L16: Fluid and Solute balance Flashcards
Focus: What is meant by fluid and solute balance?
maintain homeostasis, what comes in the body must eventually be used or excreted
Focus: Describe water balance in the body? What is it and how it is regulated?
Water balance is when the input of water = the output of water
Water input sources are:
1. h20 ingested (2.2L)
2. cellular metabolism byproduct (0.3L)
TOTAL INPUT: 2.5 L
Water output sources are:
1. feces (0.1L)
2. insensible loss + sweating (0.9L)
3. urine (1.5L)
TOTAL OUTPUT: 2.5L
It is regulated by the kidneys
Focus: How much of the body is made up of water?
~60% of body weight is water Range: 50% obese to 70% child
70kg adult: total body water = 42 L
Focus: How is total body water distributed?
Total body water is everywhere including in blood butttt other than in lumen of GI tract, kidneys, tubules and airways since these are considered outside of the body
Focus: How does water move between extracellular and intracellular compartments?
- osmosis
- starling forces
Equation for fluid and solute balance?
input + produced = used + excreted
-> Input + production = utilization + output
The ways we bring h20 into our body and how much h20 is brought in?
- Ingestion- ~ 2.2L / day
- Cellular metabolism- 0.3L / day
Total water input in a day?
2.5L / DAY
Ways h20 is lost in the body?
1.Digestive tract- Feces, 0.1L / day
2. Renal tubles - Urine, 1.5L / day
3. Other losses - 0.9L /day
- insensible loss like respiration we lose h20, ex. cold day.
- sweating
What is insensible loss?
h20 loss from surfaces of our body that we don’t detect
Total water loss/output in a day?
2.5L / day
How much is the total body water in an average 70 Kg adult?
42 L / day
Total body water (TBW)
- Everywhere other than in lumen and airways
- 42L =60% of body weight
Intracellular fluid (ICF)
- Water in all tissue cells and in RBC’s
- Make up 2/3 of TBW
- 28L
Extracellular fluid (ECF)
- Water inside of body but outside of cells
- Plasma included
- 1/3 of TBW
- 14L
2 sections:
- interstitial fluid
- plasma
Plasma
- Part of ECF
- in blood vessels plasma but NOT including RBC
- 3L
Interstitial fluid (ISF)
- Part of ECF
- outside cells and RBC’s
- outside plasma
- 11L
Organize the body water distribution from highest to lowest:
TBW, ICF, ECF, ISF, Plasma
What does body water contain and why is it important?
Contains ions, proteins and other molecules
- contribute to osm of ICF/ECF
- influence water movement b/w compartments
What comes into cells? what comes out of cells? why is it important for this exchange to happen?
In: Nutrients, electrolytes, water, oxygen, etc
Out: Wastes and unneeded material (including excess water)
Need to have a balance of things coming in and leaving
Osmosis, what is it, how water moves
Diffusion of water through a semipermeable membrane
-Always passive
-Unaffected by membrane potentials
-Water moves from area of low osm to high osm
Describe the properties of the plasma membrane and water transport occurs
- membrane is hydrophobic
- hydrophobic molecules like lipid soluble molecules can cross, h20 can cross too but only very little
- hydrophilic molecules like ions, glucose, amino acids and water use membrane proteins for transport
H20;
1. can move freely; only a little h20 can move like this
2. most h20 moves through aquaporins which are water channels
Molarity
of moles of a substance in a L of solution
Ex. Glucose in powder, weight of glucose x 6x10 to 23 = 180g , calculated by atomic weight of glucose and multiply by Avogadro’s number
examples:
180g of glucose + 1 l of water = 1 M solution of glucose
58.5g + 1 L of water – 1M solution of NaCl
Osmolarity
Concentration of particles in 1L solution
- knowing molarity you can find osm
e.g. glucose, stay intact in h20
1 Molar solution of glucose = 1 Osmolar solution of glucose
e.g. NaCl, salts dissociate in h20
1 Molar solution of NaCl = 2 Osmolar solution of NaCl
