Exam practise Flashcards
1
Q
the study of control and
connections in nature, science, and
society is…..
A
Cybernetics
2
Q
Basic concepts:
Organization (systems theory)
Information (information theory)
Control (control theory) relate to….
A
Cybernetics
3
Q
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 relates to
A
systems theory
4
Q
Formation of systems is….
A
Organisation
5
Q
• interacting structures and processes combined
for the execution of a common function
• which function is different from functions of
the separate components relates to….
A
Cybernetics
6
Q
Which systems have the following properties:
• Interact with the environment and with other
systems — connections
• Have hierarchical structure:
consist of subsystems
are subsystems of other systems
• Preserve their general structure in changing
environmental conditions
A
Cybernetic systems
7
Q
Which systems can be characterized using these three types of
functions describing the changes of system:
• component states
• structure and connections
• transmitted signals
A
Cybernetic systems
8
Q
components interact in a predetermined way
and response is predictable
A
Deterministic systems- example machine
9
Q
response can not be predicted exactly
A
Probabilistic systems- example weahter
10
Q
- the components interact with each other only
* no interactions with the environment
A
Closed systems
11
Q
the components interact with the
environment as well
A
Open systems
12
Q
What can be used for Perception of signals from other systems using
sensors?
A
Receptors(eyes, ears, ect)
13
Q
What is used for Transmission of signals to other systems?
A
Effectors(organs of speech, gestures ect)
14
Q
Which cybernetic systems have the following properties:
• varying complexity
• probabilistic
• multi-level hierarchical organization
A
Biological cybernetic systems
15
Q
Complexity of biological systems
A
very complex
16
Q
Determinism of biological systems
A
Probabilistic
17
Q
Biological systems organisation
A
Complex two way hierarchy
18
Q
- Each component can
be regarded as a system of lower-level components
• The low level components perform independently
of the higher level components as long as they are able to process all the important input information
• The high level components control the lower level
components
A
Complex two way hierarchy
19
Q
• Any set of related data
• Any meaningful event, which results in an
action
• The state of a system of interest
A
information
20
Q
…….. reduces ambiguity, removes the
lack of knowledge
A
Information
21
Q
The transmitted information
A
Message
22
Q
The physical carrier of the message
A
Signal
23
Q
The medium in
which the signal propagates
A
communication channel
24
Q
a set of simple signals which can be
used to send any message
A
Alphabet
25
generation (using
an alphabet) of a signal which carries the
message
Encoding
26
altering the alphabet
Recoding
27
extraction of the
| message from the signal
Decoding
28
physically different signals
| which carry the same message
lsomorphic signals
29
communication system disturbances
| which modify the signal
Noise
30
The ability of a system to store and
retain information, and to recall it for use at a
later moment
Memory
31
Ways to memorise information
• by changing the states of system components
• by changing the structure of the system (the
connections between its components)
32
Unit of measurement for information is...
The bit
33
DNA contains .....bases. Any
nucleotide contains only one base. Therefore, the information carried by one nucleotide is 2
bits.
4 bases
2 bits
34
The chromosomal DNA of one human sperm contains ..... nucleotides, i.e. information of 2.109 bits.
10^9 nucleotides
2.10^9
35
actions effecting a system and aimed at reaching a specific goal
Control
36
control for maintaining a specific state or process
regulation
37
is self contained in its performance monitoring and
| correction capabilities
Cybernetic Control System
38
the set of rules (algorithm) used to
| control a system
Program
39
the law describing how the controlled system must behave
Reference
40
processes information, generates and sends control messages (commands)
Controlling subsystem
41
changes according to
| the messages received
Controlled subsystem
42
communication subsystems
| transferring information between the controlling and controlled subsystems
Connections
43
• The execution of the control messages is not monitored
• Used if noise is missing and the properties of the
controlled system do not
change
Open loop control
44
Forward-coupling connection
—transmits control messages from the controlling to the
controlled subsystem
Open loop control
45
The execution of the control
messages is monitored
• Used if noise is present and/or the properties of the controlled system change
Closed Loop control
46
Back-coupling connection
(feedback)—transmits data
messages from the controlled to
the controlling subsystem
Closed loop control
47
Transform the stimulus into excitation
receptors
48
Back-coupling (feedback) channel
Afferent (sensory) neurons
49
Controlling subsystem (issues commands)
Neural centre
50
Forward-coupling channel
Efferent (motor) neurons
51
Respond to the commands
Effectors
52
the control results in increased divergence of the
| controlled subsystem
Positive feedback (self-reinforcing loop)
53
the difference between the
| current and preceding states of a system
Divergence
54
The controlled process accelerates until the
limiting constraints of the controlled subsystem
are reached.
