A&P II Chapter 19: Blood Vessels

Which of the following would decrease total peripheral resistance to blood flow? atherosclerosis vasoconstriction increasing blood vessel length decreasing the hematocrit

decreasing the hematocrit explained: Decreasing the hematocrit (fraction of whole blood consisting of blood cells) would lead to decreased blood viscosity, and thus would decrease resistance.

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

elastic membranes explained: Elastic membranes (internal and external) are found in arteries to help absorb the shock of the heartbeat and return the vessel to its natural size.

Where are the vasa vasorum located? in the tunica media of muscular arteries in the tunica intima of large veins in the tunica externa of large blood vessels in the tunica media of arterioles

in the tunica externa of large blood vessels explained: The vasa vasorum consist of tiny blood vessels that provide nutrients and oxygen to the external tissues of the blood vessel walls.

Which of the following changes would produce the greatest change in total peripheral resistance? 10% change in cardiac output 10% change in vessel diameter 10% change in vessel length 10% change in blood viscosity

10%% change in vessel diameter explained: The main determinant of total peripheral resistance is the diameter of the small arterioles. As blood vessel diameter increases, resistance goes down, and vice versa. Resistance is inversely proportional to the fourth power of the blood vessel radius. Radius is one-half of the vessel diameter. This means any change in vessel diameter will affect resistance by a factor of 1/r41/r4 where r is the radius. For example, a doubling of the vessel diameter will have a 2*2*2*2 or 16-fold reduction in resistance.

In which of the following blood vessels would you expect to find the LEAST amount of carbon dioxide? venae cavae pulmonary artery systemic capillaries pulmonary vein

pulmonary vein explained: The pulmonary vein carries blood from the lungs that is rich in oxygen and poor in carbon dioxide.

Define: Blood pressure Total peripheral resistance Blood viscosity Cardiac output (CO)

Blood pressure: the force of the blood against the vessel wall Total peripheral resistance: the amount of friction blood encounters during flow through blood vessels Blood viscosity: the friction red blood cells encounter when moving past each other Cardiac output: the volume of blood pumped out by one ventricle each minute

The following activities and body conditions affect blood pressure by changing one of the two listed factors: (1) Blood Volume (2) Total Peripheral Resistance Drag the appropriate physiological changes to their respective bins

Blood volume: blood donation, excessive sweating Total peripheral resistance: smoking, high altitude living, growth, increased sympathetic activity

Which of the following is likely during vigorous exercise?

Capillaries of the active muscles will be engorged with blood.

Which of the following increase/decrease blood pressure? Increase blood vessel diameter Increase blood viscosity Increase total peripheral resistance Increase blood vessel length Increase cardiac output Increase blood volume

Decreases BP: Increase blood vessel diameter Increases BP: Increase blood viscosity Increase total peripheral resistance Increase blood vessel length Increase cardiac output Increase blood volume

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

False explained: Arteries always carry blood away from the heart. Whether they carry oxygenated or deoxygenated blood depends on the circuit. In the pulmonary circuit, pulmonary arteries carry deoxygenated blood away from the heart to the pulmonary capillaries in the lungs, where the blood is oxygenated. This oxygenated blood is then returned to the heart through the pulmonary veins. In contrast, systemic arteries carry oxygenated blood away from the heart to the systemic capillaries, where the oxygen is delivered to the tissues. Systemic veins then carry this deoxygenated blood back to the heart.

Which statement best describes blood flow through the pulmonary veins?

Pulmonary veins carry oxygen-rich blood from lung capillaries to the heart. explained: Although most veins carry oxygen-poor, carbon dioxide-rich blood, pulmonary veins carry oxygen-rich blood from the lungs toward the heart.

Which of the choices below explains why the arterioles are known as resistance vessels?

The contraction and relaxation of the smooth muscle in their walls can change their diameter

Which description most accurately describes the functions of the superior and inferior venae cavae?

The superior vena cava primarily drains oxygen-poor blood from the body above the diaphragm, while the inferior vena cava drains oxygen-poor blood from areas below the diaphragm. explained: Blood from organs inferior to the diaphragm returns to the right atrium through the inferior vena cava. Blood from organs above the diaphragm, with a few minor exceptions, returns to the right atrium through the superior vena cava. The blood returning to the heart from systemic organs is oxygen-poor.

True/False: The pulmonary circulation does not directly serve the metabolic needs of body tissues

True

Permitting the exchange of nutrients and gases between the blood and tissue cells is the primary function of ________.

capillaries

At what point would we definitely not be able to measure the difference between systolic and diastolic pressure?

capillaries explained: By the time blood reaches the capillaries, the pulsatile pressure differences would be unnoticeable.

Which type of blood vessel typically LACKS one or more of the three tunics? capillaries veins muscular arteries elastic arteries

capillaries explained: Capillaries are so small and simple that their walls are typically one layer, or even one cell, of endothelium.

Which type of blood vessels typically are regulated by sphincters? elastic arteries muscular arteries veins capillaries

capillaries explained: Capillaries form networks called capillary beds that can contain precapillary sphincters. These sphincters regulate the amount of blood that can move through the capillary bed.

Which type of blood vessel is the most permeable? arterioles continuous capillaries sinusoid capillaries fenestrated capillaries

sinusoid capillaries explained: Capillaries allow for materials to be exchanged with interstitial fluid. Sinusoid capillaries contain the largest openings in their endothelial linings and are the most permeable of the capillary types.

What is the main function of the pulmonary circuit?

to oxygenate the blood explained: The blood must obtain oxygen by traveling through alveolar capillaries in the lungs so that the oxygen can be delivered to the rest of the body.

Which layer of the typical blood vessel is constructed from simple squamous epithelium?

tunica intima explained: The tunic intima of blood vessels, like the endocardium of the heart, is made of simple squamous epithelium.

Which structural layer of blood vessels is most responsible for maintaining blood pressure?

tunica media

Which of the following is mismatched? capillaries: exchange vessels veins: resistance vessels elastic arteries: conducting vessels muscular arteries: distribution vessels

veins: resistance vessels explained: With their large lumens and thin walls, veins are low resistance vessels that can accommodate a fairly large blood volume. Veins are called capacitance vessels and blood reservoirs because they can hold up to 65% of the body's blood supply at any time. With their small diameters, it is the arterioles that are known as resistance vessels.