Lecture 9 - Fluid Replacement Therapy Flashcards
What is osmolality?
The number of solute particles per kg of solvent
What is osmolarity?
The number of particles of solute per litre of solution
What is tonicity?
It compares the osmotic pressure gradient of two solutions separated by a semipermeable membrane
What is an isotonic solution?
When the osmolality of the solution is the same as the Osmolality within the cell
What is a hypotonic solution?
Solution has a lower Osmolality than the cell
(Less solute particles in the solution compared to the cell)
What is a hypertonic solution?
High solute in the solution outside of the cell, less solute in the cell
What is the TBW in a man?
60%
What is the TBW in a woman?
55%
Why do men have a higher percentage of water in their body?
They have more muscle than women and muscle is very good at retaining water
Describe how water is distributed throughout the body:
2/3 Intracellular fluid
1/3 extracellular fluid:
-25% in plasma
-75% in interstital fluid
What is the TBW percentage of a new baby?
75%
Why are babies very vulnerable to fluid loss?
They are 75% water so can lose lots of body weight if dehydrated
What is the TBW in the elderly?
45%
Why is the elderlys TBW % low at 45%?
As we age we lose muscle mass so can store less water
What is the main ions found in the extracellular fluid compartment (plasma + interstitium)?
Na+
Cl-
What is the main ion located in the intracellular fluid compartment?
K+
(Levels of Na+ are low)
Why is the concentration of Na+ low in the Intracellular fluid compartment?
The Na+ is able to freely flow between the leaky capillaries in the extracellular fluid compartment to the plasma and interstitial fluid
But cant freely flow into the intracellular fluid compartment, needs to cross cell membrane via transporters