Fluids and Electrolytes Flashcards
How many litres of water = 1 kg?
1 L = 1 kg
Where is 2/3 of the body’s water held: ICF or ECF?
ICF
What is the primary cation in ICF and ECF?
ICF = potassium
ECF = sodium
Define diffusion and facilitated diffusion
- Diffusion – molecules move from high to low concentration until equal, needs permeable membrane to diffusing substance, no external energy (passive)
- Facilitated diffusion – uses a protein carrier, large molecules that can’t pass on their own, high to low concentration, no external energy (passive)
o i.e., if a patient has meningitis, we have to pair the antibiotic with a protein to surpass the blood-brain barrier
Define active transport and osmosis
- Active transport – requires energy, moves against concentration gradient
o Sodium and potassium are essential and use active transport
o They can move against or with gradients - Osmosis – water moves through a semi-permeable membrane, low solute to high solute, no energy, stops when concentrations are equal OR when hydrostatic pressure builds and is sufficient to oppose any further movement of water (i.e., IV administration)
Define hydrostatic pressure and oncotic pressure
- Hydrostatic pressure – force within a fluid compartment (i.e., blood pressure) – can be referred to as a pushing pressure
o Major force that pushes water out of the vascular system at the capillary level - Oncotic pressure – osmotic pressure exerted by colloids (proteins) in a solution (can be referred to as a pulling pressure)
How can we increase hydrostatic pressure?
Increase hydrostatic pressure through an increase of fluid, such as IV
Do alcoholics have high or low oncotic pressure?
Low due malnutrition
Will malnutrition result in low or high oncotic pressure?
Malnutrition may result in low oncotic pressure – can quickly get protein into the IF through a transfusion of albumin
Define hypotonic and hypertonic
- Hypotonic - Solutions in which the solutes are less concentrated than they are in the cell (i.e., water would move into the cell)
- Hypertonic - Solutes are more concentrated in the ECF than inside the cells (i.e., water would move out of the cell to dilute the ECF)
Describe the difference between first, second, and third spacing
First spacing – normal/regular
Second spacing – abnormal accumulation of interstitial fluid (edema)
Third spacing – fluids accumulating in an area we cannot easily exchange (i.e., ascites – usually need to perform paracentesis)
How do the hypothalamus and pituitary regulate water balance?
Hypothalamus – balances intake, excretion, and known as the control centre; stimulates the ADH receptors if there is a need for drinking
Pituitary (posterior) – releases ADH, which induces water reabsorption in the renal distal and collecting tubules
How does the adrenal gland regulate water balance?
Releases glucocorticoids (i.e., cortisol, increase glucose level in the blood, which drives us to drink water) or mineral corticoids (aldosterone – causes sodium retention, which congruently retains water while dumping potassium)
How does aldosterone effect water balance?
Promotes sodium retention and thereby water retention, and dumping of potassium
How does cortisol affect water balance?
suppresses the urge to drink and urinate
How does atrial natriuretic factor (ANF) effect water balance?
ANF will be released when the atria expand due to increased fluid volume - this results in vasodilation and increased excretion from the kidneys, which decreases blood volume
How much water does the GI tract absorb on a daily basis?
2-3 L per day
What is the primary portion of the body for water balancing?
The GI tract
Define insensible water loss and how much is lost per day to this
Loss of fluid from lungs and skin
900mL of fluid lost per day – fever and hyperventilation could increase fluid loss
List four older adult concerns with water balance
Decreased kidney functions, decreased hormone and hormone functions, dermal regulation (cannot adjust as quickly to heat and cooling – sudden changes to temperature are not well adapted), decreased sense of thirst
What cardiac medication may lead to hyperkalemia?
ACE inhibitors
Leg cramping, peaked T waves, and atrial fibrillation (cardiac depolarization) are all symptoms of
hyperkalemia
Flattened t-waves and heart dysrhythmias are symptoms of
hypokalemia
impaired memory, confusion, disorientation, fatigue, muscle weakness, constipation, cardiac dysrhythmias are symptoms of
hypercalcemia
