Lecture 2 - Osmosis & Surface Tension Flashcards
Define osmosis
process by which water moves across a semi-permeable membrane due to a concentration gradient
what category of molecule will not diffuse across a membrane via simple diffusion?
a. small molecules
b. polar molecules
c. charged molecules
c. charged molecules
what will not cross the plasma membrane? select all that apply
a. nonpolar molecules
b. large polar molecules
c. small polar molecules
d. ions
d & d
T/F: water moves TOWARD the more concentrated solution
TRUE
what is osmotic pressure
pressure caused by differences in solutes between solutions separated by a semipermeable membrane; what is needed to stop osmosis
what is oncotic pressure
pressure generated by colloids (molecules that do not cross the blood vessel)
what is the primary intravascular oncotic molecule
albumin
T/F: osmotically active molecules freely cross the semipermeable membrane
FALSE
T/F: a non-effective osmole does not generate water movement as it is not freely permeable
TRUE
____ is an effective osmole, while ____ is a non-effective osmole
glucose; urea
While an effective osmole cannot cross a membrane, it stimulates osmotic water movement by
pulling water to it
what is the main intracellular cation?
potassium (K+)
What is the main extracellular cation and anion
sodium (Na+); Chloride (Cl-)
osmolality
number of osmoles per kg of solvent
osmolarity
number of osmoles per liter of solvent
what is the osmolarity of plasma
~300 mOsm/L
what is the osmole gap and what is its clinical significance
the gap occurs when calculated osmolality does not equal the measured osmolality
*present in uncontrolled diabetes or antifreeze poisoning
if a cell is placed into a hypotonic solution what happens
the cell swells (lysis)
if a cell is placed into a hypertonic solution what happens
the cell shrivels (crenation)
if a cell is placed into an isotonic solution what happens
nothing
Which of the following solutions is hypotonic compared with blood?
a. LRS (300 mOsm/L)
b. 3% saline (1023 mOsm/L)
c. 0.45% saline (154 mOsm/L)
c. 0.45% saline (154 mOsm/L)
increased surface tension promotes what
alveolar collapse
T/F: the bigger the radius, the lower the pressure
TRUE
what is surfactant
secretion of type II alveolar cells that decreases surface tension
when is surfactant produced? why is this an issue?
near parturition; when birth occurs prematurely, the neonate may suffer respiratory distress
T/F: surfactant helps alveolar collapse
FALSE
