Keef 6

Question 1

T/F The majority of our body weight is due to water. If true, what could change this?

Answer 1

True.

This could change if you become morbidly obese b/c then fat will make up a large portion of your body weight.

Question 2

What is the equation for measuring the volume of a fluid compartment w/ a tracer?

Answer 2

Volume = Quantity of Tracer/Conc’n of Tracer

Question 3

1 L of H20 is equal to how many kg of H20?

Answer 3

1

Question 4

What tracer is usu used to measure total body water?

Answer 4

D20, heavy water

Question 5

What tracer is usu used to measure total extracellular fluid?

Answer 5

sodium, iodine, inulin

Question 6

What tracer is usu used to measure plasma volume?

Answer 6

I-albumin

Question 7

What tracer is usu used to measure blood volume?

Answer 7

chromium labeled red blood cells.

Question 8

Aside from using chromium labeled red blood cells, what is another way to measure the blood volume?

Answer 8

Plasma Volume (I-albumin)/1-Hct = Blood Volume

Question 9

How do you find the volume of the interstitial fluid?

Answer 9

Interstitial Fluid = Extracellular Fluid - Plasma Volume

Question 10

How do you measure intracellular fluid volume?

Answer 10

Total Body Volume - Extracellular Fluid Volume = Intracellular Fluid Volume

Question 11

Approximately what percentage of your body weight is due to water?

Answer 11

60%

Question 12

Approximately what percentage of your body weight is due to intracellular water?

Answer 12

40%

Question 13

Approximately what percentage of your body weight is due to extracellular water?

Answer 13

20%

Question 14

About how many liters of water is in your body?

Answer 14

~42 L

Question 15

About how many liters of water is in your blood?

Answer 15

~3 L

Question 16

Joe Cell is essentially a perfect ________. The exception to this is which organ?

Answer 16

osmometer: the fluid moves where it needs to!
Exception: brain b/c of the confines of the skull–but it has compensatory mechanisms.

Question 17

When we talk about acidosis or over hydration…are we talking about outside of the cells or inside of the cells?

Answer 17

Outside of the cells. Extracellular fluid.

Question 18

What does careless over-administration of saline cause? What does it do to the ECF & ICF compartment volumes? To osmolarity?

Answer 18

Isotonic Overhydration
ECF compartment expands in volume
ICF stays the same
same osmolarity

Question 19

What does psychogenic polydipsia cause? What does it do to the ECF & ICF compartment volumes? To osmolarity?

Answer 19

Hypotonic Overhydration
ECF & ICF compartment volumes expand
Osmolarity decreases

Question 20

What does drinking sea water cause? What does it do to the ECF & ICF compartment volumes? To osmolarity?

Answer 20

Hypertonic Overhydration
ECF expands; ICF shrinks
Osmolarity increases
**patient will experience increased thirst & edema

Question 21

What does a hemorrhage do? What does it do to the ECF & ICF compartment volumes? To osmolarity?

Answer 21

Causes isotonic dehydration
ECF compartment shrinks
ICF remains constant
osmolarity remains constant

Question 22

What does Addison’s Disease cause? What does it do to the ECF & ICF compartment volumes? To osmolarity?

Answer 22

This is due to adrenal insufficiency…you lose a bunch of super salty water b/c no aldosterone for salt reabsorption
Hypotonic Dehydration (ECF becomes hypotonic)
ECF compartment shrinks
ICF compartment expands
osmolarity decreases

Question 23

What happens when you’re lost in the desert w/ no water & you sweat a lot? What does it do to the ECF & ICF compartment volumes? To osmolarity?

Answer 23

You lose water, w/o losing very much salt.
This increases the osmolarity of your ECF.
Your ECF volume decreases from sweating.
ICF shifts into ECF.
Ultimately…
ECF & ICF shrink in size
Osmolarity increases

Question 24

What happens when you have Diabetes Insipidus?

What does it do to the ECF & ICF compartment volumes? To osmolarity?

Answer 24

You lack ADH…can’t reabsorb water properly…gives blood w/ high osmolarity. Triggers thirst.
You ultimately lose more water than you do salt.
This increases the osmolarity of your ECF.
Your ECF volume decreases from lack of ADH reabsorption.
ICF shifts into ECF.
Ultimately…
ECF & ICF shrink in size
Osmolarity increases

Question 25

Extracellular sodium conc'n can remain normal in which 2 cases?

Answer 25

Isotonic Dehydration (hemorrhage) & Isotonic Overhydration (IV overadmin)

Question 26

Extracellular sodium conc'n can decrease in which 2 cases?

Answer 26

Water intoxication (hypotonic overhydration) or Addison's Disease (hypotonic dehydration)

Question 27

Extracellular sodium conc'n can increase in which 2 cases?

