Required practical 5 Heart dissection
Laura Armstrong
Teacher
Recall Questions
This topic requires prior knowledge of heart structure. You can test your knowledge on this below.
Name the four chambers of the heart and state their functions.
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Right atrium: Receives deoxygenated blood from the body.
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Right ventricle: Pumps deoxygenated blood to the lungs.
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Left atrium: Receives oxygenated blood from the lungs.
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Left ventricle: Pumps oxygenated blood around the body.
Why is the left ventricle wall thicker than the right ventricle wall?
The left ventricle has a thicker muscular wall because it pumps blood at a higher pressure to deliver oxygenated blood to the entire body, whereas the right ventricle only pumps blood to the lungs at lower pressure.
What is the function of the coronary arteries?
Coronary arteries supply the heart muscle with oxygenated blood and glucose to allow aerobic respiration, providing energy for contraction.
Topic Explainer Video
Check out this @LauraDoesBiology video that explains practical 5 heart dissection or read the full notes below. Once you've gone through the whole note, try out the practice questions!
Purpose of the Practical
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To examine and dissect a mammalian heart to observe the internal and external structures.
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To identify key features such as the atria, ventricles, valves, and major blood vessels.
Heart Dissection Procedure
1. External Examination
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Identify the left and right sides of the heart by feeling for the thicker left ventricle.
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Locate major blood vessels:
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Aorta (largest artery, carries oxygenated blood).
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Pulmonary artery (carries deoxygenated blood to the lungs).
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Vena cava (returns deoxygenated blood to the heart).
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Pulmonary vein (brings oxygenated blood from the lungs).
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Identify coronary arteries, which supply the heart muscle with blood.
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2. Internal Examination
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Use a scalpel to make a longitudinal cut along the left and right ventricles.
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Observe the thicker muscular wall of the left ventricle.
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Identify valves: the atrioventricular valves (tricuspid and bicuspid) and the semi-lunar valves. Their role is to prevent backflow of blood and maintain the unidirectional flow of blood.
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Look for the tendinous cords (chordae tendineae), which prevent valves from inverting.
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Risk Assessment
|
Hazard |
Risk |
Control Measures |
|---|---|---|
|
Scalpel |
Cuts from the blade |
Always cut on a hard surface, for example, cut on a dissection board. Cut with blade facing away from fingers. Make sure the blade is sharp. |
|
Raw Heart Tissue |
Contamination with pathogens |
Wear gloves, wash hands after handling with antibacterial hand wash, disinfect all surfaces. |
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Blood and Fluids |
Biohazard risk |
Dispose of waste properly, avoid contact with eyes/mouth |
No answer provided.
Completing a Biological Drawing
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No colouring or shading
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Sharp pencil
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Outline only
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No sketchy lines or hanging lines
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Labelled correctly
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Ruled label lines that do not cross over with no arrow heads
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Relative sizes of structure should be accurate
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Drawn to scale or an indication of size/magnification
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Explanatory Title
Key Terms
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Aorta: The largest artery that carries oxygenated blood from the heart to the body.
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Vena Cava: The large vein that returns deoxygenated blood to the heart.
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Valves: Structures that prevent the backflow of blood.
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Chordae Tendineae: Fibrous cords that prevent valve inversion.
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Coronary Arteries: Supply oxygenated blood to the heart muscle.
No answer provided.
Exam Tip
When completing a risk assessment- always give risks specific to the practical. Avoid giving general laboratory practices such as wearing googles and tie long hair back.
No answer provided.
Give two safety precautions that should be followed when dissecting a heart. (2 marks)
Accept any two suitable safety precautions for 1 mark, eg;
Use a sharp scalpel/scissors
Wash hands/wear gloves
Disinfect bench/equipment
Cover any cuts
Cut away from self/others/on a hard surface
Safe disposal of tissue
Ignore take care with scalpel/scissors or keep away from fingers
Ignore goggles
(Total: 2 marks)
Explain how the atrioventricular valves maintain a unidirectional flow of blood. (2 marks)
1. Pressure in atrium is higher than in ventricle causing valve to open
OR
When pressure above the valve is higher than below the valve it opens
2. Pressure in ventricle is higher than in atrium causing valve to close
OR
When pressure below the valve is higher than above the valve it closes
Practice Question
Try to answer the practice question from the TikTok on your own, then watch the video to see how well you did!