BIOSIGNALS

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Assoc. prof. Helena Baráni, Ing. PhD.
Institute of Medical Biophysics
MARTIN
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BIOCYBERNETICS
1. Theory of information - signal
? information carrier - living organism ?
biological system - information ?
connected by some physical quantity
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Cybernetics has close connections to biology and
medicine
Biocybernetics is the application of cybernetics
to the biological science.
Biocybernetics plays a major role in systems
biology, seeking to integrate different levels of
information to understand how biological systems
function.
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THEORY OF INFORMATION
SIGNAL as an INFORMATION CARRIER
All of the systems in an organism are
interconnected.
Example The circulatory system is connected to
all of body's cells so that it can transport
oxygen efficiently.
The circulatory, respiratory and muscular
systems The function of circulatory system is
to service the needs of body tissues - to
transport oxygen and nutrients to the cells - to
transport carbon dioxine and waste products away
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That interaction helps the organism interacts
with the environment.
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INTERACTION
The organism continually interacts with the
surroundings and with other systems.
In one direction of this interaction the organism
perceives signals arriving from the external
world and processes the information content of
these signals.
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BIOLOGICAL SIGNALS
Definition A quantity of matter, resp. change
of quantity, carrying or storing information is
called a signal.
- Information is associated with a signal. -
Information is always carried by some physical
quantity, usually it is signal.
The signal, or information, may refer to the
state of the system, to some process, etc.
parameter of status - e.g. body temperature.
- the signal
associated with this is continuous, and its
magnitude is approximately constant
- the blood sugar
concentration is an important indicator of the
metabolism
periodic processes - the ECG signal
associated with the heart function.
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Biological signals
are all signals that are produced by organs
within a body.
Biological systems - open dynamical systems,
which are enable to generate, receive, process
and emit informations Input informations
reflect to the health conditions

• Biological signals are generated in life organism
  
• - created by vital manifestation of organism or
  by stimulus from
• external space, which may affect vital
  manifestation
• - velocity changes are characterized by large
  variability

• Mediated biological signals
• - originate by interaction of organism i.a.
  with rtg radiation,
• ultraviolet wave or with the magnetic
  field.
• ? diagnostic application

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Biological signals are a manifestation of
activities of very complex biological systems,
representing real living object. These signals
are generated directly by this object.
Biological signals are caused by mechanical,
chemical or electrical activities.
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BIOLOGICAL SIGNALS
- NON-ELECTRICAL SIGNALS have to be transformed
into electrical signals - e.g. blood
pressure, respiratory pressures, volumes, flows,
body temperature
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BIOLOGICAL SIGNALS
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Low impedance electrode
1. ELECTRODES - metals, glass - filled with salt
solutions
Macroelectrodes - for a skin recording of ECG,
EEG. The electrodes have to be moistured before
using by a jell or salt solution in order to
decrease the input resistance, and then firmly
attached to the body. For ENG or EMG recording
we can use a variety of metal electrodes with
different shape and size
(plate electrodes, needle electrodes etc.)
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BIOLOGICAL SIGNALS
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BIOLOGICAL SIGNALS
Recordings
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BIOLOGICAL SIGNALS
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BIOLOGICAL SIGNALS
Signal Name Amplitude (mV) Frequency range (Hz)
ECG Electrocardiogram 0.5 - 5.0 0.01 - 250
EEG Electroencefalogram 0.01 - 50.0 0.1 - 100
EMG Electromyogram (surface electrode) 0.1 - 10.0 0.01 - 10000
EMG Electromyogram (needle electrode) 0.05 - 5 0.01 - 10000
ENG Electroneurogram 0.05 10.0 0.01 - 1000
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BIOLOGICAL SIGNALS
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BIOLOGICAL SIGNALS - EVALUATION
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BIOLOGICAL SIGNALS can be processed and analyzed
by computer analysis with large number of
methods

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Information transmission
Technical communication or information -
transmitting systems include
the telegraph, radio and
television while
biological examples are the processes of seeing,
hearing, etc.
Transmitter
Receiver
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Information transmission

• For transmitting of correct signal we have to
  use coded signal.
• The assignment of an unequivocal signal series
  to the information is called coding.

Examples of code Morse code, Brialle script
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PRIMARY SENSORY CODING   The sensory pathways
provide information on stimulus type, intensity,
and location.
This information has to be coded in the language
of action potentials conveyed over the nerve
pathways.
Action potentials are coded by frequency not by
amplitude.
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HEARING - communication system
Information source
Transmitter
Receiver
user
channel
user
noise
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Biophysics of hearing
Recording of an action potential of a single
auditory nerve fibre
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CONTROL
Biological systems are coordinated and controlled.
The concept of control includes two types of
processes
simple control control without feedback
regulation control with feedback
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CONTROL
The two basic functional elements of a control
system (without feedback) are
the
controlling unit (control centre)
the
controlled unit
Each type of control is based on the transmission
of information.
interference
base
output
INFORMATION TRANSMISSION
signal
signal
signal
In the control without feedback no information
reaches the controlling unit (centre) from the
controlled unit. Output signal does not react
upon the control centre.
Examples the adaptation of living bodies to
their environment - the
sensation ? e.g. perception of the warmth
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REGULATION
Biological systems contain many types of
regulatory circuits, with negative and positive
feedbacks.
In biological systems most parameters must stay
under control within a narrow range around a
certain optimal level under certain environmental
conditions.
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REGULATORY CIRCUITS
Regulation should be understood as an action
which minimalize difference between real
regulated values of quantities and their desired
values
Output signal
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NEGATIVE FEEDBACK
Negative feedback is a process that happens when
the systems need
to slow down
or completely stop a physiological process.
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POSITIVE FEEDBACK Positive feedback is the
opposite of negative feedback in that
encourages a physiological
process or
amplifies the action of a system.

• Example
• most positive feedbacks provide for fast
  autoexcitation of elements of endocrine and
  nervous systems (in particular, in stress
  responses conditions)
• and play a key role in regulation of growth, and
• 
  development of organs.

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CONTROL OF THE HART RATE EXAMPLE
1. The impulses generated by the cells of the SA
node are carried across the right atrium, to the
left atrium and to the AV node.
2. The electrical signal follows through the Hiss
and Purkinje systems.
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REGULATION of HEART RATE
The control of heart rate is mediated by the
autonomic nervous system.
The cardiac response to peripheral chemoreceptor
(PCh) stimulation is result of primary and
secondary reflex mechanisms.
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Normal Regulation of Blood Glucose

• When the blood sugar level rises, the islets of
  Langerhans in the pancreas release insulin into
  the blood.

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Thanks for attention