Answer 27

Drinking sea water (hypertonic over hydration) or sweating w/o water in the desert (hypertonic dehydration).

Question 28

2 cases of hypernatremia include drinking sea water & being lost in the desert...how would plasma proteins help you distinguish which of these 2 cases was actually happening?

Answer 28

Plasma proteins would be dilute if the person were drinking sea water...the sea water doesn't have plasma proteins!! Plasma proteins would be conc'nted if the person were sweating w/o water in the desert....b/c they're not sweating out plasma proteins & they're losing water.

Question 29

If a person sweats out 2L of sweat & then drinks 2 L of water...what happens to their plasma osmolarity? Intracellular osmolarity?

Answer 29

B/c they sweat out salt & didn't replace it...their osmolarity for both will decrease.

Question 30

If a person sweats out 2L of sweat & then drinks 2 L of water...what happens to their ECF compartment?

Answer 30

It will actually decrease in volume b/c the hypotonic fluid will want to shift into the intracellular compartment where there are more solute particles.

Question 31

If a person sweats out 2L of sweat & then drinks 2 L of water...what happens to their ICF compartment?

Answer 31

It will actually expand in volume b/c the hypotonic fluid that is replaced in the ECF will shift into the ICF where there is a greater conc'n of solute particles.

Question 32

When you are sweating slowly what happens to... the flow rate the osmolarity of the sweat the amount of salt reabsorption that takes place?

Answer 32

The flow rate is lower this allows more sodium to be reabsorbed... the osmolarity of the sweat is lower b/c there is less salt. Hypotonic sweat w/ low salt

Question 33

When you are sweating quickly what happens to... the flow rate the osmolarity of the sweat the amount of salt reabsorption that takes place?

Answer 33

the flow rate is faster this allows less time for sodium to be reabsorbed... the osmolarity of the sweat is greater b/c there is more salt. Hyptonic sweat STILL but w/ a higher amount of salt than if you were sweating slowly.

Question 34

When you sweat a lot & then drink a lot of water...what is the conc'n of your sweat? What is your net loss?

Answer 34

You ALWAYS have hypotonic sweat. BUT you still lose salt. | Thus, your net loss is salt!

Question 35

Losing salt from your body thru sweat & replacing only the water lost thru drinking water...is exactly the same fluid compartment story as what condition?

Answer 35

Addison's Disease. | Lack of aldosterone...not the same salt reabsorption.

Question 36

What is the equation for osmolar clearance?

Answer 36

Cosm = Uosm X V/Posm **pt is to maintain Cosm if you have a hypertonic urine you will have a lower urine volume.

Question 37

What is the equation for free water clearance?

Answer 37

V = Cosm + CH2O (free water)

Question 38

When you have a dilute urine...what does that mean for your free water?

Answer 38

It will be positive.

Question 39

When you have isotonic urine...what does that mean for your free water?

Answer 39

It will be zero. | Cosm = V

Question 40

When you have hypertonic urine...what does that mean for your free water?

Answer 40

It will be negative. | **all the H2O is taken back up in the collecting duct b/c of ADH

Question 41

During antidiuresis...where is free water created in the nephron? Where is hypertonic urine created?

Answer 41

Free water created in the thick ascending limb of the loop of Henle. This water is reabsorbed in the collection duct b/c in antidiuresis ADH is present. This creates a salty, hypertonic urine.

Question 42

During diuresis...where is free water created in the nephron? Where is hypertonic urine created?

Answer 42

Free water is created in the thick ascending limb of the loop of Henle. The urine never becomes hypertonic/salty b/c the free water is never reabsorbed. In diuresis, ADH isn't present & aquaporins aren't inserted into the collecting ducts.

Question 43

What happens to the water that is reabsorbed in the collecting duct?

Answer 43

It goes into the interstitial space & is then reabsorbed into the bloodstream by the vasa recta (this is in the medullary region).

Question 44

Which diuretic is potassium sparing? Why?

Answer 44

Amiloride. It is located in the end of the DCT. It is potassium sparing b/c it blocks sodium reabsorption. Potassium is exchanged & excreted out.

Question 45

Which diuretic acts in the location where free water is created?

Answer 45

Furosemide. | It is located in the thick ascending limb of the loop of Henle.

Question 46

How would the use of furosemide differ in its affects on V, Uosm, & CH2O when compared to thiazide?

Answer 46

Both would increase V. Furosemide would increase Uosm more. Furo would decrease CH2O significantly. This is b/c furosemide works in the thick ascending limb of the loop of Henle. If the transporter here was blocked it would increase urine flow, but decrease sodium reabsorption & never give the nephron a chance to produce that free water. Thus, the urine will be more hypertonic.