Page 83 - Concise Pathology for Exam Preparation ( PDFDrive )

68 SECTION I General Pathology

Q. Enumerate the differences between exudate and transudate.

in
Ans. Differences between exudate and transudate are tabulated Table 4.1.
TABLE 4.1. Differences between exudate and transudate

Features Exudate � Transudate
Definition Oedema associated with increased vascular Filtrate of plasma; no
blood or
vascular
permeability increase in permeability
observed
Nature Inflammatory oedema Noninflammatory oedema
g/dl)
g/dl)
Protein content 1. High (more than 4 1. Low (less than 3
2. Has high fibrinogen and tendency to 2. Mainly albumin, low fibrinogen

coagulate
Specific gravity High (more than 1.018) Low (less than 1.015)
pH .7.3 ,7.3
LDH High Low
.0.6
Fluid LDH/serum LDH ratio is Fluid LDH/serum LDH ratio is
,0.6
Cells Highly cellular; rich in Few, mainly mesothelial cells
polymorphs
congestive
Example Pus seen in infections Fluid in cardiac failure
pyogenic
Q. What are the factors affecting fluid balance across capillaries?
Ans. Factors affecting fluid balance across capillaries (Fig. 4.1) can be summarized
as follows:
Plasma colloid oncotic pressure (which tends drive water and salts into the vessels)
(a)
to
to
Capillary hydrostatic pressure (which tends drive water and salts out the vessels
(b)
of
into the interstitial space)
(c)
Lymphatic drainage (which tends drain the interstitial space)
to
(d)
Sodium balance (sodium retention increases hydrostatic pressure and causes
a
dilutional decrease the colloid osmotic pressure)
in
• �Oedema occurs when there are
(a) Abnormalities the hydrostatic and oncotic pressures acting across the vessel
in
walls
in
(b) Alterations the endothelial wall structure
in
(c) Alterations the lymphatic outflow system
o
f
• �Normally, the arteriolar end the capillary bed, the hydrostatic pressure exceeds the
a
t
plasma oncotic (colloid osmotic) pressure pushing the water and electrolytes out from
t
A
f
o
the vessels into the interstitial tissue. the venous end the capillary bed, osmotic
s
i
i
pressure more than the hydrostatic pressure and hence the fluid reabsorbed from
s
i
s
a
y
b
the interstitial tissue into the vessels this end. The interstitial fluid drained the
t
o
t
lymph vessels and this eventually returns the veins via the thoracic duct.
Oncotic pressure Oncotic pressure
25 mmHg 25 mmHg
Blood pressure Blood pressure
Blood pressure
Blood pressure
30 mmHg 10 mmHg
30 mmHg
10 mmHg
Arteriolar end Venous end
of capillary of capillary
Interstitial fluid
FIGURE 4.1. Factors affecting fluid balance across capillaries.
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