HEMA312 - HEMOSTASIS AND PRIMARY HEMOSTASIS

Hemostasis

physiological process that stops bleeding from an injured blood vessel while maintaining normal blood flow elsewhere

Arteries

have the thickest wall in the vascular system; away from the heart

Veins

larger and have more irregular lumen than arteries; towards the heart

Tunica Intima

inner layer, single layer endothelium cells thickened by sub-endothelial connective tissue layer

Tunica Media

thickest coat, composed of smooth muscle and elastic fibers

Tunica Adventitia

outer layer, Consist of fibrous connective tissue with nerve endings, small networks of blood vessels. Supplies nutrients to the tissues of the wall

Arterioles and Venules

smaller blood vessels

Arterioles

microscopic continuation of arteries giving off metarterioles joining capillaries

Venules

microscopic size of veins connecting to capillaries

Capillaries

Responsible for microcirculation that links between arterial and venous circulation

Sinusoids

Found in bone marrow, spleen and liver

Thrombocytes

cells involved in thrombopoiesis

Thrombopoietin

hormone that stimulates the production and maturation of megakaryocytes

Primary Hemostasis

Role of blood vessel and platelets in response to vascular injury

Platelet Plug

a temporary, early-stage accumulation of platelets that seals injured blood vessels to stop minor bleeding

Prostacyclin

inhibits platelet aggregation, induces vasodilation

Adenosine

induces vasodilation

Thrombomodulin

inactivates thrombin, Enhances anticoagulant activity of protein C

Protein C

inactivates I and VII

Heparin Sulphate

Enhances activity of antithrombin III

Tissue Plasminogen Activator

converts plasminogen to plasmin

Von Willebrand Factor

required for platelet adhesion

13-HODE

inhibits platelet adhesion

Vasoconstriction

neurogenic response

Collagen Exposure

causes adherence of platelets to site of injury, Activates the contact phase of coagulation

Tissue Thromboplastin Release

activates extrinsic pathway

Fibrinolysis

Release of tPA to avoid excessive coagulation

Collagen Type I and II

promotes platelet adhesion, aggregation and release reaction

Glycoprotein 1b

platelets mainly adhere to collagen via __

12-HETE

promotes platelet adhesion

Thromboxane A2

promotes platelets aggregation and acts with ADP

Thrombin

stimulates platelets to release ADP to induce aggregation

Cyclooxygenase

Arachidonic acid will be oxidized to endoperoxides by this enzyme

Tx Synthase

Endoperoxide becomes TxA2 by this enzyme