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Biophysics > 1 - Basics Of Cybernetics > Flashcards

1 - Basics Of Cybernetics Flashcards

1
Q

The object of cybernetics

A 
Cybernetics = the study of control and connections in nature, science and society 
Basic concepts:
- organization
- information
- control
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2
Q

Cybernetic Systems

Organization - definition

A 
System theory = the study of systems in general, with the goal of elucidating principles that can be applied to:
- all types of systems
- at all nesting levels
- in all fields of research
Organization = formation of systems
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3
Q

Cybernetic systems

Cybernetic system - definition

A

Cybernetic system = interacting structures and processes combined for the execution of a common function. Which function is diff from functions of the separate components
General properties of cybernetic systems:
- interact with environment and with other systems - connections
- have hierarchical structure - consists of subsystems
- preserve their general structure in changing environmental conditions

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4
Q

Cybernetic systems

Types of systems by complexity

A

3 types:

  • component states
  • structure and connections
  • transmitted signals
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5
Q

Cybernetic systems

Types of systems by the degree of determinism of their response

A
  1. Deterministic = components act in a predetermined way and response is predictable e.g. machine
  2. Probabilistic = response can not be exactly predicted e.g. weather
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6
Q

Cybernetic systems

Type of systems by the type of interaction with the environment

A
  1. Closed = the components interact with each other only and no interactions with the environment
  2. Open = the components interact with the environment as well
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7
Q

Cybernetic systems

Elements of the interaction

A
  • perception of signals from other systems using sensors (receptors) e.g. eyes, ears etc
  • transmission of signals to other systems using effectors e.g. organs of speech, gestures etc
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8
Q

Cybernetic systems

Biological cybernetic systems - properties

A 
Characteristics:
- varying complexity
- probabilistic
- multi-level hierarchical organization 
Basic properties:
- self-organization 
- self-regulation
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9
Q

Cybernetic systems

Biological systems - complexity

A

Very complex:

  • large number of components
  • complex and interrelated connections between components
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10
Q

Cybernetic systems

Biological systems - determinism

A

Probabilistic:

  • large number of components
  • large number of connections between the components
  • strong external influences
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11
Q

Cybernetic systems

Biological systems - organization

A

Complex 2-way hierarchy

  • low level components = perform independently of the higher level components as long as they are able to process all the important input info
  • high level components = control the lower level components
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12
Q

Information theory

Information - definition

A
  • any set of related data
  • any meaningful event, which results in an action
  • the state of a system of interest
    Info reduces ambiguity and lack of knowledge
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13
Q

Information theory

Transmission of information - messages, signals and channels

A

Message = the transmitted info
Signal = the physical carrier of the message
Communication channel = the medium in which the signal propagates
E.g. sound wave (signal) - air (channel)

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14
Q

Information theory

Alphabet (code), encoding, recording, decoding

A

Alphabet = a set of simple signals which can be used to send any message
Encoding (by transmitter) = generation (using an alphabet) of a signal which carries the message
Recording = altering the alphabet
Decoding (by receiver) = extraction of the message from the signal

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15
Q

Information theory

Isomorphism and noise, signal-to-nose ratio

A

Isomorphic signals = physically diff signals which carry the same message
Noise = communication system disturbances which modify the signal

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16
Q

Information theory

Storing and retaining information

A

Memory = the ability of a system to store and retain info, and to recall it for use at a later moment
Ways to memorize info:
- change the states of system components
- change the structure of the system

17
Q

Information theory

Measuring information - the bit

A

Unit of measurement = the bit
One bit is the amount of info received when we learn which one of 2 equally likely events has occurred e.g. tossing a coin

18
Q

Control and regulation systems

Control and regulation - definitions

A 
Control = actions effecting a system and aimed at reaching a specific goal
Regulation = control for maintaining a specific state or process
19
Q

Control and regulation systems

Program and reference

A 
Program = the set of rules used to control a system
Reference = the law describing how the controlled system must behave
20
Q

