Week 10: water balance and hydration

Question 1

TBW is ____% of body mass

Answer 1

50-75%

Question 2

blood plasma makes up ___% of TBW

Answer 2

7.5%

Question 3

Interstitial fluid makes up ___% of TBW

Answer 3

30%

Question 4

Intracellular fluid makes up ___% of TBW

Answer 4

62.5%

Question 5

Water is tightly regulated by(2)?

Answer 5

1. the nervous system

2. hormonal activity

Question 6

The anti-diuretic hormone function?

Answer 6

Primarily effects (water) decreasing urine output

Question 7

Aldosterone function?

Answer 7

Stimulates the absorption of sodium in kidney (sodium focused)

Question 8

____ is the main electrolyte in extracellular fluid

Answer 8

sodium

Question 9

Sodium accounts for ___% of plasma osmolarity

Answer 9

50%

Question 10

The kidneys either conserve ___ or conserve _____

Answer 10

water, sodium

Question 11

Thirst is evoked by elevated _____ osmolarity and (some) reductions in ___________…?

Answer 11

plasma, blood volume and pressure

Question 12

Hyponatremia :

Answer 12

low plasma levels

Question 13

Normal plasma sodium concentrations are _____mmol/L

Answer 13

140-144mmol/L

Question 14

Symptoms of low sodium plasma concentration occurs at ____ mmol/L and less

Answer 14

130mmol/L and less

Question 15

Sodium plasma levels below 120mmol/L can cause…

Answer 15

risk of seizures, coma and death increases

Question 16

Symptoms of initial low sodium plasma levels can be…

Answer 16

Mental confusion, weakness, fainting, (all similar to dehydration -> can cause confusion and make it worse if they drink more water!!!)

Question 17

Normal body temp:

Answer 17

36-38 degrees celcius

Question 18

Normal body temp for exercise:

Answer 18

38-40 degrees celcius (any higher can be heat exhaustion or lead to heat stroke)

Question 19

4 factors that effect the environmental stress?

Answer 19

• Ambient temp
• Relative humidity
• Wind velocity
• Solar radiation

Question 20

If body temp rises, the hypothalamus ….. (2)

Answer 20

• increase blood foo to skin

- increases sweat rate

Question 21

Conduction:

Answer 21

Transfer of heat through direct contact

Question 22

Convection:

Answer 22

Transfer of heat through fluid or gas

Question 23

Radiation:

Answer 23

Transfer of heat through electromagnetic waves

Question 24

Evaporation:

Answer 24

Heat loss through water vaporisation from skin

Question 25

Skin temp > environment temp =

Answer 25

heat lost from skin (through evaporation, convection and conduction)

Question 26

environment temp > skin temp

Answer 26

Heat is gained (through conduction and convection)

Question 27

If environment saturated with vapour, what happens to evaporation?

Answer 27

It does not occur, then body does not lose heat

Question 28

1L of O2 consumed = ____ of heat produced

Answer 28

16 kj (4 cal)

Question 29

What happens to the rest of the heat in the body? (2)

Answer 29

• Lost from overlying skin

- Passed to core core through venous BF to heart

Question 30

Can you improve thermoregulatory response?

Answer 30

Yes, by training at high intensities (70-100% vo2 max) which should increase body temp above 39 degrees celcius

Question 31

Adaptation of increase thermoregulatory response will result in…?

Answer 31

• earlier sweating onset
• increased total sweat amount
• Increased the sensitivity between core temp and sweat rate
• Hypertrophy of sweat glands (increased size not #)

Question 32

Is there an adaptation to dehydration?

Answer 32

No

Question 33

For every L of body fluid lost there is ……(3)

Answer 33

• Increase in HR by 8bpm
• decrease in CO by 1L/min
• increase in core temp by 0.3 C

Question 34

If you are dehydrated, exercise will cause….(2)

Answer 34

• body temp to rise FASTER

- higher HR

Question 35

What level of dehydration can performance be affected at???

Answer 35

1-2%

Question 36

Thirst threshold begins at __% of fluid loss

Answer 36

1%

Question 37

Stronger thirst, vague discomfort, decrease hunger begins at __% of fluid loss

Answer 37

2%

Question 38

Dry mouth, decreased urine output begins at __% of fluid loss

Answer 38

3%

Question 39

20-30% decreases in performance begins at __% of fluid loss

Answer 39

4%

Question 40

Decreased concentration, headache, impatience, sleepiness begins at ___% of fluid loss

Answer 40

5%

Question 41

Serious health conditions begins at ___% of fluid loss

Answer 41

6%

Question 42

What is actually happen to make fluid loss decrease performance?

Answer 42

⬇ blood volume
⬇  skin blood flow
⬇  sweat rate
⬆core temp
⬆rate of muscle glycogen use

Question 43

Hyperhydration goal is to…

Answer 43

maximise TBW content prior to competition

Question 44

Downsides of hyperhydration….

Answer 44

• GI discomfort
• much of the water is excreted
• may not be practical
• not as beneficial as they thought

Question 45

Strenuous exercise ___mins or less has NO advantage w/ fluid intake

Answer 45

30 mins or less

Question 46

Exercise for ___hr or in ____ conditions should have water with electrolytes-CHO

Answer 46

1 hr, hot conditions

Question 47

Why is it difficult to match fluid intake with fluid output? (4)

Answer 47

1. GI discomfort
2. Sweat rates vary
3. Some sport rules may not allow or may not be practical
4. Thirst is not a good indicator of requirements

Question 48

Sweat rate is almost __x higher in hot environments

Answer 48

2x

Question 49

Hypertonic =

Answer 49

increased solutes outside cell -> water moves out

Question 50

Hypotonic =

Answer 50

increased solutes inside cell -> water moves into cell

Question 51

Isotonic =

Answer 51

Same amount of solutes outside and inside cell, NET move zero (although they still move)

Question 52

Ensure to avoid hypotonic/hypertonic solutions

Answer 52

Avoid hypertonic solutions !!!!

Question 53

Typical fluid ingestion is ___L/hr

Answer 53

0.4-0.8L/hr

Question 54

It is better to give more/less fluid than you know they lost…

Answer 54

MORE (125-150% of what was lost)