Double circulation: the heart pumps to lungs and body
| English | 中文 | Pinyin |
|---|---|---|
| double circulation/ˈdʌbl ˌsɜːkjʊˈleɪʃn/ | 双循环 | shuāng xún huán |
| pacemaker/ˈpeɪsmeɪkə/ | 起搏点 | qǐ bó diǎn |
What would explain this observation?
- Blood passes through the heart twice on one complete circuit through lungs and body. The two pumps serve different destinations.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- The right ventricle pumps blood through the pulmonary artery to the lungs. Blood returns in the pulmonary vein, enters the left side of the heart and is pumped by the left ventricle into the aorta to the body. Blood returns through the vena cava to the right side. Coronary arteries supply the heart muscle itself. Valves prevent backflow; valve names are not required here.
- double circulation 双循环: Circulation with separate heart-to-lung and heart-to-body circuits; pacemaker 起搏点: A structure or device controlling the timing of heart activity.
Which vessel carries blood from the lungs back to the heart?
Air moves through trachea and bronchi to alveoli. Many alveoli provide a large area; thin walls, nearby capillaries and ventilation support gas exchange. Blood flow maintains concentration differences for oxygen entering blood and carbon dioxide leaving it. The natural resting rate is controlled by pacemaker cells in the right atrium; an artificial electrical pacemaker can correct some rhythm irregularities.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Air moves through trachea and bronchi to alveoli. Many alveoli provide a large area; thin walls, nearby capillaries and ventilation support gas exchange. Blood flow maintains concentration differences for oxygen entering blood and carbon dioxide leaving it. The natural resting rate is controlled by pacemaker cells in the right atrium; an artificial electrical pacemaker can correct some rhythm irregularities.
- Trace a labelled circulation model without confusing anatomical left/right with the viewer’s sides. Mark destination and oxygen status separately: an artery carries blood away from the heart, and its name does not guarantee high oxygen content. Use provided flow data rather than personal diagnosis.
Which two habits make the investigation or model in this case more defensible?
Trace a labelled circulation model without confusing anatomical left/right with the viewer’s sides. Mark destination and oxygen status separately: an artery carries blood away from the heart, and its name does not guarantee high oxygen content. Use provided flow data rather than personal diagnosis.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: a model heart moves 4,800 cm³ blood in 60 s. Mean flow=4,800/60=80 cm³/s. A second observation of 6,000 cm³ in 60 s gives 100 cm³/s. This compares volume per time; it does not by itself separate the effects of beat frequency and volume per beat.
A model circulation moves 3,600 cm³ in 60 s. Calculate mean flow. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A model circulation moves 3,600 cm³ in 60 s. Calculate mean flow.
The result is 60 cm³/s. Known: a model heart moves 4,800 cm³ blood in 60 s. Mean flow=4,800/60=80 cm³/s. A second observation of 6,000 cm³ in 60 s gives 100 cm³/s. This compares volume per time; it does not by itself separate the effects of beat frequency and volume per beat.
Check the conclusion and its limits
- The pulmonary artery carries blood toward the lungs and has lower oxygen content than the pulmonary vein. Coronary arteries are not the route carrying all blood into the heart chambers. An artificial pacemaker concerns electrical rhythm, not removal of every artery blockage.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Every artery carries oxygen-rich blood. This claim is false: The pulmonary artery carries blood toward the lungs and has lower oxygen content than the pulmonary vein. Coronary arteries are not the route carrying all blood into the heart chambers. An artificial pacemaker concerns electrical rhythm, not removal of every artery blockage.
Double circulation: the heart pumps to lungs and body: Air moves through trachea and bronchi to alveoli. Many alveoli provide a large area; thin walls, nearby capillaries and ventilation support gas exchange. Blood flow maintains concentration differences for oxygen entering blood and carbon dioxide leaving it. The natural resting rate is controlled by pacemaker cells in the right atrium; an artificial electrical pacemaker can correct some rhythm irregularities.
Every artery carries oxygen-rich blood.
The pulmonary artery carries blood toward the lungs and has lower oxygen content than the pulmonary vein. Coronary arteries are not the route carrying all blood into the heart chambers. An artificial pacemaker concerns electrical rhythm, not removal of every artery blockage.
Circulation with separate heart-to-lung and heart-to-body circuits: write the technical term.
double circulation means Circulation with separate heart-to-lung and heart-to-body circuits.