Veins

Veins

Carry blood back towards the heart
1. Tiny venules lead from the capillary network, merging into larger&larger vessels leading back to the heart
  1. Eventually 2 veins carry the returning blood to the heart
    1. Inferior vena cava (lower parts of the body
    2. Superior vena cava (upper parts of the body)
Most veins carry deoxygenated blood
1. EXCEPTIONS
  1. Pulmonary vein
    1. It carries Oxygenated blood from the lungs back to the heart for circulation
  2. During pregnancy
    1. Umbilical vein carries oxygenated blood from the placenta from the fetus
Veins can hold a large quantity of blood
1. Blood pressure in veins is low
  1. Blood pressure surges are eliminated as the blood flows through the capillary beds
  2. HOWEVER blood needs to reach the heart at a low pressure
    1. This happens using one way valves (SEMILUNAR VALVES)
      1. Blood can flow towards the heart but not away from it as the contracted muscles relax, closing the semilunar valves

Zusammenfassung der Ressource

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