W2 - Hydration Flashcards
(114 cards)
1
Q
What % of the MALE body is water?
A
60-80%
2
Q
What % of the FEMALE body is water?
A
50-60%
3
Q
How long can you survive without water?
A
100hrs
4
Q
How many litres per hour is the typical sweat rate during exercise at normal body temp?
A
1-2
5
Q
What % of H20 is in fat?
A
10
6
Q
What % of H20 is in muscle?
A
75
7
Q
Reasons why H20 is important
A
Lubricates joints
Flushes out waste products
Allows cells to grow, reproduce + survive.
Keeps mucosal membranes moist
Contributes to saliva
Regulation of body temp
Respiration
Blood flow
8
Q
What factors affect daily H20 needs?
A
Climate
Clothing
Activity levels
9
Q
Median of observed values for daily H20 needs
A
H20 balance studies
H20 turnover studies
H20 intake studies
10
Q
What are the organic substances that make up the bodys fluids?
A
Glucose
aa
FA
Hormones
Enzymes
11
Q
What are the inorganic substances that make up the bodys fluid?
A
Na+
K+
Ca2+
Magnesium
Chloride
Phosphate
Sulphate
12
Q
When does fluid balance exist?
A
When total H20 intake = total H20 loss
13
Q
Input for body H20 balance
A
Food
Fluids
Metabolism
14
Q
Output for body H20 balance
A
Urine
Faeces
Skin
Lungs
15
Q
How much of the total body water belongs to intracellular fluid?
A
40%
0.4 L/Kg
28L (for a 70kg male)
2/3rd of total body water, being 42L.
16
Q
How much of the total body water belongs to extracellular fluid?
A
20%
14L (for a 70kg male)
1/3rd of total body water, being 42L.
17
Q
What can extracellular fluid be divided into?
A
Plasma
Interstitial fluid
18
Q
What separates the ICF from surrounding interstitial fluid?
A
Plasma membrane
19
Q
What divided the interstitial fluid from the plasma?
A
Bv wall
20
Q
Solute
A
Substance dissolved in a solvent
21
Q
What machine measures osmolarity?
A
Cryoscopic osmometer
22
Q
Define osmolaLity
A
No. of osmoles (Osmol) of solute per kg of solution
23
Q
Define osmolaRity
A
No. of osmoles (Osmol) of solute in a L of solution
24
Q
What fluids does the Cryoscopic osmometer commonly measure?
A
Saliva
25
Define euhydration
State of normal body H20 level
26
What is plasma osmolality in euhydration?
285-290 mOsmol.kg-1
27
What can hypo hydration result in for urine?
High urine osmolality
28
Define hypo hydration
State of red. body water level w/in the cell
29
What is max urine osmolality in severe dehydration?
1200 mOsmol.kg-1
30
Hypertonic
Fluid around cell has a higher solute conc
= H20 diffuses OUT of cell
31
Hypotonic
Fluid around cell has a lower solute conc
= H20 diffuses INTO cell
32
Hyperhydration
State of elevated body water level in cell
33
Electrolytes
Substances that produce an electrically conducted solution when dissolved in a polar solvent.
34
What do the dissolved electrolytes do when in the solution?
Separate into cations + anions.
Then disperse uniformly through solvent causing a change in concentration.
35
Functions of electrolytes
Control osmosis between compartments of the body.(ECF + ICF)
= Helps maintain pH
Carry electrical current
Serve as cofactors
AP generation
Cardiac rhythm control
Muscle contraction
Energy storage
36
ELECTROLYTES
Whats the most abundant cation in extracellular fluid?
Na+
90% of extracellular cations
37
ELECTROLYTES IN ECF
Functions of Na+
Muscle contraction
Impulse transmission
Fluid + electrolyte balance
38
ELECTROLYTES
Whats the most abundant anion in extracellular fluid?
Cl-
39
ELECTROLYTES IN ECF
Functions of Cl-
Regulates osmotic pressure
Forms HCL
40
ELECTROLYTES
Whats the most abundant cation in ICF?
K+
41
ELECTROLYTES IN ICF
Functions of K+
Resting membrane potential
AP
Maintains intracellular vol
Regulation of pH
42
ELECTROLYTES
Whats the most abundant anion in ICF?
