Lecture 20

Question 1

embolus

Answer 1

intravascular solid liquid or gaseous mass that is transported by the blood to a site distant from its point of origin

Question 2

embolism

Answer 2

blockage of a downstream vessel by an upstream embolus

Question 3

most common embolus

Answer 3

thromboembolus

Question 4

saddle thromboembolism

Answer 4

thromboembolus that has lodged at a site of vessel bifurcation

Question 5

How to distinguish between a thrombus and thromboembolism grossly

Answer 5

thorough search for possible thrombus upstream

Question 6

Consequence of a septic thromboembolism

Answer 6

can lead to new foci of infection

Question 7

Where do most venous thrmoboeboli become trapped

Answer 7

vascular bed of the lungs

Question 8

venous thromboembolizing from GIT, stomach, pancreas, spleen or their mesenteries become trapped

Answer 8

in the vascular bed of the liver

Question 9

possible consequences of pulmonary thromboembolism(2)

Answer 9

may occlude the main pulmonary artery , impact across the bifurcation of the right and left pulmonary arteries or pass into the smaller arterial branches
lungs have dual blood supply so obstruction of medium artery will not cause pulmonary infarction

Question 10

-sudden embolic obstruction of >60% of pulmonary circulation->

Answer 10

sudden death or hypertensive right heart disease (cor pulmonale)

Question 11

Where can systemic thromboemboli be trapped(3)

Answer 11

widely distributed->likely to cause tissue infarction
ex: brain, myocardium, kidneys, spleen, liver, intestines
horse-thrombus in root of cranial mesenteric artery->impact blood supply to LI

Question 12

Other types of emboli(not thrombus)(4)

Answer 12

bacterial colonies or fungal hyphae
malignant neoplastic cells
lipid
Gas bubbles (the bends)

Question 13

Ischemia

Answer 13

hypoxic or anoxic tissue injury resulting from a local reduction in blood flow

Question 14

Infarction

Answer 14

the process by which ischemic necrosis of a localized area of tissue develops

Question 15

Infarct

Answer 15

the area of tissue wich has undergone infarction

Question 16

some conditions other than thrombosis that can cause ischemia(6)

Answer 16

arteriosclerosis (hardening of artery wall)
atherosclerosis(plaque/fat build up)
congestive heart failure
shock
dehydration
impaired venous return to heart (bloat, GDV)

Question 17

Why is infarction more common to arterial obstruction than venous

Answer 17

many tissues lack a back up (collateral) arterial blood supply, whereas venous collateral channels may be numerous

Question 18

In which organs is infarction fatal(4)

Answer 18

cerebral
myocardial
intestinal
pulmonary

Question 19

Major factors that determine prognosis with local reduction in blood flow(5)

Answer 19

Presence of an alternative oxygen supply (most important)
rate of development and degree of occlusion
size of affected vessel
cell vulnerability to hypoxia and duration of hypoxia(brain 3-4 minutes)
oxygen content of the blood

Question 20

Do functional end arteries cause infarction

Answer 20

yes, almost always

Question 21

to parallel arteries cause infarction

Answer 21

rarely

Question 22

which places have dual blood supply(3)

Answer 22

lungs
liver
distal forelimbs

Question 23

why are infarcts less likely to develop in lungs or liver

Answer 23

dual blood supply

Question 24

What type of necrosis occurs in an infarct (2)

Answer 24

coagulative- most tissues

liquefactive- brain and spinal cord

Question 25

What happens to necrotic debris over time

Answer 25

liquefied or phagocytosed by leukocytes

Question 26

gross feature allow you to recognize infarct at surgery/necropsy(2)

Answer 26

wedge shaped

red hemorrhagic infarct or white anemic infarct

Question 27

Gross appearance of infarct over time

Answer 27

becomes more sharply defined
acute- infarcted tissue seems friable
becomes whiter with age
hemorrhagic- more hemorrhage->older