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MoveSci 110 #2
Question | Answer |
---|---|
The inside of the cell has a resting potential of what with respect to the outside? | -70mV |
During resting potential, which ion is found in high concentration inside/outside the cell? | Inside-potassium (K+) Outside-sodium (Na+) |
Which two ions are responsible for the electrical potential difference? | Sodium (Na+) and Potassium (K+) |
When neuron is at rest, K+ channels are | open, to keep neuron at negative potential |
Dramatic jumps in voltage across the cell membrane are indicative of what? | Action potentials |
What is the role of transmitter substance? | To open up channels in the membrane which depolarize the cell |
Differentiate between spatial and temporal summation of action potentials | Spatial summation makes depolarization because of the action of multiple cells synapsing on the postsynaptic neuron Temproal summation makes depolarization because of several synaptic potentials close together in time |
IT is known that EPSP dies down after only 3-4 msec, how can action potential be passed on to the next neuron? What are the two processes that allow for this to occur? | Many cells firing or one cell firing many times in a row Spatial summation and temporal summation, respectively |
List the three main components of a muscle spindle. | Intrafusal fibers, sensory neuron endings, and gamma motor neuron endings |
Name two subtypes of intrafusal muscle fibers and differentiate between their ability to detect static and dynamic movement | Nuclear bag, gives dynamic information Nuclear chain, gives perception of space, relative location |
Which afferent neurons are best able to respond quickly to both stretching and sensing the rate of change? Where can they be found? | 1a afferents; equatorial region (middle) of both bag and chain |
Which intrafusal muscle fibers do type 2 afferents mainly innervate and why are they less sensitive to dynamic change in muscle length when compared to type 1a afferents? | Chain fibers, because they are thinner than nuclear bags so they are worse at detecting change |
What is the main difference between alpha and gamma motor neuron fibers? | Alpha innervates extrafusual fibers, gamma innervates intrafusal fibers |
The activation of what enhances dynamic response of 1a afferent neurons? | Gamma dynamic motor neurons |
Where are golgi tendon organs located and what are they sensitive to? | Located in muscle tendons; sensitive to muscle contractions (force muscle exerts) |
Which muscles have highest concentration of spindles? | Extraocular, neck, and hand |
What is the purpose of co-activation of alpha and gamma motor neurons during voluntary contraction? | Without coactivation, spindle sensory neurons would be silent during voluntary muscle contraction |
Name the ascending pathway that transmits somatosensory information to the cortex | Dorsal-column-medial lemniscal system |
Which neurons transfer information from muscle, tendons, and joints to the somatosensory cortex? Are there any exceptions? | Dorsal column (DC) neurons; yes, leg propioceptors have their own private pathway to the brainstem |
What is cross-modality processing? | Info from joint receptors, muscle spindles, and cutaneous receptors is integrated to give info about movement, which is then laid on a map of the body, which is distorted to reflect relative weight of sensory info from different areas. |
What are the benefits of cross-modality processing? | It is essential to the coordination of movements in space |
Do receptive fields of neurons in the somatosensory cortex change? If so, under what conditions? | Injury and experience can change dimensions |
Describe "lateral inhibition" | The cell that is excited inhibits the cells next to it, thus enhancing contrast between excited and nonexcited regions of the body |
Where is lateral inhibition found within the CNS with respect to somatosensation and how is it useful to humans? | Dorsal column, able to perceive the activation of a single tactile receptor in the hand |
A person with a lesion in area 5 would have troubles with | learning of skills that use information regarding the position of the body in space |