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edem

a

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edem

aDefinition

Abnormal increase in the

volume ofInterstitial Fluid

Types :

a- Generalized b- localized

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Tissuecell

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1-increased capillary blood pressure

Causes of edema

venous pressure

capillary pressureCauses of increased venous pressure

a- compression from outside by tumor or

pregnancyb- block from within by thrombus

c- right heart failure

d- nephrosis

e- standin for a lon eriod

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1-increased capillary blood pressure

Causes of edema

arterial pressure

x

capillary pressure

Why edema develops in some cases of

hypertension?

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2- decrease in plasma proteins concentration(hypoproteinemia)

Causes of edema

Normal plasma proteinsconcentration = 7-7.5 g/dlThe threshold for systemic

edema = 5.5 g/dl

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2- decrease in plasma proteins concentration(hypoproteinemia)

Causes of edema

Causes of hypoproteinemia:A- malnutrition

B- liver diseaseC- loss of plasma protein in urine

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3-increased capillary permeability

Causes of edema

capillarypermeability

escape of plasmaproteins into

the interstitial space

Interstitial fluidcolloid osmoticpressure

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3-increased capillary permeability

Causes of edema

Causes of increasedcapillary permeability

A- extremes of temperature

B- capillary dilatationC- oxygen lackD- nutritional deficiency

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4- lymphatic obstruction

Causes of edema

Causes of lymphaticobstruction

A- compression from outsideB- obstruction from insideC- following radical surgery

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5- salt and water retention

Causes of edema

salt and waterretention

Blood volume

Capillaryhydrostatic

pressure

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DOAA SAMY

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Cerebral

circulation

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Interruption of blood flow to thebrain for only 5-10 seconds causes

loss of consciousness

Circulatory arrest for only 3-4minutes causes irreversible brain

damage

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Cerebralcirculation

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The baroreceptor reflexmaintains blood pressure at an

adequate level to keep bloodflow to the brain.

The average cerebral bloodflow in resting conditions =750ml/min

Cerebral blood

flow

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Regulation of cerebral blood

flow1- autoregulation

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Regulation of cerebral blood

flow1- autoregulation

CO2 +H2O H2CO3 H++

HCO3-

Hypoxia anaerobic glycolysislactic acid accumulation

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Regulation of cerebral blood

flow2- neural control

Sympathetic

Parasympathetic

Role ?????

may have a role on larger vessels andthose located in the pia mater

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Regulation of cerebral blood

flow3- cerebrospinalfluid (CSF)

pressureCushing reflex:CSF pressure systemicvasoconstriction

(hypoxia)

systemic bloodpressure

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