Blood is pumped around the body. In mammals, it transports oxygen, carbon dioxide, nutrients and urea. Hormones, antibodies and many other substances are also transported by blood. Even heat is. 💖 💖 💖
In I/GCSE Biology, unicellular organisms don’t need this function as they can obtain oxygen from the surface membrane of the cell. The cell’s surface area determines how much oxygen the organism can get, and the volume of the cell determines how much oxygen the organism uses.
Ratio of supply to demand = surface area/volume
One of the main functions of a circulatory system in animals is to transport oxygen. Blood is pumped to a gas exchange organ to load oxygen. It is then pumped to other parts of the body where the oxygen can be used. There are two main types of circulatory systems:
- Single Circulatory Systems: Blood is pumped from the heart to the gas exchange organ and then directly back to the rest of the body.
- Double Circulatory Systems: Blood is pumped from the heart to the gas exchange organ, back to the heart and then to the rest of the body. We have this system. You not included.
👇👇There are two distinct parts to a double circulation: 👇👇
- Pulmonary Circulation: Blood is circulated through the lungs where it is oxygenated.
- Systemic Circulation: Blood is circulated through other parts of the body. A double circulatory system is more efficient because the heart pumps blood twice, so higher pressures can be maintained. The blood travels more quickly to organs.
How Blood Circulation Works? 🩸
- The pulmonary artery carries blood to the lungs where it gets oxygenated. The pulmonary veins carry it back to the heart.
- Blood enters the left atrium, then down to the left ventricle and up to the aorta, where it leaves the heart and goes to the body.
- Deoxygenated blood from the body goes back to the heart through the vena cava and enters the right atrium and ventricle, where it then leaves the heart through the pulmonary artery and so on.
The human circulatory system comprises of:
- The heart – The blood pumper.
- Blood vessels – These carry blood around the body; arteries carry blood away from the heart and towards other organs. Veins do the opposite and capillaries carry blood through organs.
- Blood– The transport medium. The red thing that comes out of a wound when you cut yourself. In girls, it comes out automatically every month.
That's the end of the topic!
Drafted by Joey (Biology)