PO4(3-)
| Phosphate
43
ELECTROLYTES IN ICF
Functions of PO4(3-)
PTH (Parathyroid hormone) regulation
Blood calcium levels
44
Na+ is the main electrolyte lost in sweat.
At what concentration?
40-50mmol/L
45
Why does sodium control water distribution?
Only cation to exert osmotic pressure
Na+ leaks into cells + then pumps vs their electrochemical gradient
[Na+] in ECF remains stable
Losses occur through urine + perspiration
46
Where are osmoreceptors?
Hypothalamus
47
What do osmoreceptors do?
Send signals to posterior pituitary gland = ADH released.
48
What is secretion of ADH from the pituitary gland from the osmoreceptors stimulated by?
Haemoconcentration (i.e during exercise)
⬆️ plasma osmolality
⬇️ plasma volume
49
What does Haemoconcentration result in?
⬆️ blood viscosity
50
What is Haemoconcentration caused by?
Dehydration
Artificially induced by blood doping
51
What does ADH do?
Promotes H20 retention in the kidney to dilute plasma electrolyte concentrations.
52
How does the kidney enable H20 retention?
Collecting ducts become highly permeable to H20
53
What is aldosterone?
Mineralocorticoid hormone
54
Mineralocorticoid hormones
Class of steroid hormones that reg salt + H20 balances
55
Where is aldosterone released from?
Adrenal cortex
56
What is secretion of aldosterone stimulated by?
⬇️ plasma sodium
⬇️ blood vol
⬇️ bp
High plasma potassium
57
What does aldosterone do?
Controls Na+ + K+ excretion
58
According to Goulet, 2012, when doesn't loss of water appear to impair performance?
When duration is less than 1hr
59
According to Cheuvront + Kenefick, 2014, when is endurance performance impaired - associated to loss of water?
When losses are 2% + body mass
60
What is the overall loss of water at rest?
96 ml/hr
61
What is the overall loss of water during prolonged exercise?
1325 ml/hr
62
Factors affecting sweat loss
Body size
Absolute VO2
Aerobic fitness
Heat acclimatisation
Env
63
How is sweat loss calculated?
Change in mass + fluid intake - urine
64
Cellular consequences of dehydration
Loss of solutes
⬇️ blood vol
Change in osmotic pressure
Lose H20 = shrink
65
Quantifying dehydration
Traditionally expressed as a % of body mass loss:
% dehydration or % hypo hydration
66
Why don't human always respond to physiological signs of thirst?
Dk benefits of fluid intake / not remembering to drink
Disliking H20
Lack of thirst
Lack of H20 availability
67
CHO content for hypotonic sports drinks
1-3%
68
CHO content for isotonic sports drinks
6-8%
69
CHO content for hypertonic sports drinks
10%+
70
Purpose for hypotonic sports drinks
Quickly replace fluid lost by sweat
71
Purpose for isotonic sports drinks
Quickly replace fluid lost by sweat
Provide boost of CHO
72
Purpose for hypertonic sports drinks
Supplement CHO intake
73
What are the considerations for sports beverage optimisation?
Rate of absorption
Any gastrointestinal distress?
If maintains ECF + osmolality
Offers pot to ⬆️ performance
74
What sports drink would be suggested for a 5-10km run?
Water or hypotonic sports drink
75
Longer than 10km sports drink?
More of an isotonic sports drink
76
Pre-exercise
How much H20?
When?
500ml = Adequate
1-2hr before exercise
77
During exercise
If less than an hour, how much H20?
0.5 to 1L / hour
78
H20 intake suggestion for events of more than 1hr
600-1200ML / hr
+ Na+ (0.5-0.7 g/L)
79
What does inclusion of Na+ in fluid aid??
Fluid absorption in kidneys
Water retention
80
What % of H20 do you need to drink of what you lost in exercise?
150%
81
Why does alcohol increase the rate of urination?
Due to ⬇️ release of ADH
82
What is variability in total body water primarily due to?
Differences in body composition
83
Approx what % of total body water is turned over daily?
5-10%
84
How is metabolic water formed?
By oxidation of substrates
85
Total body water per kg of body mass from infancy to maturity
Why?
Infancy = Highest
Maturity = Lower
== Fluid regulatory mechanisms mature
86
What are the 2 principle forms of body water deficit?
