Transcript Chapter 10 Body Temperature, Heat, Fat, and Movement

Chapter 10
Body Temperature, Heat, Fat, and
Movement
Control center
Actuators
Anterior
hypothalamus
set-point
Sweating
Skin vasodilation
Decrease metabolism
Posterior
hypothalmus
Muscle shivering
Skin vasoconstriction
Increase metabolism
–
Core
temperature
Skin
temperature
+
Skin thermal
receptors
Hypothalamic thermal
receptors
Figure 10.1 The human temperature regulation system can increase or decrease
body temperature.
  1 1 
RT  R0 exp     
  T T0 
Figure 10.2 Examples of resistance–temperature curve for three NTC thermistors,
 = 3000 , 3500 K, and 4000 K. R0 is the resistance at T0 = 298 K.
Voltmeter
Copper
Copper
Constantan
Cold junction, T2
(Reference)
T1 , Hot junction
(Measuring probe)
C1 and C2 are constants that depend on the thermocouple pair with T in kelvins
Figure 10.3 The J type thermocouple is formed from copper and constantan.
Digital
display
Signal conditioner
and final temperature
detector
(processor)
Probe
(thermistors)
Wheatstone
bridge
Audible
alarm
Figure 10.4 An electronic thermometer uses a thermistor sensor probe.
Shutter
Ear
IR
Ambient sensor
Micro
processor
Ta
Tb
MUX
A/D
Amp.
Sensor
Waveguide
Window
Net flux of infrared radiation:
Shutter
switch
Digital
display
A = effective body (target) area
 = Stefan-Boltzmann constant
a = emissivity of surroundings (sensor)
Tb = body temperature
Ta = sensor temperature
Figure 10.5 The infrared thermometer opens a shutter to expose the sensor to
radiation from the ear.
Insulation layer
Constantan
Metal wall
Cooling tubes
Copper
Thermocouple
connection
Figure 10.6 In a gradient layer calorimeter, thermocouples measure the difference in
temperature across the wall. Ventilating system and measurements not shown.
heat loss
air mass flow rate
specific heat
temperature change
of the ventilating air
Figure 10.7 An air–flow calorimeter measures inlet and outlet temperatures,
flows, and humidity.
Figure 10.8 The water flow calorimeter measures the inlet and outlet water
temperature.
Thermostat
Feedback control
AC
Power
source
Power
meter
Heater
Figure 10.9 The compensating heater calorimeter requires less heater power when
the subject supplies heat.
Figure 10.10 A microcomputer-based open-circuit system includes a mixing
chamber, O2 and CO2 analyzers, and the various variables (pressure, flow,
temperature) used to calculate
.
From inspired gas source
Metabolic
monitor
Inspiratory
limb
Humidifier
FIO2
Patient
CO2 and O2
analyzers
FECO2,
FEO2
Expiratory limb
F*CO2
Constant
flow
generator
Exhalation
valve
Mechanical
ventilator
Room air
Figure 10.11 A dilution system used by Deltatrac uses mechanical ventilation. FIO2 is the
inspired oxygen concentration, FECO2 is the true expired carbon dioxide concentration,
FEO2 is the expired oxygen concentration, and F*CO2 is the diluted carbon dioxide
concentration.
From ventilator
Bellows
Spirometer
Patient
CO2
Scrubber As oxygen
supply and
analyzer
Mixing
chamber
Sample
gas
CO2 analyzer
Figure 10.12 A closed-circuit system uses the volumetric loss principle. The
spirometer is used as an oxygen supply and the volume change as a function of
time in the spirometer is used to calculate the rate of oxygen consumption.
2H O deuterium water
2
H218O oxygen-18
enriched water
2H
2H
18O
labeled water
and bicarbonate
pools
labeled water
pool
disappearance (k2) =
rH2O
18O
disappearance
(k18) = rH2O + rCO2
k18 – k2 = rCO2
Figure 10.13 Principle of the doubly labeled water method. r is the production
rate, W is the size of total body water, k represents rate constants determined from
the experiment.
Shoulder
Triceps
skinfold
Lange
caliper
(a)
(b)
Figure 10.14 (a) Lange skinfold caliper used for assessing thickness of
subcutaneous fat. (b) Illustration of an example of skinfold measurement, triceps
skinfold taken on the midline posterior surface of the arm over the triceps muscle.
Excitation ac current source (I)
Detected voltage drop (E)
Figure 10.15 In resistance measurement on the ipsilateral side of the body current
flows through one arm, the trunk, and one leg.
Plastic ribbons
Connecting rods
Parallelogram
linkage
Knee joint
Vi
Vout = k 
Triaxial
goniometer
(a)
(b)
Figure 10.16 (a) A goniometer attached to the shank and thigh to measure knee
rotation. Vi is the input voltage. Vout is the output voltage that is proportional to the
angle of knee rotation. (b) Subject wearing a triaxial goniometer on knee joint.
Strain
E
a
V
Seismic
mass
Cantilever
Figure 10.17 Vertical acceleration of the accelerometer frame bends the cantilever
beam because the seismic mass remains at rest. Voltage output (V) is proportional
to the acceleration (a). E is the supply voltage.
Camera 4
Camera 1
Markers
EMG
transmitter
(option)
Force
platforms
(option)
Camera
control
and
Interface
Walk way
Computer
Display
system
Analog interface
Camera 3
Camera 2
A/D
converter
EMG
receiver
Figure 10.18 An example of a gait analysis setup includes a four-camera
kinematic system, two force platforms, and an electromyogram (EMG) telemetry
system.