Practical: Heart Dissection (SQA National 5 Biology): Revision Note

Observing structures in the heart

• It is possible to dissect parts of organisms, e.g. the heart, to better understand form and function

• Dissecting the mammalian heart allows us to observe chambers, valves, and associated vessels

Apparatus

• Dissection board

• Scalpel

• Dissecting scissors

• Forceps / tweezers

• Pins

• Mounted needle

• Biological specimen, e.g. pig or sheep heart

• Disinfectant and disposal container

Method

1. Place the specimen on a dissection board with the front facing upwards

   • The front of the heart can be identified by the location of the coronary arteries, which cross the front of the heart between the left and right ventricles as shown in the image above

2. Observe external features that are visible, e.g.:

   • coronary arteries

   • fatty deposits

   • left and right atria; these are small flaps at the top of the heart

   • some of the major blood vessels, e.g. aorta, pulmonary artery

3. Make two vertical cuts through the centre of the left and right ventricles and atria

   • This may be easier to accomplish using scissors than a scalpel

4. Use forceps, fingers or a mounted needle to gently open out the muscle tissue

5. Pin back the outer sides of the ventricles to expose internal features

6. Identify the following internal structures:

   • left and right ventricle walls; you should be able to compare the muscle thickness

   • the thin muscle walls of the atria

   • the septum

   • atrioventricular valves

   • the entrances to the major blood vessels

Safety

• Care should be taken during dissection practical work, including:

  • safety, e.g.:

    • a lab coat, gloves, and eye protection should be worn to avoid contamination with biological material

    • sharp, clean blades should be used for ease and accuracy of cutting

    • scalpel blades should cut away from the body

    • fingers should be kept away from the blade edges

  • responsible use of biological materials

    • Any biological specimen used for dissection should be from a reputable source and should be disposed of in the correct manner