PNB 2264 Practical 2 Examination with
Quality Answers 2026-2027 Updated.
Converts mechanical force into an electrical signal that can be interpreted by software to
measure muscle tension - Answer What does a force transducer do?
Raw output (millivolts) needs to be calibrated to give us the more meaningful force unit of milli-
Newtons (mN), gain precise measurements, remove tension that is not a result of muscle
contraction, zero force transducer - Answer Why do we need calibration?
Voltage at which we first see a twitch response - Answer What is a threshold stimulus?
The stimulus voltage at which the response amplitude no longer increases - Answer What is a
maximal stimulus?
1.5 times the maximal stimulus; recruitment of all muscle fibers - Answer What is a
supramaximal excitation stimulus?
All or none - Answer What kind of response does a single muscle fiber have?
Graded - Answer What kind of response do muscles (with many muscle fibers) have?
One motor neuron and all the muscle fibers it innervates - Answer What is a motor unit?
Increase in voltage - Answer What causes increased contraction of a muscle?
Frequency of stimulus - Answer What is changed to achieve tetanus?
Tetanus - Answer Prolonged contraction of a muscle that results from rapidly repeating
stimuli; Occurs because the stimulus frequency is so high that the relaxation stage goes away
completely leading to a sustained contraction
Increased stimulus amplitude - Answer What has to be changed to achieve maximal
contraction?
Build up of ADP, Pi, Mg2+, H+ (lactic acid); H+ competes with Ca2+ in binding to troponin;
Conduction failure (lack of power stroke) - Answer What are the causes of fatigue in muscles?
, C - Answer What is the optimal physiological length?
B, D - Answer What is the range of physiological lengths?
A, E - Answer Which are outside of physiological range?
Length-Tension Relationship - Answer Relates the strength of an isometric contraction to the
length of the muscle at which the contraction occurs
Lack of ATP - Answer In a state of rigor mortis, the muscles are highly contracted and difficult
to manipulate. Why does this phenomenon occur?
Decomposition of tissue (release of enzymes over time) - Answer Why does rigor mortis go
away?
Know twitch, summation, tetanus recordings and explanations - Answer
Cerebral Cortex - Answer Has pyramidal cells
Cerebellum - Answer Has purkinje fibers
It becomes more positive. - Answer What happens to Vrest if the internal Na+ concentration
decreases?
Nernst Potential - Answer Membrane potential at which the electrical gradient equals the
chemical gradient -- The potential at which there is no net flow of that particular ion from one
side of the membrane to the other.
E[ion]=58log[(ion)o/(ion)i] - Answer What is the Nernst potential formula for a cation?
E[ion]=58log[(ion)i/(ion)o] - Answer What is the Nernst potential formula for an anion?
Temperature (58=RT/zF and all but T are constants) - Answer What factor could influence
membrane potential you measured in lab to differ from predicted?
Quality Answers 2026-2027 Updated.
Converts mechanical force into an electrical signal that can be interpreted by software to
measure muscle tension - Answer What does a force transducer do?
Raw output (millivolts) needs to be calibrated to give us the more meaningful force unit of milli-
Newtons (mN), gain precise measurements, remove tension that is not a result of muscle
contraction, zero force transducer - Answer Why do we need calibration?
Voltage at which we first see a twitch response - Answer What is a threshold stimulus?
The stimulus voltage at which the response amplitude no longer increases - Answer What is a
maximal stimulus?
1.5 times the maximal stimulus; recruitment of all muscle fibers - Answer What is a
supramaximal excitation stimulus?
All or none - Answer What kind of response does a single muscle fiber have?
Graded - Answer What kind of response do muscles (with many muscle fibers) have?
One motor neuron and all the muscle fibers it innervates - Answer What is a motor unit?
Increase in voltage - Answer What causes increased contraction of a muscle?
Frequency of stimulus - Answer What is changed to achieve tetanus?
Tetanus - Answer Prolonged contraction of a muscle that results from rapidly repeating
stimuli; Occurs because the stimulus frequency is so high that the relaxation stage goes away
completely leading to a sustained contraction
Increased stimulus amplitude - Answer What has to be changed to achieve maximal
contraction?
Build up of ADP, Pi, Mg2+, H+ (lactic acid); H+ competes with Ca2+ in binding to troponin;
Conduction failure (lack of power stroke) - Answer What are the causes of fatigue in muscles?
, C - Answer What is the optimal physiological length?
B, D - Answer What is the range of physiological lengths?
A, E - Answer Which are outside of physiological range?
Length-Tension Relationship - Answer Relates the strength of an isometric contraction to the
length of the muscle at which the contraction occurs
Lack of ATP - Answer In a state of rigor mortis, the muscles are highly contracted and difficult
to manipulate. Why does this phenomenon occur?
Decomposition of tissue (release of enzymes over time) - Answer Why does rigor mortis go
away?
Know twitch, summation, tetanus recordings and explanations - Answer
Cerebral Cortex - Answer Has pyramidal cells
Cerebellum - Answer Has purkinje fibers
It becomes more positive. - Answer What happens to Vrest if the internal Na+ concentration
decreases?
Nernst Potential - Answer Membrane potential at which the electrical gradient equals the
chemical gradient -- The potential at which there is no net flow of that particular ion from one
side of the membrane to the other.
E[ion]=58log[(ion)o/(ion)i] - Answer What is the Nernst potential formula for a cation?
E[ion]=58log[(ion)i/(ion)o] - Answer What is the Nernst potential formula for an anion?
Temperature (58=RT/zF and all but T are constants) - Answer What factor could influence
membrane potential you measured in lab to differ from predicted?
