Erythrocytes Flashcards
Specialized connective tissue in fluid, extracellular matrix (plasma)
blood
How much does plasma constitute of blood volume?
55%
What is the purpose of protein in blood?
viscosity
plasma - clotting factors =
serum
Blood is the primary vehicle for what?
transport of nutrients, O2, CO2, waste products, hormones
What does blood function in?
thermoregulation and homeostasis
what is the avg blood volume in adults?
5 L
What are the 3 plasma proteins?
albumins
globulins
fibrinogens
make up bulk of plasma proteins, all synthesizes in liver
albumins
Where are albumins synthesized?
liver
What is the function of albumins?
function as transport proteins for insoluble metabolites (FA)
Albumins are responsible for maintaining what?
colloid osmotic pressure in blood vessels
Large plasma protein molecules that are used as transport proteins for lipids and heavy metal ions
globulins
What do globulins transport?
lipids and heavy metal ions
largest plasma proteins that are soluble and synthesized by liver
fibrinogens
Are fibrinogens soluble or insoluble?
soluble
Which organ synthesizes fibrinogen?
liver
plasma protein that polymerizes to form insoluble fibrin during clotting
fibrinogens
Fibrinogens polymerize to form what?
insoluble fibrin
process of converting fibrinogen to fibrin
prothrombin –> thrombin catalyzes fibrinogen –> fibrin
What catalyzes fibrinogen?
thrombin
What makes up the formed elements (“blood cells”)?
RBCs
WBCs
platelets
Where are the formed elements formed and how?
bone marrow via hemopoesis
volume of RBCs is know as:
hematocrit
what is the hematocrit in males vs females:
45% males
42% females
genetic neoplasia that causes increased RBC production
polycythemia vera
tumor of blood
neoplasia
hematocrit is approx equal to what
PCV (packed cell volume)
+/- buffy coat, depending on source
What does the buffy coat consist of?
WBCs and platelets (~1-2%)
drop of blood smeared, air dried, stained with modified Romanovsky method
blood smear
Blood smear examples
Wright
Giemsa
Diff-Quick
What are blood smears stained with?
modified Romanovsky method
process by which mature blood cells develop from precursor cells
hemopoiesis
RBC production
erythropoiesis
WBC production
myelopoiesis
What is hemopoiesis under control of?
erythropoietin
What is erythropoietin secreted by?
kidney
What does hemopoiesis begin with?
pluripotent stem cell
What does a pluripotent stem cell differentiate into?
several unipotential stem cell lines (colony forming units = CFUs)
Where does hemopoiesis occur in adult humans?
vascular sinuses of bone marrow of cert bones—especially flat bones of skull, ribs, sternum, vertebrae, pelvis, & some long bones
What is the estimated output of hemopoiesis daily?
2.5 billion (short-lived)
Where does hemopoiesis occur in the fetus during the first trimester?
blood islands in the wall of yolk sac
What is the yolk sac rich in and what is the benefit of it?
iron needed to produce hemoglobin
Where does hemopoiesis occur in the fetus during the second trimester?
liver and lymphatic tissue
Where does hemopoiesis occur in the fetus during the last month of pregnancy?
bone marrow
Where does hemopoiesis occur at the time of birth?
primary to marrow cavities
Do the number of active sites in hemopoiesis increase/decrease with age?
increase
What are the 2 types of bone marrow?
red and yellow
Type of marrow that contains large numbers of mature RBCs and large nuclei:
red
Type of marrow that is inactive and known as “fatty” marrow
yellow
What are the stages of erythropoiesis?
stem cell (CFU-E) –> proerythroblast –> erythroblast/normoblast –> reticulocyte –> mature RBC
Overall trends in erythropoiesis:
(increase/decrease) in cell size
(loss/gain) of nucleus and organelles
(increase/decrease) in hemoglobin concentration (Hb)
decrease
loss
increase
RBCs (erythrocytes) enucleate where?
mammals ONLY
type of nucleus in RBC in mammals:
enucleate
What happens to the nucleus in erythrocytes before it is release into the bloodstream?
nucleus extruded and all organelles degenerate
What do mature RBCs consist of?
outer cell membrane containing cytoplasm, Hb, and few enzymes
T/F: RBCs have a mitochondria.
false: lack mitochondria
What effect does a lack of mitochondria have on RBCs.?
limited lifespan (~120 days)
If RBCs lack mitochondria, how can they make ATP?
