Lecture 12 Flashcards
Blood Histology (13 cards)
List the characteristics and functions of each type of granulocyte
Neutrophil - most abundant leukocyte, segmented nucleus that stains very dark. Function in phagocytotic activity
Basophil - Bilobed nucleus, large granules, function in the immune response. They contain vasoactive substances and can increase vascular permeability
Eosinophil - Small, bilobed nucleus, large granules that will stain red or pink. Functions in response to allergies and parasitic infections.
List the characteristics and functions of each type of agranulocyte
Lymphocyte - Large, nucleus fills most of the cell. Functions as B (plasma precursor) and T lymphocytes
Monocyte - Largest of the leukocyte fam, kidney-shaped nucleus, have granular cytoplasm due to small lysosomes. Monocytes are the precursors of macrophages and osteoclasts
List the characteristics and functions of erythrocytes
- RBCs lack nucleus and organelles
- Major contents include: lipids, ATP, carbonic anhydrase, and hemoglobin
- 50% of proteins are peripheral
- Spectrin and ankyrin are the peripheral proteins
- Erythrocytes carry oxygen and carbon dioxide
List the characteristics and functions of platelets
Platelet is a combination of fragments of cells, they are derived from megakaryocytes. Platelets promote clot formation, and repair endothelium (platelet plug).
What are the membrane proteins that characterize red blood cells?
Spectrin - major structural protein, that associates with actin filaments forming a spectrin-actin network.
Ankyrin - links the spectrin-actin network to the membrane by binding to spectrin and another transmembrane protein.
How do the membrane proteins on RBCs relate to each other?
Ankyrin binds to the spectrin-actin network and transmembrane proteins to link the spectrin-actin to the plasma membrane
What are the steps involved with the formation of a platelet plug?
- fibrinogen in plasma binds to activated integrin receptors. Platelets are bridged to each other.
- Thrombin that is bound to the platelet surface acts on fibrinogen to cleave fibrinopeptides to form a fibrin monomer
- Fibrin monomers aggregate, forming a clot. Factor XIII cross-links the fibrin monomers. The platelets and fibrin form a platelet plug
What are the steps (beginning with prothrombin activation) to form and dissolve a blood clot?
- Prothrombin is activated and converts to thrombin
- Thrombin catalyzes the conversion of fibrinogen to fibrin
- Fibrin is polymerized and the clot is reshaped
- Tissue plasminogen activator converts plasminogen to plasmin
- Plasmin dissolves the clot (fibrinolysis)
What are some differentiating characteristics of the intrinsic clotting pathway?
The intrinsic pathway is initiated by injury to the endothelium, and everything necessary for clot formation is already in the blood
What are the major elements that make up the intrinsic clotting pathway?
- injury to endothelium exposes collagen fibers that leads to the activation of Factor XII
- activated Factor XII activates Factor XI
- activated Factor XI and thrombin activates Factor IX and Factor VIII
- Factor IX combines with Factor VIII and calcium to activate Factor X
What are some differentiating characteristics of the extrinsic clotting pathway?
Extrinsic pathways are activated by physical damage to the vessel wall, it also requires the formation of tissue factor (thromboplastin or Factor III)
Explain the process of the common clotting pathway
- Factor X combines with Factor V and calcium to activate prothrombin
- Prothrombin converts to thrombin
- Thrombin with calcium converts fibrinogen to fibrin
- Cross-linking of fibrin polymers by activated Factor XIII
What is leukocyte extravasation?
Leukocytes move out of the circulatory system and into this site of tissue damage.
