Humans have a double, closed circulatory pathway. This means that the blood is enclosed in
vessels and goes two ways throughout the heart.
The circulatory system is divided into 2 parts:
- Pulmonary circulatory system: carries blood from lungs to heart and back
- Systemic circulatory system: carries blood from heart to body/organs and back
The heart is divided into 2 distinct sections:
- Deoxygenated (low-oxygen) partition
- Oxygenated partition
Arteries
- Arteries carry blood away from the heart
- Oxygen rich
- Blood in arteries are a lighter red due to the oxygen amount
- Cell walls are 3 layers thick
Tip! : Think “A” for Away from heart
Veins
- Veins carry blood to the heart
- Oxygen poor / deoxygenated
- Blood in veins are a deeper red due to lack of oxygen
- Walls are thin but are also 3 layers thick