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72 Cards in this Set
- Front
- Back
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What is another name for red blood cells?
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erythrocytes
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what is the major function of red blood cells?
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to transport hemoglobin
which in turn, carries oxygen from the lungs to the tissues without being inside hemoglobin, only 3 percent would be able to leak into the tissues |
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Besides carrying hemoglobin, what is another function red blood cells?
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They contain carbonic anhydrase
(an enzyme that catalyzes the reversible reaction b/w carbon dioxide (CO2) and carbonic acid (H2CO3) increasing this rate makes it possible to transport enormous quantities of CO2 in the form of bicarbonate ion from the tissues to the lungs |
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What is the mean diameter and thickness of a RBC?
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7.8 micrometers in diameter
2.5 micrometers at the thickest point (1 micrometer less in the center) |
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What is the average volume of a RBC?
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90-95 cubic micrometers
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What is the average number of RBC's per cubic millimeter in women and in men?
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women: 4,700,000
men: 5,200,000 (plus/minus 300,000) *people living at greater altitudes have greater numbers of RBC's |
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What is the normal hematocrit percentage?
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40-45%
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What is the average quantity of hemoglobin in men and women?
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men: 15g / 100 mililiters of cells
women: 14g / 100 mililiters of cells |
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How much oxygen combines with one gram of hemoglobin?
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1.43ml of oxygen
20 ml of oxygen can be carried in 100 mililiters of blood in a man 19ml in women |
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during early weeks of embryonic life, where are red blood cells produced?
during middle trimester? last month of gestation and after birth? |
yolk sac
liver (main organ) spleen lymph nodes bone marrow |
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All bones produces red blood cells until what age?
in adult life, where are rbc's produced? |
5
membranous bones such as vertebrae, sternum, ribs, and ilia |
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What is the stem cell that gives rise to red blood cells?
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pluripotential hematopoietic stem cell
(as with all leukocytes) |
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What is a "colony-forming-unit" cell?
(CFU) |
A committed cell, that if grown in a dish, will produce a colony of a particular cell
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Growth and production of different stem cells are controlled by multiple proteins called growth inducers. What is the one that promotes growth and reproduction of all types of committed stem cells
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interleukin-3
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What is the function of differentiation inducers?
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each of these causes one type of of committed stem cells to differentiate one or more steps toward a final adult cell
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What is the first cell that can be identified as belonging to the red blood cell series?
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proerythroblast
(formed from CFU-E) |
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Describe the stages in erythrocyte formation.
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Proerythroblast
basophil erythroblast polychromatophil erythroblast orthochromatic erythroblast Reticulocyte Erythrocyte In succeeding generations, the cells become filled with hemoglobin |
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What is a reticulocyte?
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Stage in development of RBC.
contains small amounts of basophilic material which normally disappears within a couple of days (remnants of Golgi, mitochondria, and a few other cytoplasmic organelles) During this stage, the cell passes from the bone marrow into the blood capillaries via diapedesis |
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What is diapedesis?
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When a cell squeezes through small openings in the capillary membrane
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What is the most essential regulator of red blood cell production?
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tissue oxygenation
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What happens to red blood cells concentration in high altitudes?
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oxygen in the air is decreased, so insufficient oxygen is transported to the tissues
Red cell production is increased |
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Why would lung disease or cardiac failure increase read blood cell production?
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because tissue hypoxia would result in both of these condition
lung disease: failure of oxygen to be absorbed by the blood hear failure: decrease tissue blood flow tissue oxygenation controls red blood cell production |
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What is the circulating hormone that stimulates rbc production in low oxygen states?
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erythropoietin
(a glycoprotein) 90% formed in the kidneys 10% in liver in the absence of erthropoietin, hypoxia has little or no effect on rbc production |
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What transcription factor increases erythropoietin synthesis?
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hypoxia-inducible factor-1 (HIF-1)
it binds to hypoxia response element residing in the erythropoientin gene, inducing transcription of mRNA |
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How is norepinephrine, epinephrine, and prostaglandins related to rbc production?
