Erythrocytes Flashcards
Functions of Blood
Transportation or exchange
Protection (immunity)
Regulation (fluid volume, pH, thermoregulation)
Blood is
a connective tissue -> contains cells, a liquid ground substance (plasma), dissolved protein (fibers)
how much more viscous is blood than water
4x
average volume of blood in adults
5 liters
Components of blood
erythrocytes - make up 44% of a blood sample // %RBC volume = hematocrit
Buffy coat - composed of leukocytes and platelets // less than 1% of blood sample
Plasma - Fluid component minus the formed elements // 55% of blood sample
Formed elements in the blood
Erythrocytes = 99% of formed elements
Leukocytes = less than .01% of formed elements
Platelets = less than 1% of formed elements
blood smear
drop of blood smeared, air dried, and stained
blood smears are used to
determine the number and kind of cells present and other morphological abnormalities
components of plasma
mixture of water, proteins, other solutes
what is left when proteins are removed from plasma
serum
water makes up how much of plasma
about 92%
why is water an important component of plasma?
water facilitates the transport of materials in the plasma
One major protein of plasma that is involved in blood clotting is?
Fibrinogen
Name the proteins found in plasma? (4)
Albumins
globulins
fibrinogen
regulatory protein
What is Albumin’s function
transports many small molecules and insoluble metabolites in the blood
Where is albumin synthesized
liver
What is Fibrinogen’s function?
responsible for blood clot formation
Fibrinogen is converted into long insoluble strands of
fibrin
Fibrinogen makes up what percent of plasma proteins?
4%
what is Globulins function?
smaller alpha-globulins and larger beta-globulins primarily bind, support, and protect certain water insoluble or hydrophobic molecules, hormones, and ions
What are gamma-globulins
immunoglobulins or antibodies
What is spectrin’s function?
the main structural component of RBC
Spectrin was first identified where?
erythrocytes where it forms a filamentous network required for red blood cells to maintain their shape and elasticity
What does spectrin bind to in erythrocytes?
binds to the inner surface of the plasmalemma
Is spectrin a plasma protein?
NO! it is a cytoskeletal protein
What is hemopoiesis
the production of blood cells
Where does hemopoiesis occur
vascular sinuses of bone marrow of certain bones
Flat bones of skulls, ribs, sternum, vertebrae, pelvis, and some long bones
In a fetus where does hemopoiesis first occur
blood islands in wall of yolk sac during first trimester
where does hemopoiesis occur during the second trimester
Liver
lymphatic tissue
In the last month of pregnancy hemopoiesis occurs in
bone marrow
Number of active hemopoiesis sites do what with age
decrease
Erythropoiesis
red cell production
myeolpoiesis
white cell production
the hormone erythropoietin is secreted by
kidneys
Colony forming units (CFU)
pluripotential stem cells which differentiate into several unipotential stem cell lines
Red bone marrow
active / contains large number of mature red blood cells
yellow marrow
inactive
stages of erythropoiesis
- stem cells (CFU-E)
- proerythroblast
- erythroblast / normoblast
- reticulocyte
- mature rbc
Overall trends of erythropoiesis
- progressive decrease in cell size
- loss of nucleus and organelles
- increase in hemoglobin
proerythroblast / early normoblast
first recognizable erythrocyte precursor
basophilic stains blue/purple
Polychromatic erythroblasts / intermediate
no longer capable of division
mixture of basophilia and eosinophilia = polychromasia
less organelles more hemoglobin
orthochromatic erythroblast / late normoblast
organelles degenerate
nucleus is pushed out in this stage
reticulocyte
immature RBC with stippled cytoplasm / still have some rRNA
produced in bone marrow and released into peripheral blood
increased reticulocytes can be an indicator of anemia
Howell-Jolly bodies
occasional basophilic nuclear remnants visible within cytoplasm
usually removed by spleen
Mature erythrocytes lack
nuclei and organelles
how long do mature erythrocyte circulate
~120 days
reticulocytes account for what % of circulating RBCs
1-2%
RBCs can only make ATP by
anaerobic glycolysis
RBC lack nuclei which allows them to
carry respiratory gases more efficiently
every erythrocyte is filled with how many molecules of hemoglobin
280 million molecules of hemoglobin
describe the structure of hemoglobin
4 protein globins
2 alpha chains & 2 beta chains
all globin chains contain a nonprotein (heme) group with an Fe ion in its center
what does oxygen bind to for transport in the blood
the iron ions in the globin chains of hemoglobin
fetus hemoglobin has a _____ affinity for oxygen compared to the mother’s hemoglobin
higher
Anemia
any condition in which the quantity of erythrocytes is lower than normal
inadequate production of RBCs
lethargy, shortness of breath, pallow, fatigue, heart palpitations
*strain on heart
Polycythemia
condition of having too many erythrocytes in the blood
may have normal blood volume
thick and viscous blood
overuse EPO
*Strain on the heart
Sickle cell anemia
a point mutation where glutamic acid is replaced by valine at the sixth position in the beta globin chain
more fragile / easily damaged
causes damage to endothelial cells due to the sickle cell’s rough edges
** resistant to malaria
elliptocytosis
autosomal dominant disorder
oval shaped RBCs
caused by defective self association of spectrin subunits and defective binding of spectrin
Spherocytosis
Autosomal dominant condition involving a deficiency in spectrin
splenomegaly (enlargement of the spleen)
Platelets
thrombocytes
small non-nucleated cells containing organelles
megakaryocytes
single multi-lobed nucleus
“break into pieces to make platelets” (grace)
platelets lifespan
~8-12 days
platelets function
aid in blood clotting by forming physical plugs at site of vascular damage
extrinsic coagulation cascade
faster
initiated by the release of tissue thromboplastin as a result of tissue damage
intrinsic coagulation cascade
slower
initiated by the exposure of collagen
requires numerous clotting factors (von willebrands factor and factor VIII)
longer cascade rxn
platelets release
serotonin - constricts smooth muscle in damaged vessel to minimize blood loss
intrinsic pathway and extrinsic pathway meet at which factor
factor X
once factor X is activated what occurs in the coagulation cascade
the conversion prothrombin to thrombin
followed by fibrinogen into insoluble fibrin
Anticoagulants include
antithrombin III
Heparin
hemophilia A
deficiency of clotting factor VIII
defect in intrinsic pathway
hemophilia B
factor IX deficiency
Hemophilia C
Factor XI deficiency
defect in intrinsic pathway
Von Willebrand disease
Factor VIIII and von Willebrand Factor
defect in intrinsic pathway
