L16: Body Fluids & Compartments Flashcards
Urinary System Overview
major body fluid compartments
intracellular fluid 28 L
interstitial fluid 11 L
plasma 3 L
membranes between fluid compartments
cell membrane
capillary memb. between interstitial and plasma
extracellular ions
Na and Cl
intracellular ions
K and Pi/proteins
osmolarity
conc. of particles per L of solution
osmolality
conc. of particles per kg solvent
water in biological systems
effective osmole
refers to a solute that does not easily cross a membrane
effective because it creates an osmotic force for water
______ are effective osmoles for the vascular compartment
proteins
daily fluid intake
ingestion = 2100 mL
metabolism = 200 mL
daily fluid output
evaporation = skin and lungs (both 350 mL)
sweat = 100 mL (5000 wkt)
feces = 100 mL
urine = 1400 mL
total daily intake of fluid
2300 mL/day
total daily fluid loss
2300 mL/day
fluid loss with severe burns
can increase from 350 mL to 3-5 L/day
fluid loss w/ exercise
sweat increases from 100 to 5000 mL
urine decreases from 1400 to 500 mL
extracellular body fluid compartments
interstitial fluid
plasma
transcellular
~14 L
intracellular body fluid compartments
intracell
~28 L
total body water
~42 L / avg. male
50% weight in females (extra fat)
70-75% weight in premies/newborns
osmolar gap
difference between the measured osmolarity and the estimated osmolarity
normal around 15
common things that can evaluate the osmolar gap
- ethanol
- methanol
- ethylene glycol
- acetone
- mannitol
why is the ionic composition of plasma and interstitial fluid similar?
because they are separated by a highly permeable capillary membranes
why is there a higher concentration of proteins in plasma?
because capillaries have low permeability to plasma proteins
intracellular fluid composition
- small amounts of Na/Cl
- almost no Ca
- large amounts K/Pi
- moderate amounts Mg/S
the indicator-dilution principles is a method for?
measuring fluid volumes in body fluid compartments
determination of extracellular fluids
by a balance of hydrostatic and colloid forces across the capillary membranes
determination of fluid between intracellular and extracellular compartments
by osmotic effects primarily of Na and Cl ions
For each mOsm concentration gradient of an impermeant solute, about _______ is extered across the cell membrane
19.3 mmHg osmotic pressure
The _________ in a solution is measured in osmoles.
Number of particles
Osmolal concentration of a solution = osmolality when ?
Conc. Is expressed as osmoles/kg
Osmolal concentration of a solution is = osmolarity when?
Conc. Is expressed in osmoles/ L
For a 0.9% NaCl solution, osmolarity = ?
308 mOsm/L
About 80% of total osmolarity of interstitial fluid and plasma is due to ?
Sodium and chloride ions
For intracellular fluid, half osmolarity is due to ?
Potassium ions
If the cell membrane is exposed to pure water and the osmolarity of intracellular fluid is 282 mOsm/L, the potential osmotic pressure ?
Can develop across the cell membrane will be greater than 5400 mmhg
Potential osmotic pressure when osmolarity = 308 mOsm/L
5944 mmHg
Increased extracellular volume = _______ venous return = ________ CO
Increased
Increased
Terms isotonic, hypotonic and hypertonic refer to ?
Whether or not solutions will change the volume of a cell
Addition of isotonic saline to extracellular fluid
Osmolarity does not change
Extracell volume increases
Intracell vol. does not change
A solution of immpermeant solutes, having an osmolarity of 282 mOsm/L is ________, meaning?
Isotonic
Water cannot enter or leave cell
Examples of isotonic solutions
0.9% NaCl
5% glucose
Addition of hypertonic saline to extracellular fluid
Intracell vol. decreases
Extracell vol. increases
Osmolarity in both increases
Why does intracellular fluid volume increase in presence of hypertonic solutions?
The hypertonic saline will put water out of cell
A solution of impermeant solutes having an osmolarity greater than 282 mOsm/L is ?
Hypertonic
Water will diffuse out of the cell
Addition of hypotonic (?) saline to extracellular fluid
(Water)
Volume of extra and intra increase
Osmolarity in both decreases
Why do both fluid compartments increase in volume when a hypotonic solution is added?
Water will enter the cell to increase intra
You’re adding fluid to extra so it always increases
A solution of impermeant solutes having an osmolarity less than 282 mOsm/L is ?
Hypotonic
Water will diffuse into the cell
Relate cell size to iso/hyper/hypo -tonic solutions
Iso - cell no change
Hypo - cell grows
Hyper - cell shrinks
Effects on brain due to acute hyponatremia
Acute loss of Na or excess water causes brain to swell
Seizures, coma, permanent damage, death
Effects to brain due to chronic hyponatremia
Chronic loss of Na or excess water allows tissues to transport Na, Cl, and others into extracell space
Tissue swelling is much less than in acute hyponatremia
When interstitial fluid pressure is below 0, _____ fluid _______ in tissues. Edema safety factor = ?
Little fluid accumulates in tissues
= 3 mmhg
When interstitial fluid pressure rises above 0, _______ fluid rapidly begins to _______ in tissues.
Free fluid rapidly accumulates in tissues
Anatomical organization of kidney
Capsule
Renal cortex
Renal medulla
Renal pelvis
The renal cortex is associated with ______ capsule
Bowman’s capsule
Cortical nephrons
Have glmeruli located in outer cortex and have short loops of henle
Juxtamedullary nephrons
Have glomeruli deep in renal cortex near medulla
Long loops of henle
Long efferent arterioles
Juxtamedullary nephrons also have long ______ arterioles, associated with ?
Efferent (going out)
Peritubular capillaries
Peritubular capillaries are found _______ to nephrons
Parallel
Glomeruli sit in ______ capsule
Bowman’s
Kidneys receive ____ of total cardiac output
22%
“Grow up”
What helps regulate hydrostatic pressure in both sets of kidney capillaries?
Efferent arterioles
High hydrostatic pressure in glomerular capillaries
=60mmhg
Causes rapid fluid filtration into kidneys
(Constriction of efferent arterioles)
Low hydrostatic pressure peritubular capillaries
=13mmhg
Permits rapid fluid reabsorption into efferent arterioles
List the steps in blood flow to kidneys
- Renal art.
- Interlobar art.
- Arcuate art.
- Interlobular art.
- Afferent arterioles
- Glomerular capillaries
- Efferent arterioles
List steps in blood flow from kidneys
Peritubular capillaries
- Interlobular veins
- Arcuate veins
- Interlobar veins
- Renal veins
What are the true capillaries of the kidneys?
Peritubular capillaries
distinguish between hypo and hypernatremia
decreased Na vs. increased Na concentrations
hyponatremia can be due to ?
heart, liver, kidney diseases/failure
symptoms of hyponatremia
nausea, vomiting, lethargy, confusion, muscle weakness
seizures
coma
symptoms of hypernatremia
excessive thirst lethargy muscle spasms seizures coma
hypernatremia may be due to?
dehydration, kidney disease, burns, old age
consequences of extracellular edema
decreased tissue function
increased accumulation of waste
nutrients and waste have to travel farther to get from BV to cells
causes of intracellular edema
increased hydrostatic p.
decreased colloid oncotic p.
obstruction in lymphatic sys.
causes of extracellular edema
heart, kidney failure
excess kidney retention
increased capillary pressure
venous return failure
