6892826
Description
Flashcards by McKenzie Sanders, updated more than 1 year ago
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Created by McKenzie Sanders
over 7 years ago
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| Question | Answer |
| What are the 4 steps required in movement? | 1. Sense the environment 2. Select an appropriate response (decision) 3. Plan the motor response 4. Execute the motor response |
| What are the cutaneous sense? | Sensitivity to stimuli that involve the skin (touch) |
| What is kinesthesia? | Perception of the body's own movements |
| What are organic senses? | Senses in the inner organs of the body |
| What are the 4 stimuli for the cutaneous senses? | Pressure Vibration (texture) Heating & cooling Tissue damage |
| What are the 2 stimuli for kinesthesia? | Stretch receptors in skeletal muscle Used to control movement |
| What are the stimuli for organic senses? | Respond to stretch and sometimes temperature |
| What are the 3 somatosenses? | Touch Temperature Pain |
| What is touch defined as? | Sensitivity to pressure and vibration |
| What are the 2 thermal receptors? | Warm & cold |
| What are the 3 types of pain receptors? | High-threshold mechanoreceptors (respond to intense pressure) Extremes in heat, acids & capsaicin Sensitive to ATP |
| What are the 5 cutaneous receptors? | Ruffini's Pacinian Meissner's Merkel's Free nerve endings |
| What do Ruffini's respond to? | Edges |
| What do Pacinian respond to? | Mechanical stimulation & rapid vibrations |
| What do Meissner's respond to? | Light touch & low frequency vibrations |
| What do Merkel's respond to? | Texture |
| What do free nerve endings respond to? | Pain, temperature & itch |
| What kind of neurons are sensory neurons? | Unipolar neurons |
| Where do sensory neurons project to? | Receptors in the skin |
| Cutaneous receptors in order from closest to surface of skin to furthest away | Free nerve endings Merkel's Meissner's Ruffini's Pacinian |
| What is the dorsal column/medial lemniscal pathway involved in? | Localized information like fine touch and kinesthesia |
| What is the dorsal column/medial lemniscal pathway? | Axons from somatosensory receptors enter CNS via spinal nerves (cell bodies in dorsal root ganglion) Enter and ascend in spinal cord in dorsal columns to nuclei in medulla Cross and ascend through ML to VPN of thalamus VPN projects to S1 |
| What is the spinothalamic tract involved in? | Poorly localized information like pain and temperature |
| What is the spinothalamic tract pathway? | Axons enter CNS via spinal nerves (cell bodies in DRG) Synapse in spinal cord gray matter Ascend in spinothalamic tract in lateral horn Joins axons in ML that project to VPN of thalamus VPN projects to S1 |
| What connects muscle fibers to bones? | Skeletal muscle |
| Flexion vs. extension | Flexion is the movement that bends joints Extension is the movement that straightens joints |
| What is extrafusal muscle fiber responsible for? | Muscle contraction |
| What is extrafusal muscle fiber innervated by? | Alpha motor neurons |
| What does the ratio of alpha motor neurons to muscle fiber depend on? | Precision of muscle movement Precise movements have lower ratio of neurons to fibers |
| What is a motor unit? | Alpha motor neuron Axon Associated extrafusal muscle fibers |
| What is intrafusal muscle fiber responsible for? | Specialized sensory organs |
| How are intrafusal muscle fibers arranged? | Parallel to extrafusal muscle fibers in order to detect muscle length |
| What contracts intrafusal muscle fibers? | Gamma motor neurons |
| What does intrafusal muscle fiber NOT contribute much to? | Force of muscle contraction |
| What does intrafusal muscle fiber modify? | Sensitivity to stretch of fiber endings |
| What are myofibrils? | Overlapping strands of actin and myosin that make up muscle fibers |
| What creates striated muscle? | Regions where actin and myosin overlap |
| What is actin? | A protein that provides the physical basis for muscle contraction |
| What is myosin? | A protein that provides the physical basis for a muscle contraction |
| What are myosin cross bridges? | The small protrusions on the myosin filaments that interact with the actin filaments to produce a muscle contraction |
| How do myosin cross bridges work? | Myosin cross bridges "row" along the actin filaments Attach to the actin filament and then detach, bend back, and reattach to the actin filament at a point farther down |
| What is the neuromuscular junction (NMJ)? | The terminal button of an efferent neuron and the membrane of the muscle fiber it synapses on |
| What is the motor end plate? | The postsynaptic membrane of a NMJ |
| What is endplate potential? | PSP that occurs in the motor endplate in response to ACh release |
| Is endplate potential smaller or larger than an EPSP? | Larger |
| What induces contraction of the muscle fiber? | Each AP |
| What occurs during contraction of muscle fiber? | Depolarization of the muscle fiber opens voltage-dependent Ca2+ channels Ca2+ enters the cytoplasm which triggers the muscle contraction |
