CHAPTER 19 READING AND HOMEWORK

Which of the following statements is not true of the precapillary sphincters? A They increase or decrease rates of perfusion to the tissues served by the true capillaries. B They allow blood to bypass the true capillaries that are fed by the metarteriole. C They decrease the osmotic pressure in the thoroughfare channel. D They regulate the flow of blood to tissues served by the true capillaries.

A precapillary sphincter is a cuff of smooth muscle that regulates the flow of blood into the capillaries. True False

Which of the following would have the least influence on blood pressure? A white blood cell count B cardiac output C blood volume D peripheral resistance

The influence of blood vessel diameter on peripheral resistance is ________. A significant because resistance is directly proportional to the blood vessel diameter B insignificant because vessel diameter does not vary C the only factor that influences resistance D significant because resistance is inversely proportional to the fourth power of the vessel radius

The outermost layer of a blood vessel is the tunica intima. True False

Which layer of the typical blood vessel is constructed from simple squamous epithelium? A tunica media B tunica intima C tunica externa

Which layer of the typical vessel can be regulated to constrict or dilate the lumen? A tunica externa B tunica intima C vasa vasorum D tunica media

Which of these features is found only in arteries? A vasa vasorum B lumen C valves D elastic membranes

Which type of vessel is most suited to expanding and recoiling in response to the ejection of blood from the heart? A elastic artery B large veins C arteriole D muscular artery

What type of vessel is capable of allowing the passage of gases and nutrients though its walls to nourish surrounding tissue? A arterioles B small veins C capillaries D venules

Arteries always carry oxygenated blood away from the heart. True False

The aorta receives the full force of blood exiting the heart during ventricular systole. Which of the following statements best describes the adaptive anatomy of the aorta? A Smooth muscle is relatively thin in the aorta to increase lumen size and systemic blood flow. B The tunica external of the aorta is nearly absent compared to other vessels. C The aorta's tunica media is thick with dense regular connective tissue to withstand the blood's pressure. D Elastic fibers are extensive in the tunica media of the aorta and dampen the pulse pressure generated by the heart.

Which tunic of an artery is most responsible for maintaining blood pressure and continuous blood circulation? A tunica media B tunica externa C tunica intima D tunica adventitia

Which vessels carry blood toward the heart? A muscular arteries B veins C capillaries D arterioles

Which statement best describes arteries? A All contain valves to prevent the backflow of blood. B All carry oxygenated blood to the heart. C Only large arteries are lined with endothelium. D All carry blood away from the heart.

Which of the choices below explains why the arterioles are known as resistance vessels? A Their prime function is the exchange of nutrients and wastes between the blood and tissue cells. B The contraction and relaxation of the smooth muscle in their walls can change their diameter. C They distribute blood to various parts of the body. D They contain a large quantity of elastic tissue

The most permeable capillaries, which contain fenestrations and large intercellular clefts, are __________. A sinusoid capillaries B continuous capillaries C fenestrated capillaries D arterioles

Permitting the exchange of nutrients and gases between the blood and tissue cells is the primary function of ________. A capillaries B arterioles C arteries D veins

Which of the following is true about veins? A Veins have valves; arteries do not. B Veins are more muscular than arteries. C Veins have a smaller diameter lumen than arteries. D Veins carry blood away from the heart, while arteries carry blood to the heart

Factors that aid venous return include all except ________. A venous valves B pressure changes in the thorax C activity of skeletal muscles D urinary output

Which of the following is the most significant source of blood flow resistance? A blood viscosity B blood vessel diameter C blood vessels type D total blood vessel length

The pulse pressure is ________. A systolic pressure divided by diastolic pressure B systolic pressure minus diastolic pressure C systolic pressure plus diastolic pressure D diastolic pressure plus 1/3 (systolic pressure plus diastolic pressure)

A patient with essential hypertension might have pressures of 200/120 mm Hg. This hypertensive state could result in all of the following changes except ________. A increased work of the left ventricle B decreased size of the heart muscle C increased incidence of coronary artery disease D increased damage to blood vessel endothelium

Which of the following signs of hypovolemic shock is a relatively late sign? A rapidly falling blood pressure B cold, clammy skin C rapid, thready pulse D increased heart rate