9.3Transport in Animals
Blood vessels — Cambridge IGCSE Biology 0610 Revision Notes & Topical Questions
5 min read 11 parts Lesson 4 of 7 1 quiz
Lesson summary
9.3 Blood vessels — IGCSE BIOLOGY notes: Describe the structure and function of arteries, veins and capillaries and identify the main vessels of the body.Blood vessels — A system of closed tubes within which blood flows.Different directions — Different types carry blood in differ…
- Leaky walls
- Arterioles
- Hepatic artery
- Hepatic portal vein
- Hepatic vein
- Different directions — Different types carry blood in different directions and to different parts of the body
Part 1 of 9Types of blood vessel
Types of blood vessel
Blood vessels
- A system of closed tubes within which blood flows.
Different directions
- Different types carry blood in different directions and to different parts of the body.
Network
- Arteries narrow to arterioles and capillaries; capillaries widen to venules and veins.
Part 2 of 9Arteries
Direction
- Carry blood away from the heart at high pressure.
Blood
- They transport oxygenated blood, except the pulmonary artery.
Wall
- Thick and muscular with elastic fibres to withstand high pressure and maintain it as the wall recoils.
Lumen
- Narrow, which maintains high pressure.
Part 3 of 9Veins
Direction
- Carry blood towards the heart at low pressure.
Blood
- They transport deoxygenated blood, except the pulmonary vein.
Wall
- Thin compared with arteries.
Lumen
- Wide, because blood pressure is low.
Valves
- Prevent backflow of blood.
Part 4 of 9Capillaries
Capillaries
Function
- Carry blood to the cells of the tissues for exchange.
Wall
- One cell thick, so substances diffuse in and out easily.
Leaky walls
- Gaps let plasma leak out and form tissue fluid around cells.
Lumen
- Very narrow.
Part 5 of 9Vessels compared
| Feature | Artery | Vein | Capillary |
|---|---|---|---|
| Direction of flow | Away from the heart | Towards the heart | Between arteries and veins |
| Pressure | High | Low | Low |
| Wall | Thick, muscular, elastic | Thin | One cell thick, leaky |
| Lumen | Narrow | Wide | Very narrow |
| Valves | No | Yes | No |
Part 6 of 9Arterioles and venules
Arterioles
- Narrow vessels connecting arteries to capillaries.
Venules
- Narrow vessels connecting capillaries to veins.
Order
- Heart, artery, arteriole, capillary, venule, vein, heart.
Part 7 of 9Main vessels of the body
| Organ | Towards organ | Away from organ |
|---|---|---|
| Heart | Vena cava and pulmonary vein | Aorta and pulmonary artery |
| Lungs | Pulmonary artery | Pulmonary vein |
| Kidneys | Renal artery | Renal vein |
Part 8 of 9Vessels of the liver (Supplement)
Hepatic artery
- Brings oxygenated blood from the heart to the liver.
Hepatic portal vein
- Transports deoxygenated blood from the gut to the liver.
Hepatic vein
- Carries deoxygenated blood from the liver back to the heart.
Part 9 of 9More from the specification
More from the specification
Ventricle
- Lower chamber of the heart that pumps blood out.
Nucleus
- The part of the cell that controls its activities.
Circulatory system
- Blood vessels, a pump and valves transporting blood around the body.
Coronary arteries
- Blood vessels that supply the heart muscle with oxygen and glucose.
Muscle cell
- Mitochondria
Platelet
- Cell fragment involved in blood clotting.
Phagocyte
- White blood cell that engulfs and digests pathogens.
Key terms
| Term | Meaning |
|---|---|
| Artery | Vessel carrying blood away from the heart at high pressure. |
| Vein | Vessel carrying blood towards the heart at low pressure. |
| Capillary | Tiny vessel with a wall one cell thick. |
| Lumen | The space inside a blood vessel. |
| Arteriole | Narrow vessel linking an artery to capillaries. |
| Venule | Narrow vessel linking capillaries to a vein. |
| Hepatic portal vein | Vessel carrying blood from the gut to the liver. |
Avoid these mistakes
1
Saying all veins carry deoxygenated blood — the pulmonary vein carries oxygenated blood.
2
Saying all arteries carry oxygenated blood — the pulmonary artery carries deoxygenated blood.
3
Giving arteries valves — valves are in veins.
4
Saying veins have narrow lumens — veins have wide lumens and arteries have narrow ones.
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