| Why do the physical effects of skeletal muscle contraction last longer than the AP? | Elasticity of muscle Time required to rid the cell of Ca2+ |
| What can a rapid succession of APs produce? | Sustained muscle contraction |
| What is stretched when the muscle lengthens? | Intrafusal muscle fibers |
| What do intrafusal muscle fibers detect? | Muscle length |
| What is the Golgi tendon organ? | Stretch receptors in the tendons |
| What does the Golgi tendon organ detect? | Total amount of stretch exerted on a muscle How hard a muscle is pulling |
| What is the Golgi tendon organ encoded by? | Firing rate |
| What is the muscle-spindle feedback circuit? | 1. Tension on tendon activates sensory neuron 2. Sensory neuron stimulates interneuron 3. Interneuron inhibits motoneuron 4. Tension on tendon is reduced |
| What does reflexive control of movement reflect about the spinal cord? | Spinal cord has some degree of autonomy |
| What can particular stimuli elicit in the spinal cord? | Rapid response via neural connections in the spinal cord |
| What does monosynaptic stretch reflex do? | Control of posture Correction for weight added to a muscle |
| What is the monosynaptic stretch reflex? | Reflex in which a muscle contracts in response to being quickly stretched |
| How does the monosynaptic stretch reflex occur? (List steps) | 1. Stretching stimulates sensory receptor (muscle spindle) 2. Sensory neuron excited 3. Within integrating center (spinal cord), sensory neuron activates motor neuron 4. Motor neuron excited 5. Effector (same muscle) contracts and relieves the stretching |
| What is the polysynaptic reflex arc? | 1. Golgi tendon detects muscle stretch 2. Synapses on inhibitory interneurons that synapse on the alpha motor neuron of that same muscle 3. Decreases the strength of muscular contraction when there is a danger of damage to tendons or bones |
| How do the brain and the spinal cord control movement in the motor system? | Simultaneously control particular types of movement |
| Where is the primary motor cortex located? | Precentral gyrus in the frontal cortex Frontal part of the parietal lobe |
| What does stimulation of the primary motor cortex produce? | Produces movement of the body |
| What is the supplementary motor area to the primary motor cortex? | Frontal cortex |
| What is the motor homunculus? | Physical representation of the human body, located within the brain Neurological "map" of the anatomical divisions of the body |
| What is the premotor cortex involved in? | Involved in planning of movements which get executed via their connections with primary motor cortex |
| What two visual streams are involved in movement? | Ventral visual stream in the inferior temporal lobe Dorsal visual stream in posterior parietal lobe |
| Why are visual streams involved in movement? | Need to know where your arms, legs, etc. are and where objects are to correctly manipulate these objects |
| In what way is the parietal lobe involved in movement? | Organizing visually guided movements |
| What does the pathway from the parietal lobe to the frontal cortex control? | Controls movements of arms and legs in a goal-directed context |
| Where does the primary motor cortex receive information from? | Primary somatosensory cortex |
| What information does the primary somatosensory cortex provide? | Body part to body part organization Rapid feedback to the motor system during the manipulation of objects |
| What are the two descending groups of pathways in which the primary motor cortex controls movement? | Lateral group Ventromedial group |
| What does the lateral group control? | Control of independent limb movements |
| Which 2 pathways are associated with the lateral group? | Dorsolateral corticospinal tract Dorsolateral corticorubrospinal tract |
| What does the ventromedial group control? | Automatic movements Gross movements of the trunk Coordinated limb and trunk movements involved in posture and locomotion |
| Which pathways are associated with the ventromedial group? | Ventromedial corticospinal tract Ventromedial cortico-brainstem-spinal tract |
| Describe the dorsolateral corticospinal tract. | 1. From primary motor cortex through pyramidal tract 2. Cross at the dorsolateral portion of ventral horn of the spinal cord 3. Projects to the muscle fiber in the limb |
| Describe the ventromedial corticospinal tract. | 1. From primary motor cortex through the pyramidal tract 2. Travels through ventromedial portion of ventral horn of spinal cord (does not cross) 3. Projects to the muscle fiber in limb |
| What does destruction of the basal ganglia cause? | Motor impairment |
| What are the 3 motor nuclei? | Caudate Putamen Globus Pallidus (internal & external divisions) |
| What are the 3 inputs of the basal ganglia? | Primary motor cortex Primary somatosensory cortex Substantia nigra (SN) |
| The 3 outputs of the basal ganglia are done via what part of the brain? | Thalamic nucleus (VA/VL) |
| What are the 3 outputs of the basal ganglia? | Primary motor cortex Supplementary motor area Premotor cortex |