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they stimulate erythropoietin
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Why would a person who has had both kidneys removed be anemic?
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because 10% of erythpoietin formed by the liver is an insufficient amount to make red blood cells needed
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In an atmosphere with low oxygen, when had the production of erythropoietin reached it's maximum?
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within 24 hours
*yet almost no new red blood cells appear until 5 days later |
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What are the 2 vitamins that are important for final maturation of a red blood cell?
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vitamin B12 and folic acid
required for formation of thymidine triphosphate, one of the essential building blocks of DNA |
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What is a macrocyte?
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an abnormally large rbc due to lack in vitamin B12 and/or folic acid
they have a flimsy membrane and is often oval instead of the normal biconcave disc Can carry oxygen, but they have a short life |
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Deficiency of either vitamin B12 or folic acid causes....
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maturation failure in the process of erythropoiesis
cells proliferate more slowly and produce larger than normal cells |
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What is the name of the disease where there is rbc maturation failure due to poor adsorption of B12 from the gastrointestinal tract?
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pernicious anemia
(the basic abnormality is atrophic gastric mucosa failing to produce normal gastric secretions) |
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In the gut, what binds with B12 to make it available for adsorption?
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intrinsic factor secreted by the parietal cells of the gastric glands
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Describe B12 adsorption process.
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1) Intrinsic factor binds protecting it from digestion
2) intrinsic factor binds to the brush border of mucosal cells in the ileum 3) B12 is transported into the blood during the next few hours by pinocytosis (intrinsic factor and B12 together go through the membrane) |
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What is the minimum amount of B12 required each day to maintain normal rbc maturation?
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1-3 micrograms
However, the liver stores 1000 times this amount. 3-4 years of defective b12 adsorbtion is usually required to cause maturation failure anemia |
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Where do you get your supply of folic acid?
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green vegetables, some fruits, and meats
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What is sprue?
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the frequently occurring small intestinal disease causing difficulty absorbing both folic acid and B12
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When does synthesis of hemoglobin occur?
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begins on proerythroblasts and continues into the reticulocyte stage of red blood cells.
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Describe the formation of hemoglobin?
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succinyl-CoA, formed in the Krebs cycle, binds with glycine to form the pyrrole molecule.
4 pyrroles combine to form protoporphyrin IX, with combines with iron to form the heme molecule Finally each heme molecule combines with a long polypeptide chain, a globin synthesized by ribosomes, forming a subunit of called hemoglobin chain 4 of these bind loosely to form a hemoglobin molecule |
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What are the 4 types of chains in hemoglobin?
a combination of which two types makes a human hemoglobin A? |
alpha chains
beta chains gamma chains delta chains a combination of alpha and beta |
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How many iron atoms are in each hemoglobin molecule?
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4
these 4 iron molecules can each bind with one molecule of oxygen, making a total of 8 oxygen atoms |
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What happens to the hemoglobin in sickle cell anemia?
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the amino acid valine is substituted for glutamic acid at one point in each of the 2 beta chains
when it is exposed to oxygen, elongated crystals are form inside the rbc making it impossible for these cells to pass through small capillaries elongated crystals are likely to rupture the cell membranes |
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Does oxygen combine with the two positive bonds of the iron in the hemoglobin molecule?
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No
it binds loosely with one of the so-called coordination bonds of the iron atom. Oxygen does not become ionic, but is carried as molecular oxygen |
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What is the total quantity of iron in the body?
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4-5 grams
65% of that is in the form of hemoglobin |
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What binds to iron after it is absorbed in the small intestine?
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apotransferrin (a beta globulin)
to form tranferrin which is then transported into the plasma |
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Where is excess iron stored in the body?
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mainly liver hepatocytes
less in the reticuloendothelial cells of bone marrow |
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What does iron combine with in the cell cytoplasm?
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apoferrin to form ferritin
iron stored in ferritin is called "storage iron" |
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What is hemosiderin?
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extremely insoluble form of iron storage
collects in cells in the form of large clusters |
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What is unique about the transferrin molecule?
