NUR 339 Exam 11 - - ICF large amounts of K and small amounts of C...

NUR 339 Exam 11

• Differences between ICF and ECF in fluid volume, key cations and anions

- ICF large amounts of K and small amounts of Ca, Na, Cl, bicarb, Mg, and phosphate

ECF

large amounts of Na and Cl, small amounts of K, Mg, Ca, and phosphate

• Movement of solutes

• diffusion

• osmosis
• active transport

• Diffusion

• random movement of particles from higher concentration to area of lower concentration

• electrolytes will move from hypertonic to hypotonic side until isotonic relationship is

reestablished

• movement opposite than osmosis

• Osmosis

• movement of water from lower to higher concentration through semi-permeable membrane

• fewer solutes to more solutes

• Osmolality 1 / 3

osmolar concentration in 1 kg of water normal

280-295 mOsm/kg

• Tonicity

tension or effect that osmotic pressure of solution wit impermeable solutes exerts on cell size because of H2O movement across the cell membrane

• What conditions will affect different capillary dynamics?

hydrostatic and osmotic pressure are opposing factors that drive capillary dynamics

8. ADH

renin-angiotensin-aldosterone system

• release of ADH from posterior pituitary causes increased absorption of H2O and Na from

kidney

• increased thirst

• What triggers ADH release?

osmoreceptors (sense increased osmolarity)

• What triggers activation of RAA system?

baroreceptors (sense low blood volume)

• What are the determinants of fluid shift between ECF and ICF? 2 / 3

• capillary filtration pressure

• interstitial hydrostatic pressure

opposes movement of water out of capillary

• capillary colloidal osmotic pressure

osmotic pressure generated by plasma pro- teins too large to pass through pores of capillary wall; pulls fluids back into capillary

• tissue colloidal osmotic pressure

pulls water out of capillary into interstitial spaces

• What causes fluid shift from ICF and ECF? ECF to ICF?

• Fluid shifts between compartment until their relative osmolality equilibrated and a new steady

state is achieved

• changes in osmolality affect ECF first because it is most in contact with outside world
• once ECF osmolarity changes, water shifts into or out of cellular compartment within

minutes until a new osmolar equilibrium is achieved between the ECF and ICF

• What causes edema and 3rd spacing?

• Occurs when too much fluid moves from the intravascular space (blood vessels) leak into the

interstitial or third space

• Can cause edema, reduced cardiac output, and hypotension

• isotonic

same osmolality as body fluids

• / 3