Module 11

It pertains to the prevention of Blood loss.

Causes: local myogenic spasm, autacoids (Thromboxane A2), and nervous reflexes.

The cells responsible are the Platelets.

Blood Coagulation Process which is initiated by either a traumatized tissue (A. extrinsic way) or the platelets that have been exposed to a traumatized vessel (B. intrinsic way) to stimulate the prothrombin activator; this in turn, triggers a series of processes (an example of a positive feedback mechanism which is beneficial to the body)

The platelets that have been exposed to a traumatized vessel.

A traumatized tissue

It stimulates the prothrombin activator (it started from tissue trauma/damaged vessel)

It stimulates prothrombin activator and it started from the traumatized blood cells (platelets) upon contact with exposed collagen in the damaged vessel.

Deficiency in the number of platelets.

Any Liver diseases that destroy the liver hepatocytes; these tissues are responsible for the production of _____ and _____.

Accidental ingestion of anticoagulants like _____ and _____ (poisoning).

Individual suffering from bleeding tendency (Hemophilia) due deficiency of Anti _____ factor.

Blood coagulation process requires the use of several substances called _____ (which hastens the occurrence of the process) and in contrast, it is hindered by substances called _____.

Examples of pro coagulants are listed below except:

Anticoagulants are classified into:

These are the substances normally present in the body that hinders the occurrence of coagulation process Examples: Heparin, Antithrombin III, prostaglandins, Heparin co-factor, Protein C

These are the substances that can be bought in the market and commonly used in the laboratory. Examples: Heparin (both physiological and commercially available) Coumarin, Warfarin, EDTA, Ca EDT

Initiated by Fibroblast Stimulating Factor/Vascular Endothelial Growth Factor released by platelets.

They are the third group of blood cells that originate from the Megakaryocytes. They are regarded as the FRAGMENTS of MEGAKARYOCYTES (regarded as the 7th type of WBC).

Physical Properties of Platelets: They are minute cells formed from the Megakaryocytes.

Physical Properties of Platelets: They are called the "Fragments of Megakaryocytes".

Physical Properties of Platelets: Life span in the circulation = 20 days

Physical Properties of Platelets: Oval or coma-shaped cells.

Physical Properties of Platelets: Pilable cells

Physical Properties of Platelets: Concentration – varies in different species

Approximately = 150000- 200,000 per microliter of blood (normal values vary in different animals).

Chemical/Functional Properties of Platelets: They have contractile structures called Actin and Myosin molecules and Thrombosthenin.

Chemical/Functional Properties of Platelets: They have residual of ER and Golgi apparatus that can synthesize various enzymes and store large quantities of Iron.

Chemical/Functional Properties of Platelets They have Mitochondria (produce ATP).

Chemical/Functional Properties of Platelets: They have enzymes that synthesize Prostaglandins that causes vascular and tissue reactions.

Chemical/Functional Properties of Platelets: They release Fibrinogen-Stabilizing Factors

Chemical/Functional Properties of Platelets: They release vascular “Endothelial Cell Growth Factor”

Chemical/Functional Properties of Platelets: They have Glycoprotein on their surfaces. Glycoprotein repulses adherence of platelets to normal endothelium but causes adherence to damaged/ injure endothelial cells.

Chemical/Functional Properties of Platelets: They release Bilipids that activate multiple stages of blood clotting process.