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it binds strongly with receptors in the cell membranes of erythroblasts in the bone marrow and is ingested by the erthroblast by endocytosis
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What is hypochromic anemia?
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when people do not have adequate amounts quantities of transferrin in their blood. This results in failure of to transport iron to the erythroblasts
(red blood cells that contain much less hemoglobin than normal) |
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When a rbc is destroyed, it's hemoglobin is ingested by monocyte-macrophages and stored....
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mainly in the ferritin pool
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What secretes apotransferrin?
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the liver secretes it into the bile
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True or false?
Iron absorption from the intestines is extremely slow. This means that even when there is tons of iron in the food we eat, only small proportions can be absorbed. |
True
However rate of absorption can be increased/decreased based on the body's need. |
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What is the life span of a rbc?
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120 days
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What is the function of the enzymes in a rbc?
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maintain pliability of the cell membrane
maintain membrane transport ions keep iron of the cells hemoglobin in the ferrous form rather than ferric form prevent oxidation of the protein in the red cells |
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Where do many red blood cells self-destruct?
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in the spleen when they have to squeeze through the red pulp
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After the rbc dies and releases it's hemoglobin, what do macrophages convert the porphyrin portion of the hemoglobin molecule into?
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bile pigment bilirubin
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What is anemia?
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deficiency of hemoglobin in the blood
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after rapid hemorrage, how long does it usually take to replace the fluid portion of plasma?
red blood cells? |
1-3 days
3-6 weeks |
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What is microcytic, hypochromic anemia?
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results from chronic blood loss
not enough iron being absorbed red blood cells are smaller than normal and have too little hemoglobin |
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What is aplastic anemia?
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(bone marrow aplasia)
lack of functioning bone marrow exposed to high-dose radiation or chemotherapy or high doses of certain chemicals or lupus erythematosus (immune system attacks healthy cells such as bone marrow stem cells) |
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What is meloblastic anemia?
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anemia that results in fewer, large, odd shaped red blood cells because of loss of B12, folic acid, or intrinsic factor
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What is hemolytic anemia?
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anemia where the cells are so fragile, that they easily rupture when going through capillaries or the spleen
production is normal, lifespan is short |
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What are the different types of hemolytic anemia?
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hereditary spherocytosis
sickle cell anemia erythroblastosis fetalis |
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What is hereditary spherocytosis?
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red cells are spherical rather than biconcave
cannot withstand compression |
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describe sickle cell anemia.
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present in .3-1% of West African and American blacks
abnormal shape- hemoglobin S elongates crystals in the presence of oxygen |
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What is erythroblastosis fetalis?
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when Rh-positive red blood cells in the fetus are attacked by antibodies from the Rh-negative mother
antibodies cause cells to rupture |
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What is the normal value of blood viscosity?
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3
this decreases in anemia |
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How is anemia related to cardiac output?
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blood viscosity falls as a result of fewer red blood cells
decreases resistance to blood flow in peripheral vessels increases cardiac output and pumping workload on the heart ** sometimes this offsets the reduced oxygen-carrying effect and masks anemia however exercise will increase tissues demand for oxygen, extreme tissue hypoxia results and acute cardiac failure may ensure |
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What is secondary polycythemia?
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when tissues become hypoxic because of high altitudes or cardiac failure, and the blood forming organs automatically produce large quantities of red blood cells (about 30% more that normal)
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What is physiologic polycythemia?
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a type of secondary polycythemia that occurs in natives who live at high altitudes or 14,000 to 17,000 feet
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What is polycythemia vera?
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aka: erythremia
caused by genetic aberration in the hemocytoblastic cells that produce the cells. The blast cells no longer stop producing red cells when there are too many already present hematocrit and total blood volume also increases viscosity increases |
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How is polycythemia vera related to the circulatory system?
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increase viscosity
sluggish blood flow increase in venous return (since blood volume is increased) cardiac output is not far from normal the person will usually have a ruddy complexion with bluish (cyanotic) tint to the skin |
