Cs2

Question 1

Highways have lanes that separate traffic. They also have access ramps that take vehicles to and from roads. Similarly

Answer 1

the body also has a network of channels—the blood vessels. Blood vessels circulate blood throughout the body and help keep the blood flowing to and from the heart. The fact that there are different kinds of blood vessels was first observed by Greek physician Praxagoras. The three major blood vessels are arteries

Question 2

ARTERIES

Question 3

Oxygen-rich blood

Answer 3

or oxygenated blood

Question 4

Arteries are composed of three layers: an outer layer of connective tissue

Answer 4

a middle layer of smooth muscle

Question 5

CAPILLARIES

Question 6

Arteries branch through the body like the branches of a tree

Answer 6

becoming smaller in diameter as they grow farther away from the main vessel. The smallest branches are capillaries. Capillaries are microscopic blood vessels where the exchange of important substances and wastes occurs. Capillary walls are only one cell thick. This permits easy exchange of materials between the blood and body cells

Question 7

The diameter of blood vessels changes in response to the needs of the body. For example

Answer 7

when you are exercising

Question 8

VEINS

Question 9

After blood moves through the tiny capillaries

Answer 9

it enters the largest blood vessels

Question 10

BLOOD VESSELS

Question 11

Artery

Question 12

Artery

Question 13

Endothelium

Question 14

Smooth muscle

Question 15

Connective tissue

Question 16

Capillaries

Question 17

Vein

Question 18

Vein

Question 19

Valve