Lecture 5 – The RBC structure and function

Question 1

RBC Structure (6)

Answer 1

• RBC- unique amongst eukaryotic cells.
 Lacks nucleus, mitochondria and ER.
 it is essentially a “bag of haemoglobin
• Biconcave, 8-micron cells, but able to deform & pass through 3-micron capillaries or reticuloendothelial system without fragmentation.
• Its biconcave shape maximises the surface area to increase efficiency of oxygen absorption.
• Structural properties are linked to membrane.
• Have flexible membrane with a high surface-to-volume ratio.
• High surface to vol ratio that facilitates large reversible elastic deformation of the RBC as it repeatedly passes through small capillaries of 3um size during microcirculation

Question 2

Functions of the red cell membrane (5)

Answer 2

o	Maintenance of cell volume
	Na+ and K+ content 
	Osmotic fragility
o	Ca+2 Homeostasis
o	Anion exchange

Question 3

Factors affecting red cell deformability (4)

Answer 3

o Cytoplasmic viscosity
o Intracellular rubbish
o Membrane rigidity
o Surface area to volume ratio