Red Blood Cells

RBC Physiology

-Red blood cells contain hemoglobin, which contains four iron-binding heme groups. -Oxygen binds the heme groups of hemoglobin. Each hemoglobin molecule can bind four oxygen molecules. -The binding affinity of hemoglobin for oxygen is cooperative. It is increased by the oxygen saturation of the molecule. Binding of an initial oxygen molecule influences the shape of the other binding sites. This makes binding more favorable for additional oxygen molecules. -Each hemoglobin molecule contains four iron-binding heme groups which are the site of oxygen binding. Oxygen-bound hemoglobin is called oxyhemoglobin. -Red blood cells alter blood pH by catalyzing the reversible carbon dioxide to carbonic acid reaction through the enzyme carbonic anhydrase. -pH is also controlled by carbon dioxide binding to hemoglobin instead of being converted to carbonic acid

RBC Anatomy

-The biconcave shape allows RBCs to bend and flow smoothly through the body's capillaries. It also facilitates oxygen transport. -Red blood cells are considered cells, but they lack a nucleus, DNA, and organelles like the endoplasmic reticulum or mitochondria. -Red blood cells cannot divide or replicate like other bodily cells. They cannot independently synthesize proteins. -The blood's red color is due to the spectral properties of the hemic iron ions in hemoglobin. -Each human red blood cell contains approximately 270 million hemoglobin biomolecules, each carrying four heme groups to which oxygen binds.

Hemoglobin

-gives blood red color -transports carbon dioxide

Hemoglobin count

14-18 grams per deciliter for men; 12-15 grams per deciliter for women

RBC count

4.7-6.1 million cells per microliter for men; 4.2-5.4 million for women

Hematocrit count

42-50%