Science · Suggested Class 7 · school sequences vary
“Arteries carry oxygen-rich blood” sounds tidy—until blood travels from the heart to the lungs. Name vessels by direction first, then track oxygen.
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Arteries carry blood away from the heart; veins return it. The pulmonary loop connects heart and lungs, while the systemic loop connects heart and body.
Original BananaLearn guide · 7 November 2026
On a narrow screen, swipe the diagram or open it full size.
Cells use oxygen and nutrients and produce wastes such as carbon dioxide. Blood transports materials, while the heart supplies the pressure that keeps blood moving around connected vessels.
The lungs exchange gases; the heart pumps blood. Breathing air into the lungs and circulating blood through the body are connected processes, but they are not the same movement.
The right atrium receives returning blood from the body and passes it to the right ventricle. That ventricle pumps towards the lungs. The left atrium receives blood from the lungs and passes it to the left ventricle, which pumps to the body.
Left and right are the person’s anatomical sides, not necessarily your left and right when looking at a front-view diagram. Follow labels rather than guessing from the side of the page.
Body-returning blood reaches the right atrium, then the right ventricle and pulmonary artery. In lung capillaries, carbon dioxide passes towards the air spaces and oxygen enters the blood. The pulmonary veins return blood to the left atrium.
“Oxygen-poor” means lower in oxygen relative to oxygen-rich blood, not completely oxygen-free. Diagram colours identify the relative state; actual blood is not blue.
On a narrow screen, swipe the diagram or open it full size.
From the left atrium, blood passes to the left ventricle and leaves through the aorta. Arteries branch towards body tissues. In tissue capillaries, substances exchange with the surroundings of cells. Veins then return blood to the right atrium.
A full journey through both loops passes through the heart twice. This double circulation keeps the lung and body circuits connected while their pumping paths are separated.
An artery carries blood away from the heart and a vein carries it towards the heart. These are direction definitions. Pulmonary arteries carry relatively oxygen-poor blood, and pulmonary veins relatively oxygen-rich blood.
Capillaries are very small exchange vessels connecting the arterial and venous sides of a circuit. Blood does not normally pour out of these vessels to bathe body tissues in this closed circulation model.
Heart valves help prevent backflow as pressure changes during pumping. Blood moves because of pressure differences, not because a valve actively pulls it along. Many veins, especially in limbs, also have valves.
The left ventricle pumps through the body circuit and has a thicker muscular wall than the right ventricle. This supports different pressure demands; it does not mean the two sides send unequal volumes in a normal steady circulation.
Write body → right atrium → right ventricle → lungs → left atrium → left ventricle → body. Add the major vessel names and mark where gas exchange occurs.
Check each arrow against the previous location. A route from the right ventricle directly to the aorta would skip the lungs and mix up the two circuits.
Use one paper token to represent a red blood cell and move it through labelled stations. At the lungs, change its oxygen-status label; at body tissues, show delivery and carbon-dioxide collection. This is a simplified teaching model, not a physiological measurement.
Keep the discussion about pathways and exchange. This lesson does not interpret symptoms, fitness measurements or medical conditions. For parent practice, ask the learner to explain the pulmonary exception using direction rather than reciting an isolated fact.
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Try each task before opening its explanation. These are original BananaLearn questions, not official exam or past-paper questions. Where several answers can work, the explanation gives the criteria.
Heart
The lungs perform gas exchange.
Right atrium
It precedes the right ventricle in that route.
Right ventricle
It pumps into the pulmonary artery.
Pulmonary veins
They lead to the left atrium.
Left ventricle
The aorta begins the body route.
Away from the heart
Do not define it by oxygen level.
Towards the heart
Pulmonary veins also obey this definition.
Across the lung air-space and capillary surfaces
The heart is not the site of that air–blood exchange.
No
The label describes a relative level.
Backflow
Their action follows pressure changes.
A complete lung-and-body journey passes through the heart twice
The two connected circuits have different routes.
No
Blue is often used as a diagram label.
Copy these headings and fill them for one worked task, then for a fresh attempt. Use your own evidence rather than copying the model answer.
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Original BananaLearn explanations, examples, illustrations and practice. Source facts checked 7 November 2026. Suggested levels are learning guides, not a claim that every board or textbook uses the same sequence.
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