Body Fluid Compartments Flashcards
Volume contraction vs expansion?
- Contraction is a decrease in volume
- Expansion is increase in volume
Iso, hypo, hyper osomotic?
- Isosmotic means no change in osmolarity
- Hyposmotic means body fluid osmolarity is decreased
- Hyperosmotic means body fluid osmolarity is increased
What makes up ECF?
- Plasma 20%
- Interstitial fluid 80%
What is 60-40-20 rule?
- 60% of body weight is water
- 40% of body water is intracellular fluid
- 20% body water is ECF
What is the only fluid that can be directed acted on to control volume and compositon?
- Plasma
- A change in plasma regulates the entire ECF
What electrolytes are found in the ECF vs intracellular fluid?
Plasma/Interstitial fluid:
- Na greater amouont than ICF
- K
- Cl
- Bicarb
- (no proteins in interstitial fluid)
ICF:
- Na
- K greater amount than ECF
- Phosphate
- Proteins
What is typical body osmolarity?
290 mOsm
Hypertonic cellular environment will cause cells to ___.
- Hypertonic cellular environment will cause cells to shrink as there will be a net movement of water out of the cell
Hypotonic cellular environment will cause a cell to ____
Hypotonic cellular environment will cause a cell to swell due to a rush of fluid into the cell
What are the four hormonal mechanisms to balance fluid compartments?
- Renal sympathetics
- RAAS
- Vasopressin
- Natriuretic peptide
Activation of what receptor will cause release of renin?
B1 adrenergic
What four things can cause releasae of ADH?
- Angiotensin II
- Atrial receptors in presence of low preload
- Increased osmolality of blood
- Sympathetic nervous activation
What does ANP do?
- Secreted in response to excessive preload of attia and ventricles
- Induces arteriolar dilation decrreasing TPR
- Increases fluid loss to decrease preload
- Inhibits renin
What does ANP do to ADH?
Inhibits its secretion and actions
Patient comes into ER soaked in sweat and light headed and dizzy. States they haven’t drank water the entire 90 degree sunny day they were working outside. What is happening to him regarding body fluid?
- Fluid is shifting from Intracellular to extracellular
- The fluid the cells are sitting in is now hypertonic and to balance out the fluid will leave the cells causing shrinkage
- This increases osmolarity in both compartments and decreases volume of both
What is hyponatremic dehydration?
- Loss of sodium is greather than the loss of water in the ECF
- Serum [Na] in ICF is now greatehr than ECF’s
- Water will chift from ECF to ICF to establish osmotic =
- Serum sodium and osmolality will be less than the normal range but equal
What occurs in hypernatremic dehydration?
- Loss of water is greater than loss of Na in ECF
- Serum [Na] in ECF is greater than ICF so water shifts from ICF to ECF
- water follows sodium
- Serum osmolality exceeds 300 mOsm/kg
- Serum sodium will be more than 150 mEq/L
What happens with a hyperosmotic volume contraction due to dehydration?
- Volume in both ECF and ICF decreases which will increase osmolality
How does diabetes insipidus cause hyperosmotic volume contraction?
- body can’t produce/respond to ADH
- There is an increase in water loss as the distal tubules can’t reabsorb water
What does adrenal insuffiiency do to fluid compartments?
- Causes Hyposmotic volume contraction
- ICF volume increases and ECF decreases
- Osmolarity of both decreases
- Aldosterone leads to excesssive loss of NaCl which will decrease ECF osmolarity so fluid will shift to ICF (which has higher Na levels) until it equilibrates
What does SIADH cause?
- Hyposmotic volume expansion
- Gain hypotonic fluid
- It is as if the patient is drinking water in excess
- Increases ECF and ICF volume and osmolality will decrease
What will a hemorrhage, diarrhea, or vomiting cause the body fluids to do?
- Isosmotic volume contraction
- Diarrhea wil lcause a loss of isosmotic fluid from GI
- Results in decrease ECF volume but no change in ICF volume or osmolality
What can cause an isosmotic volume expansion?
- Infusion of isotonic NaCl
- ECF volume will expand but ICF doesn’t change and osmolarity doesn’t chagne
Describe hypertonic volume expansion.
- Increase volume of ECF decrease ICF volume
- Increased osmolarity
- Due to excessive high intake of NaCl or infusion of hypertonic solution
What happens to hematocrit and plasma protein with an isosmotic volume contraction?
- Hct will increase
- Plasma protein increases
- caused by diarrhea or burns, ecf vol decreases icf volume same, osmolarity same
What happens to Hct and plasma protin with a hyperosmotic volume contraction?
- Hct is same
- Plasma protien increases
- d**ue to sweating fever or diabetes insipidus, ecf volume decreases icf volume decreases, osmolarity increases
What happens to Hct and plasma protien with a hyposmotic volume contraction seen with adrenal insufficiency?
- Hct will increase
- Plasma protein increases
- Ecf vol decreases, icf vol increases, osmolarity decreases
What happens to Hct and plasma proteins with an isosmotic voume expansion seen with infusion of NaCl?
- Both will decrease as volume of ECF is increasin but osmolarity is staying the same
What happens to Hct and plasma proteins in a hyperosmotic volume expansion?
- Both decrease
- Ecf vol increases, Icf vol decreases, osmolarity increases
What happens to Hct and plasma proteins with a hyposmotic volume expansion??
- Hct stays same
- Plasma protien decreases
- ecf inc and icf inc, osmolarity dec
- seen with SIADH
