16 Flashcards
– the thrombi become larger and larger eventually obstructing
the lumen of the blood vessel where they are formed.
Propagation
– portions of the thrombi break and
are carried into the circulation
Fragmentation to form thrombo-emboli
– lysis of the thrombi by plasma-derived
fibrinolytic system or through slow phagocytosis by phagocytic cells.
Dissolution by fibrinolysis
– invasion and growth of fibrous tissue could
happen, along with recanalization and restoration of blood flow.
Fibrous tissue organization
Thrombi are clinically important for two reasons:
a) they cause obstruction
of blood vessels, and b) they can be a source of emboli.
of the left chamber of the heart usually produces
emboli in the systemic circulation, while when it occurs in the right chamber, the
emboli are at the lungs.
Valvular thrombosis
One of the notorious “seeders” of emboli is the disease
called _________ that causes multiple embolisms in the
kidneys.
bacterial valvular endocarditis
A reduction in the flow of arterial blood to an organ or tissue result to a condition
called ____
ischemia
The reduction of blood supplies maybe partial and is called
,
hypoxia
complete reduction in the oxygen supplied to tissues called .
anoxia
obstructing the
cranial mesenteric artery.
Strongylus vulgaris
– In some organs, there are two separate blood
supply originating from different points. This includes the lungs (pulmonary
artery and bronchial artery), and the liver (hepatic artery and portal vein).
Thus, pulmonary and hepatic infarctions are rarely seen, although they
may occur in association with chronic passive venous congestion in which
the dual blood supply is compromised.
Dual Blood Supply
is considered one of the “silent” killers of humans.
Myocardial
infarction
_________ associated with subsequent formation of
thrombin. This leads to platelet aggregation and fibrin formation resulting
to microthrombosis of vascular capillaries, and infarction in many organs.
hypercoagulable phase
___________ associated with the activation of
the fibrinolytic system with consequent release of fibrin and fibrinogen
degradation products that suppresses fibrin polymerization.
Thrombocytes are depleted at this phase, including the various clotting
factors, notably fibrinogen, Factor VIII (anti-hemophilic factor), and Factor
V (proaccelerin).
hypocoagulable phase
DIC is
also known as consumption
coagulopathy or defibrination syndrome
is a state of peripheral circulatory failure caused by sudden and
severe injury.
Shock
where there occurs
reflex vasoconstriction in an attempt to maintain blood pressure and
cardiac output. It is at this phase that the counter regulatory mechanisms
are activated with the net effect of increasing heart beat (tachycardia),
peripheral vasoconstriction and fluid conservation in the kidneys.
Stage of ischemic hypoxia (non-progressive phase)
that is associated with
gradual fading of pre-capillary vasoconstriction with pooling of blood in the
capillary, a decline in venous return, and diminishing blood pressure; and
Stage of stagnant hypoxia (progressive phase)
where there occurs shift of fluid from the
intravascular space to the extravascular space and microembolization of
capillaries.
Stage of irreversibility
– produces peripheral
vasoconstriction and tachycardia. Blood is redistributed to vital organs.
Activation of the sympathetic nervous system
– Activation of the
apneustic and pneumotaxic areas of the brain following hypoxia brought
about by reduced ventilatory surface in events of hemodynamic alteration
of lung surface.
Stimulation of the respiratory centers in the brain
– release of catecholamines (epinephrine
and norepinephrine) from the adrenal medulla, and glucocorticoids from
the adrenal cortex. These result to peripheral vasoconstriction, and
release of glucose from storage areas.
Stimulation of adrenal gland
– result to
conservation of sodium ions and water by increasing kidney tubular
reabsorption.
Activation of the Renin-Angiotensin-Aldosterone Axis
. Some lesions found postmortem may be very
suggestive, or in some cases diagnostic, of severe shock
Congestive atelectasis
The term congestive
atelectasis is appropriate for these changes, which are also called
shock lung.
. Blood fall resultant of diapedeses or rbcs. In cattle that die
with a failing circulation, considerable fluid may be present in the intestine, and
the fluid contains so many red cells that the fluids look like blood.
Visceral pooling
. A fall in blood pressure causes reflex renal
vasoconstriction
Acute Renal Tubular Necrosis
refers to slowing down of the circulation, settling out of red
cells from plasma and increased stickiness of blood. Sludging is common in
shock.
Sludging
The norm blood pH is maintained between _______ by several buffer
system, the main one being the bicarbonate and carbonic acid.
7.35 and 7.45
