Locate atrioventricular and semilunar valves
Identify both valve categories in a mammalian-heart schematic.
Section 9.2 · Heart
Extended only (Supplement); Biology 0610, 2026–2028. Use the stated specimen features and evidence. Diagrams are schematic. Written practice is self-checked
Before you begin
- Recall chambers, arteries and one-way valves.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What does atrioventricular identify?
What you will learn
- Atrioventricular valves lie between receiving and pumping chambers
- Semilunar valves lie at the ventricular exits
Atrioventricular valves lie between receiving and pumping chambers
Atrioventricular means between an atrium and a ventricle. The right atrioventricular valve lies between the right atrium and right ventricle; the left lies between the left atrium and left ventricle. Their role is to prevent ventricular blood moving backwards into the atria when ventricles contract.
In the supplied front-view model, G marks the right atrioventricular valve. A matching flap is between C and D on the anatomical left. The right valve is also called tricuspid and the left mitral or bicuspid; recognising category and position is the key syllabus requirement.
Semilunar valves lie at the ventricular exits
Semilunar valves lie where blood leaves each ventricle into its artery. H marks the pulmonary semilunar valve on the right-ventricular exit towards the pulmonary artery. I marks the aortic semilunar valve on the left-ventricular exit towards the aorta.
They prevent artery blood flowing back into ventricles when ventricular pressure falls. Do not put them between the atria and ventricles or at the vein entrances to atria. The diagram is deliberately schematic: category and connection matter more than an imagined identical valve shape.
Pause and explain
Which category is H at the pulmonary artery exit?
Worked example
Classify a flap between an atrium and ventricle and a valve at an arterial exit.
Show the worked solution
- The chamber junction is atrioventricular.
- The ventricle-to-artery junction is semilunar.
Answer Atrioventricular at the atrium–ventricle junction; semilunar at the ventricular arterial exit.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Classify G, H and I in the model.
Give me a hint
Use junction versus arterial exit.
Compare my reasoning
- G lies between right atrium and right ventricle.
- H/I lie at pulmonary and aortic exits.
G atrioventricular; H pulmonary semilunar; I aortic semilunar.
Look for these in your work
- Correct categories
- Identify both semilunar exits
Describe the two positions where atrioventricular valves occur.
Give me a hint
There is one between the atrium and ventricle on each side.
Compare my reasoning
- Right atrium–right ventricle junction.
- Left atrium–left ventricle junction.
Between right atrium/right ventricle and between left atrium/left ventricle.
Look for these in your work
- Identify both sides
- Retain chamber-junction position
A diagram puts a semilunar valve between left atrium and left ventricle. Correct the label and state where an aortic semilunar valve belongs.
Give me a hint
Separate chamber junction from artery exit.
Compare my reasoning
- Left atrium–ventricle has an atrioventricular valve.
- Aortic semilunar belongs between left ventricle and aorta.
Relabel the chamber-junction valve atrioventricular; place aortic semilunar at the left-ventricular exit to the aorta.
Look for these in your work
- Correct the misplaced category
- Give the aortic exit position
Common mistakes
- Calling every valve atrioventricular.
- Placing semilunar valves at venous entrances to atria.
What can you explain now?
Which category is H at the pulmonary artery exit?
Compare with the explanation
Semilunar
H lies between right ventricle and pulmonary artery.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Locate both categories without relying on the names tricuspid or mitral.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.