Fluid And Electrolyte Balance Flashcards
Percent of water in older adult
45-55%
Percent of water in average adult?
60%
Percent of water in newborn
78-80%
Percent of water in early human embryo
97%
What are the importance of water?
Universal biological solvent
Transport gases and substances
Dilute toxic substances and waste products and transports them to the kidney and liver
Medium for all chemical reaction
Minimize temperature changes throughout the body
Importance of water.
Universal solvent due to:
Polar asymmetry
High affinity to polar molecule
The total body fluids is distributed mainly between two compartments
Intracellular fluid (ICF) Extracellular fluid (ECF)
Intracellular fluid
40% of the body weight
Fluid found within the cell
Extracellular fluid
20% of body weight
Extracellular fluid further subdivided into
15% interstitial fluid ( between cells and blood vessels)
5% intravascular fluid ( inside blood vessels )
Sources of wAter
Preformed water (2,100ml) Metabolic water (200ml)
Total body water =
Wt in kg x 0.60
Total body water can change depending on the following factors
Age (mas matanda decrease water)
Fats ( obesity, mas mataba decrease ang water)
Gender ( mas madaming tubig ang lalake sa babae 65-55)
Other extracellular fluids
Lymph
Transcellular fluids
Water that are found in food and drinks ingested
Preformed water
Water produced through the catabolic breakdown of nutrients during cellular respiration.
Metabolic water
Net diffusion of water across a selectively permeable membrane from a region of high water concentration to one that has a lower water concentration.
Osmosis
Water will diffuse into the cell, causing it to swell
If the cell is placed into a hypotonic solution
Water will flow out of the cell into the extracellular fluid, causing cell shrinkage or crenation.
If a cell is placed in a hypertonic solution
Factors affecting fluid movement
Starlings forces
For filtration forces (pushing forces)
Capillary hydrostatic forces
Interstitial fluid colloid osmotic pressure
For absorption forces (pulling forces)
Interstitial fluid hydrostatic pressure
Capillary plasma colloid pressure
Capillary hydrostatic forces
Function
Outward the capillary membrane
Capillary hydrostatic forces
Arterial end
30-40 mmHg (favors filtration)
Capillary hydrostatic forces
Venous end
10-15 mmHg (favors re absorption)
Interstitial fluid colloid osmotic pressure
Function
Osmosis of water outside
Interstitial fluid colloid osmotic pressure
Pressure
8mmHg
Interstitial fluid hydrostatic pressure
If positive
Inward
Interstitial fluid hydrostatic pressure
If negative
Outward
Interstitial fluid hydrostatic pressure
Pressure
3mmHg
Capillary plasma colloid pressure
Function
Osmosis of water inward
Capillary plasma colloid pressure
Pressure
28mmHg
19mmHg from dissolved proteins
9 mmHg from donnan effect
Extra osmotic pressure caused by?
Cations
Summation of starling forces
If positive : filtration
If negative: absorption
For arterial end (filtration)
Outward force : 41 mmHg
Inward force : 28 mmHg
Net outward force : 13 mmHg
For venous end (reabsorption)
Outward force: 21mmHg
Inward force: 28 mmZhg
Net inward force : 7 mmHg
Note: venous end is 10-15 mmHg it is contributing factor only
Normal values of plasma sodium concentration
140-145 mEq/L
Two primary systems are involved in regulating the concentration of sodium and osmolarity of extracellular fluid
The osmoreceptor- ADXh system
Thirst mechanism
Regulation of body fluid volume and osmolarity
Center:
Hypothalamus
Regulation of body fluid volume and osmolarity
Hormones
ADH and aldosterone
Regulation of body fluid volume and osmolarity
Major determinant of osmolarity
Sodium
Regulation of body fluid volume and osmolarity
Plasma sodium concentration
140-145
Regulation of body fluid volume and osmolarity
Extracellular fluid osmolarity
300 mOsm/L
Osmoreceptors -ADH system
Location
Hypothalamus
Osmoreceptors -ADH system
Function
Signals for ADH production
Osmoreceptors -ADH system
Signals for ADH production
Dehydration (with loss of water)
Relative dehydration (without loss of water but elevated sodium ions)
Increase plasma osmolarity
Thirst response system
Location
Hypothalamus
Thirst response system
Factors for stimulation
Increase plasma osmolarity
Dryness of mucosal linings
Stretch receptors of GIT
Osmoreceptors common denominator
Increased plasma osmolarity
When osmolarity (plasma sodium concentration) increase because of water deficit, this feedback system operates
Osmoreceptor -ADH feedback System
Osmoreceptor -ADH feedback system
Increase in extracellular fluid osmolarity
Sending nerve signals to pituitary gland ti posterior pituitary
Release ADH
ADH acts on kidney tubules,
Increased water reabsorption
Correcting the initial excessively concentrated extracellular fluid.
