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Chapter 4

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Biophysics Quiz on Chapter 4, created by Y Y on 26/06/2019.
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Quiz by Y Y, updated more than 1 year ago
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Question 1

Question
Which of the following terms is NOT one of the known types of tissue-polarization due to application of an external electric current?
Answer
  • a) electronic polarization;
  • b) electrode polarization;
  • c) electret polarization.

Question 2

Question
How many different types of polarization in living tissue can be accounted for?
Answer
  • a) two;
  • b) nine;
  • c) six.

Question 3

Question
Which of the following tissue-polarization types has the longest time constant?
Answer
  • a) electrode polarization;
  • b) dipole polarization;
  • c) macrostructural polarization.

Question 4

Question
Which of the following types of polarization takes place 10-16 s after the application of external current through the tissue?
Answer
  • a) electronic;
  • b) ionic;
  • c) superficial.

Question 5

Question
Choose the correct relationship between the frequency of alternating current (AC) and the number of different types of polarizations that take place in the tissue:
Answer
  • a) higher frequency → higher number of polarizations;
  • b) lower frequency → higher number of polarizations;
  • c) lower frequency → lower number of polarizations.

Question 6

Question
What happens to the current passing through living tissue, when a constant DC voltage is applied across?
Answer
  • a) current increases continuously;
  • b) current decreases exponentially;
  • c) current remains constant.

Question 7

Question
What causes the decrease of the DC current passing through living tissue? c
Answer
  • a) generation of polarization potential, opposing the external voltage;
  • b) increase of the internal resistance of the tissue;
  • ) the leakage of charge out of the tissue.

Question 8

Question
What is the path of the electric current through the body of patient who is subjected to galvanization?
Answer
  • a) through the cytosol;
  • b) through the interstitial spaces;
  • c) through cellular membranes, via nexus junctions between cells.

Question 9

Question
What type of polarization occurs in the double electric layers surrounding cells, suspended in ionic solution, when constant electric field is applied?
Answer
  • a) surface polarization;
  • b) macrostructural polarization;
  • c) orientational polarization.

Question 10

Question
Which of the following types of polarization occur within the cell volume, due to the application of a constant electric field?
Answer
  • a) superficial polarization;
  • b) macrostructural polarization;
  • c) electrode polarization.

Question 11

Question
What type of impedance to the propagation of electric current is found in living tissues?
Answer
  • a) resistive and capacitive;
  • b) resistive and inductive;
  • c) capacitive and inductive.

Question 12

Question
What is the predominant type of electrical impedance in cellular fluids?
Answer
  • a) resistive, because cellular fluids are rich in electrolytes;
  • b) capacitive, because cellular fluids have sub-structures;
  • c) inductive, because there are inductive currents in the fluids.

Question 13

Question
What causes the capacitive properties of biological tissue?
Answer
  • a) extra- and intra-cellular fluids;
  • b) cellular and intra-cellular membranes;
  • c) the free movement of ions.

Question 14

Question
The neuromuscular junction (myoneural synapse) is:
Answer
  • a) a type of action potential;
  • b) the location where a neuronal excitation is transferred to a muscle;
  • c) the structure that opens voltage-gated Ca2+ channels.

Question 15

Question
In which of the following practices uses electro-muscular stimulation?
Answer
  • a) echography;
  • b) physical therapy;
  • c) electrophoresis.

Question 16

Question
When direct current (DC) is applied through biological tissue:
Answer
  • a) there is polarization of dissolved ions;
  • b) the conductivity of the cell increases due to temperature increase;
  • c) the current will decrease with time.

Question 17

Question
When pulsed current is applied through biological tissue:
Answer
  • a) there will be polarization of the ion channels;
  • b) the conductivity of the cell increases due heating;
  • c) the current decreases with time.

Question 18

Question
When very high frequency alternating current (AC) is applied through biological tissue:
Answer
  • a) there is a polarization of the ion channels;
  • b) there is a heating effect;
  • c) there is a decrease of the current due to accommodation.

