Edexcel iGCSE Biology-3.19 Circulatory System: General Structure- Study Notes- New Syllabus
Edexcel iGCSE Biology-3.19 Circulatory System: General Structure- Study Notes- New syllabus
Edexcel iGCSE Biology-3.19 Circulatory System: General Structure- Study Notes -Edexcel iGCSE Biology – per latest Syllabus.
Key Concepts:
3.19 understand the general structure of the circulation system, including the blood vessels to and from the heart and lungs, liver and kidneys
The Circulatory System – General Structure
📝 Introduction
Humans have a double circulatory system:
- Pulmonary circulation → between heart and lungs.
- Systemic circulation → between heart and rest of body.
This ensures blood is pumped at high pressure to body organs and efficient gas exchange in lungs.
🔄 Pathways of Blood
1. Heart & Lungs (Pulmonary Circulation)
- Pulmonary artery → carries deoxygenated blood from right ventricle → lungs.
- In lungs → gas exchange (CO₂ out, O₂ in).
- Pulmonary vein → carries oxygenated blood back to left atrium.
2. Heart & Body Organs (Systemic Circulation)
- Aorta → carries oxygenated blood from left ventricle → all body tissues.
- Vena cava (superior & inferior) → returns deoxygenated blood from body → right atrium.
3. Heart & Liver (Hepatic Circulation)
- Hepatic artery → oxygenated blood from aorta → liver (supplies energy for liver cells).
- Hepatic portal vein → carries nutrient-rich blood from small intestine → liver (for processing & storage).
- Hepatic vein → returns blood from liver → vena cava.
4. Heart & Kidneys (Renal Circulation)
- Renal arteries → oxygenated blood from aorta → kidneys (for filtration of wastes, urea removal).
- Renal veins → return deoxygenated, filtered blood → vena cava.
📊 Summary Table
| Organ Connection | Artery (to organ) | Vein (from organ) | Function |
|---|---|---|---|
| Lungs | Pulmonary artery | Pulmonary vein | Gas exchange (O₂ in, CO₂ out) |
| Body (general) | Aorta | Vena cava | Transport O₂, nutrients, wastes |
| Liver | Hepatic artery & hepatic portal vein | Hepatic vein | Supplies O₂, processes nutrients |
| Kidneys | Renal artery | Renal vein | Filtration of blood, removal of urea |
⚡ Quick Recap
Double circulation: Pulmonary (heart ↔ lungs) + Systemic (heart ↔ body).
Pulmonary artery: only artery with deoxygenated blood.
Pulmonary vein: only vein with oxygenated blood.
Liver: gets blood via hepatic artery & portal vein → sends out via hepatic vein.
Kidneys: renal arteries in, renal veins out.