Hypertonic hypovolemia
Isotonic hypovolemia
87
What is the physiology behind hypertonic hypovolemia?
Body H20 loss > solute loss (greater than)
H20 moves from ICF--> ECF
Partial restoration of ECF
88
What is the physiology behind isotonic hypovolemia?
Isotonic body H20 + solute loss
NO net movement of H20 among body fluid compartments
89
What are the complex markers for hydration assessment techniques?
Total body water (dilution)
Plasma osmolality
90
What are the simple markers for hydration assessment techniques?
Urine concentration
Body mass
91
Advantages of complex markers for hydration assessment techniques
Accurate
Reliable (gold standard)
92
Disadvantages of complex markers for hydration assessment techniques
Analytically complex
Expensive
Req. baseline (for total body water)
Invasive (for plasma osmolality)
93
Advantages for simple markers for hydration assessment techniques
Easy
Rapid
Screening tool
94
Disadvantages for simple markers for hydration assessment techniques
Urine concentration
Easily confounded
Timing is critical
Freq + colour is subjective
95
Disadvantages for simple markers for hydration assessment techniques
Body mass
Confounded by changes in body composition
96
What other markers can be used under the hydration assessment techniques
Plasma vol
Plasma sodium
Fluid balance hormones
Bioimpedence
Saliva
Physical signs
Thirst
97
What can be used to indirectly estimate urine osmolality?
Urine colour chart
98
What can be used to directly assess urine osmolality?
Refractometer
99
When using a cryoscopic osmometer what will a higher osmolality lead to?
Freezing point depression
100
How can total body water be estimated?
Multi-frequency bioelectrical impedance analyser
-- Indirect method
101
What happens to the multi-frequency bioelectrical impedance analyser at low frequencies (5Hz)?
Current can't penetrate cell membrane
Estimates extracellular H20 = 1/3rd of total body water
102
What happens to the multi-frequency bioelectrical impedance analyser at high frequencies (200Hz)?
Current can penetrate cell membrane.
Estimates intracellular water = 2/3rds of total body water
103
What does H20 pass through in osmosis?
Partially permeable membrane
104
Calculation for urine osmolality
(160.48 x urine colour) - 150.48
105
Step by step for the assessment of urine colour + osmolarity
Urine in container
Determine colour using urine colour chart
Estimate osmolarity using urine osmolality
Determine urine osmolarity using refractometer
106
Step by step for the assessment of saliva osmolarity
Saliva in sampling tube
Determine urine osmolarity using cryoscopic osmometer
107
Equation for plasma volume (L)
(0.042 x Lean Mass) + 0.578
| Sawka et al., 1992
108
Equation for interstitial volume (L)
Extracellular vol (L) - Plasma vol (L)
109
What are the typical values for assessing hydration + body water
What % of BM does ... count for?
1. Total body H20
2. Int. Cellular vol
3. Ext. Cellular vol
4. Interstitial vol
5. Plasma vol
Total body H20 = ~60% body mass (BM)
Int. cellular vol = ~ 40% BM
Ext. cellular vol = ~ 20% BM
Interstitial vol = ~ 16% BM
Plasma vol = ~4% BM
110
What is the bioelectrical impedance analysis based on?
Electrical conductance characteristics of hydrous (FF) + anhydrous (Fat component) tissues.
111
What must subject do/not do prior to the bioelectrical impedance analysis?
NO food or drink in 4hrs b4
NO exercise 12hrs b4
NO alcohol 48hrs b4
NO diuretics w/in 7 days b4
Must have urinated w/in previous 30 mins
112
In the bioelectrical impedance analysis, how long must the subject lie quietly for before repeating procedure?
5 mins
113
In the bioelectrical impedance analysis, 4 electrodes are prepared w/ electro-conducting gel + attached to which sites on the foot?
Dorsal surface of right foot.
Proximal to 2nd metatarsal-phalangeal joint.
Anterior surface of right ankle between medial + lateral malleoli.
114
In the bioelectrical impedance analysis, 4 electrodes are prepared w/ electro-conducting gel + attached to which sites on the RIGHT hand?
Proximal to dorsal surface of 3rd metacarpal-phalangeal joint.
Dorsal surface of wrist adjacent to head of ulna.
