Transcript Lubriction of bone joints

Dr. Taqey AlMosawey
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A bone joint composed from synovial membrane
in cased two bone ends and synovial fluids (fig.5)
.the surfaces of the joint are articular cartilage .
the surface of the cartilage is rough which plays
an useful role in joint lubrication by trapping
some of the synovial fluid . this fluid squeezed in
the joint according to the stress applied on the
joint .the amount and the viscosity of synovial
fluid change according to the applied stress .
when a continues stress applied on the knee joint
, synovial fluid in continually squeezed in the
joint which cause a swollen in the joint .
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i: rheumatoid arthritis which result in over
production of synovial fluid in the joint and
causes swollen joints and
ii: ostpoarthrosis a disease of the joint it self
. threads squeeze synovial fluid from the
porosi , of bone low viscosity means good
lubrication the coefficient of friction reduced
between the bones in the knee by synovial
fluid to less than 0.01 where that of steel
blade on ice s about 0.03 .
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energy of the body:
all activities of the body include energy changes .
the energy converted to work e.g. climbing a hill ,
lifting a weight ….
The potential energy can be change to a kinetic
energy .
At based rest condition ,the energy conserved by
the body in nearly follows:
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2770 used by liver and spleen
25% used by skeletal muscle and the heart .
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19% used by brain .
10% used by kidney .
19% digestive system , heat loosen … etc.
The body uses food …………..
The food n changed to molecules by the
digestive system to combine with oxygen to
produce the energy .
There are continuous changes in the energy
of the body when it is doing work or not .
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The conservation of energy in the body can be
given by the first law of thermodynamics:
ΔU=ΔQ-ΔW…..(1) where
ΔU=change in stored energy (-ve or +ve)
ΔQ=heat loose or gained
ΔW=work done by the body
When the change of ΔU,ΔQ and ΔW in a short
interval of time Δt,thus the
Rate of change of ΔU,ΔQ and ΔW is given by:
is the mechanical power .
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The unit of these are :_
Food energy : kcal or cal
Energy: joul/sec or watt or erg
Energy (English unit) : foot – pound .
Energy change in the body :
Food is oxidized by the cells of the body after
the food digested to molecules of glucose the
oxidation of one mole .
C6H12O6+6O2→6H20+6CO2+686 kcal
This means that:
One mole of glucose (180gm) + 6 moles of O2
(192gm) → 6 moles of H2O (108gm) + 6
moles of CO2 (264gm) + 686 kcal of heat .
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Note thate one mole of a gas at normal
conditions (normal temperature and normal
pressure) has a volume of 22.4 liters .
Q1/ calculate the energy released per 1 gm of
fuel and 1 lit of O2 used ?
Q2/ calculate the volume in liters of each O2
and CO2 used per/gm of fuel ?
The basal metabolic rate BMR is the lowest
rate of energy can consumption needed to
perform minimal body function under resting
condition when the body
The typical person consumes energy when
completely at rest at a rate of about 92
kcal/hr or 107 w which is called 1 met .
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BMR is affected by the thyroid activity, it is
higher for the persons having over active thyroid
.
The chemical activity of the body is increasing or
decreasing rapidly with the increase or decrease
of the body temperature e.g. increase of body
temperature will result in the increase of the
chemical activity by 10% , and 2C˚ increase
cause increasing of chemical activity by 20% .
3C˚ increase in the temperature causes 30%
increase of 30% of the chemical activity . the
decrease in the body temperature with result in
decreasing the chemical activity of the body in
the same rates an above . internal body
temperature change in body
C˚
Temperature %
38
10% more
39
20% more
40
30% more
36
10% less
35
20% less
34
30% less
Note that the increase in food more than the consumption of
energy will result in increasing of the weight and vice visa .
hence to keep your weight steady you have to get food
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The conserved energy is converted to
external work and life preserving functions.
The external work is given by :
ΔW=FΔX …..(3)
Where :
F= the force moved a distance
ΔX and in its direction the power is the rate of
doing work :
Where v= velocity =
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The external work is done when person is
climbing a hill or walking up stairs which is
equal weight of the body x vertical distance h
I.e. ΔW=mgh…. (5)
Energy of 4.8 to 5 kcal is produced by
consuming each liter of O2 .
The efficiency of the body is given by :
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The body is consider a good efficient
machine its efficiency can be up to about 20%
is cycling and heavy exercises ..with external
power production of 370w (0.5) and
metabolic rate of 1850w
If you are riding a bicycle on level ground
with constant speed there is no change in
kinetic or potential energy and the power
supplied is used to overcome friction and
wind resistance long term power is
proportional to the maximum rate of O2
consumption in the working muscles for a
healthy man this consumption = 50
ml/(kg.min).
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Pressure is defined as the force per unit area
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For solid the force per unit area = stress the
pressure for liquid column:
p=ρgh……..(2)
where ρ= density of liquid , g= gravity
acceleration and h= high of liquid .
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measurement of pressure in the body :
part of the body
instrument
normal pressure (mmHg)
pressure
Blood systole: 100-140 sphygmomanometer
Skull diastole : 60-90 (mercury colomn )
aneroidsealed container with needle or
digital.