Science 7–10 · Year 8

Sheep heart dissection: chambers, valves and the thickness of the walls

Science understanding: Biological sciences

PracticalMedium risk

School laboratory, not for home

In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.

The idea

The structure of each part of the heart matches its job: the left ventricle wall is thickest because it pumps blood to the whole body, and one-way valves keep the flow in one direction.

Safety card

Medium riskA teacher supervises

Setting: In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.

Hazards

Sharp instruments
Raw animal tissue and its microorganisms
Slips on wet floors

Controls

Gloves and safety glasses; cuts made away from the body with scissors, scalpel work by the teacher
Tissue from a butcher, supermarket or abattoir only, kept refrigerated and used the same day
All biological material treated as contaminated; benches and boards disinfected; tissue double-bagged to the bin
Anyone who declines to dissect observes and records

Note

Animal tissue: follow the NSW Department of Education guidance on using animals in Stage 4 and 5 (dissection of whole dead animals or parts purchased from a butcher, supermarket, fish market or abattoir is a permitted teaching activity; no live animal may be acquired or bred for the sole purpose of dissection) and use the Queensland CARA biological activities guideline as a hygiene reference only; it is Queensland policy, and the permission to dissect comes from the NSW guidance. Record a RiskAssess risk assessment.

What you need

Sheep heart, one per pair, bought from a butcher or abattoir (the NSW Department of Education guidance on using animals in Stage 4 and 5 permits dissection of animal parts purchased from a butcher, supermarket, fish market or abattoir)
Dissecting board, scissors with a blunt tip, a scalpel handled by the teacher if a scalpel is used, blunt probe, forceps, ruler
Disposable gloves, safety glasses, paper towel, disinfectant spray, a lined bin for tissue

How to do it

Identify the outside features: the pointed apex, the two atria as flaps at the top, the coronary vessels on the surface, and the large vessels (aorta with its thick wall, pulmonary artery, venae cavae).
Push the probe down the aorta and note which chamber it enters.
Cut with scissors from the apex up through the left ventricle wall to the aorta; open the chamber and find the bicuspid valve with its cords (chordae tendineae) and the semilunar valve at the base of the aorta.
Make a matching cut into the right ventricle and find the tricuspid valve and the valve into the pulmonary artery.
Measure the thickness of the left and right ventricle walls with the ruler at the same height and record both.
Trace the path of blood through the heart on a diagram, naming the vessel, chamber and valve at each step.
Wrap tissue in paper, bag it and bin it; disinfect the board and bench; wash hands.

What you should see

The left ventricle wall is clearly thicker than the right; record both measurements. The probe passed down the aorta enters the left ventricle; the valves are thin flaps anchored by cords on the atrioventricular side and pocket-shaped at the artery bases. The learner knows it worked when both ventricles are open, both wall thicknesses are measured, and every valve on the diagram was seen.

What changes

This activity lists no variables to change, measure and keep the same.

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

The heart has two chambers, one for oxygenated blood and one for deoxygenated.
Valves are muscles that squeeze blood along; they are passive flaps.
The right side of the heart is weaker because it moves less blood; it pumps the same volume as the left side, but into the lungs, where the pressure and resistance are much lower than in the circuit to the body.

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

Science 7–10 Syllabus (2023)SC4-LIV-01 SC4-WS-01 SC4-WS-08
Australian Curriculum v9AC9S8U02AC9S8I03

Sources

The pages the author read to write this activity.

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