Human Physiology, 14th edition (2016)

458 Chapter 14

5. decreased plasma protein concentration, as a result of

liver disease (the liver makes most of the plasma proteins)

or kidney disease where plasma proteins are excreted in

the urine;

6. obstruction of the lymphatic drainage due to para-

sitic larvae in elephantiasis ( fig.  14.10 and table 14.2 )

or to surgery (breast surgery is a leading cause of

lymphedema).

(during pregnancy, for example)—which produces a con-
gestive increase in capillary pressure;
3. leakage of plasma proteins into interstitial fluid, which
causes reduced osmotic flow of water into the capillaries
(this occurs during inflammation and allergic reactions as
a result of increased capillary permeability);
4. myxedema —the excessive production of particular glyco-
proteins (mucin) in the extracellular matrix caused by
hypothyroidism;

Figure 14.9 The distribution of fluid across the walls of a capillary. Tissue, or interstitial, fluid is formed by filtration
( yellow arrows ) as a result of blood pressures at the arteriolar ends of capillaries; it is returned to the venular ends of capillaries by the
colloid osmotic pressure of plasma proteins ( orange arrows ).
See the Test Your Quantitative Ability section of the Review Activities at the end of this chapter.

(Pc + πi) – (Pi + πp)

(Fluid out)

Where Pc = hydrostatic pressure in the capillary

πi = colloid osmotic pressure of interstitial fluid

Pi = hydrostatic pressure of interstitial fluid

πp = colloid osmotic pressure of blood plasma

(37 + 0) – (1 + 25)

= 11 mmHg

Net filtration

(17 + 0) – (1 + 25)

= –9 mmHg

Net absorption

(Fluid in)

N

et

fi

ltr

ati

on

Ne

t (^) a
bs
or
pt
io
n
Arteriole Venule
Blood
flow
Capillary
Tissue
fluid
Venous end
of capillary
Arterial end
of capillary
Net
force out
Net
force in