Haem Anatomy & Physiology Flashcards
List the 3 main cellular components of blood
RBCs (erythrocytes), Leukocytes, plasma
State the main components of plasma
Water (92%), proteins (7%), other solutes ( Ions- Na+,K+, gases, waste, nutrients)
The buffy coat is made up of _____ and ____?
Leukocytes and platelets
Explain why each hemoglobin molecule can only transport 4 O2 molecules.
Hb is made up of heme + globin
- Heme: Pigment containing Fe that can bind to O2.
- Globin: 4 polypeptide chain (2alpha & 2beta chain). Each chain can only bind to 1 heme group = bind to 4O2 molecules in total
List at least 3 causes for erythropoiesis
1) Hypoxia due to decreased RBC number or function
2) Decreased oxygen availability
3) Increased tissue demand for oxygen (exericse)
4) Anemia
5) Reduced blood flow to kidney
6) Blood donation
During the destruction of RBCs, _____ is converted to bilirubin
Heme
Describe how bilirubin is excreted.
- Bilirubin is conjugated by the liver
- Secreted into the intestines
- Metabolised to stercobilin by bacteria and then excreted into feces
Which of the following is/are true? There may be more than 1 answer
- RBC rupture and dying RBC are taken up by macrophages
- Hemoglobin splits into heme and globin
- Globin is converted into bilirubin which is excreted by the liver and bile into urine and feces
- Iron from heme is recycled and stored in liver or reused in bone marrow
1,2,4
option 3 happens for bilirubin, not globin
List the 3 phases of hemostasis
- Vasoconstriction
- Platelet plug
- Fibrin clot
True or False?
Platelets contain nucleus
False (platelets are fragments of megakaryocytes)
List at least 4 components found in platelets
- contain contractile proteins (actin & myosin).
- contain organelles.
a) mitochondria: release of ADP.
b) ER and Golgi: storage of Ca2+, synthesis of enzymes. - contain enzyme systems for synthesis of prostaglandins.
- contain growth factors (PDGF, VEGF).
- contain factor XIII (Fibrin-stabilizing factor).
Which cellular component facilitates the binding of platelets to collagen fibres?
Von Willebrand’s Factor
State 5 functions of thrombin
- Enhances its own generation (positive feed back loop)
- Factor XIII activation (stabilization of fibrin mesh)
- Stimulates conversion of fibrinogen to fibrin
- Enhances platelet activation.
- Release of PF3 from platelets (activation of intrinsic pathway - not to be confused with tissue Factor III in extrinsic pathway)
State the tissue factors involved in the extrinsic pathway.
- Tissue factor (aka Factor 3),
- Factor VII (7)
- Factor X (10)
State the tissue factors involved in the intrinsic pathway.
- Factor XII (12)
- Factor XI (11)
- Factor IX (9)
State the tissue factor(s)
& component(s) involved in the common pathway
- Factor X & Factor Xa
- Prothrombin & Thrombin
- Fibrinogen & Fibrin
Describe the role of tissue plasminogen activator in fibrinolysis.
- tPA cleaves inactive plasminogen to plasmin.
- plasmin degrades fibrin clots, leading to dissolution of clots (fibrinolysis)
Macrophages remove the remains of the clot
Describe the role of factor XIIIa in hemostasis
Factor XIIIa is a fibrin stabilising factor which cross-links fibrin strands to form the fibrin mesh
True Or False?
The intrinsic pathway is stimulated by trauma to tissues
False. Extrinsic pathway is stimulated by trauma to tissues.
Intrinsic pathway is stimulated via exposure to collagen
Define clot retraction
Stabilization of clot by squeezing serum from the fibrin clot. This further closes the leak
Describe the role of prostacyclin in the regulation of blood clotting
Inhibits platelet activation and limits spread of blood clotting.
(Prostacyclin is a prostaglandin produced by intact endothelial cells),
Explain how serotonin inhibits blood clotting
Serotonin at high concentrations inhibits ADP activity = (?less expression of P2Y12 receptor to prevent platelet aggregation)
List 2 procoagulants
- Tissue factor
- Collagen (active Factor XII of intrinsic pathway)
List at least 2 endogenous anticoagulants
- Antithrombin III,
- Heparin
- Protein C
- Protein S
- Tissue plasminogen activator
- Smoothness of endothelial surface,
- Thrombomodulin
