Question

The diameter of human red blood cells is

• A. 15 $\mu m$
• B. 8.2 $\mu m$
• C. 2 $\mu m$
• D. 50 $\mu m$

Answer 1

The correct option is B 8.2 $\mu m$

Red blood cells, also known as RBCs, red cells are the most common type of blood cell and the vertebrate's principal means of delivering oxygen (O2) to the body tissues—via blood flow through the circulatory system.[2] RBCs take up oxygen in the lungs, or gills of fish, and release it into tissues while squeezing through the body's capillaries. The cytoplasm of erythrocytes is rich in hemoglobin, an iron-containing bio-molecule that can bind oxygen and is responsible for the red color of the cells and the blood. The cell membrane is composed of proteins and lipids, and this structure provides properties essential for physiological cell function such as deformability and stability while traversing the circulatory system and specifically the capillary network. A typical human red blood cell has a disk diameter of approximately 6.2–8.2 µm and a thickness at the thickest point of 2–2.5 µm and a minimum thickness in the centre of 0.8–1 µm, being much smaller than most other human cells. These cells have an average volume of about 90 fL[17] with a surface of about 136 μm2, and can swell up to a sphere shape containing 150 fL, without membrane distension.

So the correct option is '8.2 µm'.