ischaemia and infraction Flashcards
the cardiovascular system:
* The cardiovascular system comprises all — , — and—
* All roads lead to and from the — (indirectly the — system)
* Vessels are lined by — cells
blood vessel , heart , lymphatics
heart
lymphatic system
endothelial cells
isechemia:
Reduced — and/or increased —
requirements but no —
* Characterised by insufficiency of —, lack of — substrates and inadequate— of metabolites(— )
1. Blood not getting—
2. Increase in — by tissue
3. Blood not getting –
blood supply
tissue
necrosis
02
nutrients
removal ( perfusion )
in
requirements
out
susceptibility of tissue ischaemia:
1. Poor — e.g. atheromatous arterial supply
2. Presence or absence of — circulation– (latter may compensate for reduced — )
Good collateral circulation:
- Liver, lung, bowel, brain (arterial anastomoses)
Poor collateral circulation:
- Kidney, spleen +/- heart
3. — Requirements
Organs with — metabolic rate and aerobic metabolism — susceptible (heart)
Supporting tissues (—, —) — susceptible
- suspectibiltiy to schema/infraction:
* Vulnerable tissues
‘ —’ areas (esp. during—/—)
- Splenic flexure of the—
- — ant/middle cerebral artery
- Deep —
* ‘One main supplying— ’ - pituitary, renal, exocrine pancreas
blood supply
collateral ciruclation
perfusion
tissue metabolism
high
more
fibrous, bone
less
watershed
shock/hypotesnion
colon
brain
deep myocardium
artery
ACUTE/CHRONIC ISCHAEMIA
* Acute ischaemia - thromboembolus to — , intermittent — , — , acute — ischaemia
* Chronic ischaemia - — lower limb — changes, ischaemic —
* Do not let ischaemia turn into –!
* Stercoral ulceration of rectosigmoid colon is a – —-impacted – faeces - local — of — wall by hard faeces —-
-faecal peritonitis - one study only 8% cases diagnosed
preoperatively
leg
claudication
angina
mesenteric
chronic
trophic
colitis
infraction
chronic
consotpation
hard
local pressure ishcmeia
bowel wall
perforation
reperfusion injury is due to – of blood supply following – of blood supply
* Restoration of blood flow after ischaemia may cause a — increase in —
* This is due to:
Formation of — following— of — supplied to cells
Failure of — pumps - cells unable to control levels of cytosolic – and accumulation in —
Calcium excess causes loss of cell — and —
Neutrophils, Reduction NO, cytokines, complement
* Clinically relevant with — into — and —
Amenable to- – intervention e.g. Tx: calcium channelblockers to slow the re-entry of Ca into cells
See Robbins for more info
restoration
loss
paradoxical
cell injury
free radicals
restoration of 02
Ca2+-ATPase
calcium
mitochondria
cell integrity and cell death
haemorrhage into cerebral and myocardial infracts
therapeutic
infraction : cell/tissue – due to – blood supply
* Area of — caused by — of either the — supply or the — drainage in a particular tissue
* What are the commonest sites for death due to ischaemic necrosis? (Infarction)
* Define necrosis – Cell death in living tissue. A form of
cell death caused by loss of membrane intregrity, intracellular organelle swelling and ATP depletion
leading to an influx of calcium, it is always pathological
- common clinical illnesses due to infraction :
* Myocardial infarction
* Cerebrovascular accident (infarct)
* Pulmonary infarction
* Bowel infarction
* Ischaemic necrosis of the extremities - what does this
mean?
death
reduced
ischaemic necrosis
occlusion
arterial
venous drainage
causes of ishcemeia and infraction reduced blood supply:
* —
Hypotension
Septic
Cardiogenic
*— of blood vessel
ATHEROSCLEROSIS
THROMBOSIS
EMBOLUS
* Other
Vasculitis
Local vasospasm e.g. cocaine
Extrinsic compression of vessel
Extrinsic compression of blood supply by oedema or entrapment
(hernia)
Torsion of vessel (testis)
Traumatic rupture of blood supply
* Which is the commonest cause in an artery and which in a vein?
shock
obstruction
- Definition of Thrombosis: — mass in — blood
- Definition of Embolus:— or — or— mass that moves from one part of the circulation to another
1- causes of thrombi :
*— Triad - — damage
- Must be able to give clinical causes of these
- Causes differ in arteries and veins
2- types of emboli: - Thrombus
- Tumour
- Septic
- Fat
- Air
- Cholesterol
- Foreign Body
- Nitrogen
- Amniotic fluid
solid
flowing
solid/gaseous/liquid
Virchow’s
endothelial
hyper coagulability
stasis
macroscopic appearances of infract:
* — shaped (occluded vessel at apex)
* Early
— defined, —
Narrow rim of — at edge due to inflammation/repair
* Late
Solid organ ( — )
Few RBC — –> some haemosiderin pigment
— and — defined
Spleen heart kidney
* — Infarction
this infarctions appear – due to— of — (extravasation). These can be seen in situations where a vessel
becomes twisted such as—. They can be seen in organs that have a loose — (lungs, brain, GIT) where there is a – blood supply.
wedged
poorly , iregular
hyperaemia
white
lysed
pale and sharply defined
haemorrhage infraction
red
escape
red blood cells
torsion
parenchyma
dual
( pls check slide 20 and other slides for pics )
microscopic features of infracts:
* May be — in first – to — , only—- (if patient survives)
— tissue stimulates — response at — (—)
— of cellular — and – tissue
— phase with — formation
— exception –> — necrosis
little
12 to 18 hrs
haemorrhage
necrotic
inflammatory
edge
1-2 days
phagocytosis
debris and dead tissue
reparative
scar
brain
liquefactive
anticoagulant in brain infraction:
* Why are you very careful of giving anticoagulants in a brain infarct due to a thrombus or embolus?
* An infarct in the brain may become—Why?
* — also ischaemic and ruptures
* Worsen situation by converting an — infarct to an— infarct
haemorrhage
vessel wall
ischemic
hameorrhagic
myocardium w polymorphs MI early:
- acute inflammatory cells ( — ) in between necrotic cells within —
- healing: 1-2 weeks replacement by — tissue
- scar: — tissue deposition causing scar formation
polymorphs
24 hours
granulation tissue
fibrous
what are the consequences of scar/fibrosis of myocardium following an infract:
* Loss of — function, causing —
failure
summary on microscopical changes in infraction in response to necrosis:
* Cell —
* acute —
* chronic—
*— tissue
*—
* Must be able to define all of these
muscle pump
left ventricular
necrosis
inflammation
inflamamtion
granulation
scar
- types of necrosis - review :
Definition: Necrosis cell – in – tissue - Coagulative - —
- Liquefactive - —
- Gangrenous - —
- Fat necrosis - Trauma to –
- Caseous - —
death
living
MI
stroke
diabetes
fat
TB
- factors determining degree of ishcmia/infraction summary:
- Availability of — blood supply
lungs, liver, vs kidney, spleen - — of development of —
e.g. coronary arteries & atherosclerosis - — of tissue
Neuron( — mins) vs Myocyte (—mins) vs Fibroblast (– ) - — content of blood –— increases
likelihood of ischaemia - summary ischmaeia vs hypoxia:
Hypoxia: – deficiency, causes —
Ischaemia: – of blood supply due to impeded — flow or— drainage
— is ischaemic necrosis
Myocardial infarct and stroke are the 2 major vascular killers in Ireland
alternative
rate
occlusion
vulnerability
3-4 min
20-30 min
hours
oxygen
anaemia
oxygen
cell injury
loss
artieral
venous
infraction