Extracellular fluid becomes too dilute
Hypo osmotic
Excess water
Less ADH is formed
Baroreceptors location
Atria of the heart,
Pulmonary artery and vein
Barorecptors
Message are relayed to the hypothalamus via the
Vagus nerve
Barorecptors
ADZh secretion is stimulated by
Changes in circulating volume of body fluids
Barorecptors
Reduction of around how many volume of water due to hemorrhage or excess perspiration will result in ADH secretion
8-10%
Connected to the response of the osmorecptors
Thirst response
Center of thirst?
Hypothalamus
Other factors involved in osmorecptors
Degree of dryness of mucosal linings of mouth and pharynx
Stretch receptors in the GIT
Loss of more solute specially sodium than water in ECF
Hypotonic dehydration
Hypotonic dehydration
Fluid shift
Blood stream to cells
Hypotonic dehydration
Results
Decrease vascular fluid volume
Shock
Cellular swelling
Cerebral edema (headache, IICP and confusion)
Hypotonic dehydration
Seen in
Heat stroke or exhaustion
Hypotonic dehydration
Manifestation
Hypotension Tachycardia Low serum sodium Low urine specific gravity Increase urine volume
Uncommon
Hypotonic dehydration
Most common form of dehydration
Isotonic dehydration
Isotonic dehydration
Equal loss of solutes and water
Isotonic dehydration
Fluid shift
No shift
Isotonic dehydration
Cause
Diuretic therapy Vomiting Urine loss Hemorrhage Decrease fluid intake
Isotonic dehydration
Manufestation increase
Hematocrit Protein BUN Urine specific gravity Dryness
Isotonic dehydration
Manifestation decrease
Body weight Blood pressure( orthostatic hypotension) Pulse Urine volume and output (oliguria) Skin tugor
Isotonic dehydration
If severe
With shock
2nd most common
Hypertonic dehydration
Hypertonic dehydration
Loss of more water than solute in ECF
Hypertonic dehydration
Fluid shift
Blood stream
Hypertonic dehydration
Result
Cell shrinkage
Hypertonic dehydration
Cause
Excess fluid loss Hyperventilation Watery diarrhea Diabetic ketoacidosis Diabetes insipidus Latrogenic (tube feeding without inadequate water)
Hypertonic dehydration
Manifestation
Thirst
Decrease skin tugor
Increase urine specific gracity
Sign of shock are usually not present
Isotonic expansion of the ECF
Isotonic overhydration
Isotonic over hydration
Interstitial fluid=intravascular fluid
Fluid overload or hyper volemia
Isotonic over hydration
Rarely happen in persons with
Normal heart and kidneys
Isotonic over hydration
Causes
IV isotonic fluids
Saline enemas
Increase sodium intake resulting in compensatory water retention
Isotonic over hydration
Manifestation
Hypertension Crackles in lungs Distended neck veins Elevated respiration Polyuria Weight gain Increase respiration
Hypotonic expansion of ECF
Decrease serum osmolarity
Hypotonic overhydration
Hypotonic overhydration
Fluid shift
Blood stream to cell
Hypotonic overhydration
Result
Cell swelling
Interstitial edema
Electrolyte dilution
Hypotonic overhydration
Cause
IV D5W (increase glucose metabolism)
Patient in NPO with ice chips
Tap water enemas
Excess plain water
Hypotonic overhydration
Manifestation
Photophobia Muscle twitching leading to convulsion Diorientation Polyuria Hyperiritability
Hypertonic expansion of the ECF
Increase serum osmolarity
Hypertonic overhydration
Hypertonic overhydration
Fluid shift
Cell to blood stream
Hypertonic overhydration
Result
Cell shrinkage
Hypertension
Increase cardiac work load leading to congestive heart failure
Hypertonic overhydration
Causes
Administrations of hypertonic ( IV fluids, enemas, tube feedings)
Sea water ingestion