capillaries reabsorb more fluid than they filter.
Correct Answer
False
False. Capillaries filter slightly more fluid than they reabsorb each day. The remaining fluid is collected by lymphatic vessels and returned to the blood.
Category: Capillary Exchange
Question 12
Lymph collected from the tissues returns to the bloodstream by draining into the subclavian veins.
Correct Answer
True
True. Lymphatic vessels carry the excess interstitial fluid, now called lymph, through lymph nodes and into large lymphatic ducts. These ducts empty into the subclavian veins near the base of the neck, returning the fluid to the blood.
Category: Capillary Exchange
Question 13
An increase in blood pressure decreases the firing rate of baroreceptors.
Correct Answer
False
False. Rising pressure stretches the vessel wall and increases baroreceptor firing. The cardiovascular centers respond by slowing the heart and dilating arterioles to bring pressure down.
Category: Vascular Regulation
Question 14
Angiotensin II is a powerful vasoconstrictor that also stimulates the release of aldosterone.
Correct Answer
True
True. Angiotensin II raises blood pressure by constricting vessels, and it stimulates aldosterone release, which increases sodium and water retention. It also triggers thirst and ADH release.
Category: Vascular Regulation
Question 15
Erythropoietin is secreted mainly by the liver in response to low oxygen levels.
Correct Answer
False
False. Erythropoietin is secreted mainly by the kidneys when oxygen delivery is low. It stimulates red blood cell production in the bone marrow.
Category: Vascular Regulation
Question 16
Nitric oxide released by endothelial cells causes nearby vascular smooth muscle to relax, dilating the vessel.
Correct Answer
True
True. Nitric oxide is a potent local vasodilator. Endothelial cells release it in response to signals such as low oxygen, which increases blood flow to the tissue.
Category: Vascular Regulation
Question 17
Pulmonary arteries carry oxygen-rich blood from the lungs to the left atrium.
Correct Answer
False
False. Pulmonary veins carry oxygen-rich blood from the lungs to the left atrium. Pulmonary arteries carry oxygen-poor blood from the right ventricle to the lungs.
Category: Circulatory Pathways
Question 18
The great saphenous vein is a superficial vein of the lower limb.
Correct Answer
True
True. The great saphenous vein runs just beneath the skin along the medial leg and thigh and drains into the femoral vein near the groin. It is often harvested for coronary bypass grafts.
Category: Circulatory Pathways
Question 19
The umbilical vein carries oxygen-poor blood from the fetus to the placenta.
Correct Answer
False
False. The umbilical arteries carry oxygen-poor blood from the fetus to the placenta. The umbilical vein carries oxygen-rich, nutrient-rich blood from the placenta to the fetus.
Category: Vessel Development and Fetal Circulation
Question 20
After birth, the ductus venosus closes and becomes the ligamentum venosum.
Correct Answer
True
True. The ductus venosus lets fetal blood from the umbilical vein bypass the liver. Once the umbilical circulation stops after birth, it closes and remains as the ligamentum venosum.
Category: Vessel Development and Fetal Circulation