anaerobic glycolysis (enough to maintain cell integrity)
Which organs remove senescent (old) RBCs?
liver and spleen
occasional, basophilic nuclear remnants visible within cytoplasm during erythropoiesis
Howell-Jolly bodies
immature RBCs with stippled cytoplasm and still have some rRNA, but slightly larger than mature RBCs (erythropoiesis)
reticulocytes
increased reticulocytes in circulation associated with chronic blood loss, hemolytic anemia— aka “left shift”
reticulocytosis
What leads to large cells called macrocytes?
vit B12 and B9 deficiency
large numbers of erythrocyte precursors in peripheral blood
megaloblastic anemia
**What is the size of RBCs?
6-8 um (micrometer) diameter
What is the concavity of RBCs?
biconcave discs
What is the primary structural protein in RBCs?
spectrin
What is the function of spectrin in RBCs?
provides resiliency and deformability
Where does spectrin bind?
inner surface of PM
What is the purpose of the biconcave shape of erythrocytes?
increase surface area for gas exchange
which cells are involved in O2 and CO2 transport
rbcs (erythrocytes)
which cells contain large amount of Fe containing pigment, hemoglobin
rbcs (erythrocytes)
Fe containing pigment
hemoglobin
what do RBCs transport?
o2 and co2
What makes up Hb?
4 polypeptide chains associated with 4 Fe-containing heme groups
decreased Fe or blood loss
anemia
type of anemia where rbc’s are small (microcytic) & pale staining (hypochromic)
Fe deficient anemia
vs. normocytic and normochromic
single AA substitution that causes a change in 3D structure of Hb molecule
sickle cell anemia
What is the AA substitution in sickle cell anemia?
valine for glutamic acid at position 6 of beta-globulin chain
sickle cell anemia causes a _____ change in cell which leads to “_____” shape; more ___ and easily _____.
conformational
sickle
fragile
damaged
What do sickle-shaped RBCs damage?
endothelial cells of capillary walls due to rough edges
What is a potential benefit to sickle cell anemia?
resistance to malaria
disease caused by an intracellular parasite, Plasmodium spp.
malaria
thrombocytes =
platelets
small, non-nucleated cells containing organelles
platelets
Do platelets have nuceli?
no
Do platelets have organelles?
yes
What are platelets formed from?
megakaryocytes
large, polyploid cells in bone marrow with single, multi-lobed nucleus
megakaryocytes
megakaryocytes develop _____ channels in the _____ which causes platelets to do what?
demarcation
cytoplasm
tear off
What is the function of platelets?
blood clotting - form vascular plugs at site of vascular damage
What can impair platelet function?
drugs like aspirin
Result of cascade interaction between plasma proteins & coagulation factors
coagulation
When does coagulation occur?
only if endothelial lining of vessel is injured
What are the 2 pathways fo coagulation?
intrinsic
extrinsic
Which coagulation pathway is faster?
extrinsic
The extrinsic coagulation pathway is initiated by what?
release of tissue thromboplastin as result of tissue damage
The intrinsic coagulation pathway is initiated by what?
exposure of collagen
What does the intrinsic coagulation pathway require?
numerous clotting factors (Willebrand’s factor, Factor VIII) and longer cascade reaction
Describe the steps of coagulation
- When wall of blood vessel breaks, tissue injury results
- Releases thromboplastin, initiates extrinsic pathway —Also exposes collagen, initiates intrinsic pathway
- Platelets mechanically adhere to exposed collagen; also release serotonin (potent vasoconstrictor—constricts sm Mm in damaged vessel to minimize blood loss)
Extrinsic & intrinsic pathways converge to form ____ pathway (at point where ______ activated)
common
Factor X
Converging of extrinsic and intrinsic pathways results in what?
conversion of prothrombin to thrombin, converts soluble fibrinogenin to insoluble fibrin
What does coagulation trap?
platelets and RBCs
What stops clotting?
- Exhaustion of fibrinogen and removal of thrombin from blood during conversion of fibrinogen to fibrin
- anticoagulants: antithrombin III & heparin
Inappropriate clot formation leads to what?
heart attack, stroke, DIC
Deficiency in clotting factor(s), so blood can’t clot; defect in intrinsic pathway
hemophiia
Hemophilia is ___-linked and found in (males/females)
sex
males
Which chromosome is hemophilia present on?
X chromosome
deficiency of clotting Factor VIII
Hemophilia A
Factor IX deficiency
Hemophilia B
Factor XI deficiency
Hemophilia C