Physiology: hemoglobin, erythrocytes and lymphoid tissue

Components of blood

Plasma (55%) : protein solution in water (90% water, 8% protein)

Buffy coat (<1%): platelets and cells of immunity

Hematocrit (45%): erythrocytes which contain iron that provides the density

Formed element vs. true cell

FORMED ELEMENTS (don't have cellular machinery [nucleus, ER, ribosomes, etc.] anymore) vs TRUE CELLS (have cellular machinery)

True cells: cells of the immune system (we will become very familiar with immune cells soon)

Formed elements: platelets, erythrocytes

all blood cells and formed elements are made where?

red bone marrow

​​What’s in the buffy coat?

macrophages (true cells), granulocytes (true cells), B & T lymphocytes (true cells), platelets (formed elements!)

Development of erythrocytes

​​Hematopoietic stem cell → proerythrocytes → normoblasts → reticulocytes → erythrocytes.

Normoblast dispose of or eject nucleus (they are last cell in series that makes protein)

Reticulocyte: flecks of remnant ER

• effect of nonsteroidal antiinfammatories affect mucous layer in stomach by reducing it, they break down epithelial cells leading to break down of blood vessel. Long term use causes anemia. Signs seen in large quanity of reticulocytes

Oxygenation

​​Because the only force pushing oxygen is diffusion, we need very short travel distance.

concentration of O2 flows downward and binds to iron in heme. Depend on short distance

pneumonia is build up of fluid in alveolar sac that increases diffusion distance

Hemoglobin

4 subunits called globin chains

​​There are 2 alpha chains and 2 beta chains

each chain contains an iron atom in a porphyrin ring

​​the iron has a slight positive charge, which gives it the ability to bind to the slight negative charge of an oxygen molecule

Fate of erythrocytes

must be replaced every 90-120 days because they cannot regenerate tthei rprotein

They are degreded in the spleen. splenic vein: takes blood out of the spleen

Red pulp: Macrophages in the RED PULP of the spleen check the oxidation status of the glycosylated (sugar-tagged) transmembrane proteins on erythrocytes. Older erythrocyte = more oxidized proteins

Polyphyrin ring NOT recycleable. Moves out small intest as biliverden and bilirubin

Hormonal control of erthrocyte production

Kidneys recieve 20-25% of oxygenated blood leaving L ventricle

pericytes in kidneys monitor oxygen levels. Lower o2 levels trigger secretion of ERYTHROPOIETIN (protein hormone heavily glycosylated)

Receptor tyr kinase bind EPO. This increases proerythrocyte surivival and proerthrocyte rate of division, thus increasing erythrocyte production

Erythropoietin as a drug

first developed for patients in renal failure to stimulate production of EPO.

Stitched gene in humans that produces EPO into hamster ovary cells to mass produce EPO.

Lance armstrong caught