BTEC Applied Science Unit 1: Biology - Blood Vessels

Types of Blood Vessels

Arteries

• Function: Carry blood away from the heart.
• Blood Pressure: High pressure.
• Oxygen Content: High oxygen content (bright red), except for the artery going to the lungs.
• Structure:
  • Outer layer of connective and elastic tissue.
  • Thicker layer of smooth muscle tissue to help pump blood.
  • Endothelial layer on the inside.

Veins

• Function: Carry blood to the heart.
• Blood Pressure: Lower pressure.
• Oxygen Content: Less oxygen content (not bright red).
• Structure:
  • Outer layer of connective and elastic tissue, thicker in veins to prevent collapse.
  • A layer of smooth muscle tissue.
  • Endothelial layer on the inside.

Capillaries

• Function: Tiny blood vessels that take blood to and from cells (e.g., muscles).
• Structure: Essentially just an endothelial layer.

Atherosclerosis

• Definition: A disease characterized by fatty deposits in the arteries.
• Fatty Deposits (Atheroma): Can block an artery or lead to blood clotting (thrombosis).
• Consequences:
  • Can cause coronary disease or heart attack.
  • Can cause strokes if it affects blood flow to the brain.

Development of Atherosclerosis

• Endothelial Damage: Caused by smoking or high blood pressure.
• Cholesterol Accumulation: LDL cholesterol builds up causing inflammation.
• Inflammation Response: White blood cells, calcium salts, and fibers accumulate forming plaque.
• Effects:
  • Artery becomes narrow and less elastic.
  • Blood flow is restricted.
  • Increases risk of blood clotting.

Smoking and Atherosclerosis

• Toxic Chemicals: Cigarette smoke contains chemicals that thicken the blood and damage the endothelium.
• Fatty Deposits: Thick blood from smoking causes more fatty deposits.
• Increased Blood Pressure and Heart Rate: Raises blood pressure further damaging the endothelium.

Key Questions

• Sketch and describe the structure of the three types of blood vessel.
• What is atherosclerosis? Describe how it develops.
• What major diseases can it cause?
• Describe how smoking can lead to atherosclerosis.