Positive feedback (self-reinforcing loop)
55
—amplify vital processes
—provide adaptation - fast response to external factors and transition from the initial state to another, more appropriate state
Positive feedback loops
56
aggravate morbid conditions
Positive feedback loops
57
the control results in
| balancing of the controlled subsystem
```
Negative feedback (self-correcting loop or
balancing loop)
```
58
minimizing the difference between the controlled parameter and the reference
(setpoint)
Balancing
59
Ensures the quality and reliability of the control system
Negative feedback
60
* stability of body functions
* constant values of vital parameters
* resistance to external factors
Negative feedback loops
61
Basic mechanism of:
• Homeostasis (the stable condition inside the body)
• the balance of energy and metabolites in the body
• the control of the populations of species etc.
Negative feedback loops
62
— area between the curves of the reference
| and actual values of the controlled parameter
Control area
63
a simplified physical or mathematical representation of a system used for its
investigation
Model
64
methods for investigation of systems using their models
Modelling
65
```
•Mathematical description of
some aspects of the real system.
• Uses mathematics and
computers to produce
information about the studied
system.
```
Mathematical model
66
Material object performing
| similarly to the real system
Physical model
67
• physically separate the cell from the environment
• divide the cell into many smaller compartments
with diverse functions
Barrier functions of bio-membranes
68
• ensure high speed and efficiency due to their
large total area
• ensure the vectoral (directed) flow of complex
biological processes
Metabolic functions of bio-membranes
69
Each membrane has two surfaces - inner and
| outer
Asymmetrical membranes
70
the surfaces have
| different composition, structure and functions
Asymmetrical membranes
71
....... are:
•general (e.g. cytosolic)
• specialized (e.g. myelinated)
Natural biomembranes
72
........... molecule is placed into water and it takes up space between the
water molecules restricting their ability to hydrogen bond with each other
Hydrophobic/ non polar
73
Enthalpy needed to break some of the hydrogen
| bonds between the water molecules
Hydrophobic/non polar interactions
74
In hydrophobic reactions the presence of a nonpolar (hydrophobic) molecules ......... the entropy of the water
decrease
75
easily hydrogen bond with water
Hydrophilic interactions
76
Release of water from surface increases its entropy
Hydrophilic interactions
77
are both hydrophobic and
| hydrophilic
Amphiphilic molecules
78
water mobile phase freely exchangeable with
| water inside or outside of the cell
free
79
Water - mobile phase surrounded by lipids,
which is slowly exchanged with water inside or
outside of the tell
captured
80
immobile water molecules
| surrounding the polar parts of lipids and proteins due to solvation
Bounded
81
At physiological temperatures the lipids are in a ......... state
mesomorphous (liquid crystalline)
82
* ordered structure of the membrane
| * sufficient fluidity of the membrane is ensured by.......
mesomorphous (liquid crystalline)
83
........ proteins are positioned on the surface of the lipid bilayer (surface proteins) or are partially submerged in the bilayer
Peripheral
84
......... proteins - span the entire bilayer
Integral
85
attached to proteins and lipids on the extracellular surface
Carbohydrates
86
Half life of proteins
2-140 hours
87
Half life of Lipids
14 to 80 hours
88
Formed on a water-air boundary by a single layer of lipids
Flat monolayer membranes
89
Used to investigate:
• the changes of the states of the lipids at different
temperatures,
• the area occupied by a single lipid molecule in
different states,
• the effect of medicinal substances on the lipid
bilayer
Flat monolayer membranes
90
Both surfaces of the membrane are in contact with water
Flat bilayer membranes
91
Used to study:
• the electrical resistance of membranes,
• the generation of surface electric charge on
membranes,
• the mechanism of action of antibiotics, etc.
