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Heart structure & double circulation

Science · Organisms & Life Processes · ages 12-13

Name ______________________ Date ____________

What is the job of the atria?
- To pump blood into the outgoing arteries
- To receive blood entering the heart
- To prevent blood from entering the heart
Which chamber receives blood coming in from the body through the vena cava?
- Right atrium
- Left atrium
- Right ventricle
The heart has four chambers: two atria and two ventricles.
Circle one: True False
The left ventricle squeezes and pressure inside it rises sharply. What happens to the working valve between the left atrium and left ventricle?
- It closes to prevent blood returning to the atrium
- It opens so blood can return to the atrium during the squeeze
- It stays open so blood can flow freely in both directions
Trace blood from the right ventricle through the lungs and body back to that ventricle. Which list puts the main stops in order?
- Lungs, right atrium, right ventricle, aorta, body, left atrium, right ventricle
- Lungs, left atrium, left ventricle, body, aorta, right atrium, right ventricle
- Lungs, left atrium, left ventricle, aorta, body, right atrium, right ventricle
Compared with veins and capillaries, which type of blood vessel has thicker muscular walls to handle blood pumped from the heart?
- Vein
- Artery
- Capillary
The valve between the right atrium and right ventricle fails to close properly. What is most likely to happen when the ventricle squeezes?
- Blood is diverted directly from the right ventricle to the aorta
- All forward blood flow through the pulmonary arteries must stop
- Some blood flows backward into the right atrium
A student calls the route 'single circulation' because blood returns to its starting point. Which feature shows that it is double circulation?
- Blood passes through the heart twice per complete trip.
- Blood goes through the lungs twice before returning to the body.
- Blood travels to the body without returning to the heart between loops.

Answer key

For grown-ups. Fold this page away before handing over the rest.

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To receive blood entering the heart · Atria receive blood entering the heart and help move it into the ventricles. Ventricles pump blood into the outgoing arteries.
Right atrium · The venae cavae return blood from the body to the right atrium. Blood then passes into the right ventricle.
True · Each side has one atrium and one ventricle. Together, the two sides have two atria and two ventricles.
It closes to prevent blood returning to the atrium · When ventricular pressure rises above atrial pressure, the valve closes. This prevents blood being pushed back into the left atrium.
Lungs, left atrium, left ventricle, aorta, body, right atrium, right ventricle · The right ventricle sends blood to the lungs. It returns to the left atrium, enters the left ventricle and leaves through the aorta for the body. Body blood returns to the right atrium, then the right ventricle.
Artery · Arteries carry blood away from the heart. Their thicker muscular, elastic walls withstand higher pressure than veins.
Some blood flows backward into the right atrium · An incompletely closed valve leaves a route back into the right atrium. Some blood can flow backward while other blood still flows toward the lungs.
Blood passes through the heart twice per complete trip. · Returning to a starting point makes a route a loop. It is double circulation because one complete trip includes a passage through the right side of the heart and a passage through the left side.