The diagram given below represents the simplified pathway of the circulation of blood. Answer the questions that follow: The diagram given below represents the simplified pathway of the circulation of blood. Answer the questions that follow:
Name the blood vessels labelled 1 to 4.
Topic: Blood vessels of the circulatory pathway
Answer
1 — SUPERIOR VENA CAVA (returning deoxygenated blood from the head to the heart) 2 — AORTA / artery (carrying oxygenated blood from the heart to the body) 3 — PULMONARY VEIN (carrying oxygenated blood from the lungs to the heart) 4 — PULMONARY ARTERY (carrying deoxygenated blood from the heart to the lungs)
Work out each vessel from the DIRECTION of its arrow and the two organs it joins, rather than trying to recall a diagram.
THE TWO RULES that settle every label: a vessel leaving the heart is an ARTERY; one entering it is a VEIN anything joining the heart to the LUNGS is PULMONARY
So a vessel from heart to lungs must be the pulmonary ARTERY, and from lungs to heart the pulmonary VEIN — and these two are the great exceptions to the usual oxygen rule, since the artery here carries DEOXYGENATED blood and the vein OXYGENATED.
Remember the definition is about DIRECTION, not oxygen: an artery carries blood AWAY from the heart, a vein TOWARDS it.