Why do we sweat when we exercise?
Because our muscle are not efficient in doing work and generate heat, which is dissipated as sweat evaporates off the skin,
What is the best fluid to replace sweat?
What happens at 2% body weight fluid loss? How many liters of sweat does that represent?
Impaired performance 1.5 L
What happens at 4% body weight fluid loss? How many liters of sweat does that represent?
Decreased capacity for muscular work (capacity to do work) 3 L
What happens at 5% body weight fluid loss? How many liters of sweat does that represent?
Heat exhaustion 3.5 L
What happens at 7% body weight fluid loss? How many liters of sweat does that represent?
Hallucinations 5 L
What happens at 10% body weight fluid loss? How many liters of sweat does that represent?
Circulatory system collapse/Heat stroke 7 L
What were unicellular organisms not capable of doing?
They had no way of regulating themselves if the environment is not right
What body compartment do cells bathe in?
What is another name for the milieu interieur?
Who coined the term milieu interieur?
Through what do nutrients arrive at the capillary bed?
Through what do metabolites leave at the capillary bed?
Role of circulatory system? Made of which two parts?
To “pump” and circulate nutrients to the cells and take waste products away Heart and vasculature
Role of respiratory system?
To deliver O2 and excrete CO2
Role of gastrointestinal system?
To take in nutrients and break them down to be able to utilize them and then eliminate what we don’t need
Role of renal/urinary system?
To monitor and regulate all of the electrolytes in the body
What is an electrolyte?
A substance (as sodium or calcium) that is an ion in the body regulating the flow of nutrients into and waste products out of cells
Role of musculoskeletal system?
To physically obtain whatever nutrients we need
What are the two physiological systems that regulate our vital functions?
The nervous (PNS/CNS) and endocrine systems
Role of immune system?
To defend our body from pathogens
Is the reproductive system a physiological system? Why?
No because its purpose is to protect the species as a whole not homeostasis of an individual organism
What is the definition of homeostasis?
The process by which the body maintains constancy in internal function in the face of changes in the external environment
How does our % total body water change from birth to adulthood?
What is the % TBW of an adult?
What is the % TBW of an obese adult?
What is the % TBW of an emaciated adult?
Why do fat people have a lower % TBW than skinny people?
Fat cells have less water!
Is there a difference in % TBW between men and women? Why?
Yes, women tend to have less TBW than men because they contain more subcutaneous adipose tissue in their bodies.
Is there more water inside or outside cells? What are the exact ratios?
2/3 inside and 1/3 outside
What are blood's 2 phases? In which fluid is each?
Fluid/plasma (ECF) and cellular (ICF)
Draw the TBW diagram (you can do it!)
What separates the interstitial fluid from the plasma?
The capillary endothelium
What separates the ECF and the ICF?
The cell membrane
What fraction of the ECF does the interstitial fluid represent?
What fraction of the ECF does the plasma represent?
How can the physiological systems affect the milieu interieur?
Only by affecting the plasma compartment of the ECF first
What compartment is the main target of an IV?
The plasma compartment
What compartments will be affected by changes to the plasma compartment? Until what?
Interstitial fluid and ICF, until all 3 compartments are in steady state
How to go from grams to moles?
Grams / Molecular Weight = Moles
What does 1 mole of substance correspond to?
The weight of 6.02 x 1023 molecules of that substance
What is the definition of concentration? What are its units?
The quantity of the substance dissolved in a volume of fluid
What are molar equivalents?
Equivalents do not equal moles for non-univalent cations/anions. For example, since calcium is a divalent cation, 1 mol of Ca would equal 2 Eq of Ca
What is the relation between the number of anions and cations in the human body? What is a caveat?
The total number of cations and anions needs to equal.
However, these charges can be distributed in different ways within the body. For example, in order to maintain an electrical gradient across a neuron, there needs to be a separation of charges across the cell membrane.
Draw the diagram of the electrolyte composition of plasma (including what is included in the shaded area)
Shaded area: Ca2+, Mg2+ , and PO42-
Draw the diagram of the electrolyte composition of the intersitial fluid
Draw the diagram of the electrolyte composition of the ICF
What is the main difference between the electrolyte composition of the plasma vs the interstitial fluid?
The anionic proteins in the plasma
How does the electrolyte composition of the ICF relate to that of the ECF?
What is a technique to measure the volume of all of the body fluid compartments? Explain it.
The indicator dilution technique:
1. Dissolve substance in a fluid to obtain a known concentration
2. Inject fluid in plasma and let the substance disperse freely
3. Once it's done equilibrating, measure new concentration of substance in the fluid compartment
4. Calculate volume of compartment(s)
What is the equation to calculate the volume of the fluid compartment using the indicator dilution technique?
Volume of Fluid Compartment = Quantity Injected (in grams or moles)/Final concentration (g/L or mol/L) of substance in Flui Compartment
What tracer to use to calculate volume of plasma?
Radiolabeled albumin or any dye that binds to proteins (e.g. Evans blue dye), or large starches
What tracer to use to calculate volume of ECF?
- Radioisotopes of selected ions (sodium, chloride, sulfate thiocyanate)
- Nonmetabolizable saccharides (insulin, mannitol, raffinose)
- Radioactive iothalamate (125I-iothalamate)
What tracer to use to calculate volume of TBW?
Either titrated water (3H2O) or deuterium oxide (D2O)
How do you calculate the volume of the ICF?
TBW - ECF
How do you calculate the volume of the interstitial fluid?
ECF - Plasma
Describe the cell membrane
Highlly selective phospholipid bilayer that lets nonpolar molecules through (also has Na/K pumps)
Describe the capillary wall (or endothelium)
Porous membrane that lets sugars and electrolytes through (but not proteins because they are too big)
What accounts for the asymmetry in electrolyte composition between the ICF and the ECF? How much energy does this consume?
Metabolic pumps that keeps Na+ out of the cell and K+ inside: Na+/K+ ATPase
This consumes 33 to 50% of our daily energy
What is % TBW of a premature infant?
What happens if you poison the Na+/K+ pump?
The cell will die
What are 2 necessary properties of the substances we use in the indicator dilution technique?
1. Not metabolized or altered
2. Are able to distribute evenly throughout the compartment
What is hematocrit? How do you calculate it?
The percentage of blood volume that is composed of red blood cells (the cellular phase of blood: ICF)
Blood Volume= Plasma Volume/(1-Hematorcit)
What is the K+ concentration inside the cell?
What is the Na+ concentration inside the cell?
What is the Na+ concentration outside the cell?
What is the K+ concentration outside the cell?
What is molality?
Moles/kg of solvent
What are milligrams percent (mg%)
number of milligrams of a substance/100 ml of solution.
What is the difference between molar equalivents and osmolar equivalents?
mEq: has to do with charge
osmEq: has to do with # of active particles
What is serum?
Plasma without clotting factors
What is bulk flow?
The movement or flow of solutions resulting from the application of an external force (i.e., hydrostatic pressure)
What is the %TWB at birth?
What is the standard blood volume?
What body fluid compartments can inulin go in?
ECF: plasma and interstitial fluid