Human Circulatory System Chapter

Blood Composition

• Blood is composed of red blood cells, white blood cells, platelets, and plasma.
• Red blood cells transport oxygen.
• White blood cells fight infection.
• Plasma transports chemicals and maintains body temperature.
• Platelets clump together to form blood clots.

Heart Structure and Function

• The heart is roughly the size of a clenched fist.
• It's located on the left side of the chest.
• The heart is made of cardiac muscle.
• It contracts to pump blood throughout the body.
• The right side pumps blood to the lungs.
• The left side pumps blood to the rest of the body.
• Key heart structures include the left atrium, right atrium, left ventricle, and right ventricle.

Blood Vessels

• Arteries carry blood away from the heart.
  • Blood flows from high to low pressure (arteries to veins).
  • Arterial walls are thick and strong to withstand high pressure.
  • Arteries do not have valves.
• Veins carry blood to the heart.
  • Blood pressure is low in veins.
  • Vein walls are thinner and weaker than arteries.
  • Veins contain valves to prevent backflow.
• Capillaries are tiny blood vessels that connect arteries and veins.
  • Capillary walls are thin to allow material exchange.

Heart Rate and Health

• To find your pulse, place your hand on your wrist or neck.
• Regular exercise reduces the risk of heart disease, diabetes, and certain cancers.
• Exercise promotes weight management.