Transport In Humans: Heart
11.3 Blood Vessels
Main Blood Vessels To/From Organs
- Heart → Aorta (away), Vena cava (to).
- Lungs → Pulmonary artery (away, deoxygenated), Pulmonary vein (to, oxygenated).
- Liver → Hepatic artery (oxygenated), Hepatic vein (to heart), Hepatic portal vein (from intestines).
- Kidneys → Renal artery (oxygenated blood in), Renal vein (blood out).
Structures Of Blood Vessels
| Vessel | Wall Thickness | Lumen Size | Valves | Function |
|---|---|---|---|---|
| Artery | Thick, muscular, elastic | Narrow | No | Carry blood away from heart at high pressure |
| Vein | Thin wall | Wide | Yes | Return blood to heart at low pressure |
| Capillary | One cell thick | Very narrow | No | Exchange of substances between blood and tissues |
Written And Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change O Level And IGCSE Biology Full Scale Course
Adaptations Linked To Blood Pressure
- Arteries: Thick elastic walls withstand high pressure, recoil to maintain flow.
- Veins: Valves prevent backflow, rely on skeletal muscle contractions.
- Capillaries: Thin walls (one cell thick) allow fast diffusion of gases and nutrients.
Key Points To Remember
- All arteries carry oxygenated blood except pulmonary artery.
- All veins carry deoxygenated blood except pulmonary vein.
- Capillaries connect arteries to veins and enable exchange with tissues.
Written And Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change O Level And IGCSE Biology Full Scale Course