Body Fluid Compartments (Muster) - W1 Flashcards
How much of our body is made up of water?
60%
Defined as the total free solute per Kg of solvent
OsmolaLITY
Defined as the total free solute per liter of solvent
OsmolaRITY
Where is plasma found and what are its components?
- Intravascular space (inside the blood vessel)
- Huge amount of negative charge - comes from albumin
- total solute = 300
- Sodium = 140
- Choridie = 105
- HCO3 = 26
- Urea = 6
- Weak organic acid = 6
- glucose =5
- K+ =4
- Ca++ = 4
- Mg+ = 1
- H2PO4 = 1
- Albumin =1
How do we calculate the anion gap and what is responsible for it?
- Albumin generates anion gap
- Na+ - (Cl + HCO3+)
- a wide differenence in the gap indicates disease
What is interstitial fluid and what separates it from plasma?
- IF = plasma without albumin
- capillary wall separates the two
What are the forces at play between the IF and plasma?
- Cl- wants to flow across into plasma, water would follow
- Albumin generates oncotic pressure and acts as a draw.
- Pressure inside capillary favors FILTRATION.
- Oncotic pressure favors REABSOPRTION.
- Pressure in IF favors REABSORPTION.
- Oncotic pressure in IF favors FILTRATION.
What are the components of intracellular fluid?
- More K+ = 140
- PO4- = 4
- Cl - = 20
- Protein = lots
- Na+ = 10
- Mg+ = 10
- SO4- = 20
- Total = 240
What are the forces acting on the intracellular and interstitial fluid and what separates them?
- separated by cell membrane
- sodium wants to flow INTO CELL, K+ wants to flow out. Water would flow in and lead to bursting.
- prevent with Na/K ATPase to maintain gradient.
Any solution that has ~300mOsmos
Isosmotic
Any solution that WILL NOT change the VOLUME of a cell.
isoTONIC
Decribe how water is distributed in the body between the compartments.
- Total body water = 60%
- intracellular = 2/3
-
extracellular = 1/3
- interstitial = 3/4
- plasma = 1/4
Explain what happens with the EC compartements when you water to a patient?
- Volume - INCREASES in both IC and EC
- EC Na+ decreases.
- IC K+ decreases.
Explain what happens with body compartments when you give NS?
- ONLY goes into EC compartment
- Volume = INCREASED IN EC
- NA REMAINS SAME. = ISOTONIC
Explain what happens with compartments when you give pure salt:
- only goes into EC compartment
- Na+ INCREASES in EC
- water moves from IC to EC
- DECREASED cell volume
- INCREASED EC volume
What is volume depletion?
- Extracellular volume loss from ANY CAUSE - most often loss of salt and water.
What is dehydration?
- presence of hypernatremia (increased osmolality) due to pure water loss
If you drink IL of water, how will it distribute?
- 2/3 IC = 666
- 1/3 EC = 333
- 3/4 interstiial = 250
- 1/4 plasma = 83
What will happen if you infuse normal saline?
- Increased PRESSURE in the plasma
- decreased oncotic pressure in plasma
- will flow into interstital but be STUCK THERE
- Overall
- 750mL to interstitial
- 250mL to plasma
- no change in overall osmolality.
What situations call for NS?
- DKA - diabetic ketoacidosis
- volume depleted - water follows glucose into urine
- may be hypotensive and tachycardic
- Sepsis
In what situations would you give 1/2NS and how does it affect the cell?
-
Distribution
- NS goes extracellular
- water goes everywhere
- Known as a maintenance fluid
-
Situations
- Sweat loses - water, Na, Cl- is lost
- Hospitalization - patients are often sweating and have fever + water loss w/higher RR
What situations would you give 1L of D5W and how does it distribute?
- distributes everywhere
- glucose gets removed completely - sol’n is isosmotic in bag but hypotonic in vivo.
- Situations
- Diabetes insipidus - pee lots of water
- Severe hypoglycemia
