Arteries and veins

Each kind of vessel is built for the pressure it faces. Blood leaves the heart in strong spurts, so arteries must be tough. Blood comes back slowly, so veins need help to keep it moving one way. Capillaries join the two. Their walls are one cell thick, so food and oxygen can pass through.

• Artery: thick, muscular and elastic wall; narrow space inside (the lumen); no valves.
• Vein: thin wall with less muscle; wide lumen; valves that stop blood flowing backwards.

A small example

Press two fingers on your wrist and you feel a pulse. That is an artery stretching with each beat. The blue lines on the back of your hand are veins. Press one near your knuckles with one finger. With a second finger, stroke it towards your wrist, then lift only the second finger. The stretch between stays flat, because a valve stops blood flowing back into it.

Where marks go

Question 7(iii) of the 2024 ICSE Biology paper asked for two structural differences, for 2 marks. The marking scheme in CISCE's 2024 Biology report lists the lumen, the muscle layer, elasticity and valves. The examiners call "arteries were thick and veins were thin" incorrect. Our reading: it does not say which part is thick. Answers that gave functions instead of structure lost marks.

So write each difference as a matched pair: "artery: narrow lumen; vein: wide lumen". See how to write answers that earn every mark.

About the author

Deepti Sardana

Founder Member & Academic Lead

An IIT alumna (M.Sc., M.Phil.) with over 25 years in teaching, child psychology and learning assessment. As Academic Lead at EduBrahma, she leads the method TRUtesting uses to find where and why a child loses marks.

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