Quotes from Dee Unglaub Silverthorn

The common embryological origin of the endothelium and blood cells perhaps explains why many cytokines that control hematopoiesis are released by the vascular endothelium.

What is even more remarkable is the fact that as late as 1923, an American medical textbook advocated bleeding for treating certain infectious diseases, such as pneumonia!

There are several isoforms of globin proteins in hemoglobin. The most common isoforms are designated alpha (a), beta (b), gamma (g), and delta (d), depending on the structure of the chain. Most adult hemoglobin (designated HbA) has two alpha chains and two beta chains, as shown. However, a small portion of adult hemoglobin (about 2.5%) has two alpha chains and two delta chains (HbA2 ).

The presence of proteins in the plasma makes the osmotic pressure of the blood higher than that of the interstitial fluid. This osmotic gradient tends to pull water from the interstitial fluid into the capillaries and offset filtration out of the capillaries created by blood pressure

Although blood synthesis in adults is limited, the liver, spleen, and inactive (yellow) regions of marrow can resume blood cell production in times of need.

White blood cells are the only fully functional cells in the circulation. Red blood cells have lost their nuclei by the time they enter the bloodstream, and platelets, which also lack a nucleus, are cell fragments that have split off a relatively large parent cell known as a megakaryocyte {mega, extremely large + karyon, kernel + -cyte, cell}.

Erythropoietin is usually called a hormone, but technically it fits the definition of a cytokine because it is made on demand rather than stored in vesicles.

In adults, the only areas producing blood cells are the pelvis, spine, ribs, cranium, and proximal ends of long bones.