| What do ventromedial pathways provide? | Motor nuclei in the brainstem |
| What is the loop between the cortex and basal ganglia? | 1. Frontal, parietal, and temporal cortex project to the striatum (caudate & putamen) 2. Striatum projects to the globus pallidus (GP) 3. GP projects to VA/VL nuclei of the thalamus 4. VA/VL to motor cortex |
| What information does the loop between the cortex and basal ganglia provide? | Basal ganglia is informed of planned movements and can influence these movements via this loop |
| What are the outputs of the cerebellum? | Every major motor structure of the brain |
| What does cerebellar damage cause? | Uncoordinated jerky movements |
| What does the cerebellum consist of? | 2 cerebellar hemispheres 4 deep cerebella nuclei |
| What are the 4 deep cerebellar nuclei? | Flocculonodular lobe (caudal end) Vermis (midline) Lateral Zone Cerebellar cortex |
| What is the function of the flocculonodular lobe? | Involved in postural reflexes |
| What is the function of the vermis? | Influences automatic behaviors and posture |
| What is the function of the lateral zone? | Control of independent skilled movements Calculates closely timed sequences of muscular contractions to execute rapid skilled movements |
| What is the function of the cerebellar cortex? | Control of arms and legs |
| How do we find evidence of the function of the cerebellum? | Human brain damage patients |
| What does damage to the flocculonodular lobe result in? | Disturbances in posture and balance |
| What does damage to the intermediate zone result in? | Deficits in movements produced by the rubrospinal tract |
| What does damage to the lateral zone produce? | Weakness and decomposition of movement Impaired timing of ballistic movements |
| What are the characteristics of Parkinson's disease? | Muscular rigidity Slowness of movement Resting tremor Postural instability |
| What is Parkinson's disease caused by? | SN dopamine neuron death |
| Why does SN DA neuron death result in Parkinson's disease? | DA input to striatum facilitates movements Lack of DA input ultimately results in an increase in the inhibitory output of the GPi so there is too much inhibition of the motor cortex Less inhibition of the inhibitor |
| What are the effects of the decrease of GPi inhibition on the ventromedial system? | Muscular rigidity Postural instability Both an increase and decrease in inhibitory outputs Levels of complexity increase as a function of multiple neurotransmitters with both excitatory and inhibitory receptors |
| What are the pharmacological treatments for Parkinson's disease? | L-DOPA DA agonists |
| What is the issue with treating Parkinson's disease with L-DOPA? | Eventually stops working because there are not enough SN DA neurons to increase DA output |
| What are the side effects associated with DA agonists? | Dyskinesia Dystonia |
| What are the lesion therapies for Parkinson's? | Pallidotomies Subthalamic nuclei lesions |
| Why is a pallidotomy a treatment for Parkinson's? | Destruction of the GPi Often reduces rigidity and improves movement Activity of motor cortex increases to normal levels post-surgery |
| How do lesions to the subthalamic nuclei work to treat Parkinson's? | Damage seems to reduce some of the inhibition of the motor cortex Usually excites the GPi |
| What are the 3 other treatments for Parkinson's? (Not pharmacotherapy or lesion therapies) | Implantation of electrodes into the subthalamic nuclei Fetal tissue transplant Gene therapy |
| How does the implantation of electrodes into the subthalamic nuclei help to treat Parkinson's? | Deep brain stimulation can be as effective as the lesions with less side effects Implies that stimulation has an overall inhibitory effect on the subthalamic nuclei |
| What does fetal tissue transplant do to treat Parkinson's disease? | Transplant fetal SN cells to the patient's SN Good results in terms of recovery of function Hard to get tissue because 90% of the cells die before implantation |
| How does gene therapy treat Parkinson's? | Put GAD gene attached to a virus into the subthalamic nuclei to calm it down Effects are slow but long lasting Simpler than deep brain stimulation Making progress in effectiveness |
| Which toxins attribute to the onset of Parkinson's disease? | Exposure to pesticides and herbicides MPTP |
| What is autosomal recessive juvenile parkinsonsism? | Mutation in the parkin gene Toxic accumulation in proteins in the cells that express this gene |
| What expresses the parkin gene? | SN cells |
| What is PLP? | Phantom limb pain Sensations in a missing limb Frequently pain |
| What is thought to be important in mediating PLP? | Reorganization of neurons in the spinal cord Cortical plasticity |
| Which therapy showed a 100% decrease in pain for PLP? How did it do so? | Mirror box therapy Prevents cortical restructuring |
| What does the effectiveness of mirror box therapy show? | Critical role of visual feedback in learned paralysis |
| Prevention of PLP can occur only in __________. | Planned amputation |
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