Control and regulation systems

Control system - definition

A

Cybernetic control system = one that is self-contained in its performance monitoring and correction capabilities

21
Q

Control and regulation systems

Open-loop control

A
  • execution of the control messages is not monitored
  • used if noise is missing and the properties of the controlled system do not change
  • forward-coupling connection = transmits control messages from controlling -> controlled subsystem
22
Q

Control and regulation systems

Closed-loop control

A
  • execution of the control messages is monitored
  • used if noise is present and/or the properties of the controlled system change
  • back-coupling connection = transmits data messages from controlled -> controlling subsystem
23
Q

Control and regulation systems

Closed-loop control system in the body (reflex arc)

A
  • receptors: transform the stimulus into excitation
  • afferent (sensory) neurons: back-coupling channel
  • neural centre: controlling subsystem
  • efferent (motor) neurons: forward-coupling channel
  • effectors: respond to the commands
24
Q

Positive and negative feedback

Positive feedback

A

Positive feedback = the control results in increased divergence of the controlled system
Controlled process accelerates until the limiting constraints of the controlled subsystem are reached

25
Q

Positive and negative feedback

Significance of positive feedback loops

A 
Beneficial:
- amplify vital processes 
- provide adaptation (fast response to external factors)
Detrimental:
- aggravate morbid conditions
26
Q

Positive and negative feedback

Beneficial feedback - example

A

Products of food digestion:

  • stimulate secretion of gastric juice
  • more products of food digestion leads to increased secretion of gastric juice
  • more products of food digestion, etc (arrow to beginning)
27
Q

Positive and negative feedback

Detrimental positive feedback - example

A

Cardiac insufficiency reduces blood supply to the heart:

  • capacity of heart to pump blood is reduced
  • supply of blood to heart is further reduced
  • capacity of heart to pump blood is reduced even more, etc (arrow to beginning)
28
Q

Positive and negative feedback

Negative feedback

A

Negative feedback = the control results in balancing of the controlled subsystem
Ensures the quality and reliability of the control system

29
Q

Positive and negative feedback

Negative feedback regulation system

A
  • determine the error deltaX of the actual value X relative to the setpoint Xo
  • generate a control message such as to reduce deltaX
30
Q

Positive and negative feedback

Significance of negative feedback loops

A 
Ensure:
- stability of body functions 
- constant values of vital parameters
- resistance to external factors
Basic mechanism of:
- homeostasis 
- balance of energy and metabolites in the body
- control of the populations of species etc
31
Q

Positive and negative feedback

Negative feedback - example

A

Regulation of body core temp:

  1. Body temp exceeds setpoint
    - intensity heat loss from body (vasodilation swearing, flat lying skin hairs etc)
    - reduce heat production (restricted movements, less food consumption etc)
  2. Body temp below setpoint
    - reduce heat loss
    - intensify heat production (shivering, metabolic efficiency etc)
32
Q

Positive and negative feedback

Types of control and quality of the control system

A

Static control GRAPH
Dynamic control GRAPH
Quality of control : min control area

33
Q

Modelling

Models and modelling

A

Model = a simplified physical or mathematical representation of a system used for its investigation
Modelling = methods for investigation of systems using their models
Types of models: mathematical, physical, biological

34
Q

Modelling

Mathematical models

A
  • mathematical description of some aspects of the real system
  • uses mathematics and computers to produce info about the studied system
  • e.g. regulation of blood glucose conc
35
Q

Modelling

Physical models

A
  • material object performing similarly to the real system

- e.g. electrical circuit modeling transitional processes in a nerve fiber

36
Q

Modelling

Biological model

A
  • lab animal used to reproduce specific conditions of the human body
  • requires less simplifying assumptions than mathematical and physical models
  • e.g. investigation of infections, poisons, pharmaceuticals, etc

Biophysics (2 decks)

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