Question 1

What is blood made of?

Accepted Answer

Blood is a fluid connective tissue composed of plasma and formed elements. Plasma is the colourless matrix, while the formed elements include red blood corpuscles, white blood corpuscles and platelets.

Question 2

Are red blood cells round discs with a hole in the middle?

Accepted Answer

Red blood cells are biconcave discs: they are thinner in the centre and thicker towards the edge. They are solid cells rather than empty rings, and mature human RBCs do not contain a nucleus.

Question 3

How are platelets different from white blood cells?

Accepted Answer

White blood cells are larger nucleated cells involved in immune defence. Platelets are much smaller membrane-bound cell fragments, not cells containing smaller fragments, and they are essential for blood coagulation.

Question 4

Where are ABO antigens and antibodies found?

Accepted Answer

A and B antigens are located on the red-cell surface. Their corresponding anti-A and anti-B antibodies are found in plasma: group A has anti-B, group B has anti-A, group O has both, and group AB has neither.

Question 5

What does Rh-positive mean?

Accepted Answer

Rh-positive red cells carry the D antigen, while Rh-negative red cells lack it. An Rh-negative person can form anti-D after exposure to Rh-positive blood, and those antibodies can agglutinate Rh-positive cells on a later exposure.

Blood & Blood Groups — Plasma, Formed Elements, ABO and Rh in 3D

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