Fiberssheets in its wall a inferior vena cava b

fibers/sheets in its wall?
A. inferior vena cava
B. pulmonary vein
C. thoracic duct
D. descending aorta
E. radial artery
11.003 Which of the following vessels contains a significant amount of
longitudinally arranged smooth muscle in its tunica adventitia?
A. aorta
B. inferior vena cava
C. superior vena cava
D. basilar artery
E. renal vein
11.004 When the number of circularly arranged smooth muscle cells in the tunica
media of an arterial vessel is reduced to about 2-3, what is this vessel called?

A. muscular artery
B. arteriole
C. small vein
D. metarteriole
E. continuous capillary
11.005 With respect to the capillaries of the brain, which of the following is a
characteristic feature separating these vessels from other vessels of similar
caliber?
A. a lumen of 8 micrometers
B. cell to cell junctions of the fascia occludens type
C. cell to cell junctions of the zonula occludens type
D. cell to cell junctions of the macula occludens type
E. an intact basal lamina outside the endothelium
D. is correct.
D. is convect.
The ascending aorta, its arch and the descending aorta and their immediate
branches are classified as elastic arteries because of the many elastic fibers or
sheets in their walls. This high amount of elasticity provides for elastic recoil of the
vessel wall after distention by the systolic ejection of blood into them. This keeps
the systemic blood pressure from falling to zero during diastole.
B. is correct.
The inferior vena cava and some of its immediate branches have circular smooth
muscle fibers in their tunics media, but since these veins are bringing blood
against gravity toward the heart they have a well developed layer of longitudinally
arranged smooth muscle fibers which officially are classified as being in the
deeper aspect of the tunica adventitia.
B. is correct.
Arterioles have from 2 to perhaps 5 layers of circular smooth muscle, and a small
lumen relative to the thickness of the wall. Metarterioles have one layer of smooth

muscle cells and these are intermittent or "disappearing" as the vessel approaches
its capillary morphology.
C. is correct.
Most endothelial cells outside of the central nervous system have fascial type
occludens junctions. Since fascia occludens do not completely surround the entire
periphery of the cell, there are areas between adjacent endothelial cells which
permit the passage of tissue fluid and perhaps white blood cells. The presence of
zonula occludens in the capillaries serving the CNS is what is known as the blood-
brain barrier.