1.9 (PSIO 202)

Physical Properties of Blood and Erythrocytes

What is the order that nutrients and oxygen follow when diffusing from the blood?

blood → ISF → cells

What order does wastes move in?

cells → ISF → blood

What are erythrocytes?

red blood cells

What is plasma?

special cell fragments

What are leukocytes?

white blood cells

What are the granular leukocytes?

neutrophils, eosinophils, basophils

What are the agranular leukocytes?

lymphocytes and monocytes

What are thrombocytes?

platelets

What is the major function of platelets?

blood clotting

What is blood plasma’s composition?

>90% water, \~7% proteins, and \~2% other solutes

Where are plasma proteins created?

the liver

What proteins are present in plasma?

albumin, immunoglobulins, and fibrinogen

What is albumin?

maintains blood osmotic pressure

What are immunoglobulins?

antibodies that bind antigens; form antigen-antibody complexes

What is fibrinogen?

for clotting; precursor to fibrin, the sticky protein to form clotting network

What other solutes are present in plasma?

electrolytes, nutrients, hormones, gases and waste products

What is the normal hematocrit range in females?

38-46%

What is the normal hematocrit range in males?

40-54%

What is anemia?

not enough RBCs (or hemoglobin) for proper O2 transfer

What is polycythemia?

having an excess of RBCs; can result in dehydration, tissue hypoxia, blood doping

What is hemoglobin?

a protein that carries oxygen

What is hemoglobin composed of?

\-globins; 4 large protein chains (2 alpha 2 beta)

\-a heme group (within each chain)

What is the heme group?

a porphyrin ring that surrounds a single iron molecule

How many O2 molecules can each hemoglobin carry?

4

What does CO2 bind to in hemoglobin?

amino acids in the globin portion

What is erythropoiesis?

RBC formation

Where does erythropoiesis occur?

in the red bone marrow

What are RBCs formed from after birth?

stem cells

Stem cells differentiate into:

proerythroblasts

Proerythroblasts then become _____ __and then__ ________.

erythroblast; reticulocytes

When a reticulocyte reaches maturity, hemoglobin is produced and the nucleus is ejected, resulting in the formation of a mature __________.

erythrocyte

What is the role of hemopoietic growth factors?

regulation of differentiation and proliferation of blood cells

What are the 3 hemopoietic growth factors?

erythropoietin, thrombopoietin, and cytokines

What does erythropoietin do, and what produces it?

increases RBC precursors, produced by kidneys

What does thrombopoietin do, and what produces it?

stimulates platelet formation, produced by liver

What are cytokines and what do they do?

local hormones of bone marrow; stimulate proliferation in other marrow cells; colony-stimulating factors (CSFs) and interleukins stimulate WBC production

What is an example of a medical usage of erythropoietin?

treating decreased RBC production of end-stage kidney disease

What is an example of a medical usage of thrombopoietin?

helps prevent platelet depletion during chemotherapy

How long do RBCs live?

about 120 days

What causes RBCs to wear out?

bending to fit thru capillaries

What happens to worn out RBCs?

removed by macrophages in the spleen and liver; the globin portion is broken down into amino acids and recycled; the heme portion is split into iron and biliverdin

What happens to the iron portion of the heme of a worn down RBC?

it is transported in blood attached to protein transferrin; stored in liver, muscle, or spleen; attached to ferritin protein; transported to bone marrow for use in hemoglobin synthesis