Lecture 9: Fluid, Electrolyte, and Acid-Base Balance Flashcards
(104 cards)
1
Q
What is total body water?
A
The amount of water in the body
2
Q
We have a range of total body water % and can be affected by…
A
age and gender
3
Q
Through the normal lifespan of a human, that normal range is…
A
45-75%
4
Q
A newborn is going to have the highest TBW percentage. This is about…
A
75%
5
Q
It will gradually decrease. We don’t see gender differences in TBW until
A
we get to puberty. Reproductive Hormone levels will be very high.
6
Q
When we get to puberty, we start to see differences in TBW. How?
A
Primarily, bc those who have estrogen go up, we get blessed w/ more fat. Those that have testosterone go up, they get more muscle.
7
Q
Once we hit puberty, males will have a TBW than females bc…
A
they have a higher muscle mass and a lower total body fat
8
Q
A young non-obese male, who is post-puberity and not yet elderly, they will have a TBW of
A
about 60%
9
Q
A woman of the same age would be about 50%. It doesn’t matter if we have a size difference between a young non-obese male and female, bc
A
it’s what percentage of THEIR body weight is made up of water.
10
Q
What is the difference between those two?
A
Due to the effect of the reproductive hormones, women will have more adipose tissue and less water. Men will have more muscle mass and more water.
11
Q
In an elderly man and an elderly woman, they will both have a TBW of ~ 45%. Why?
A
Our elderly male has lost muscle mass and replaced it with fat. Our elderly woman has lost muscle mass and replace it with fat.
12
Q
We have 3 places in the body where we can have water. What are they?
A
- outside of cells (extracellular fluid)
- inside of cells (intracellular fluid)
- plasma
13
Q
Extracellular fluid can be divided into different categories
A
- interstitial fluid *
- plasma *
- aqueous humor in eyeballs
- cerebrospinal fluid
- synovial fluid in joints
14
Q
if we’re talking about this young but post-pubscent, non-obese male, who has total of 40 L of TBW, the breakdown is what?
A
intercellular fluid volume = 25 L
interstitial fluid volume = 12 L
Plasma = 3 L
15
Q
Intercellular fluid volume is…
A
the biggest compartment
16
Q
Smallest compartment of the 3 major compartment is
A
Plasma
17
Q
What is the major difference between Plasma vs. Interstitial fluid?
A
Plasma has a lot more proteins.
18
Q
What are the similarities between plasma and ECF?
A
ECF and plasma has the main cation is sodium. The main anion in both is chloride. They have the same amount of concentration of bicarb in each. There’s the same concentration of potassium in each.
19
Q
IF looks a lot like plasma why?
A
IF comes from plasma.
20
Q
If we look at the ICF and compare it to plasma, we see differences.
A
- main cation in ICF is K
- little bit of Na and a lot of K in ICF (opposite is true in plasma)
- A lot more Mg in ICF than plasma
- A lot more protein in ICF than ECF
21
Q
Mg is used a lot by enzymes…
A
inside cells as a cofactor to help enzymes work more effectively.
22
Q
Why is there a lot more protein in I.F than E.F ?
A
Membrane protein, structural proteins, carriers inside cell, cytoskeleton, lots of phosphate
23
Q
4 things you need to keep in mind when talking about water balance?
A
- can adjust ECF and NOT the ICF
- Receptors measure plasma volume & osmotic concentration
- a. Water always moves by osmosis
b. Water follows Na - Balance depends on water in.vs. out
24
Q
We don’t have any way to measure how much fluid is in a specific fluid compartment.What we’re looking at ALWAYS is the osmotic concentration….
A
We monitor the osmotic concentration of cerebrospinal fluid of our brain bc it’s a reasonable reflection of the osmotic concentration of the blood. We don’t have any way to monitor these things.
25
What are the primary regulating hormones that are going to affect fluid and electrolytic balance?
- ADH
- Aldosterone
- Angiotensin II
- ANH
26
Where does ADH come from?
Posterior Pituitary gland
27
When is ADH released?
When osmotic concentration of body fluids is higher than it should be
28
What are the effects of ADH?
- ^ water reabsorption ( in the DCT in the kidney)
- stimulate thirst center
- vasoconstrictor
29
If you drink more water and lose less water and vasoconstrict, what do you wind up with in respect to water?
higher bp and higher TBW
30
Where does Aldosterone come from?
Zona Glomerulosa of adrenal cortex
31
What's the MAIN stimulus of Aldosterone release?
Angiotensin II
32
Another stimulus of Aldosterone would be...
low sodium concentration
33
What are the effects of Aldosterone?
- ^ Na secretion
- ^ K secretion
- ^ H ion secretion
34
Besides stimulating Aldosterone secretion, Ang. II also stimulates the thirst centers. How?