Question 19

Question
Which of the following is related to dipole polarization?
Answer
  • a) the reorientation of mostly water molecules due an external field;
  • b) the conversion of the double electric layer into directional dipoles;
  • c) the formation of dipole moment due to the external field.

Question 20

Question
Dipole polarization:
Answer
  • a) is related mostly to water molecules;
  • b) involves the formation of a double electric layer;
  • c) decreases the intercellular communication.

Question 21

Question
Ionic polarization:
Answer
  • a) involves mostly water molecules;
  • b) relates to the formation of a double electric layer;
  • c) increases the electromotive force (EMF) generated in biological tissue.

Question 22

Question
165. Ionic and dipole polarizations:
Answer
  • a) occur predominately in bone tissue;
  • b) cause heating in soft tissue;
  • c) decrease the magnitude of currents passing through soft tissue.

Question 23

Question
Electro-muscular stimulation is used in the following condition:
Answer
  • a) epilepsy;
  • b) arrhythmia;
  • c) muscle atrophy.

Question 24

Question
When the frequency of electrical stimulation is increased significantly, skeletal muscles will respond with:
Answer
  • a) a muscle twitch;
  • b) muscle relaxation;
  • c) complete tetanus.

Question 25

Question
For efficient electro-muscular stimulation this type of current is used:
Answer
  • a) pulsed current above the threshold;
  • b) direct current with high voltage;
  • c) direct current with variable voltage.

Question 26

Question
When constant direct current is applied to living tissue, the magnitude of the current will decrease with time. What is the explanation?
Answer
  • a) the activation of voltage-gated Ca2+ channels;
  • b) the increase of the active resistance of the skin;
  • c) the polarization of the tissue.

Question 27

Question
Electro-muscular stimulation is used for:
Answer
  • a) observation of the spontaneous contractions in smooth muscles of the gastrointestinal tract;
  • b) conditioning mostly of skeletal muscles;
  • c) stimulation of the peripheral nerves.

Question 28

Question
The electrical conductance of biological tissue is:
Answer
  • a) a passive property;
  • b) an active property;
  • c) biological tissue has only resistance.

Question 29

Question
Choose the INCORRECT statement regarding the conductance of direct current (DC) through biological tissues:
Answer
  • a) DC does not flow through cells, only in the extracellular fluid;
  • b) DC flows through the cells;
  • c) DC decreases exponentially with time, regarding of the applied constant voltage.

Question 30

Question
Single muscle twitch is cause by:
Answer
  • a) sub-threshold stimulation;
  • b) single action potential;
  • c) a series of fast local responses.

Question 31

Question
Tetanic muscle contractions are the result of:
Answer
  • a) a series of sub-threshold stimuli;
  • b) a series of over-threshold stimuli;
  • c) a series of fast local responses.

Question 32

Question
Choose the best definition for tetanic muscle contraction:
Answer
  • a) series of fast sequential muscle contractions;
  • b) series of muscle contractions, where new contractions begin before the ending of previous contractions;
  • c) group of sequential muscle contractions, triggered by singlesub-threshold stimulation.

Question 33

Question
A complete (smooth) tetanus is achieved when:
Answer
  • a) the interval between action potentials is shorter than the duration of the muscle contraction;
  • b) the interval between action potentials is longer than the duration of the muscle contraction;
  • c) when the duration of the action potential is longer then the duration of the muscle contraction.

Question 34

Question
Electro-muscular contraction of denervated muscles is:
Answer
  • a) a muscle contraction resulting from depolarization;
  • b) a muscle contraction triggered by a high voltage;
  • c) a muscle relaxation following the polarization of muscle cells.

Question 35

Question
The specific electrical conductance is the greatest for this type of tissue:
Answer
  • a) blood;
  • b) muscle tissue;
  • c) fat tissue.

Question 36

Question
When constant magnitude voltage is applied to biological tissue the resulting current does not follow Ohm’s law. This is due to:
Answer
  • a) depolarization;
  • b) polarization;
  • c) induction.

Question 37

Question
Electro-muscular stimulation for physical therapy uses:
Answer
  • a) low frequency pulsed current;
  • b) high frequency pulsed current;
  • c) sine-wave current.
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