Part 13: Primary Hemostasis

Tunica Intima

Simple squamous epithelium lining the blood vessels; forms the smooth glistening surface of endothelium that lines the inner tubular cavity (lumen)

Tunica Media

Composed of smooth muscle and elastic fibers; thickest coat

Tunica Adventutia

Composed of fibrous connective tissue that contains autonomic nerve endings and the vaso vasorum

Tunica Intima

Endothelium is found in what part of the blood vessel

Arteries

Blood vessel: 4 mm; distributing blood vessels that leave the heart

Veins

Blood vessel: 5mm; collecting blood vessels to the heart

Prostacyclin

Inhibits platelet activation

Eicosanoid pathway

Prostacyclin is produced in what pathway in the endothelial cells?

Prostaglandin I2

Prostacyclin is also known as

Adenosine

Stimulates vasodilation

Thrombomodulin (TM)

Binds thrombin and reduces its ability to participate in the clotting process

Protein C and TAFI ( Thrombin Activatable Fibrinolysis Inhibitor)

Thrombomodulin+ Thrombin = activation of ?

Protein C

Inactivates factor Va and VIIIa ( switch off mechanism of inactivating factor V and VIII to prevent thrombocytosis)

Heoaran sulfate

Weakly enhances activity of Antithrombin III

TPA

Major plasminogen activator; converts plasminogen to plasmin

Plasmin

Aka fibrinolysis; Enzyme that dissolved clot

vWf

Aids in platelet adhesion and acts at carrier protein for Factor VIII

Endothelial cells and megakaryocytes

Site of synthesis of vWf

Weibel-Palade bodies and Alpha granules

Site of storage for vWf

vWf

In the absence of _____, Factor VIII becomes unstable and eventually destroyed

ADAMTS-13 ( A Disintergrin And Metalloproteinase with Thrombospondin type 1 motif , member 13)

aka vWf-cleaving protease; regulates the size of circulating vWf by cleaving ultraong vWf multimers into shorter segment

TTP

Disease caused by deficiency of ADAMTS 13

2 days

Platelets remain in the spleen for ____

2/3

Approximately ____ of the total number of platelets remain in the circulation

1/3

Approximately ____ of the platelets are in the spleen

8-10 days

Lifespan of platelets

7-21 cells per 100x field

On a Wright-stained PBS, you can see how many platelets?

Reticulated platelets

Stress platelets is also known as

2.5 um

Size of platelets

6.8 to 10.2 fL

Reference Range of PLT’s MPV

20%

EDTA causes swelling of platelets by ____ in MPV during the first hour

X-linked recessive

Inheritance pattern of WAS

Autosomal recessive

Inheritance pattern of BSS ( Bernard Soulier Syndrome) and GPS ( Gray Platelet Syndrome)

Autosomal Dominant

Inheritance pattern of MHA (May-Hegglin), Sebastian and Fechtner Syndrome

Biconvex or disk-shaped

Shape of platelets

Spherical with pseudopods

Shape of activated platelets

Granuomere

Centrally located; granular

hyalomere

peripherally located; non granular

TPO

Major regulator of PLT regulation

Liver

TPO is produced primarily in

2 to 4 megakaryocytes per 10 lpf

On a normal BM smear, how many platelets can one see?

Endomitosis

Nuclear division without cytoplasmic division

LD-CFU

Megakaryocyte Progenitor that is incapable of normal mitosis but performs endomitosis

MK-1

Megakaryocyte precursor: Megakaryoblast

Mk-II

Megakaryocyte precursor: Promegakaryocyte

MK-III

Involve in platelet shedding

2000 to 4000 platelets

One megakaryocyte may shed ___ plt

LD-CFU MG, MK-I, MK-II

3 cells that perform endomitosis

DMS

Ultimately delineates individual platelets during thrombopoiesis