Body Fluid Compartments

Question 1

Volume contraction vs expansion?

Answer 1

• Contraction is a decrease in volume
• Expansion is increase in volume

Question 2

Iso, hypo, hyper osomotic?

Answer 2

• Isosmotic means no change in osmolarity
• Hyposmotic means body fluid osmolarity is decreased
• Hyperosmotic means body fluid osmolarity is increased

Question 3

What makes up ECF?

Answer 3

• Plasma 20%
• Interstitial fluid 80%

Question 4

What is 60-40-20 rule?

Answer 4

• 60% of body weight is water
• 40% of body water is intracellular fluid
• 20% body water is ECF

Question 5

What is the only fluid that can be directed acted on to control volume and compositon?

Answer 5

• Plasma
• A change in plasma regulates the entire ECF

Question 6

What electrolytes are found in the ECF vs intracellular fluid?

Answer 6

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

Question 7

What is typical body osmolarity?

Answer 7

290 mOsm

Question 8

Hypertonic cellular environment will cause cells to ___.

Answer 8

• Hypertonic cellular environment will cause cells to shrink as there will be a net movement of water out of the cell

Question 9

Hypotonic cellular environment will cause a cell to ____

Answer 9

Hypotonic cellular environment will cause a cell to swell due to a rush of fluid into the cell

Question 10

What are the four hormonal mechanisms to balance fluid compartments?

Answer 10

1. Renal sympathetics
2. RAAS
3. Vasopressin
4. Natriuretic peptide

Question 11

Activation of what receptor will cause release of renin?

Answer 11

B1 adrenergic

Question 12

What four things can cause releasae of ADH?

Answer 12

1. Angiotensin II
2. Atrial receptors in presence of low preload
3. Increased osmolality of blood
4. Sympathetic nervous activation

Question 13

What does ANP do?

Answer 13

• Secreted in response to excessive preload of attia and ventricles
• Induces arteriolar dilation decrreasing TPR
• Increases fluid loss to decrease preload
• Inhibits renin

Question 14

What does ANP do to ADH?

Answer 14

Inhibits its secretion and actions

Question 15

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?

Answer 15

• 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

Question 16

What is hyponatremic dehydration?

Answer 16

• 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

Question 17

What occurs in hypernatremic dehydration?

Answer 17

• 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

Question 18

What happens with a hyperosmotic volume contraction due to dehydration?

Answer 18

• Volume in both ECF and ICF decreases which will increase osmolality

Question 19

How does diabetes insipidus cause hyperosmotic volume contraction?

Answer 19

• body can’t produce/respond to ADH
• There is an increase in water loss as the distal tubules can’t reabsorb water

Question 20

What does adrenal insuffiiency do to fluid compartments?

Answer 20

• 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

Question 21

What does SIADH cause?

Answer 21

• 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

Question 22

What will a hemorrhage, diarrhea, or vomiting cause the body fluids to do?

Answer 22

• 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

Question 23

What can cause an isosmotic volume expansion?

Answer 23

• Infusion of isotonic NaCl
• ECF volume will expand but ICF doesn’t change and osmolarity doesn’t chagne

Question 24

Describe hypertonic volume expansion.

Answer 24

• Increase volume of ECF decrease ICF volume
• Increased osmolarity
• Due to excessive high intake of NaCl or infusion of hypertonic solution

Question 25

What happens to hematocrit and plasma protein with an isosmotic volume contraction?

Answer 25

* Hct will increase * Plasma protein increases * *caused by diarrhea or burns, ecf vol decreases icf volume same, osmolarity same*

Question 26

What happens to Hct and plasma protin with a hyperosmotic volume contraction?

Answer 26

* Hct is same * Plasma protien increases * *d**ue to sweating fever or diabetes insipidus, ecf volume decreases icf volume decreases, osmolarity increases*

Question 27

What happens to Hct and plasma protien with a hyposmotic volume contraction seen with adrenal insufficiency?

Answer 27

* Hct will increase * Plasma protein increases * *Ecf vol decreases, icf vol increases, osmolarity decreases*

Question 28

What happens to Hct and plasma proteins with an isosmotic voume expansion seen with infusion of NaCl?

Answer 28

* Both will decrease as volume of ECF is increasin but osmolarity is staying the same

Question 29

What happens to Hct and plasma proteins in a hyperosmotic volume expansion?

Answer 29

* Both decrease * *Ecf vol increases, Icf vol decreases, osmolarity increases*

Question 30

What happens to Hct and plasma proteins with a hyposmotic volume expansion??

Answer 30

* Hct stays same * Plasma protien decreases * *ecf inc and icf inc, osmolarity dec* * *seen with SIADH*