SN - Water 1

bethdrysdale94's version from 2017-03-29 10:44

Section 1

Question Answer
Whats the difference between absolute and relative water balance?Absolute - water volume of an individual. Relative - water vol in comparison to other body components relative to individual
What is a function of adipose tissue?water content
What has the highest and lowest water content in the body?blood = 83%, organs =76% skin = 72%, muscle = 76%. adipose = 10%, skeleton = 22%
How do you measure water content?tracer technologies (deuterium D2O)
How do you use tracer methods?urine sample >> D2O ingestion in the evening (eg 10g) >> urine sample in the morning >> measure D2O content of urine sample and compare to control
What does larger adipose tissue mean for relative water content?less relative content as adipose only has 10% water

Section 2

Question Answer
Which compartments is body water distributed into?ECF (1/3) and ICF (2/3)
What is ECF split into?interstitial fluid (ISF 3/4) and intravascular (IVF 1/4)
Fluid intake components and mlfluid intake (1600), food intake (1000), metabolic water (400) from respiration
Fluid losses components and mlurine (1400), expired air (320), faeces (100), skin loss (530) and sweat loss (650)
What is Euhydration?normal blood chemistry, plasma osmolality <290mosmol/kg, urine osmolality <700mosmol/kg, urine specific gravity <1.020
Which water intake/loss components balance each other out even during exercise?metabolic water and expired air

Section 3

Question Answer
What range is plasma osmolality regulated in?280-290 mosmol/L, regulated by kidneys and thirst mechanism
control centres hypothalamus/forebrain do what?respond to changes; osmoreceptors triggered by 2-3% change in plasma osmolality, baroreceptors respond to around 10% change in blood volume/pressure
is most fluid intake habitual or due to physiological needs?habitual
intracellular fluid componentslow sodium (12mmol/L), high potassium (150mmol/L), low chloride (4mmol/L)
extracellular/plasma componentshigh sodium (140mmol/L), low potassium (4mmol/L), high chloride (104mmol/L)
correcting hypohydrationincreased osmolality, osmoreceptors detect this, increase thirst and fluid intake, increase AVP (ADH) which acts on the kidneys to decrease urine output, more water retained, plasma osmolality goes down
correcting hyperhydrationdecreased osmolality, osmoreceptors detect this and decrease thirst, decrease AVP (ADH) which reduces actions on kidneys so urinary excretion is increased, water is excreted so plasma osmolality increases

Section 4

Question Answer
What determines how much drink post exercise is retained?the effect it has on AVP
What is the rehydration process?ingestion, gastric emptying, intestinal absorption and then rentention in the circulation
what is considered hydrated for urine osmolality700-900mosmol/kg
What is important to note about hypohydrated athletes during training?they dont consume all the water they lose when hypohydrated, rehydration is therefore not effective
Which is better, bolus or metered rehydration? (measure by urine output)bolus = 700ml urine output, metered = 400ml output (metered =100% sweat loss over 4h hours,)

Section 5

Question Answer
Effects of sodium in post exercise drink - Low/High Na in 50,100,150 and 200% rehydrationsodium improves retention in all except 50%. in both groups, it requires 150% consumption to reach hydrated state
What happens to urine output when sodium is increased?decreases because Na increases plasma osmolality
What effects do CHO (GLU) and milk protein have on urine output?also decrease, similarly to Na
Why doesnt whey protein have the same effect on urine as milk protein?whey protein is a "fast" protein
What are the important factors for post-exercise rehydration?drink palatability, volume, composition and rate of drinking.
Two ways in which a rehydration drink can increase drink retentionslow delivery rate of drink to circulation influencing AVP response, increase drink retention once drink reaches circulation by influencing AVP response