PNB 2264 PRACTICAL II 2026 QUESTIONS AND ANSWERS | A+ GRADED | WITH EXPERT
SOLUTIONS
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
,PNB 2264 PRACTICAL II 2026 QUESTIONS AND ANSWERS | A+ GRADED | WITH EXPERT
SOLUTIONS
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?
, PNB 2264 PRACTICAL II 2026 QUESTIONS AND ANSWERS | A+ GRADED | WITH EXPERT
SOLUTIONS
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?
E=(ENa x GNa + EK x GK + ECl x GCl)/(GNa + GK + GCl) - (answer)What is the membrane potential or
parallel conduction equation?
Sodium, potassium, chloride - (answer)1)Which three ions are the primary contributors to Vrest?
Permeability - (answer)Chemical concept, measuring the relative likelihood of ions being able to cross a
membrane
Conductance - (answer)Electrical concept, relating charge movement to driving force on the charges
Resting membrane potential will be closer to the membrane potential of ion that has more permeability
- (answer)Describe the role sodium and potassium ions have on the establishment of the resting
membrane potential.
Normal Action Potential - (answer)Normal; Na+ channels open, then K+ channels open and Na+ channels
begin to close (inactivated)
Tetrodotoxin (Puffer fish, porcupine fish, ocean sunfish, trigger fish) - (answer)Voltage gated Na+
channels prevented from opening (irreversible)
SOLUTIONS
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
,PNB 2264 PRACTICAL II 2026 QUESTIONS AND ANSWERS | A+ GRADED | WITH EXPERT
SOLUTIONS
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?
, PNB 2264 PRACTICAL II 2026 QUESTIONS AND ANSWERS | A+ GRADED | WITH EXPERT
SOLUTIONS
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?
E=(ENa x GNa + EK x GK + ECl x GCl)/(GNa + GK + GCl) - (answer)What is the membrane potential or
parallel conduction equation?
Sodium, potassium, chloride - (answer)1)Which three ions are the primary contributors to Vrest?
Permeability - (answer)Chemical concept, measuring the relative likelihood of ions being able to cross a
membrane
Conductance - (answer)Electrical concept, relating charge movement to driving force on the charges
Resting membrane potential will be closer to the membrane potential of ion that has more permeability
- (answer)Describe the role sodium and potassium ions have on the establishment of the resting
membrane potential.
Normal Action Potential - (answer)Normal; Na+ channels open, then K+ channels open and Na+ channels
begin to close (inactivated)
Tetrodotoxin (Puffer fish, porcupine fish, ocean sunfish, trigger fish) - (answer)Voltage gated Na+
channels prevented from opening (irreversible)
