Chapter 27: Fluid, Electrolytes And Acid Base Homeostasis Flashcards
Body Fluid
Substance, usually a liquid that is produced by the body.
Consists of water and dissolved substances.
2/3 is intracellular fluid
Extracellular Fluid
Fluid found outside the cells.
Most abundant cation: Na - accounts for nearly half of osmolarity
Most abundant anion: Cl
80% of ECF is interstitial fluid: occupies space between tissues cells
20% of ECF is blood plasma: liquid portion of blood.
Includes:
Lymph
Blood Plasma
CSF
Synovial Fluids
2 General Barriers Separate Fluid, Interstitial Fluid and blood Plasma
- Plasma Membrane: separates intracellular fluid from the surrounding interstitial fluid.
- Blood Vessel Walls: divide the interstitial fluid from blood plasma.
Fluid Blance
The body is balanced when the required amount of water and solute are present and are correctly proportioned among the various compartments.
Water
Largest single component of the body
45-75% of total body mass, depends on age, gender and amount and adipose tissue
Electrolytes
Inorganic compounds that dissolve into ions.
Sodium, potassium, chloride
Functions:
1. Controlling osmosis
2. Maintaining acid base balance
3. Carry electrical currents
4. Serve as cofactors
Metabolic Water
The bodies other source of water.
Is produced in the body mainly when electrons are accepted by O2 during aerobic respiration and to a smaller extent during dehydration synthesis reactions.
Thirst Center
Area in the hypothalamus.
Governs the urge to drink
Dehydration
When water loss is greater than water gain.
Is a decrease in volume and an increase in osmolarity of body fluid occurs.
Urinary Salt (NaCl) Loss
Main factor that determines bodies fluid volume.
Reason: water follows solutes in osmosis.
2 main solutes in ECF are Na and Cl.
Antidiuretic Hormone (ADH) in Water loss
Or vasopressin. Regulates water balance.
Promotes insertion of water channel proteins into apical membranes of princely cells in collecting ducts of kidneys by insertion of aquaporin-2 into cells.
As a result water permeability of these cells increases and more water is reabsorbed causing reduces loss of water.
Aldosterone in Water Loss
Controls Na levels in blood
By promoting urinary reabsorption of Na increases water reabsorption via osmosis.
Causes reduced loss of water in urine.
Atrial Natriuretic Peptide (ANP) in Water Loss
Promotes natriuretic elevated urinary excretion of Na, accompanied by water.
Increase loss of water in urine.
Water Intoxication
When a person consumes water faster than the kidneys can excrete or when renal function is poor.
Dilute body fluids
Decrease in the osmolarity of interstitial fluids
Is a state in which excessive body water causes cells too swell dangerously.
Causes: mental confusion, seizures, coma and possible death.
4 General Function in the Body when Electrolytes Dissolve and Dissociate
- They are largely confined to particular fluid compartments and are more numerous than non electrolytes. Certain ions control the osmosis of water between fluid compartments.
- Ions help maintain the acid base balance required for normal cellular activities
- Ion carry electrical current, which allows production of action potentials and graded potentials.
- Several ions serve as cofactors needed for optimal activity enzymes.
Contractions of Electrolytes in Body Fluids
Typically expressed in units of milliequivalent per liter (mEq/liter).
These units give the concentration of cation and anion in a given volume of solution.
Sodium
136-148 mEq/liter
Most abundant ion in ECF.
Accounts for 90% of extracellular cations.
Hyponatremia
Caused by a decrease sodium intake.
Due to sodium loss through vomiting, diarrhea, aldosterone deficiency or consuming certain diuretics and excessive water intake.
S & S: muscular weakness, dizziness, headache, hypotension, tachycardia, shock, mental confusion, stupor and coma.
Hypernatremia
May occur with dehydration, water deprivation or excessive sodium in diet or receiving too much IV fluid.
S & S: intense thirst, hypertension, edema, agitation and convulsion.
Chloride
Cl-
Normal blood plasma concentration is 95-105 mEq/liter.
Most prevalent anions in ECF.
Moves easily between the extracellular and intracellular compartments because most plasma membranes contain many Cl leakage channels and antiporters.
Hypochloremia
Due to excessive vomiting, over hydration, aldosterone deficiency, congestive heart failure and receiving certain diuretics such as Lasix.
S & S: muscle spasms, metabolic alkalosis, shallow resps, hypotension and tetany.
Hyperchloremia
Results from hydration due to water loss or water deprivation, excessive chloride intake, severe renal failure, hyperaldosteronism, certain types of acidosis and some drugs.
S & S: lethargy, weakness, metabolic acidosis and rapid deep breathing.
Potassium
Most abundant cations in intracellular fluid.
3.5-5.0 mEq/liter
Plays a key role in establishing the resting membrane potential and in repolarization phase of action potentials in neurons and muscle fibers.