The Blood

Question 1

List the constituents of plasma.

Answer 1

Plasma proteins (7%)
electrolytes
nutritients
waste products
hormones
gases

Question 2

Define Pluripotent stem cells.

Answer 2

Cells capable of developing into any one of no. of cell types, and all blood cells develop from this.

Question 3

How is erythrocytes’ shape suited to their function?

Answer 3

The biconcavity increases their surface area for gas exchange and the thin central portion allows fast entry & exit of gases.

Question 4

Describe the structure of hemoglobin.

Answer 4

It is a large complex molecule containing a globular protein(globin) and a pigmented iron containing complex called haem. Each hemoglobin molecule contains 4 globin chains and 4 haem units, each with one atom of iron.

Question 5

Explain the mechanism of destruction of erythrocytes.

Answer 5

• Ageing erythrocytes are extracted from the circulation by macrophages in the spleen, liver, and bone marrow & broken down (hemolyzed) under controlled conditions.
• Iron released by hemoglobin breakdown is returned to the bone marrow for ongoing hemoglobin synthesis.
• The haem part of the hemoglobin is broken down to the green pigment biliverdin, which in turn is almost completely reduced to the yellow pigment bilirubin, before being bound to plasma globulin and transported to liver.
• In the liver bilirubin is converted from a fat soluble to a water soluble form to be excreted in bile.