Flat bilayer membranes
92
Water dispersions of lipids- micelles and liposomes
Spherical membranes
93
monolayer spherical membranes (the hydrophobic fatty chains of the lipids are oriented towards the centre)
Micelles
94
spherical membranes consisting of one or more lipid bilayers
Liposomes
95
• investigation's of the structure of lipid bilayers
• investigation's of the permeability of
membranes to various substances
• Delivery of drugs directly into cells
Applications of liposomes
96
........depend on
| the proteins-to-lipids mass ratio which varies from 1:4 to 4:1
Mechanical properties of membranes
97
Thickness of bio-membranes can be measured by:
X-ray scattering: 11 nm
| electron microscope: 7 nm
98
the ability of the membrane to support mechanical stress when stretched or bent
Elasticity
99
Membrane viscosity n can be measured using
Stokes-Einstein equation
100
The diffusion constant D depends on the
microscopic structure of the membrane
101
Biomembnanes are: permeable to .....
water and neutral lipophilic substances
102
Biomembnanes are:
| poorly permeable to .....
polar (hydrophilic)
| substances
103
Biomembnanes are: practically impermeable to......
charged molecules
| and small ions
104
Membrane permeability depends on....
the relative concentrations of the various types of lipids
105
- carry one positive and one negative charge on
| different atoms but no net charge
zwitterions (hybrid ions)
106
phosphatidylserine
one negative charge
107
cardiolipin
two negative charges
108
ln a membrane lipids are arranged to ......... the potential energy of the interactions between them and the surrounding water molecules:
minimize
109
* lipids are fluid and anisotropic
| * stable in a limited temperature range
Mesomotphous (liquid crystalline) state
110
Lipids are
thermotropic mesomorphs
111
The characteristic temperature at which lipids
melt from solid (gel) to mesomorphous (liquid
crystalline) state
Phase transition temperature
112
Phase transition temperature depends on the ....... and the number
of .......... in them
length of the fatty chains
double bonds
113
Tp = +44 degrees C to + 86 Degrees C for
saturated chains
114
Tp = -49 degrees C to + 13 degrees C for
unsaturated chains
115
• Shift in the ratio between the gel, and mesomorphous states which leads to changes of all mechanical properties of the membrane
• Changes of mechanical properties of the
membrane are associated with...
Changing the temperature or the degree of unsaturation
116
Longer hydrocarbon tails ...........dispersion
forces making it more difficult to melt the
bilayer
increase
117
Unsaturated lipids and lipids with shorter tails
| have ......... melting temperatures
lower
118
In general, anything that weakens dispersion
forces will ......... the melting temperature,
......... fluidity, and ........ permeability
reduce
increase
increase
119
A measure of transport is the
flux density
120
- the amount (of substance)
that moves through a unit area normal to the
direction of motion x during a unit time interval
Flux density
121
An Exergonic (spontaneous) process is...
Passive transport
122
Passive transport
reduces the free energy of the system
123
```
The gradients move substances from
high to low:
—concentration
—potential
—pressure
```
Passive transport
124
the net transport of solute
molecules through random motion in the bulk of a
solution
Simple diffusion
125
Describes the variations of the concentration of the diffusing substance in time and space
Fick's Second Law
126
Concentration falls with the square of distance diffused
Fick's Second Law
127
Diffusion time 𝛕 increases with the square
| of distance:
Fick's Second Law
128
passive transport
| facilitated by a transport protein (transporter, carrier)
Facilitated diffusion
129
the protein transports only one substance or a group of similar substances
Specific
130
The diffusion of the solvent (water) across a membrane
| separating areas with different concentrations of the solute
Osmosis
131
The driving force of osmosis is the
osmotic pressure
132
.......solutions have equal osmotic pressures
Isotonic
133
......... solutions have higher osmotic pressure
hypertonic
134
......... solutions have lower osmotic pressure
Hypotonic
135
Passive transport of the solvent across a
membrane due to hydrostatic pressure
gradient
Filtration
136
The solvent flux for filtration depends on
the .......... of the solvent and can be
calculated by ........
