Capillaries is the answer in this question
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Capillaries are the tiniest blood vessels. They connect arteries and veins.
"capillaries"
Capillaries are the tiniest blood vessels. They are the site of gas exchange and connect veins and arteries.
Capillaries are the tiniest of the blood vessels. They connect arteries and veins.
Capillaries are the tiniest of the blood vessels. They connect veins and arteries, and are the site of gas exchange.
Capillary
The tiniest blood vessels that carry oxygen-rich blood are the capillaries. These capillaries form a bed. The arterioles that carry the blood into the bed are high in oxygen. The oxygen is released to the cells. The rest of the bed is low in oxygen and venules carry deoxygenated blood to the veins back to the heart.
Arteries divide into smaller vessels called Arteriols. Arteriols subdivide into even smaller vessels called capillaries, where oxygen, nutrients, hormones are delivered to the tissues of the body. Waste products are also picked up by capillaries and delivered to venules which grow into larger vessels called veins. Veins deliver deoxygenated blood back to the heart.
Blood Vessels-are the passageway of blood.
Blood Vessels-are the passageway of blood.
Nicotine is the blood vessels' constrictor. Not all blood vessels, of course, but mainly the peripheral blood vessels, including the brain capillary blood vessels.