Fluid, Electrolyte, and Acid-Base Homeostasis Flashcards
What plays a crucial role in sustaining homeostasis?
Fluids
Electrolytes
pH
Body Fluids are a combination of what?
Water and Solutes
What does water do for cells?
Carries nutrients into cells
Waste products out of cells
Blood cells around the body
Carries Enzymes in digestive secretions
What are the fluid types?
Intracellular (ICF) & Extracellular (ECF)
Define ICF (intracellular fluid)
Fluid found INSIDE the cells
Define ECF (extracellular fluid)
Fluid found OUTSIDE the cell
What two compartments are extracellular fluid divided into?
Interstitual & Intracellular
Interstitial definition
Between the cells
Intravascular definition
Inside the blood vessels
To preserve its stability the body exchanges what between compartments?
- to compensate for conditions that increase or decrease loss
Solutes and Water
What does water movement depend on?
Hydrostatic (pull) and osmotic (pull) pressures
Define Tonicity
Osmotic pressure between two solutions separated by a semipermeable membrane
What is tonicity influenced by?
Solutes that cannot cross the membrane
What is an isotonic solution?
Solution that has concentrations of solutes EQUAL to those in the intravascular (in blood vessels) compartment
What kind of shift does Isotonic solutions cause?
Doesn’t cause notable shifts in fluid volume.
- moves equally between all compartments
Hypotonic Solution definition
LOWER concentration of solutes than the solution in the intravascular compartment
What kind of shift does a Hypotonic solution cause?
A shift from intraVASCULAR compartment to intraCELLULAR space
Define Hypertonic Solution
HIGHER concentration of solutes than the solution in the intravascular compartment
What shift does a hypertonic solution cause?
A shift from intraCELLULAR compartment to intraVASCULAR compartment
How is fluid primarily lost?
through urine and feces
What is insensible fluid loss?
Immeasurable losses through skin (sweating) and respiratory tract (breathing)
What is the minimum urine output for a 2,000mL fluid input?
800mL per day
What is osmolarity?
Solute concentration
Increased osmolarity (solute concentration) and Decreased fluid volume trigger what?
The thirst mechanism in the hypothalamus
Thirst sensation decrease w/ age is called what?
Hypodipsia
What is ADH (Antidiuretic Hormone) function?
Regulate fluid volume by controlling water losses through urine
When does the pituitary release ADH?
Increase in osmolarity & Decrease fluid volume
What does ADH promote?
Reabsorption of water into the blood from the renal tubules
Why is Aldosterone released?
To conserve more water when necessary
Aldosterone increases reabsorption of what, where?
Sodium and water in the Renal tubules
Fluid intake should =
Fluid loss
Define Edema
Excess fluid in the INTERSTITIAL space
What is edema a problem of?
Fluid Distribution
Anascara is?
Generalized Edema throughout the body
HYPERvolemia =
Fluid volume excess
Define HYPERvolemia
Excess fluid in the intravascular compartment
What does hypervolemia often result from?
Excessive sodium or water intake/insufficient losses
Define water intoxication
Fluid excess in the INTRACELLULAR space
What can water intoxication lead to?
Lysis (cell bursting)
When does Fluid Deficit occur?
When total body fluids are insufficient to meet the bodies needs (dehydration)
Hypovolemia =
Fluid Deficit
Define Hypovolemia
Fluid deficit of the INTRAVASCULAR compartment
Define Crenation
Cell shrinking
When does crenation occur?
When water losses are greater than shifts
What does a decrease in fluid volume cause?
Hypotension
Define Electrolytes
Minerals w/ electrical charges
Where are electrolytes found in the body?
Blood
Urine
Bodily Fluids
What do electrolytes aid in?
Muscle and Neural Activity
Acid Base Balance
Fluid Balance
Most significant Cation
SODIUM
Most prevalent electrolyte in the Extracellular fluid =
Sodium
What is Sodium’s primary function?
Control serum osmolality and water balance
What is sodium regulated by?
Kidneys and Aldosterone produced in the adrenal cortex
Kidney Sodium Retention =
Low blood volume
High serum osmolality
Aldosterone Released
Kidneys Release Sodium =
High blood volume
Low serum osmolality
Increased glomerular filtration =
Increase sodium excretion
Decrease Glomerular filtration =
Decreased sodium excretion
Normal Serum Sodium levels
135-145 mEq/L
RAAS mechanism triggers when?
Times of decreased renal perfusion (blood flow)
What is the primary intracellular anion (-)?
Potassium
Normal Serum Potassium levels?
3.5-5 mEq/L
Potassium’s crucial role:
Acid-Base balance
Electrical conduction
Metabolism
Where is potassium excreted and lost?
Excreted in the kidneys lost through gastrointestinal tract.
Where is calcium found?
Bones and teeth
Normal serum Calcium levels
4-5 mEq/L
Calcium ⬆️ Phosphorus ⬇️
Inverse relationships
Hypocalcemia is associated with what signs?
Trousseau and Chvostek
Where is calcium absorbed?
GI tract
Where is calcium excreted?
Urine and stool
Vitamin D aids in?
Calcium absorption
Normal serum pH
7.35-7.45
Metabolic Acidosis
Deficient (base) bicarbonate
Excess (acid) hydrogen H+
