Fluid & Electrolyte Balance (PART 1) Flashcards
Interrelationship of Fluid & Electrolyte Balance X 3
- Fluid and electrolyte balance implies _______
- ________ have chemical bonds that allow dissociation into ions, which carry an electrical charge; of critical importance in fluid balance.
- Fluid balance and electrolyte balance are
______________
homeostasis
Electrolytes
interdependent
Total Body Water
- Water content of the human body ranges from
_____ to ______ of its total weight - Water content varies according to ____, _______ & __________
50% TO 70%
age, gender, and weight
Body Fluid Compartments X 2
Two major fluid compartments:
- _____________ fluid compartment (ECF) constitutes the INTERNAL environment of the body – 40%
– Consists mainly of plasma and interstitial fluid
– Lymph, CSF, and specialized joint fluids are considered extracellular
– Functions of ECF provide a relatively constant
environment for cells and transport substances to and
from the cells. - Intracellular fluid (ICF) – 20%
– Functions to ________ intracellular chemical reactions
that maintain life
– By volume, ICF is the largest body fluid compartment
Extracellular
facilitate
Body Fluid Compartments
Extracellular vs. intracellular fluids:
- Plasma and interstitial fluid are almost identical in
chemical make-up, with intracellular fluid showing striking differences - Extracellular fluids
– Difference between blood and interstitial fluid; blood
contains a slightly larger total of _____than interstitial
fluid
– Functionally important difference between blood and
interstitial fluid is the number of ______ _____; blood
has an appreciable amount, whereas interstitial fluid
has hardly any
ions
protein anions
Shift of Water Between Compartments
• Volume of fluid compartment depends on the
amount of ________ it contains.
• ____________ is the concentration of osmotically
active particles, expressed as mOsm/L.
• In the steady state, IC osmolarity is equal to EC
osmolarity.
• Solutes such as NaCl and NaHCO3 and large
sugars such as mannitol are assumed to be
confined to the ECF compartment.
solute
Osmolarity
Movement of Water
- Water enters the body via the ______ ________; water is also added to the total fluid volume from each cell as it catabolizes food, and the resulting water enters the bloodstream
• Water leaves the body via four exits: – \_\_\_\_\_\_\_\_\_\_\_ – \_\_\_\_\_\_\_\_ – Skin – Intestines
digestive tract
Kidney
Lungs
General Principles of Fluid Balance (Osmoregulation)
- Cardinal principle of fluid balance is: fluid balance can be maintained only if _______ equals ________
- Mechanisms are available to adjust output and intake to maintain fluid balance, e.g., _________ mechanism,
renin-angiotensin mechanism - Most rapid fluid balance devices are mechanisms for
controlling _______ movement between fluid compartments of the body; will maintain normal blood volume at the expense of interstitial volume
intake
output
aldosterone
water
Mechanisms That Maintain Homeostasis of Total Fluid Volume X 4
- Under NORMAL conditions, homeostasis of total volume of water is maintained or restored primarily by adjusting ______ volume and secondarily by fluid intake
- Regulation of fluid intake – when _________ begins to develop, salivary secretion decreases, producing the sensation of thirst; individual increased fluid intake to offset increased output tends to restore fluid balance
urine
dehydration
Mechanisms That Maintain Homeostasis of Total Fluid Volume X 4
- Regulation of urine volume – two factors determine urine volume:
a – GFR remains fairly constant
b – Rate of tubular reabsorption of water fluctuates
considerably; normally adjusts urine volume to fluid intake; influenced by amount of _____ and aldosterone - Factors that alter fluid loss under abnormal conditions – rate of respiration and volume of sweat secreted may alter ______ output; vomiting diarrhea, or intestinal drainage can produce fluid and electrolyte ___________.
ADH
fluid
imbalance
REGULATION of Water and Electrolyte Levels in PLASMA and Interstitial Fluid X 3
- Starling’s Law of Capillaries – the control mechanism for water exchange between plasma and interstitial fluid consists of four pressures: ________ hydrostatic and colloid osmotic pressure on one side of the capillary membrane and __________ fluid hydrostatic and colloid osmotic pressures on the other side.
– Blood hydrostatic pressure (BHP)
– Blood colloid osmotic pressure (BCOP)
– Interstitial fluid hydrostatic pressure (IFHP)
– Interstitial fluid colloid osmotic pressure (IFCOP)
blood
interstitial
Regulation of Water and Electrolyte Levels in Plasma and Interstitial Fluid X 3
- The ____ and _______ of fluid exchange between capillaries and interstitial fluid are determined by the hydrostatic and colloid osmotic pressures of the two fluids.
- Some principles about transfer of water between
blood and interstitial fluid:
– No net transfer of water occurs as long as
(BHP+IFCOP)=IFHP+BCOP)
– Fluid shifts out of blood into interstitial fluid whenever
(BHP+IFCOP)>(IFHP+BCOP)
– Fluid shifts out of interstitial fluid into blood whenever
(BHP+IFCOP)
rate
direction
Control of Extracellular Osmolarity (NaCl Concentration)
Mechanism:
INCREASED extracellular osmolarity (NaCl) stimulates______release, which INCREASES H2O reabsorption, and stimulates thirst (intake of water)
ADH
Concentration and Dilution of the Urine
- MAXIMAL urine concentration
=______-________ mOsm / L
(specific gravity ~ 1.030) - MINIMAL urine concentration
= _____–________ mOsm / L
(specific gravity ~ 1.003)
1200 - 1400
50 - 70
Formation of a DILUTE urine
- Continue electrolyte reabsorption
- ____________ water reabsorption
Mechanism:
DECREASED ADH release and reduced
water permeability in ______ and collecting tubules
Decrease
distal
Formation of a CONCENTRATED Urine
- Continue electrolyte reabsorption
- ____________ water reabsorption
Mechanism :
INCREASED ADH release which INCREASES water permeability in distal and collecting tubules
a. High osmolarity of _______ medulla
b. Countercurrent flow of tubular fluid
Increase
renal
