Chapter 22: The Hematologic System Flashcards
Erythropoietin
released from the kidney is response to hypoxia
Reticulocyte
precursor cells (immature RBCs) an increased # indicates RBC acceleration
Hematocrit
measures volume of RBCs/100 ml of blood
expressed as percentage
Hemoglobin
major component of RBCs
carries O2
Hemoglobin molecule
adult (HbA): 2 alpha and 2 beta chains
fetal (HbF): beta and gamma chains
surrounds an iron atom
The rate of Hgb synthesized depends on…
iron availability
HbF
beta and gamma chains provide higher affinity to transfer O2 across placenta
replaced with HbA within 6 months of birth
Mean Corpuscular Volume (MCV)
measures average size of RBCs
microcytic - normocytic - macrocytic
Mean Corpuscular Hemoglobin Concentration (MCHC)
measures Hgb content within 1 RBC
hypochromic - normochromic - hyperchromic
RBC Distribution Width (RDW)
measures the size differences of RBCs
useful in predicting anemias; changes before the MCV
Blood Smear
provides actual visualization of the RBC morphology
sizes, color, and shape of red cells
Pluripotent Stem Cell
blood-forming stem cell in bone marrow
not committed to any particular cell type
indispensable source of reserve cells
Progenitor (Parent) Cells
Differentiate along a single pathway
Lymphoid stem cells
Myeloid stem cells
Lymphoid stem cells
T and B cell progenitors
Myeloid Stem Cells
progenitor of monocytes, granulocytes, megakaryocytes, and erythrocytes
Leukocytes (WBCs)
protect against harmful bacteria and infection
Granular Leukocytes: neutrophils, eosinophils, basophils
Nongranular Leukocytes: monocytes, lymphocytes
Neutrophils
most abundant
arrive first at site of infection (last 1-3 days)
phagocytic
Eosinophils
increase during allergic response and parasitic infections
Basophils
help with initiating inflammation
releases histamine and heparin
Monocytes/Macrophages
participates in immunity, can act as APCs
phagocytic
can survive months to years
Lymphocytes
B lymphocytes
T lymphocytes
Natural Killer (NK) cells
B-Lymphocytes
produce antibodies (humoral immunity) memory cells
T-Lymphocytes
regulates cell-mediated immunity
T-helper and T-cytotoxic
NK Cells
destroy foreign cells
Thrombocytes
Platelets
cell fragments of megakaryocytes
assist to minimize blood loss
Primary Hemostasis
platelet plug
Secondary Hemostasis
activation of the coagulation cascade (clot)
Hemostasis: 1 Vessel Constriction
mediators contribute to constriction: thromboxane A2, serotonin, endothelin-1
Hemostasis: 2 Formation of Platelet Plug
adhesion and aggregation of platelets
requires vWF for adhesion
release of ADP for aggregation
linked plt and binding = GPIIb/IIIa
_____ is required for the coagulation cascade of hemostasis
Calcium
Hemostasis: 3 Coagulation Cascade
factors begin activating each other in sequence to convert fibrinogen to fibrin = clot
X activates prothrombin to thrombin
thrombin activates fibrinogen to fibrin
fibrin forms a meshwork
Intrinsic Pathway
initiated by Factor XII - XI - IX - VIII - X
slower and longer pathway
clinically measured as PTT
Extrinsic Pathway
begins with trauma to blood vessel
much faster than intrinsic
begins with Factor VII - III - X
Procoagulation Factors
platelet activation
clotting factors
Anticoagulation Factors
heparin on endothelial cells (inactivates thrombin and Factor Xa)
antithrombin-III (neutralizes thrombin)
Hemostasis: 4 Clot Retraction
platelets use actin and myosin filaments to pull edges of broken blood vessels together
requires large #s of platelets
Hemostasis: 5 Clot Dissolution
fibrinolysis = clot dissolves
Tissue Plasminogen Activator (tPA) activates plasminogen which activates plasmin (digests fibrin)
