Page 517 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

CHAPTER 25 ■ Principles of Hemostasis and Thrombosis: Vasculature and Platelets 501

■ Bloo p sses ro the rteri l to the venous syste vi the ■ Bone rrow eg k ryocytes re erive ro pluri-
c pill ries. C pill ries re the thinnest w lle n ost potenti l ste cells. T e sequence o evelop ent ro

nu erous o the bloo vessels. eg k ryocytes to pl telets is thought to progress ro

■ Contr ction o the bloo vessel w ll is c lle the proli er tion o progenitors to polyploi iz tion, th t
v soconstriction. is, nucle r en ore uplic tion, n f n lly to cytopl s ic

■ One o the b sic ch r cteristics o nor l, int ct en o- tur tion n the or tion o pl telets.
theliu is its nonre ctivity with pl telets n in bility to ■ An ver ge eg k ryocyte pro uces pproxi tely 1,000

initi te sur ce cont ct ctiv tion o clotting ctor XII. to 2,000 pl telets. M rrow tr nsit ti e, or the tur tion

■ Mini l inter ctions le ing to pl telet ctiv tion or clot perio o the eg k ryocyte, is pproxi tely 5 ys.
or tion occur between the circul ting bloo n int ct ■ It is believe th t pl telets initi lly enter the spleen where

en otheli l sur ces. Disrupte en otheli l cells rele se they re in or 2 ys. Following this perio , pl telets re

thro bopl stic subst nces th t c n initi te co gul tion. in either the circul ting bloo or the ctive splenic pool.

Coll gen, in p rticul r, initi tes cont ct ctiv tion o c- ■ At ll ti es, pproxi tely two thir s o the tot l nu -

tor XII, thereby initi ting bloo co gul tion. Disruption ber o pl telets re in the syste ic circul tion, where s

o the en otheliu irectly ctiv tes ll our co ponents the re ining one thir exist s pool o pl telets in the

o he ost sis. spleen th t reely exch nge with the gener l circul tion.

9
■ A nor l person h s n ver ge o 250 × 10 /L (r nge, 150
× 10 /L to 450 × 10 /L) pl telets in the syste ic circul tion.
9
9
The Megakaryocytic Cell Series
■ T e li e sp n o ture pl telet is 9 ys ± 1 y. At the

■ M ture pl telets (thro bocytes), et bolic lly ctive cell en o their li e sp n, pl telets re ph gocytize by the
r g ents, re the secon critic l co ponent in the in- liver n spleen n other tissues o the ononucle r

ten nce o he ost sis. ph gocytic syste .

■ T ese nucle r cells circul te in the peripher l bloo er ■ A pl telet count is un ent l co ponent in the ev lu-
being pro uce ro the cytopl s o bone rrow eg - tion o p tient.

k ryocytes, the l rgest cells oun in the bone rrow. ■ Antipl telet rugs c n i pe e the process o he ost sis.

REVIEW QUESTIONS

*Indicates ML (optional) and MLS advanced content. 8. All bloo n ly ph tic vessels re line with

1. Nor l he ost sis epen s on ll o the ollowing A. en otheliu

except B. nerve en ings

A. n int ct v scul r syste C. str tif e epitheli l cells

B. in equ te nu bers o pl telets D. si ple squ ous epitheliu

C. ppropri te co gul tion ctors

D. f brinolysis 9. Bloo p sses ro the rteri l to the venous syste vi
A. rterioles

2 through 6. Te sequence o events ollowing injury to B. c pill ries

s ll bloo vessel is (2) to (3) to (4) C. veins

to (5) to (6) . D. rteries

A. cont ct between ge bloo vessel, bloo pl te-

lets, n co gul tion proteins 10. T e initi ting sti ulus to bloo co gul tion ollowing

B. or tion o pl telet plug injury to bloo vessel is

C. f brinolysis n reest blish ent o v scul r integrity A. cont ct ctiv tion with coll gen

D. evelop ent o bloo clot roun the injury B. v soconstriction

E. bloo vessel sp s (v soconstriction) C. stenosis
D. rele se o serotonin

7. Which bloo vessels h ve the thickest w lls?

A. Veins *11. En otheliu is involve in the et bolis n cle r-

B. Arteries nce o olecules such s

C. C pill ries A. serotonin

D. Arterioles B. ngiotensin
C. br ykinin

D. ll o the bove

(continued)