Fluids & Electrolytes Balance Flashcards
What are the functions of body water?
Act as a lubricant,
Solvent for electrolytes
Medium for transport of solutes
Required for cellular metabolism
Digestion & Elimination
Maintains body temperature
What does the total percentage of water depend on?
Age and gender
What is the average percentage water in males and females?
Males = 60%
Females = 55%
What causes the difference in percentage between individuals?
Amount of adipose tissue
What is the water content in :
Plasma
Skin
Skeleton
Adipose tissue
Plasma: 90%
Skin: 70 to 80%
Skeleton: 22%
Adipose: 10%
Why is water in urine and alveoli not considered part of total body water volume?
It is from an external environment
What is intracellular fluid?
Blood cells’ water volume and water within other cells too
What is extracellular fluid?
Water present outside of cells or circulatory system
What does extracellular fluid divide into?
Plasma and Interstitial fluid
What is plasma?
Water outside of the cells but within the circulatory system.
What is interstitial fluid?
Water volume between cells
What percentage does intracellular volume take up?
2/3 of all body fluids (~67%)
Where is the extracellular fluid contained?
In the extracellular compartment
What is transcellular fluid?
Special type of ECF that is grouped with interstitial fluid
What does the transcellular fluid include?
Lymph, CSF, synovial fluid, aqueous humor, vitreous body, endolymph, perilymph, pleural, pericardial and peritoneal fluid
What is osmosis?
The movement of water between interstitial and intracellular fluid
What is the water between plasma and interstitial fluid occurred by?
Filtration, reabsorption
What are filtration and reabsorption governed by?
Capillary blood pressure and colloid osmotic pressure
What happens if you add hypotonic NaCl to an isotonic solution?
Decreased osmolarity,
Increased ICF and ECF
Cells swell
What happens if you add hypertonic NaCl to an isotonic solution?
Increase in osmolarity
Decrease in ICF and increase in ECF
Cells will decrease in size
What is the normal osmolarity of NaCl?
0.9%
What does acute hyponatremia lead to?
Brain edema
What does chronic hyponatremia lead to?
Na+, Cl- and K+ are transported from ICF to ECF, accumulates osmotic flow of water into cells and swelling of tissue
What are the three main mechanisms with which substances enter and leave the capillaries?
Diffusion
Transcytosis
Bulk flow (filtration and reabsorption)
What is the most important method of capillary exchange?
Simple diffusion
What happens during simple diffusion?
Oxygen and nutrients move from blood to interstitial fluid
Carbon dioxide and wastes move from interstitial fluid to blood
Why can’t most plasma proteins and red blood cells pass through to capillaries?
Due to their size, too large
What is transcytosis?
When substances within blood plasma enter endothelial cells through endocytosis, move across and exit the cell through exocytosis.
How do substances enter the endothelial cells during endocytosis of transcytosis?
Within tiny pinocytotic vesicles
What kind of substances is transcytosis important for?
Large, lipid-insoluble molecules, such as insulin and antibodies
What is bulk flow?
Large numbers of ions, molecules or particles in fluid moving together in the same direction
What direction does bulk flow happen in?
From area of high concentration to area of lower
What is filtration?
Pressure driven movement of fluid and solutes from blood capillaries into interstitial fluid
What is reabsorption?
Pressure-driven movement of fluid and solutes from interstitial fluid into blood capillaries
Why is bulk flow important?
Regulation of relative volumes of blood and interstitial fluid.
How is water exchange between plasma and interstitial fluid determined?
Balance between hydrostatic pressures and colloid osmotic pressures ( Starling equilibrium)
What are the four pressures in Starling’s equilibrium?
Blood Colloid Osmotic Pressure (towards capillary)
Interstitial Fluid Hydrostatic Pressure (towards capillary)
Blood Hydrostatic Pressure (away from capillary)
Interstitial Fluid Osmotic Pressure (away from cAPILLARY)
What is the equation for net flow balance?
(BHP + IFOP) - (BCOP + IFHP)
Which pressures promote filtration?
BHP and IFOP
Which pressure promote reabsorption?
BCOP and IFHP
What volume of water is taken in and lost everyday?
2.5 liters
How is water gained?
Ingestions of liquids and moist food (2.2 to 2.3l)
Metabolic synthesis (0.2 to 0.3l)
How is water lost?
Insensible water loss through skin by evaporation ( 0.6l) and by exhalation (0.3l)
Feces (0.1l)
Urine (1.5l)
What is the osmolarity through-out the body?
Osmolarity is identical in all fluid compartments
