Hemostasis is the maintainence of the clotfree state of blood amp the prevention of blood loss via the formation of hemostatic plug Hemostasis depends on three general components ID: 932377
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Slide1
4-Hemostasis and Blood Coagulation
Hemostasis
is the
maintainence
of the clot-free state of blood & the prevention of blood loss via the formation of hemostatic plug.
Hemostasis
depends on three general components
:
a)
Vascular
wall
b)
Platelets
c
)
Coagulation pathways
Slide2Whenever
a vessel is ruptured or severed, hemostasis is achieved by several mechanisms:
A
. Vascular spasm
B
. Formation of platelet plug
C.
Formation blood clot as a result of blood coagulation
D
. Eventual growth of fibrous tissue in to the blood clot to close the hole in the vessel permanently.
Slide35-Thrombosis
Thrombosis is defined as the formation of a solid or semisolid mass from the constituents of the blood within the vascular system during life.
Slide4Slide5Pathogenesis
***There
are three factors that predispose to thrombus formation. These factors are called Virchow’s triad:
A
:
Endothelial
injury
B:
Stasis or turbulence of blood
flow
C:
Blood hypercoagulability
Slide6Morphology of Thrombi
1-
Arterial thrombi
a) Arise at the site of endothelial injury
b
) Grow in a retrograde
fasion
,
against site
of attachment
. flow
towards the heart
c
) Has firm attachment
d
) They usually occlude the blood flow
Slide7Slide8Slide92-Venous
thrombi
a
) Arise at area of stasis
b
) Grow in the direction of blood flow from
its
c) Has loose attachment, hence, propagating. tail may undergo fragmentation.
d) Almost invariably occlusive
Slide10Slide11Slide12Slide13Slide14Slide15Slide16Fates of a thrombus
A:
Propagation
:
B:
Embolization:
C:
Dissolution
:
D:
Organization and
recanalization
Slide176-Embolism
An
embolus is a detached intravascular solid, liquid or gaseous mass that is carried by blood to sites distant from its point of origin. After traveling via the blood, the embolus can obstruct a vessel.
Slide18Slide19Slide20Slide21Slide22Causes of embolism
An
embolus can arise from:
Thrombus
(99% of emboli arise from a thrombus. Such an embolus is called
thromboembolus
)
Platelets
aggregates
Fragment
of material from ulcerating
atheromatous
plaque
Fragment
of a
tumour
Fat
globules
Bubbles
of
air
Amniotic
fluid o Infected foreign
material
Bits
of bone
marrow
Slide23Thromboembolism
a)
Pulmonary thromboembolism (PTE)
b)
Systemic
thromboembolism
c)
Crossed embolism (Paradoxical embolism)
Slide24Slide25Slide26Slide277-Infarction
An infract is an area of ischemic necrosis caused by occlusion of either
the arterial
supply or venous drainage in a particular tissue
.
Slide28Slide29The development & the size of an infarct are determined by the following
factors
A
.
The nature of the vascular supply
B
. The rate of development of occlusion
C.
Suceptibility
of the tissue for hypoxia
D.
Oxygen content of the blood
E.
The severity & duration of ischemia
Slide30Types of infarcts
Infarcts
are classified
depening
on
:
A)
the basis of their
colour
(reflecting the amount of
haemorrhage
) into:
1.
Hemorrhagic (Red) infarcts
2.
Anemic (White) infarcts
B)
the presence or absence of microbial infection into:
1.
Septic infarcts
2.
Bland infarcts
Slide31Clinical examples of infarction
A.
Myocardial infarction
B.
Cerebral infarcts
C.
Lung infarcts
D.
Splenic infarcts
Slide32Slide33Slide34Thank you for listening