If i get dehydrated enough to lower my bp, i'm going to trigger RAAS and ultimately get more Ang. II. That's gonna make me drink more water.
35
If I hemorrhage enough, to lower my Bp, it's gonna activate...
RAAS and eventually get Ang. II which would make me thirsty and I will drink more water.
36
Generally speaking, the things that are gonna make me thirsty are...
- ADH
- Ang. II
- Dry Mouth
- Talking about things that make you thirsty
37
ANH is the one hormone we secrete more of to lower TBW. Where does ANH come from?
Atrium
38
What is the stimulus for ANH?
High Blood pressure
39
What is ANH gonna do?
- decrease Na reabsorption at kidney
- blocks Aldosterone release
- blocks ADH
- block epinephrine and norepinephrine so i can't vasoconstrict
40
If water can ONLY move bc of osmosis, we look at the 4 pressure associated with those pressures.
CHP = out pressure
COP = in
IFHP = in
IFOP = out
41
Those 4 pressures determine...
how much water is in the plasma compartment vs how much is in the I.F compartment.
42
How much water in the I.F compartment is going to determine...
Whether water moves from I.F into cells OR from cells into I.F
43
We have two ways that water gets into the body. They are:
1. Digestive tract (we drink water or there's water in the food we ate)
2. Cellular Metabolism
44
if I don't have the digestive system water...
I don't get enough water that is produced by cellular metabolism to keep me alive.
45
There are 4 ways water can leave the body. What are they?
1. Air we breathe out
2. Sweat
3. Urine
4. Feces
46
Why is urine the most important pathway for water to leave the body?
Urine volume is the only thing in that list of 4 that we can control for the purpose of controlling water volume.
47
We do control urine to control...
TBW
48
If i want to have water balance, the volume of water that I bring in for my digestive tract or cellular respiration...
has to equal the amount of water leaving my body thru respiration, sweat or urine. Otherwise, I'm not in water balance.
49
If we are going to regulate TBW, we're gonna regulate input & output. Our 2 main players will be...
Regulation of Urine Volume and Regulation of Fluid Intake
50
What are the 2 factors that determine urine volume?
regulation of GFR and water reabsorption in the kidney
51
Which one is most important?
Water reabsorption in the kidney
52
If you can't change GFR it's...
useless as a tool of how much water is gonna reabsorb the body.
53
Regulation of Intake is all about...
making us thirsty
54
Those osmoreceptors in the hypothalamus has a couple of groups of them. The paraventricular nuclei & Supraoptic of hypothalamus that make ADH, those nuclei are osmoreceptors...
You're gonna make and release ADH when those things are measuring a higher osmotic concentration of cerebrospinal fluid. That's also going to make you thirsty .
55
There's another area called the subfornical organ (SFO) that is in the midline of the brain. If we put those three things together, what we have...
functionally is a thirst regulator. They are all looking at the same thing.
56
If that concentration is higher than it should be, we're gonna...
get ADH out of the hypothalamic nuclei and their gonna work with the subfornical organ to make you drink more water.
57
If you have a patient who can't take anything by mouth in an extended period of time, there's no way they can maintain fluid balance. Why not?
If they're NPO, we're not adding anything thru the main pathway to add water. The cellular respiration pathway doesn't make enough water.
58
This also means...
They're losing water. Your patient is still breathing and losing water thru respiration.
59
If your patient is NPO? What do you need to do?
Give them fluid in a different way.
60
If I look at my 4 capillary pressures and my outward ones are higher than inward ones...
I move my plasma into the I.F
61
If my inward pressures are more than my outward pressures...
I move fluid from I.F into the plasma
62
Ex: Prof meyer has been talking a lot and is thirsty. what does this mean?
This means, as she keeps losing water, the osmotic concentration of my blood is going up, the osmotic concentration of my plasma is going up and she's gonna tend to suck water in to her plasma.
63
What happens to your patient's blood when they're dehydrated?
If osmotic concentration goes up > suck more water in from the interstitial fluid compartment
64
When you take water out of the I.F. C, I didn't take Na. So in this area, I have the same amount of Na, in less water. What happens to I.F Na concentration?
Interstitial Na concentration goes up > suck water out of the cell > water move until osmotic concentration in I.F is = to osmotic concentration in the cell
65
Dehydration is a decrease in TBW is gonna leave me in a situation where in my blood, I have the same # of particles and less water...
That raises my COP. In the process, I made an osmotic gradient between I.F and the capillary. Water moves toward the area w/ higher particle concentration (capillary). Moves there until osmotic pressures are equal.
66
By moving water out of I.F and into the plasma, I left behind the same amount of Na in less water.
That raises the Na concentration here. Now, I've made an osmotic gradient between the cell and the I.F. I move water out of cell into I.F until the osmotic concentration in the cell = osmotic concentration in the I.F.
67
All of this is called...
