In this IBDP Blog Post, we will look at:
- The human circulatory system
- Double circulation
- Structure of heart
- Blood flow
William Harvey's discovery and Circulatory Systems
- Bloodflow through vessels is unidirectional with valves to prevent backflow
- The heart pumps blood out of the arteries and that blood returns to the heart through veins
- Predicted that many fine vessels link arteries to veins these vessels are within the tissues of the body
Single Circulatory System - Fish
Blood passes through the heart once. Oxygenated and deoxygenated blood is mixed
Double Circulatory System - Mammals
Blood passes through the heart twice. Oxygenated and deoxygenated blood is not mixed
Heart Structure
4 major blood vessels
- Vena Cava
- Pulmonary Artery
- Pulmonary Vein
- Aorta
4 Valves
- Semilunar valve (Pulmonary Artery)
- Semilunar valve (Aorta)
- Tricuspid valve in right ventricle
- Bicuspid valve in left ventricle
Blood Flow
From the lungs oxygenated blood enters the pulmonary vein which enters the heart through the left atrium
Blood flows from the left atrium to the left ventricle through the bicuspid valve
Blood is pumped to the body via the Aorta
From the body deoxygenated blood enters the Vena Cava which enters the heart through the right atrium
Blood flows from the right atrium to the right ventricle through the tricuspid valve
Blood is pumped to the lungs via the Pulmonary Artery to be oxygenated
The Steps of Double Circulation
Pulmonary Circulation (between heart and lungs)
- Deoxygenated
blood from the heart to the lungs
- Oxygated
blood from the lungs to the heart
Systemic Circulation (between the heart and body)
- Oxygenated blood from the heart to the body
- Deoxygnated blood from the body to the heart
1. Deoxyganted blood enters the heart by the right atrium
2. Moves from the right atrium to the right ventricle and is pumped to the lungs where CO2 is offloaded and oxygen is picked up
3. Oxygenated blood enters the left atrium
2. Moves from the left atrium to the left ventricle where it is pumped to the body
3. Oxygen is used for respiration and carbon dioxide is collected as a waste product
4. The blood is now dexygenated and moves to the right atrium and the cycle starts again
That's the end of this topic, well done!
Drafted by Venetia (Biology)