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osmolarityrelated

Osmolarity-related refers to anything influenced by or related to osmolarity, the concentration of osmotically active particles in a solution. Osmolarity is defined as the number of osmoles of solute per liter of solution (Osm/L). In human physiology, osmolarity and osmolality are closely related; for practical purposes they are often treated as equivalent, though osmolality is measured per kilogram of water. The relevant solutes include electrolytes (sodium, potassium, chloride), glucose, and urea, as well as other small molecules that generate osmotic pressure. Permeant solutes contribute to osmotic pressure but may have different effects on cell volume depending on membrane permeability.

Through osmosis, water moves across semipermeable membranes toward higher solute concentrations. An increase in extracellular osmolarity

Measurement and clinical relevance: Serum osmolality is measured directly by osmometry or estimated from common solutes

Physiological regulation: The body maintains plasma osmolality within a narrow range (~275–295 mOsm/kg) via thirst and

causes
water
to
exit
cells,
potentially
shrinking
them;
a
decrease
causes
swelling.
Osmotic
pressure
can
be
described
by
the
van't
Hoff
relation
in
simple
solutions,
though
real
biological
systems
are
more
complex
due
to
membrane
selectivity
and
solute
permeability.
Tonicity
refers
to
the
effect
of
extracellular
solute
on
cell
volume,
distinguishing
permeant
vs
impermeant
solutes.
using
calculated
osmolarity
equations
(for
example,
2
×
[Na+]
+
glucose/18
+
BUN/2.8
in
mOsm/kg).
Osmolar
gap
refers
to
the
difference
between
measured
osmolality
and
calculated
osmolarity,
used
to
detect
unmeasured
solutes
such
as
alcohols.
Abnormal
osmolarity
can
accompany
dehydration,
overhydration,
or
disorders
affecting
solute
balance,
with
hyponatremia,
hypernatremia,
or
diabetic
hyperglycemia
being
common
contexts.
antidiuretic
hormone
(vasopressin)
signaling,
adjusting
renal
water
excretion.
Osmolarity-related
disturbances
influence
cell
volume
and
can
have
widespread
effects
on
neural
function,
cardiovascular
stability,
and
metabolism.
In
research,
osmolarity
manipulation
is
used
to
study
cell
physiology,
fluid
balance,
and
pharmacodynamics.