RENAL- body fluids

Question 1

why is water necessary

Answer 1

60% of body weight is water
life depends on chemical reactions that take place in an aqueous environment
medium for metabolic processes
diffusion of nutrients and waste products
universal solvent
stable volume, BP, composition of body fluids is essential for metabolism

Question 2

what are the different fluid compartments in the body

Answer 2

intracellular fluid - 40% of body water is intracellular

interstitium - extracellular - 20%
blood plasma, lymphatic

Question 3

what is the difference between fluid composition inside and outside of the cell

Answer 3

intracellular - K, P
extracellular -NaCl, Bicarbonate

important for different chemical reactions and the generation of action potentials for contraction

Question 4

how do fluids and solutes move from one compartment to another

Answer 4

depends on pressure - ionic pressure, osmotic pressure

depends on the nature of the barrier - cell membrane, capillary wall

diffusion - movement of molecules from higher to lower concentrations

osmosis - net diffusion of water across a semipermeable membrane

Question 5

define tonicity

Answer 5

effect of a solution (and solutes that cannot cross) on osmotic movement of water across a membrane-

hypotonic cells are swollen
hypertonic cells are crenated- shrunken

Question 6

how is volume in different fluid compartments measured

Answer 6

directly

dilution method
concentration = amount / volume
volume = (amount added - amount lost) / concentration
- uses radioactive water / sodium / albumin

Question 7

outline the mechanism of oedema

Answer 7

increased capillary fluid pressure
decreased capillary osmotic pressure
leaky membrane (coefficient)
blocked lymphatics