Blood Circulation
What, if anything, keeps oxygen-poor and oxygen-rich blood from mixing in a bird's heart?
Birds have a double circulation and a four-chambered heart.
Which of the following occurs when precapillary sphincters contract?
Blood flows through the thoroughfare channel to move from arteriole to venule.
Two forces, blood pressure and osmotic pressure, help regulate the flow of fluid into and out of capillaries. Which of the following is a correct statement of the relationship of these forces to each other?
Blood pressure is higher toward the arterial end of a capillary, while osmotic pressure is higher toward the venous end of the capillary.
At what point in the cardiac cycle do the atrioventricular (AV) valves close?
During the first part of systole, when the ventricles contract.
Why are patients on kidney dialysis, whose kidneys no longer function, at risk for anemia?
Erythropoietin (EPO), a hormone that stimulates the bone marrow to make red blood cells, is no longer manufactured at adequate levels.
How is blood moved back towards the heart after it passes through the capillary bed?
Skeletal muscles contract and force the blood through the veins, aided by the one-way venous valve system.
Which of the following explains how arterioles lower blood pressure?
Smooth muscles in arteriole walls relax, allowing more blood to flow from arteries to capillaries.
What happens during the slight delay that occurs at the AV node as the electrical impulse travels from the SA node to the apex of the heart?
The atria finish emptying blood into the ventricles.
Which of the following is NOT a consequence of chronic hypertension?
The left ventricle shrinks, often becoming almost atrophic.
Which animals have a circulatory system with the following characteristics: single ventricle, lungs, pulmocutaneous circuit, and ridge separating oxygen-poor and oxygen-rich blood within the ventricle?
amphibians
Of all the blood vessels, the _________ have(has) the highest blood pressure and highest blood velocity.
aorta
What order does blood leave the aorta?
arteries, arterioles, capillaries, venules, veins
Besides being a banned substance in athletic competitions, synthetic erythropoietin can lead to which of the following complications?
blood clotting, stroke, heart failure
A "heart murmur" at the beginning of systole represents which of the following?
blood squirting "backwards" through a defective atrioventricular valve
The exchange of fluids between the blood and the interstitial fluid takes place only across the walls of ________. Why?
capillaries: Their walls are very thin and leaky.
Someone with an abnormally low number of platelets might experience which of the following?
excess bleeding from minor cuts and scrapes.
What effect do you think a sudden increase in blood pressure would have on the volume of lymph? What effect do you think a sudden increase in the protein concentration of the blood would have on the volume of lymph?
increase: decrease
Stem cells in the bone marrow divide into two main populations: __________ stem cells, which develop into erythrocytes and other cells, and __________ stem cells, develop into lymphocytes
myeloid: lymphoid
You are a red blood cell in the right ventricle of Tom, a marathon runner. Trace your path through Tom's circulatory system from start to end of your own little "race" as you complete one cardiac cycle. Which choice fills in the blanks correctly from start to finish? Start, right ventricle, then: _____, ______, _______, _______, ______, ______, _______, ______, ______: End, right ventricle
pulmonary arteries, lungs, pulmonary veins, left atrium, left ventricle, aorta, body, vena cava, right atrium
Oxygen is inhaled into the lung, enters capillaries in the lung, and is taken to the heart via the __________. Where in the body are the capillaries located that release carbon dioxide to the environment?
pulmonary veins: lungs
The contraction phase of the cardiac cycle is called __________. What occurs during this phase?
systole: atria contract, then ventricles contract