Introduction to medical
physiology
G. Ogweno
Basics
Calor, dolor, rubor and tumor
Aulus Cornelius Celsus
)
medicina,
A.D.
25
ADebasic
wayc. in
which
the body reacts
to infection, irritation or other injury,
the key feature being redness, warmth,
swelling and pain. Inflammation is now
recognized as a type of nonspecific
immune response
The discipline
Physiology:knowledge of nature; function of
body;grk natural phylosophy
• Physis-nature
• Logos-discourse
• Knowledge of mechanism of life at organ,
tissue, cellular and molecular levels
• Contribution of organ -system to
homeostasis
What is physiology?
• Dynamic study of life
• Describes “vital” functions of living organs,
cells, molecules
• Branches: medical, comparative,
• Evolved disciplines: biochemistry,
biophysics, neurosciences, molecular
genetics, molecular biology, cell biology
Physiological genomics
• Functional genomics: understanding roles
of genes play in physiology
• Link between cells, molecules genes and
functions
• Polymorphisms and group effects on
population=gene variants
Methods of study
•
•
•
•
•
•
Hypothesis formation
Accurate observations
Experimentation
Methodical documentation
Quantitative approach to analytical experimentation
Establishment of identity of
fact:perception(observation),inference,comparison
(logic), testimony(authority)
• Begin by accepting nothing on trust from any source
whatsoever, by questioning everything and forming our
own conclusions
Colligative properties of molecules
Property dependent on number of solute
molecules present and not their
characteristics:
• Lowering of vapor pressure
• Elevation of boiling point
• Depression of freezing point
• Osmotic pressure
Units of concentration of solutes
• Moles:gram molecular weight=Avogadro’s number
• Equivalent:applies to electrical/charged particles;1 eq=1 mol of
ionized substance divided by its valence
• Gram equivalent: wt chemically equivalent to 8.0g of oxygen
• Normality: no. of gram equivalent in 1 L
• pH=-log H+ conc
• Osmoles: gram molecular weight of substance divided by number of
freely moving particles that each molecule liberates in
solution=osmotically active particles
• 1 osm=1 mole of solution depressing freezing point of water by
1.86ºC
• Osmolarity=number of osmoles per lit of solution, affected by temp
and vol
• Osmolality=osmoles/Kg solvent, indepent of temp& vol
Fluids:descriptive terms
• Mixture:two or more components intermixed
• Solution:homogenous mixture of components
e.g gases, lig, solid
• Solvent: present in greatest amount, dissolving
medium
• Solute: present in smaller amount
• True solution:gases,lig,solids dissolved in
water,usually transparent; solutes(individual
atoms& molecules) not visible to naked eye,
don’t settle out, don’t scatter light ,path of beam
of light invisible
contd
• Colloids: emulsions or heterogenous mixture that often
appear translucent or milky; solutes larger than soln but
don’t settle out, scatter ligth;visible path of light; undergo
sol (fluid)-gel(solid) transformation reversible
• Suspension: heterogenous mixture with large, often
visible solutes that tend to settle out e.g mixture of sand
and water, blood
• Azeotrope: mixture which vaporizes into the same
proportions as the volume concentration of the
components in solution e.g alcohol in water 96%; lowers
its vp, less volatile, bp is raised
Solutes and water movement
• Diffusion:tendency of molecules or ions to scatter evenly
throughout the environment by kinetic energy and
random; along or down concentration gradient. Speed
influenced by molecular size and temperature
• Osmosis:movement of solvent molecules e.g water into
a region predominanlty higher solutes to which
membrane impermeable; tendency of migration of
solvent to region of greater solutes; depends on
membrane types, solutes
• Osmotic pressure: force counteracting water movement
• Tonicity: ability of solution to change the shape or tone of
cells by altering their internal water volume;osmolality of
solution relative to plasma, how it affects cell
volume(conc&permeability)
Body fluids
Ideal solution:
• O.p=nCRT/v
• 1 Mole solute depressefreezing point of 1
Kg by 1.86ºC
Normal plasma:
• O.P=7.3 atmos
• 280-300 mOsm/L
• Freezing point=-0.54ºC
Avoiding
The
Final
Meltdown