20.1 Structure and Function

What are the three types of blood vessels?

Arteries, capillaries, and veins.

What is the main function of arteries?

They convey blood from the heart to capillaries.

In which direction do arteries carry blood?

Away from the heart toward tissues.

What is the main function of capillaries?

They exchange substances between blood and tissues.

How are capillaries described structurally?

They are microscopic and porous blood vessels.

Why are capillaries described as porous?

They have openings that allow substances to move between blood and tissues.

What types of substances are exchanged in capillaries?

Gases, nutrients, and wastes.

Why are capillaries important for tissue function?

They allow delivery of oxygen and nutrients and removal of wastes.

What is the main function of veins?

They transport blood from capillaries back to the heart.

In which direction do veins carry blood?

Toward the heart.

What is the sequence of blood flow through these vessels?

Heart → arteries → capillaries → veins → heart.

Which vessel type is responsible for delivering blood to tissues?

Arteries.

Which vessel type is responsible for exchange between blood and tissues?

Capillaries.

Which vessel type is responsible for returning blood to the heart?

Veins.

Why is blood flow slow in capillaries compared to arteries?

To allow enough time for exchange between blood and tissues.

Which vessel type connects arteries and veins?

Capillaries.

Which vessel type carries blood directly from the heart?

Arteries.

Which vessel type carries blood directly into the heart?

Veins.