viscosity
Poiseuille's law
137
Usually ........ and ........are most important for the transport of water across
cell membranes
osmosis
electroosmosis
138
Dominating type of water transport:
| ........ at the arterial end -water leaves the capillaries
Filtration
139
Dominating type of water transport:
......... at the venous end - water enters
into the capillaries
Osmosis
140
sum of the
| chemical, concentration, and electric potentials:
Electrochemical potential
141
• Facilitated diffusion
• Diffusion through pores and channels in the
membrane
• Simple non-mediated diffusion through the
lipid bilayer
Mechanisms
| Of The Passive Transport Of Ions
142
– small hydrophobic molecules (carriers) which shield the charge of the ion
and facilitate its diffusion through the membrane
Ionophores
143
Carrier operation is temperature dependent in
Ionophores
144
Pore-forming amphiphilic antibiotic
Gramicidin
145
—Two gramicidin molecules located head to-head in the lipid bilayer form a ......... pore
• The pore lets through up to 108 cations per
second – much faster transport than by a
........ molecule
cationic
carrier
146
Gramicidin selectivity
low
147
Mechanically-gated channels are membrane
| ......... capable of responding to ........ over a wide dynamic range of external mechanical stimuli
proteins
mechanical
stress
148
– substances which selectively
| block ion channels
Inhibitors
149
Bind to centres inside the channel and
| stop the flow of ions
Inhibitors
150
Determines the passive flux density of an ion species through a membrane
The Electrodiffusion Model
151
The input ion flux density Ji depends only on the ion concentration in the.....
extracellular liquid
152
The output ion flux density Je depends only on
the ion concentration ci
in the ........
intracellular liquid
153
The diffusion rate for cations through the
membrane of a nerve cell is about ....... times higher than the
diffusion rate of .......
10
anions
154
.........is a transient
| phenomenon – it gradually decays to zero because the concentrations on both sides becomes equal
Diffusion potential
155
........ is valid for thick membranes and not for the thin lipid bio-membranes
Henderson's equation
156
In cells:
........... ions are close to equilibrium – the
Nernst equation can be used to calculate the
potential drop on the membrane
Potassium
157
In cells: ........ ions are far from equilibrium
Sodium
158
The cytoplasm has a .......... electric potential relative to the extracellular fluid
negative
159
Sodium ion concentration in the cell is .....
much less than outside of the cell
160
Potassium ion concentration in the cell is .........
much higher than outside of the cell
161
Chlorine ion concentration in the cell is ,,,,,,,,
less than outside of the cell
162
......... move ions from low
| to high electrochemical potential
Active transport systems
163
The sodium potassium ion pump works in the presence of .......... and
..........
Mg2+
ATP
164
The hydrolysis of one adenosine triphosphate
(ATP) molecule provides energy for the active
transport of:
-three sodium ions out of the cell, and
| —two potassium ions into the cell
165
• Exchange of ions with unequal charges
• Modifies the transmembrane potential
Example: three Na+ exchanged for two K+
Electrogenic Ion transport
166
```
• Exchange of ions with equal charges
• Does not modify the transmembrane
potential
• Maintains concentration gradients
• Example: one Na+ exchanged for one K+
```
Nonelectrogenic Ion Transport
167
For different types of cells the resting potential varies from ........
–50 mV to –100 mV
168
The strongest contribution to the resting potential is from the ion with the ......... membrane permeability
highest
169
The flux of potassium ions across the
membrane increases the absolute value of
the resting potential or .......
(makes it more negative)
170
The flux of sodium ions across the membrane
decreases the absolute value of the resting
potential or ..........
