Body Fluids and Homeostasis Flashcards
set point
value around which the normal value fluctuates around
dynamic constancy
homeostasis relies on this principle; no rigidity in body processes allows for minor fluctuations since the internal environment is constant and can return to set point on their own
disease
LOSS of homeostasis
negative feedback
homeostatic mechanism that REDUCES a change in a regulated variable; inhibition of a variable further in the pathway leads to decrease in variable earlier in the pathway
(MORE COMMON)
positive feedback
homeostatic mechanism that AMPLIFIES a change in a regulated variable; increase of a variable earlier in the pathway leads to increase in variable later in the pathway (LESS COMMON i.e blood clotting)
Who coined the term “homeostasis”?
Walter Cannon
Who developed the concept of compartmentalization of the internal environment of fluid surrounding tissues and organs?
Claude Bernard
Define: body fluids
the water solutions within the body
Functions of body fluids
thermoregulation, shock absorption, lubrication, transport of nutrients and waste
Total body water (TBW) and ECF/ICF/IF contributions
body is 60% water and of that 60%:
- 2/3 (40%) intracellular fluid
- 1/3 (20%) extracellular fluid
–> of the ECF 80% interstitial fluid and 20% plasma
blood vessel structure
capillaries= 1 endothelium cell thick with water-clefts
- allows for max diffusion of nutrients, gas exchange and waste disposal
plasma membrane components
BILAYER of hydrophilic heads and hydrophobic tails, proteins and glycoproteins, and cholesterol
calculate blood volume
plasma, buffy coat of WBCs (<1%) and RBCs
so BV= plasma + RBC volume
hematocrit
volume of RBCs to total blood volume (BV)
= RBC Volume/BV x100%
NORMAL RANGE: 35%-50%
Molarity
moles of solute per liter of solution
units: mol/L (M)
CaCl2= 1 mol CaCl2
Normality
number of EQUIVALENTS of solute per liter of solution
CaCl2= 2Eq= 2 normal
Osmolarity
number of osmoles (osmotically active particles) of solute per liter of solution
CaCl2= 3 osmolar
Osmolality
number of osmoles per kg of solvent
Ionic composition of: SODIUM
Na(in)= 12
Na(OUT)= 140
- [Na] higher OUTSIDE the cell
Ionic composition of: POTASSIUM
K(IN)= 150
K(out)= 4
- [K] higher INSIDE the cell
Ionic composition of: CALCIUM
Ca(in)= 10^(-4)
Ca(OUT)= 2.5
- [Ca] higher OUTSIDE the cell
Ionic composition of: MAGNESIUM
Mg(IN)= 30
Mg (out)= 1
- [Mg] higher INSIDE the cell
Ionic composition of: CHLORIDE
Cl(in)= 10
Cl(OUT)= 110
- [Cl-] higher OUTSIDE the cell
Ionic composition of: PROTEINS
[Protein-]= higher INSIDE the cell
Macroscopic electroneutrality
on the BROAD spectrum, the positive and negative charges in the ICF are equal; and the positive and negative charges in the ECF are equal
Osmolality of most/all cells in the body
~285mOsm/kg solvent
–> 300 mOsm/L
Diffusion
the movement of molecules from an area of higher solute concentration to lower solute concentration d/t their thermal energy
Simple Diffusion
the PASSIVE movement of molecules from an area of higher solute concentration to lower solute concentration d/t their thermal energy so no outside energy is required
Facilitated Diffusion
the MEDIATED passive movement of molecules from high to low concentration with the help of channels and/or carriers
Osmosis
the SIMPLE diffusion of water
Fick’s law of diffusion
determines the net flux of particles that will diffuse across a membrane
equation: J= PA(C1-C2)
Determinants of ion permeability across a membrane
- temperature (higher temp –> increased movement of particles)
- molecular weight
- B (lipophilicity; higher lipophilicity–> increased movement of particles
- charge (charged particles cannot PASSIVELY cross the membrane)
Limitations of diffusion
why we would need assistance getting particles across the membrane:
- low permeability
- uphill transport
- long distances
- small surfaces
