Unit 4 - Osmosis and Membrane Processes Flashcards
What is osmolality?
Measurement of solute concentration in a fluid
What does high osmolality equal?
High solute concentration
What does increased osmolality in blood tirgger? 2
Desire to drink
Release of antidiuretic hormone
What does decreased osmolality in blood trigger? 2
inhibits desire to drink
Inhibits release of antidiuretic hormone
What does serum osmolality tests assess? 4
Hydration status
hyperglycemia
functioning of hypothalamus
posioning by ethylene glycol
Describe antifreeze poisoning. What happens and how do you treat it?
Oxidation reactions in liver + kidneys metabolize ethylene glycol
Toxic metabolites causes metabolic acidosis and nephrotoxosis. Oxalate is cytotoxic
IV fluid therapy to restore hydration,
correct electrolyte imbalances, promote
kidney function and excretion of ethylene
glycol
Sodium bicarbonate often included to
counteract excessive acid levels 6
How do you treat antifree poisoning
Solution of diluted ethanol often given as
treatment
Works by competing with ethylene
glycol for binding site on enzyme that
converts ethylene glycol into toxic
metabolites
Ethylene glycol can be eliminated from
the body unchanged
Describe Isotonic fluid therapy
- Osmolality comparable to that of normal blood
Extracellular fluid has same conc. of dissolved substances as intracellular fluid
What is an ex of isotonic fluid therapy
0.9 % NaCl (saline)
Describe Hypotonic fluids
Osmolality is less than that of blood
Higher concentration of solutes in the cytoplasm than in the extracellular fluid
water flows into the cell and causes it to swell and possibly to break
Describe hypertonic fluids
Osmolality is greater than that of blood
extracellular fluid has higher concentration of solutes than the cytoplasm
water leaves the cell, causing the cell to shrink and become shriveled
Describe Electrolytes
Small and most abundant solute in body
Greatest ability to cause fluid shifts
between compartments
Concentration in body fluids is
expressed as milliequivalents per liter
Describe organic molecules in body fluids. List some examples. 4
Large and not as numerous
Unevenly distributed among fluid
compartments
Examples: soluble proteins,
phospholipids, cholesterol,
triglycerides
What is the relationship between osmolality and water?
Any change in the concentration of
any solute incurs movement of
water from one compartment to
another
water crosses cell membrane
or
water crosses capillary walls
13
Describe what an edema is. What are common signs?
Abnormal, excess accumulation of
fluid in tissue
Common sign of abnormal movement
of fluid from vascular space into
interstitial space
Pulmonary edema
Cutaneous edema
Describe the type of fluid: Crystalloid
Compo of water rich with electrolytes. Either hypotonic or isotonic
- Solutes are small, can cross vascular wall
- Good for rehydration of extravascular spaces and correcting acid/base imbalances
Describe the type of fluid: Colloid
Heavy molecules suspended in
isotonic crystalloid
Solutes too large to cross vascular
wall
“hold” fluid in intravascular space
Give two specific examples of solutes in the body
Electrolytes, organic molecules
What type of fluid is used for fluid therapy contains large solutes
Hypertonic?
What is membrane processes used for?
Absorption of nutrients or excretion
of waste through plasma membrane
may occur with or without
expenditure of energy (ATP)
What two membrane processes are there?
Passive processses
Active processes
What three ways can a membrane be permeable
freely permeable
impermeable
selectively impermeable