Self Study Of Fluid Movement Flashcards
What happens to a patients ECF when given an infusion of Sodium chloride 0.9%
Volume will increase, osmolality will remain unchanged
when given an infusion of Sodium chloride 0.9% , What will happen to the osmolality of the ICF
Remain unchanged
Will water move from ICF compartment to ECF compartment when a patient is given an infusion of 1L sodium chloride 0.9%
No
What will happen to plasma protein conc and haematocrit when a patient is given an infusion of 1L sodium chloride 0.9%
Nothing
Will a patients RBCs be swollen when a patient is given an infusion of 1L sodium chloride 0.9%
No
What will happen to a patients arterial BP when a patient is given an infusion of 1L sodium chloride 0.9%
It will increase
What happens to ECF in a patient with severe diarrhoea
ECF volume decreases, osmolality increases, water shifts from ICF to ECF
What happens to plasma protein and haematocrit as a result of diarrhoea
Will increase
Will a patient with diarrhoea have swollen RBCs
No
What does severe diarrhoea do to bp
Decrease it
What happens to ECF in a man who consumed an XS amount of NaCl
ECF Volume increases, ECF osmolality increases, ICF osmolarity increases, water shifts from ICF to ECF
What is the major cation in sweat
Sodium
What happens to ECF as a result of 24 hours in desert with no water
Osmolality of ECF will have increased due to loss of fluid in sweat
Water will shift from ICF to ECF, osmolarity of ICF increases, volume of ICF decreases
Osmotic Properties of sweat
Hyperosmotic in comparison to plasma
Increased osmotic pressure as a greater amount of solutes in solution than plasma
what happens to ECF in a patient with SIADH
Osmolality of ECF will decrease due to increased retention of water
ICF and ECF volumes increase = Hyponatraemia
What happens to ECF protein conc in SIADH
Decreases
Physical findings expected in a man who has just run a marathon in high heat
Dehydrated: conjunctiva and mucous membranes are dry, increased skin turgor
Tachycardia, increased RR,
hyperventilation (respiratory compensation due to acidosis caused by dehydration)
Hypotension
What is the effect on blood volume and pressure of a significant decrease in water and salt
Bp and BV decrease
Sweat decreases ECF, increases osmolarity
Kidneys retain extra Na+ and water to compensate
Dehydration reduces ECF
What causes high pulse rate in dehydration
Compensatory mechanism along with vasoconstriction by the sympathetic reflex as a response to decreased circulating volume
What causes dizziness and light-headedness in dehydration
Reduced brain perfusion
How could a dehydrated person develop an AKI
Hypovolemic and low BP
Dehydration causes reduced blood flow to kidneys, build up of waste/acid/myoglobin
Renal perfusion is inadequate, acid-base balance not maintained
Biochemical changes in AKI
Increased: plasma urea, creatinine, urate, potassium, phosphate
Metabolic acidosis
Increased anion gap
Decreased: plasma calcium, sodium
What fluid should be given to someone with AKI due to dehydration
Not strong hypotonic as would help cells but not blood volume, dont want to exceed sodium and chloride requirements
Want to increase circulating volume, cardiac output and perfusion pressure
Give 0.9% NaCl
Why would blood not be the correct treatment for AKI due to dehydration
Needs electrolytes and large volumes of fluid not blood
What would happen to someone given hypertonic saline
Too much NaCL
ECF volume increased
Water drawn out of ICF into ECF
Cell volume decrease
Cell shrinkage
Which 2 physiological mechanisms exist to help maintain plasma osmolality
Thirst, ADH
Which of the two physiological mechanisms that control plasma osmolality is the first line of defence
ADH
Osmotic threshold for ADH secretion is lower than thirst
Thirst only invoked if ADH cannot handle alone
Where is the hormone that regulates water reabsorption made
Hypothalamus
Where after synthesis is ADH stored
Neuro-hypophysis or posterior pituitary
What is the most important physiological effect of ADH
Conserve body water by reducing water loss in urine
Increases urea recycling: aids in maintenance of medullary conc. grad so allows maximum water to be reabsorbed from CD
Describe action of ADH in kidney
Binds to receptor on basolateral membrane of principal cells in CD
Coupled to G proteins, promotes insertion of Aquaporin-2 channels on apical membrane
No ADH = CD virtually impermeable to water, water excreted as dilute urine
Always a little released
