Question

3. The figures given below show diagrammatic cross-sections of three kinds of blood vessels. (4)
(a) Identify the blood vessels A, B and C.
(b) Name the parts labeled 1-4.
C
(c) Mention two structural differences between A and B.
(d) Name the kinds of blood that flow through A and through B respectively.​

Answer 1

Explanation:

(a)

A represents Artery

B represents Vein

C represents Capillary

(b)

1 represents the External layer made of connective tissue

2 represents Lumen

3 represents the Middle layer of smooth muscles and elastic fibres

4 represents Endothelium

(c)

Arteries (A)

1. Progressively branched, decreasing in

size.

2. Smallest artery breaks into arterioles.

3. Have thick and more muscular walls.

Veins (B)

1. Progressively unite increasing in size.

2. Smallest vein arises from venules.

3. Have thin and less muscular walls.

(d)

Arteries A carry fully oxygenated blood and Veins B carry partially deoxygenated and CO

2

laden blood.

(e)

At the capillary level the actual exchange of gases takes place.