Fluid Shift
68
The fluid shift goes with water ultimately going...
from the cells into the plasma when you're dehydrated or Bp is low.
69
When you're thirsty, you borrow water from the cells. You get thirsty to pay back the cells. So if I add water to my body, some of that water goes to the blood first. So, you have the same # of particles and even more water. What happens to my COP if I add water and I haven't moved particles?
My COP goes down and becomes higher than the IFOP. You take water OUT of the capillary.
70
When water goes to I.F, you've got Na in more water than b4. What happens to the osmotic gradient between the cell of the I.F?
Now, i've got one again and I have a lower concentration of particles than i had and water moves into the cell. I've borrowed it and paid it back in a 2 step process.
71
When we're moving water from plasma to cell or cell to plasma,
we ALWAYS goes through the I.F
72
The alternate name for Bowman's capsule is...
Glomerular capsule
73
When someone has liver failure, you don't have enough plasma proteins. I have the same volume of fluid but I have fewer particles. What does that do to my COP?
My COP goes down > Na concentration hasn't changed >Water moves out to I.F
74
If a patient has an extreme edema, the water moving out decreased the Na concentration. In I.F, the osmotic concentration in the cell didn't change. We have a gradient again. It goes into the cell.
The osmotic concentration is higher in the cell. If I have a lot of edema, more a gradient to move water in the cell. If you put too much water in the cell, it "blows" up and kills cells.
75
When somebody has liver failure...
- Blood Volume drops
- Hypotensive
- BP drop that Urine output drops
76
What is Hypovalemia?
Lower than normal TBW
77
You can get Hypovalemic by...
- Dehydration
- Hemorrhaging
78
Common Causes for Hypovalemic...
Losing a lot thru digestive tract (Vomiting & Diarrhea)
79
What are the symptoms of being Hypovalemic?
- Low Bp
- Low CO
- Electrolyte imbalance
- Dizzy
- Light headed
- Tachycardia
- Weakness
- Poor skin turgor (skin elasticity)
80
What are the differences between being Dizzy and being Light headed?
Dizzy involves sensation of spinning.
Light headed is when you need to sit down.
81
Hypovolemia is going to look the same as a high Na concentration. Why?
I have the same amount of Na in less water when i'm dehydrated. So my Na concentration is in fact high. These two things tend to be found together.
82
The opposite of Hypovolemia is...
Hypervalemia
83
What is Hypervolemia?
TBW higher than normal
84
What can cause Hypervolemia?
- Congested Heart failure ( messes w/ pressure in capillary and put more fluid in I.F)
- Liver failure (bc water is leaving, my art. bp is dropping and activate RAAS)
- Renal failure
85
What are the symptoms for Hypervolemia?
- Weight gain
- Edema
- Dyspnea
- Tachycardia
- Renal failure
86
Why would you experience weight gain?
Water is heavy
87
Why would you might see Dsypnea in someone who's hypervolemic?
If edema is in abdominal cavity, it's gonna limit how far their diaphragm can go down so they may have trouble breathing in. Alternatively, they may have fluid in their lungs bc of a shift in pressures at the pulmonary capillaries.
88
How do you treat this?
You have to figure out what has caused the fluid to leave the blood circulation and go into the I.F
89
What is water intoxication?
An extreme situation of hypervolemia. Where a person holds so much water, it makes their Na concentration really l=really low. It can put you into a coma or kill.
90
What can cause water intoxication?
- drinking too much water
- giving somebody who can't make urine, large volumes of water
- brain tumors that can cause inappropriate thirst (DRINK ANYTHING!! )
91
Mild water intoxication, you can get...
lethargy and confusion
92
Why are you getting lethargy and confusion?
bc you diluted your Na so much, that you cant make a decent action potential going
93
Someone who has severe water intoxication could have...
seizures, coma, die
94
What is the treatment for water intoxication?
water restriction
95
How much charge we have comes in a unit called...
the equivalent
96
This means that if I have 1 equivalent of Na (charge of +1),
I have the same # of charges of Ca ( charge of +2)
97
When we're looking at for equivalents...
a concentration of charge
98
What things do we have that can help us adjust Na concentration?
How much water we reabsorb
99
if my Na+ concentration is getting higher,
I need to reabsorb more water
100
What hormone is going to get me that?
ADH
101
if my Na concentration is LOW and I need more Na+,
I will get Aldosterone
102
If I have a higher concentration of Na, I will have a bizarre combination...
A little bit mixing of ANH (bc of Na concentration being high) and ADH (so we can get the concentration right)
103
What are the 3 Hormones that would adjust Na concentration?
ADH, ANH, and Aldosterone
104
Remember, the ADH is not changing the amount of Na+ you reabsorb or lose. It's changing...
the amount of water you have that Na in. ANH and Aldosterone will change the amount of Na you have.
