T2: Water and Electrolyte Balance Part 1 Flashcards
4 factors wich must be controlled in the human body to maintain homeostasis
- water balance between fluid compartments
- Electrolyte balance
- pH - 7.40
- Temperature - 37C
All water within cell membranes; the medium though which CHEMICAL REACTIONS OF CELLULAR METABOLISM occur
Definition of intracellular fluid
major ions/constituents in intracellular fluid
- Cations: potassium and magnesium
- Anions: protein, organic phosphates, and sulfates
- Low concentrations of: sodium, chloride, bicarbonate
All water outside of cell membranes; the medium though which all METABOLIC CHANGES occur
Definition of extracellular fluid
major ions/constituents in extracellular fluid
interstitial Fluid and Plasma
The directly measurable plasma is known as what?
Intravascular fluid
major ions/constituents in intravascular fluid
- Large amount of proteins
- High concentrations: sodium and chloride
- Moderate concentrations: bicarbonate
- Low concentrations: calcium, magnesium, phosphate, sulfate, potassium, organic acids
Fluid that directly bathes the cells of body includes pericardial, pleural, peritoneal, and synovial body fluids; cannot be sampled for direct measurement
Definition of interstitial fluid
major ions/constituents in interstitial fluid
High: sodium and chloride
Medium: bicarbonate
Low: NO proteins
The force that tends to move water from dilute solutions to concentrated solutions
definition of osmotic pressure
How do osmotic pressure differences maintain the composition of extracellular and intracellular fluids?
*Predominance of K in the intracellular fluid and Na in the extracellular fluid PLUS plasma proteins that are the major contributors to the osmotic pressure between these compartments
What maintains electroneutrality between compartments?
Gibbs-Donnan Equilibrium
How does the Gibbs-Donnnan equilibrium maintain the composition of extracellular and intracellular fluids
It maintains the electroneutrality between compartments by keeping the anion total equaling the total cations (the use of non-diffusible anions is important)
3 chemical constituents that contribute to osmotic pressure differences between EXTRACELLULAR and INTRACELLULAR fluid compartments
Potassium, sodium, and plasma proteins
3 means by which water balance is maintained between INTERSTITIAL and INTRACELLULAR fluid compartments
- membrane characteristics
- colloid osmotic pressure
- Na-K-ATPase pump
How do passive transport differences maintain an equilibrium between intravascular and interstitial fluids, including importance of maintaining normal plasma protein concentrations in homeostasis
*
How do colloid osmotic pressure differences maintain an equilibrium between intravascular and interstitial fluids, including importance of maintaining normal plasma protein concentrations in homeostasis
Protein in the plasma causes water to move into the plasma from the interstitial fluid because there is no protein in the ISF. This movement is from colloid osmotic pressure
How do hydrostatic pressure differences maintain an equilibrium between intravascular and interstitial fluids, including importance of maintaining normal plasma protein concentrations in homeostasis
Hydrostatic pressure from the heart causes fluid to move from the plasma into the interstitial fluid
How do colloid osmotic pressure differences maintain an equilibrium between interstitial and intracellular fluids
Because there is protein in the cells and not in the interstitial fluid, water flows from the interstitial fluid to the cells due to osmotic pressure
How do membrane characteristics (lipid solubility, size of solute, water permeability, and charge) maintain an equilibrium between interstitial and intracellular fluids
permeability is directly related to lipid solubility and size and inversely related to the water solubility of the solute
How does the NA-K-ATPase pump maintain an equilibrium between interstitial and intracellular fluids
The pump actively pumps sodium out of cells and pumps in K+ maintaining equilibrium
Why is the NA-K-ATPase pump necessary for water balance?
*keeps the water balanced between the interstitial and intercellular fluids
Na-K-ATPase pump movement of substances IN or OUT of the cell
- Water?
- Na?
- K?
pumps Na OUT of the cell and K IN to the cell. Water follows sodium
How does the hypothalamus regulate water balance?
Neurons shrink and hypothalamus signals need for water
Four stimuli for both the water-intake and water-output areas of the hypothalamus
- increase in extracellular water osmolarity
- increase in Angiotensin II
- decrease in intravascular volume
- decrease in baroreceptor and distension receptor activity
Natriuretic Peptides
- two conditions that result in their release and increase in the blood
Secreted in response to intravascular volume expansion and defend against salt-induced CHF
Natriuretic Peptides
- Source and three physiological effects of atrial natriuretic peptide (ANP)
Source: cardiac atria
Effects: reduce the increase in venous pressure, increases vascular permeability and promotes natriuresis and diuresis
Natriuretic Peptides
- Source and three physiological effects of brain natriuretic peptide (BNP)
Source: produced in cardiac ventricles
Effects: cardiovascular, natriuretic, and diuretic effects similar to ANP
Natriuretic Peptides
- Three sources and one physiological effect of C-type natriuretic peptide (CNP)
sources: brain, vascular endothelial cells, renal tubules
Effect: venous dilator
Primary stimulus for antidiuretic hormone (ADH) release and the effect that ADH has on the renal collecting ducts
- increase in ECW osmolality
- Stimulation of water output area of the hypothalamus causes pores of the collecting ducts to become more permeable to water (increasing water reabsorption)
Typical causes for hypernatremic dehydration
- Water and food deprivation
- diabetes insipidus
- excessive sweating
- Osmotic diuresis association with glucosuria
- Diuretic therapy
