What’s the Fundamental Principal in Physiology?
At all level of organization, functional activities are directed at maintaining HOMEOSTASIS (the relative constancy of the MILIEU INTERIEUR)
Who coined the term ‘‘Milieu interieur’’ and what characteristics did he find?
Claude Bernard
- The environment surrounding individual cell is vastly different from the EXTERNAL environment.
- The INTERNAL environment remains relatively constant under conditions of health
The Milieu Interieur includes various body fluids. Name the aspects that composes body fluids.
Volume
Distribution
Characteristics
Functions
Which fluid is the most abundant constituent of the body?
Water ranging from 45% to 75%
What happens in body water?
- Solutes are dissolved
- Metabolic reactions take place
- Transfer of nutrients and oxygen around the body
Name body water key functions
- Moistens tissues (mouth, eyes and nose)
- Protects body organs and tissues
- Helps prevent constipation
- Helps dissolve minerals and other nutrients to make them accessible
- Regulates body temperature
- Lubricates joints
- Flushes out waste products (helps lessen burden on kidneys and liver)
- Carries nutrients and O2 to cells
What % of Water do we find in the following tissues:
- Skin
- Muscle
- Heart, liver, brain, kidney
- Bone
- Fat
- Skin: 70%
- Muscle: 75%
- Heart, liver, brain, kidney: 70%
- Bone: 25%
- Fat: 10%
How can we determine the differentiation in Total Body Mass between individuals?
By looking at the Total Body Water which is determined by the amount of adipose tissue an individual has.
How much is the Total Body Water in an individual who has high adipose tissue vs low adipose tissue?
Total Body Water is inversely proportional to adipose tissue.
Therefore: High adipose tissue = low Total Body Water and Low adipose tissue = High Total Body Water
What happens to the difference in Total Body Water between individuals if we look at their Lean Body Mass?
As we’re excluding fat, the differences between individuals become insignificant.
What are standard values for a Physiological Reference Individual
- 21yr, white male, 70kg
- 60% Body Water
What happens to body water as we age?
Body water decreases as we age because we lose muscle tissue and it gets replaced by connective tissue which is drier.
What is the formula to calculate body water?
Absolute amount of water (L)=mass(kg)xBW%
Why is it important to know the amount of body water percentage?
Because it is necessary when administering water-soluble medication.
What is the formula to calculate the final concentration of medication on the body based on weight and absolute body water (how do you find it)?
- Find absolute water in L and convert to ml. Water(L)=mass(kg)xBW%=Water(ml)
- Final concentration=mass of meds(mg)/Water(ml)
How can we consider ourselves physiologically in health?
When body water remains constant, in a dynamic steady state between:
- The individual and the external environment
- Different compartments internally
How do we maintain water balance in our body?
When Total Fluid Intake = Total Fluid Output
How much is our Total Fluid Intake and by what is it composed?
Oral Fluid: 1.2L
Oral Intake as food: 1.2L
Oxidative water from metabolism: 0.4L
Total: 2.7L
How much is our Total Fluid Output and by what is it composed and which are sensible?
Insensible
Lungs: 0.4L
Skin: 0.5L
Sensible
Kidneys (urine): 0.5L (1.2L facultative)
Stool (feces): 0.1L
Total=2.7L
Describe the main differences between Obligatory losses vs. Facultative losses.
Obligatory losses: Required 1.5L loss of water/day through lungs, skins, urine and stool
Facultative losses: Vary with intake via urine and is necessary to maintain balance (kidney is key homeostatic balance for water)
Describe the differences between Insensible perspiration and Sweating.
Insensible perspiration: Passive evaporation of pure water via entire skin surface continuous and obligatory.
Sweating: Active secretion (energy dependent) via sweat glands that is activated by heavy work or high temperatures
What is water turnover?
The amount of water coming in and out of the body.
How much is water turnover in an adult and in a child?
Adult: 3-4% of Total Body Weight
Child: Around 10% of Total Body Weight
We know that body water is constant under conditions of health. What does this helps maintain?
Normal solute concentrations
Normal blood volume and pressure
Leading to adequate supply of O2 to tissues
