1. Which thin-walled blood vessels lack muscular walls? aVeins bArterioles cCapillaries dArteries 2. In what way do arteries differ in structure from...

1. Which thin-walled blood vessels lack muscular walls?

a Veins

b Arterioles

c Capillaries

d Arteries

a Arteries have more elastin in tissue than veins and capillaries.

b Arteries appear flatter in a cross section than veins and capillaries.

c Arteries have valves which are absent in veins and capillaries.

d Arteries have walls that are thinner than veins and capillaries.

a Pulmonary vein

b Pulmonary artery

c Capillaries

d Arteriole