Lab Exam II Study Guide
Nerve Stimulation
Define threshold by the definition given in your lab manual.
The minimum stimulus needed to produce a response
Know the relationship between threshold, voltage, and frequency of stimulation.
Voltage
o The stimuli and/or amount of stimuli
Frequency of Stimulation
o How often stimulus occurs
Muscle Contraction
Review anatomy of muscles. Which bands or zones disappear during muscle contraction?
H-band and I-Band
Be able to relate the lab experiment using the rabbit muscle fibers and ATP with the mechanism for muscle
contraction learned in lecture.
ATP breaks the cross-bridge between myosin and actin, allowing for muscle contraction to resume.
Differentiate the terms twitch, summation, and tetanus.
Twitch
o When a muscle is stimulated with a single stimulus
Summation
o One twitch before the first twitch ends
Tetanus
o No time between twitches, the fuse, sustain maximal contractjion
In addition, be able to identify these features on a myogram.
/
What factors produce sustained muscle contractions?
Sustained stimulus
o Sustained Action potentials
Asynchronous recruitment
o modulated firing of somatic motor neurons so that different motor units take turns maintaining
muscle tension
Identify the ways graded contractions can be produced.
Graded Contractions
o Increasing the frequency of action potentials
o Recruitment of motor units
More motor units = greater contraction
Differentiate how summation of twitches is produced in the lab activity vs in your body.
In lab
o Stimulation was voltage which opened Na+ channels
In body
o The Frequency of action potential
Senses
Review the terms: adequate stimulus, Law of Specific Nerve Energies, sensation, perception, accommodation
bind spot, and two-point threshold.
, Adequate Stimulus
o The type of stimulus to which the receptor is most sensitive
Law of Specific Nerve Energies
o Regardless of how a sensor receptor is stimulated, it can only give rise to one sensation
Sensation
o The awareness of a stimulus as a result of its perception by sensory receptors.
Perception
o Central processing of sensory stimuli into a meaningful pattern.
Accommodation
o The ability for the eye to focus on objects that are at different distances
Blind spot
o Place of the retina where blood vessels and nerves attach
Two-point threshold
o The minimum distance at which two points can be felt
When stimulating your photoreceptors with pressure, what part of your brain integrates this information?
Explain why the neck is less sensitive than the fingertip.
When stimulating your photoreceptors with pressure the somatosensory cortex of parietal lobe
integrates this information
Neck is less sensitive than the fingertip because a smaller portion of the somatosensory cortex is
devoted to the neck than the finger tip
Explain the relationship between the receptor field size of a particular area of the skin with the size of the
somatosensory cortex (postcentral gyrus) devoted to that area.
The receptor field size of a particular area of the skin is proportionate to the size devoted to that
area in the somatosensory cortex. The large the area of devotion in the somatosensory cortex the
more sensitive that part of the skin is.
Explain why adaptation occurs and explain why “after image” occurs after the stimulus, rubber band, was
removed.
Adaptation occurs:
o Phasic Receptors – adapting
When stimulus is constant, action potentials decrease over time
*Action potentials may increase when stimulus is removed
“Rubber band overhead”
After an amount of time your pressure receptors will adapt and you won’t
feel the rubber band
After Image:
o After removal of rubber band pressure receptors activate again
Know the causes of conduction and sensory/nerve deafness. Identify which part(s) of the ear is affected in
each type of deafness.
Conduction Deafness
o Interference with the transmission of sound waves through the external auditory canal
Sensory/Nerve Deafness
o Damage to the hair cells and/or the Vestibulocochlear nerve
Nerve Stimulation
Define threshold by the definition given in your lab manual.
The minimum stimulus needed to produce a response
Know the relationship between threshold, voltage, and frequency of stimulation.
Voltage
o The stimuli and/or amount of stimuli
Frequency of Stimulation
o How often stimulus occurs
Muscle Contraction
Review anatomy of muscles. Which bands or zones disappear during muscle contraction?
H-band and I-Band
Be able to relate the lab experiment using the rabbit muscle fibers and ATP with the mechanism for muscle
contraction learned in lecture.
ATP breaks the cross-bridge between myosin and actin, allowing for muscle contraction to resume.
Differentiate the terms twitch, summation, and tetanus.
Twitch
o When a muscle is stimulated with a single stimulus
Summation
o One twitch before the first twitch ends
Tetanus
o No time between twitches, the fuse, sustain maximal contractjion
In addition, be able to identify these features on a myogram.
/
What factors produce sustained muscle contractions?
Sustained stimulus
o Sustained Action potentials
Asynchronous recruitment
o modulated firing of somatic motor neurons so that different motor units take turns maintaining
muscle tension
Identify the ways graded contractions can be produced.
Graded Contractions
o Increasing the frequency of action potentials
o Recruitment of motor units
More motor units = greater contraction
Differentiate how summation of twitches is produced in the lab activity vs in your body.
In lab
o Stimulation was voltage which opened Na+ channels
In body
o The Frequency of action potential
Senses
Review the terms: adequate stimulus, Law of Specific Nerve Energies, sensation, perception, accommodation
bind spot, and two-point threshold.
, Adequate Stimulus
o The type of stimulus to which the receptor is most sensitive
Law of Specific Nerve Energies
o Regardless of how a sensor receptor is stimulated, it can only give rise to one sensation
Sensation
o The awareness of a stimulus as a result of its perception by sensory receptors.
Perception
o Central processing of sensory stimuli into a meaningful pattern.
Accommodation
o The ability for the eye to focus on objects that are at different distances
Blind spot
o Place of the retina where blood vessels and nerves attach
Two-point threshold
o The minimum distance at which two points can be felt
When stimulating your photoreceptors with pressure, what part of your brain integrates this information?
Explain why the neck is less sensitive than the fingertip.
When stimulating your photoreceptors with pressure the somatosensory cortex of parietal lobe
integrates this information
Neck is less sensitive than the fingertip because a smaller portion of the somatosensory cortex is
devoted to the neck than the finger tip
Explain the relationship between the receptor field size of a particular area of the skin with the size of the
somatosensory cortex (postcentral gyrus) devoted to that area.
The receptor field size of a particular area of the skin is proportionate to the size devoted to that
area in the somatosensory cortex. The large the area of devotion in the somatosensory cortex the
more sensitive that part of the skin is.
Explain why adaptation occurs and explain why “after image” occurs after the stimulus, rubber band, was
removed.
Adaptation occurs:
o Phasic Receptors – adapting
When stimulus is constant, action potentials decrease over time
*Action potentials may increase when stimulus is removed
“Rubber band overhead”
After an amount of time your pressure receptors will adapt and you won’t
feel the rubber band
After Image:
o After removal of rubber band pressure receptors activate again
Know the causes of conduction and sensory/nerve deafness. Identify which part(s) of the ear is affected in
each type of deafness.
Conduction Deafness
o Interference with the transmission of sound waves through the external auditory canal
Sensory/Nerve Deafness
o Damage to the hair cells and/or the Vestibulocochlear nerve
