Blood vessels

 

There are three different types of blood vessels:

 

• Arteries - carry blood away from the heart.
• Capillaries - where gas exchange takes place.
• Veins - carry blood to the heart.

 

Arteries

• Carry blood away from the heart.

• Have thick walls composed largely of muscle and elastic tissue.

• Have small passageways for blood (internal lumen).

• Contain blood under high pressure.

 

 

Veins

 

• Carries blood back to the heart.

• Have thin walls.

• Have larger passageways for blood (internal lumen).

• Contain blood under low pressure.

• Contain valves which stop the blood flowing the wrong way .

 

 

Capillaries

 

• Found in the muscles and lungs.
• Walls are one cell thick to allow substances to pass over.
• Very low blood pressure.
• Where gas exchange takes place - oxygen passes through the capillary wall and into the tissues, while carbon dioxide passes from the tissues into the blood.

 

 

🔬 Knowledge Check: Blood Vessels

Test your understanding of arteries, veins, and capillaries based on the information from this page.

1. Which type of blood vessel carries blood away from the heart at high pressure?

• Veins
• Arteries
• Capillaries

2. Why are capillary walls only one cell thick?

• To withstand high blood pressure from the heart.
• To allow valves to open and close easily.
• To provide a short diffusion distance for exchange of substances.

3. Which structural feature is found in veins but NOT in arteries?

• Valves
• Elastic fibres
• Thick muscular walls

4. How does the lumen of a vein compare to the lumen of an artery?

• The lumen of a vein is much narrower.
• The lumen of a vein is wider.
• The lumens are exactly the same size.

5. Which vessels link arteries and veins together?

• Capillaries
• Muscle fibres
• Elastic Recoils

Click to Reveal Answers

1. Arteries (They carry blood at high pressure away from the heart).
2. To provide a short diffusion distance (Thin walls allow oxygen and food to pass out to cells easily).
3. Valves (Veins have valves to prevent the backflow of blood).
4. The lumen of a vein is wider (Veins have a relatively large lumen compared to arteries).
5. Capillaries (These microscopic vessels link arteries to veins).

 

Tags:Blood, vein, artery, arteries, capillaries, red blood cells white blood cells and platelets, red blood cell white blood cell and platelets