extracellular fluid Flashcards
what is ECF
all the fluids outside the cells
(in constant motion thru body)
extracellular fluid
what does extracellular fluid contain
- ions and nutrients to maintain life
what 5 things are found in the phospholipid bilayer + (percentage make up)
- proteins 55%
- phosphloipids 25%
- cholesterol 13%
- other lipids 4%
- carbs 3%
what is the role of lipids in the phospholipid bilayer
- provide barrier preventing movement of water and water-soluble substances
role of proteins in phospholipid bilayer?
provide specific pathways for passage of substances
what are the 3 means of transport through a membrane
active transport
facilitated trasnport
diffusion
describe active transport, facilitated diffusion, diffusion
active transport = against conc gradient, movement of ions using Na+/K+ pump and sodium/glucpse symport protein (protein carriers) uses ATP
facilitated diffusion = down conc gradient, ion movement with help of channel/carrier protein
diffusion = movement of molecules down conc gradient
What criteria of molecules can diffuse thru membranes
- small hydrophobic e/g o2
- small uncharged e.g h10
why can glomerulus allow passage of molecules with slightly bigger size compare to regular cell membran
has bigger pores allowing passage of substances with Mol WT of up to 55-60000
define osmolarity
concentration of a solution expressed as the total number of solute particles per litre.
(a number of osmoles per kg of solvent)
( number of active particles per unit volume (not size))
what is osmosis
a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one till equilibrium is reached
quantifying osmolairt:
number of osmoles of substance in 1L of solution
1 mole provides 1 osmole if the molecules remain unchanged in solution
80% of the total osmolarity of the interstitial fluid and plasma is due to what
Na+ and Cl- (NaCl)
if the solute dissociates into ions, they each become osmotically active
plasma osmolarity is 280-290 mOsm/L, how does this effect administration of IV fluids
most fluids that are administered via IV must have same osmolarity as plasma to prevent water movement/shifting
how is a cell affected if placed in isotonic, hypertonic or hypotonic solution
isotonic = no change
hypertonic = shrinks
hypotonic = swells
what percentage of human body is fluid and what fraction of this is intracellular or extracellular fluid
60%
2/3 = intracellular
1/3 = extracellular
(remaining 40% = bones and tissue)
For a 70kg person:
ICF = 25L
IF = 12L
Plasma = 3L
these proportions change with age, gender and degree of obesity
how much water is lost thru the skin and lungs dailyq
700ml
fluid composition differs in interstitial, plasma and intracellular fluid.
What is the majority 2 ionic components found in each of them
interstitial = Na+ (140g/L) and Cl- (115)
plasma = Na+, Cl-
intracellular = K+ (140) and HPO4 2- (100)
(vast majority of osmolarity in ECF made by NaCl)
compare fluid composition of ECF and ICF
ECF = NaCL, bicarbonate, o2, glucose, fatty acids and amino acids
ICF = K+, Mg2+ and phosphate ions