(makes it less negative)
171
The concentrations of ions in the extracellular
| fluid are .........for all human tissues
the same
172
The concentrations of ions in the intracellular
| fluid are ........ in all human cells
almost the same
173
The resting potential of various types of cells
is .......... because their membranes have
different permeabilities
different
174
The rapid change in electrical potential that
occurs between the inside and outside of a
cell when it is stimulated by a sufficiently strong stimulus
Action potential
175
The action potential is generated when the
| membrane potential ........ a threshold
rises above
176
– a new action
potential can not be generated, whatever the
strength of the stimulus (lasts 2…5 ms in nerve
fibres)
Absolute refractory period
177
a new action
potential can be generated but the threshold is
higher than usual
Relative refractory period
178
The sodium-potassium ion pump has ......... effect
on the depolarisation and repolarisation
phases
no
179
The function of the sodium-potassium ion
pump is to ........... the concentration
gradients of the sodium and potassium ions
replenish
180
The action potentials generated by different
| cells are .........
almost identical
181
The impulses propagating down nerve fibres
| have......... shapes and peak values
identical
182
A ....... stimulus initiates the next impulse
earlier during the relative refractory period
than a .......... stimulus
strong
weak
183
The strength of the stimulus is coded by the
| .......... of the impulses
repetition frequency
184
The burst length carries information about the
| ...........
duration of the stimulation
185
* the external surface is charged negatively
| * the internal surface is charged positively
Excited section of membrane
186
currents on the surfaces of the membrane between the excited and non-excited sections
Local currents
187
Direction of The Local Currents On the external surface of the membrane –
from the unexcited towards the excited section
188
Direction of The Local Currents on the internal surface of the membrane
from the excited towards the unexcited
| section
189
•the membrane potential decreases (becomes
less negative)
• reaches the threshold value
• an action potential is generated
In the vicinity of the excited section
190
At the initial excited section
—Repolarisation takes place
191
Describes the variations of the membrane
| potential over time and along the nerve fibre
The cable equation
192
The membrane potential .......... exponentially away from the point of excitation
decreases
193
The decay rate is determined by the .........
| and ........... resistances
membrane
cytoplasm
194
............grows with increasing the :
—diameter of the nerve fibre D:
—membrane thickness d:
—membrane resistivity 𝛒m
The Length Constant
195
......... diminishes with increasing the
| —cytoplasm resistivity 𝛒i
The Length Constant
196
The action potential impulses propagate without
| decay along the membrane
Non decremental Conduction
197
A substance composed of:
—lipids (about 80%);
—proteins (about 20%);
—cholesterol.
Myelin
198
Depolarisation takes place only at the nodes
| of Ranvier
Depolarisation
| Of Myelinated Fibres
199
• The excitation jumps from node to node –
| ..........
saltatory conduction of the impulse
200
Advantages
| Of Saltatory Conduction
* High conduction speed of the impulses
| * More efficient conduction
201
—the resistivity of the surrounding fluid
increases
—the diameters of the nerve fibres increase
The interactions become stronger
202
The surface of the membrane builds up electric
| charge due to.......
- dissociation
| - adsorption
203
Adsorption is very ,,,,,,, because of the
| hydration of the protein molecules
weak
204
In Acidic Solutions:
........... groups dissociate from the
protein molecule
• Protein ........... are obtained:
Basic OH-
cations
205
In Proteins In Basic Solutions
• .......... dissociates from the protein
molecule
• Protein ,,,,,,,,,, are obtained :
Acidic H+
anions
206
• The ions which:
—remain on the cell surface on dissociation
—are attached to the cell surface by
adsorption
Potential Determining Ions
207
```
The ions which:
• dissolve in the liquid phase on
dissociation
• remain in the liquid phase on
adsorption
```
Counterions
208
The ions of the Stern layer are attached to the surface by ............
adsorption forces
209
The ions of the diffuse layer are attracted by ........
Coulomb (electrostatic)
| forces
210
counterions are
| attracted towards the surface
Electrostatic forces
211
counterions diffuse
| away from the surface (from high to low concentration)
Thermal motion
212
The electrical potential
......... exponentially
away from the surface
decays
213
the motion of the dispersed
| phase relative to the fluid caused by an external electric field
Electrophoresis
214
The fluid pH value at
which the electrophoretic
mobility of the suspended
particles vanishes
Isoelectric point
215
Electrophoretic method for separation of proteins with only slightly differing
electrophoretic mobilities:
Immunoelectrophoresis
