Experiments

Question 1

Destroy brain but keep spinal cord intact. the frog becomes unconscious and unresponsive to pain (brain dead)

Answer 1

Single Pith

Question 2

Both brain and spinal cord are destroyed. Frog is completely unresponsive

Answer 2

Double Pith

Question 3

Cranial (Brain) Reflexes

Answer 3

• Blinking
• Righting
• Visual tracking, auditory startle
• Swallowing

Question 4

Spinal Reflex

Answer 4

• Withdrawal reflex
• Trunk or limb twitch to vibration or touch
• Stretch reflex
• Flexor reflex, crossed extensor reflex

Question 5

Purpose of Sodium Bicarbonate in Experiment 1 (Reflex Action)

Answer 5

• Neutralization of acid
• Prevents ongoing stimulation
• Minimizes tissue damage

Question 6

Sensory nerve endings that detect and respond to potentially harmful stimuli, like heat, pressure, or chemicals, that could damage tissue

Answer 6

Nociceptors

Question 7

Effect of NaCl crystals on reflex action

Answer 7

Lowers the threshold for action potential

Question 8

Mimics the natural extracellular fluid environment to keep tissues alive and functional in vitro

Answer 8

Amphibian Ringer’s Solution or Isotonic Saline

Question 9

Binds to the inner portion of voltage-gated Na⁺ blocking Na⁺ influx and depolarization

Answer 9

Lidocaine (Anesthetics)

Question 10

Is the collective response of the action potentials generated by all the nerve
fibers fired by a stimulus

Answer 10

Compound Action Potential

Question 11

Reflects the recruitment of nerve fibers with varying electrophysiological
properties rather than just a single fiber

Answer 11

Graded Response

Question 12

Occurs immediately after an action potential, wherein no new action potentials can be generated, regardless of the strength and frequency of the stimulus

Answer 12

Absolute Refractory Period

Question 13

Stronger-than-normal stimulus can induce an action potential since axon
excitability is reduced but is not completely missing

Answer 13

Relative Refractory Period

Question 14

Speed at which electrical
impulses (action potential) travel along nerves

Answer 14

Nerve Conduction Velocity

Question 15

Factors affecting Nerve Conduction Velocity

Answer 15

• Axon diameter (Larger diameter leads to faster conduction)
• Myelination (myelinated fibers leads to faster conduction via saltatory conduction)
• Temperature (warmer temperature leads to faster conduction)

Question 16

Main neurotransmitter at the
neuromuscular junction, is responsible for transmitting signals from motor neurons to muscle fibers, triggering contraction

Answer 16

Acetylcholine

Question 17

Neuromuscular blocker and an active component of curare, inhibits this process by acting as a nicotinic antagonist, muscle relaxant, and drug allergen (Acetylcholine blocker)

Answer 17

Tubocurarine

Question 18

Muscle Contraction Cycle

Answer 18

1. Resting: Myosin head energized and actin sites blocked
2. Cross-bridge forms Ca²⁺ exposes binding sites; myosin binds actin
3. Power stroke: Myosin pulls actin, ADP + Pi released
4. Detachment: ATP binds; myosin releases actin
5. Reactivation: ATP hydrolyzed; myosin head resets

Question 19

The brief delay and slight tension drop as calcium is released and diffuses

Answer 19

Latency

Question 20

Progressive increase in force
generation with increasing stimulus voltage

Answer 20

Twitch Recruitment

Question 21

Minimum stimulus intensity required to activate the first motor units and elicit a
measurable contraction

Answer 21

Threshold Voltage

Question 22

Refers to how multiple simultaneous stimuli from different locations combine at the postsynaptic neuron to influence whether it fires an action potential

Answer 22

Spatial Summation

Question 23

Encloses the sarcoplasm, maintaining the cell’s integrity and environment. The reason why direct muscle stimulation requires higher voltage to exhibit a response

Answer 23

Sarcolemma

Question 24

Happens when nerves are repeatedly and rapidly stimulated, temporarily
decreasing their ability

Answer 24

Synaptic Fatigue

Question 25

Principle stating that when a muscle receives a nervous impulse, it either contracts and gives a maximal output or none at all

Answer 25

All or None Principle

Question 26

Principle stating that motor units are recruited from smallest to largest based on their size during increasing muscle effort. Says that first units to be activated are low threshold slow (S) units, then fast fatigue-resistant (FR) units. Last to be activated are fast fatigable (FF) units

Answer 26

Henneman's Size Principle

Question 27

Refers to the passive tension and resistance to stretch of a muscle without any active contraction

Answer 27

Resting Force

Question 28

Refers to a sustained muscle contraction resulting from rapid, repeated stimulation without allowing the muscle to relax between stimuli. If the stimuli come fast enough, the muscle reaches a continuous, smooth contraction

Answer 28

Tetanus

Question 29

Two types of tetanus

Answer 29

- Incomplete (unfused) tetanus: Some partial relaxation between stimuli. - Complete (fused) tetanus: No relaxation at all; a smooth plateau of maximal tension.