PHYSIOLOGY 209 = BODY FLUIDS

Relative constancy of the milieu intérieur (interior environment)

Homeostasis

What happens if homeostasis (no more dynamic constancy)

Disease

How is body water important to the body?

1) Moisten tissues (mouth, nose)

2) Prevent constipation

3) Lubricates joints

4) Regulate body temperature

5) Lessen the burden of kidneys + liver by flushing out waste products

6) Dissolve solutes and minerals to make them accessible to the body

7) Carries oxygen and nutrients to cells

Body water percentage of each tissue

1. Skin

2. Muscle

3. Brain, liver, kidney, heart

4. Fat

5. Bone

1. 70%

2. 75%

3. 70-80%

4. 25%

5. 10%

Variants of body water percentage in different people

1. Age

2. Sex

3. Amount of fat (adipose)

How does age affect amount of body water percentage

As we age, we put on more adipose tissue (FAT) = so BW goes down

Elderly = lose muscle mass = connective tissue replaced = dry

How does sex (woman or men) = affect Body water percentage

Woman are more prone of having a lower body water percentage because of estrogen

Estrogen = store fat in buttock and chest, which men don’t

BW of women lower than men

How to calculate body water?

Body weight (female or men) X %WATER diviser 100 = Body water = in liters

What is the importance of calculating % of body water?

To deliver water-soluble medication

BODY WATER PROBLEM HERE

Dosing problem here in terms of the body water percentage

What is important to keep the water balance constant?

The water intake has to be equal to the output

What are the different forms of water intake?

1) Oral intake (how much water we drink)

2) Food intake (water in food)

3) Oxidative reaction water from metabolism

What are the different forms of output?

1) skin (passive evaporation), lungs (breath in-n-out) (sensible = unaware)

2) stool, kidney (insensible = aware)

What is passive evaporation affected by?

Ambient temperature, relative humidity

What is facultative loss?

Amount of water loss for body water balance

How can you lose the excess water (facultative)?

Through urine (kidney) = that’s why called homeostatic organ for water balance

What about sweat?

Sweat is a sensible loss = but neither obligatory nor facultative

Différences between sweat and insensible perspiration (water loss through the skin)

1. Type of loss

   Sweat = electrolytes (salt), I.P = pure water

2. Mechanism

   Sweat = needs energy, active secretion, I.P = passive evaporation

3. Location

   Sweat = only occur at sweat glands, I.P = entire skin surface

4. Occurrence

   Sweat = activated by heavy work, high temp., I.P = continuous and obligatory

Explain the term turnover?

Amount of water lost and replaced in a 24h period

Percentages for adults and infants?

Adults = 3-4% of total body weight

Infant = 10% of total body weight = more susceptible for water loss

Why are infants susceptible to water loss (turnover = amount lost and recovered is high)?

Because their kidneys are not as developed and stable as adults

The constancy of body water volume helps with what?

Helps maintain blood pressure and volume levels, normal solute concentrations = necessary to adequate supply of O2 to tissues

Body water balance breaks = negative water balance, what it is? And causes?

Negative water balance

Water loss > Water intake

Causes:

1) less of water intake

2) Gut loss = vomiting, diarrhea

3) Increase in urine (excessive)

4) Increase in breathing = higher altitude (excessive loss in expired air)

5) Excessive sweating

What about water intoxication? Is it common? Causes?

Water intoxication

Water intake > water loss

It’s less common because our kidneys are doing a great job at eliminating excess water

Causes:

1) Excessive water intake

2) Renal system failure