Lecture 1: Blood and vessels Flashcards
What are the different layers of a vessel?
- Tunica adventitia
- Tunica media
- Tunica intima
- Endothelium
What are physiological processes which lead to blood vessel formation?
- Ovulation
- Menstruation
- Placenta formation
- Wound healing
- Retinal development
What are the different types of blood vessel growth?
- Vasculogenesis = de novo formation of blood vessels from progenitor cells
- Angiogenesis = sprouting of new capillaries from existing capillaries
- Arteriogenesis = enlargement of pre-existing arterial connections to completely developed and functional arteries
What triggers angiogenesis?
Hypoxia
Gradient of growth is established by VEGF
Name three promotors of vessel growth
VEGF
FGFs
Angiopoietins
Name an inhibitor of vessel growth
Angiopoietins
How would you induce angiogenesis or arteriogenesis?
Cell therapy → introducing cells in host environment to induce blood vessel formation to decreases chances of blockage
Works better than only introducing growth factors
What are the causes of leg oedema?
- Immobility
- Pregnancy
- Heart failure
- Low plasma protein
- Chronic venous insufficiency
- DVT
- Lymphatic insufficiency
- Chronic renal failure
What factors influence haematological homeostasis?
- Vascular hydrostatic pressure pushing fluid out
2. Plasma colloid pressure drawing fluid in
What are the primary causes of lymphoedema?
- Syndromic primary lymphoedema (Turner’s, Noonans, Prader Willi)
- Lymphoedema with overgrowth, vascular, or cutaneous manifestations
- Congenital onset lymphoedema (<1 year of age) (Milroys: VEGFR3 mutation)
- Late onset lymphoedema (> 1 year age) (FOXC2 mutation)
What are secondary causes of lymphoedema?
- Radiotherapy
- Surgery
- Cellulitis
- Filariasis (parasite)
How would you manage lymphoedema?
- Treatment of underlying cause
- Elevation
- Compression
- Massage
- Good skincare
- Surgery (specifically in lymphoedema)
How do platelets get activated in tissue damage?
- Damage to blood vessel
- Exposure of platelets to collagen and vWF in extracellular matrix and (later) exposure to thrombin
- Platelets adhere and activate
- Release of mediators
- Vasoconstriction + aggregation of platelets
- Formation of soft platelet plug
What does the initiation phase of clotting lead to?
Activated by tissue factor (TF), eventually thrombin activates platelets
What does the amplification phase of clotting lead to?
Initiated by thrombin and takes place on activated platelets, ultimately leads to a significant increase in thrombin accumulation which causes:
- Fibrinogen will be cleaved into fibrin and cross-linking promotes stable clot
- Crosslinking is stimulated by factor XIIIa, which is under the influence of calcium
What are the fibrinolytics?
Alteplase (Activates plasminogen, but only when it is bound to fibrin)
Streptokinase (Binds and activates plasminogen)
What does prothrombin time indicate?
measures the integrity of the extrinsic system as well as factors common to both systems
What does partial thromboplastin time indicate?
measures the integrity of the intrinsic system and the common components
What does thrombin time indicate?
measures the time it takes for a clot to form in anticoagulated blood plasma, after an excess of thrombin is added
What does D-dimer indicate?
are fibrin degradation products. Measured In patients to test suspected thrombotic disorders
What does international normalised ratio indicate?
used to normalise PT, since this will be affected by manufacturer’s TF
Main use is to exclude thromboembolic disease.
What is the mechanism of action of Abciximab, Eptifibatide and Tirofiban?
Glycoprotein IIb/IIIa Inhibitor
What is the mechanism of action of aspirin?
Irreversible inhibition of COX enzyme
What is the mechanism of action of warfarin?
Vitamin K antagonist
