Purpose and equipment
A mammalian heart can be opened to examine its chambers, valves and connected vessels directly and relate visible anatomy to function.
Suitable apparatus includes:
- dissection board
- scalpel
- dissecting scissors
- forceps or tweezers
- pins
- mounted needle
- a mammalian heart specimen, such as a pig or sheep heart
- disinfectant and a suitable disposal container
Safety
- Use a lab coat, gloves and eye protection to limit contact with biological material.
- Direct cuts away from yourself when using a scalpel or scissors.
- Keep hands clear of the cutting path while using sharp instruments.
Method
- Orient the heart with its anterior surface uppermost. Coronary arteries running across the front between the ventricles can be used to identify this surface.
- Inspect the outside before cutting. Look for coronary arteries, fatty tissue, the small atrial flaps at the top, and visible major vessels such as the aorta and pulmonary artery.
- Make two vertical cuts, one through each side of the heart, passing centrally through the atrium and ventricle on that side. Scissors may be easier to control for these cuts than a scalpel.
- Gently separate the cut surfaces using forceps, a mounted needle or your fingers so that the internal cavity can be seen.
- Use pins to hold the opened ventricular walls back and keep the internal structures exposed.
- Identify the left and right ventricular walls, the thinner atrial walls, the septum, atrioventricular valves and the openings leading into the major vessels.
Exam Tip: In a dissection-method answer, name the instruments used and explain what the cutting and opening steps expose. For example, scissors can open the chamber wall and forceps can help separate tissue so internal structures can be identified.