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Sensory-MotorPathway
Exam 6 - Lecture 6
| Question | Answer |
|---|---|
| Special Receptors take in stimuli for: | Hearing, Balance, Smell, Taste, Sight |
| Somatic Receptors take in stimuli for: | Skeletal muscle, Position, Temperature, Chemicals, Distortion |
| Visceral Receptors take in stimuli for: | Temperature, Chemicals, Distortion |
| Somatic Effectors respond to stimuli in: | Skeletal muscles |
| Visceral Effectors respond to stimuli in: | Smooth muscle, Cardiac muscle, Glands, Adipocytes |
| Visceral signals don’t go into the Cortex, only into the __________ | Middle Brain |
| We have ___ times more cold receptors than warm receptors | Three times more |
| Tactile Mechanoreceptors respond to: | Touch, pressure, vibration |
| Baroreceptor Mechanoreceptors respond to: | Pressure, stretch |
| Proprioceptor Mechanoreceptors respond to: | Position |
| Thermoreceptors | Temperature |
| Chemoreceptors | Small Chemicals (CO2, O2, H+) |
| Mechanoreceptors | Distortion |
| Nociceptors | Chemicals, extreme temperature or distortion (pain, itch) |
| Pleasure receptors do not exist, pleasure is merely an absence of ________ | Pain |
| Steps from Stimulus to Perception: | Stimuli (pressure, temp, chem, sound, light) → Sensory Receptor → Receptive Field → Transduction (conversion of stimulus to AP) → Sensation (info arriving at CNS) → Perception (conscious awareness of sensation) |
| Receptive Field | Area monitored by a single Receptor Cell |
| Receptive Field diameter on Skin | 2.5” diameter |
| Receptive Field diameter on Tongue | .025” diameter |
| Transduction | Conversion of a stimulus to an action potential |
| Sensation | Information arriving at the CNS |
| Perception | Conscious awareness of a sensation |
| Are all sensations that are perceived real? | No, electrical activity in the brain can cause a sensation that’s not really there |
| Are all sensations perceived? | No, only about 1% are (mostly due to adaptation) |
| Only about __% of all sensations are perceived, mostly due to _________ | 1%; Adaptation |
| Adaptation | Reduced sensitivity in the presence of a constant stimulus |
| Which two areas of the Brain help focus attention? | Mesencephalon (Midbrain) and Thalamus |
| Fast Adaptation occurs with: | Sound, Temperature, Pressure, Smell |
| Slow Adaptation occurs with: | Pain |
| Hyperesthesia | Adaptation being slow or absent |
| Simplified version of Stimulus to Perception: | Stimulus → 1st order neurons → 2nd order neurons → 3rd order neurons → Cerebral Cortex → Perception |
| When looking at the Spinal Cord, the tips of the “butterfly wings” will always point ________ and the tips are where sensory information always goes | Away from you |
| What do First Order Neurons do? | Bring information to CNS |
| What to Second Order Neurons do? | Cause unconscious “Sensation” |
| Decussation | Crossing over of neurons (at the spine or Brainstem) |
| What do Third Order Neurons do? | Cause conscious “Perception” |
| Where do Third Order Neurons synapse? | In the Thalamus; then bring information to Cerebral Cortex |
| Mechano, Thermo, and Nociceptors follow what path? | Afferent Fibers (First Order Neurons) to Spinothalamic Ascending Tract (Second Order Neurons; from spine to Thalamus) and then from the Thalamus to the Cortex (Third Order Neurons – cause Perception) |
| Proprioception follows what path? | Afferent Fibers (First Order Neurons) to Spinocerebellar Ascending Tract (Second Order Neurons; from spine to Cerebellum – causes Sensation) |
| Which tract gets messed up when people drink too much? | Spinocerebellar Tract |
| Sensory Homunculus | Pictoral demonstration of relative amount of sensory receptors/neurons at peripheral locations |
| Three ways that people can experience Phantom Limb Pain | 1. Stimulus originates at 1st Order Neurons of missing limb via nerve endings 2. Stimulus “jumps the tracts” to stimulate 2nd or 3rd Order Neurons 3. Stimulus arrives at intended sensory cortex area but overflows into another area |
| Two spots where stimulus can “jump the tracks”: | 1. At the point where First Order Neurons synapse with Second Order Neurons in the Spinal Cord 2. At the point where Second Order Neurons synapse with Third Order Neurons in the Brain |
| Referred Pain | Pain from a body part is felt in another body part that is not injured (like left arm pain from a heart attack) |
| Two ways that Referred Pain can occur: | 1. Stimulus “jumps the tracks” to stimulate 2nd or 3rd Order Neurons of the other body part 2. Stimulus arrives at intended sensory cortex area but overflows into another area |
| When was the clitoris added to the Sensory Homunculus? | July 2009 |
| Where is the Motor Cortex located? | In a band just infront of (anterior) the Sensory Cortex in a “headband” of the Brain |
| Where is the headquarters of Motor Pathways? | Cerebral Cortex |
| Initiation of a Motor Pathway can be: | Independent of a sensory signal, and may be conscious or unconscious |
| Pathway from Desire to Motion: | Desire [Cerebral Cortex] activates upper motor neurons which synapse with and activate lower motor neurons which synapse on skeletal muscle fibers, release ACh, and cause Motion |
| Corticobulbar System (look at coin) | Cortex → Brainstem → Cranial Nerves (control of head muscles) |
| Corticospinal System (pick up coin) | Cortex → Brainstem → Spinal Nerves (control of torso/limb muscles – AKA Pyramidal System because the funneling of nerves forms a triangle shape) |
| Ataxia (Ataxic) | ”Lacking order;” Unorganized movement (Parkinson’s, Huntington’s, Cerebral Palsy, ALS) |
| Pyramidal System (Corticospinal System) | Conscious control of basic movement “template” |
| Pyramidal System (Corticospinal System) consists of: | MC = Motor Cortex (initiates but is also influenced) – signals to skeletal muscles |
| Extrapyramidal System | Subconscious coordination of entire movement process |
| Extrapyramidal System consists of: | BS = Brainstem Nuclei (from Brainstem to Spinal Cord), C = Cerebellum (from Cerebellum to Brainstem and Motor Cortex), BN = Basal Nuclei (from base of Cerebrum to Motor Cortex and Brainstem) |
| Function of Brainstem Nuclei (BS) | Coordinate fine/gross movements, vestibular info |
| What is the Brainstem Nuclei (BS) regulated by? | Basal Nuclei (BN) and Cerebellum (C) |
| Function of Cerebellum (C) | Coordinates proprioceptive/vestibular information with movement |
| What is the Cerebellum (C) regulated by? | None – just regulates Motor Cortex (MC) and Brainstem Nuclei (BS) |
| Function of Basal Nuclei (BN) | Help coordinate conscious movements |
| What is the Basal Nuclei (BN) regulated by? | None – just regulates Motor Cortex (MC) and Brainstem Nuclei (BS) |
| Function of Motor Cortex (MC) | Signals to skeletal muscles (control of basic movement) |
| Motor Cortex (MC) is regulated by: | Basal Nuclei (BN) and Cerebellum (C) |
| What two neuron populations do the Basal Nuclei (BS) have? | GABA Secreting and ACh Secreting |
| What do GABA Secreting Basal Nuclei (BS) neurons do? | Inhibit neurons in MC and BS to prevent contaction of antagonistic muscles |
| What do ACh Secreting Basal Nuclei (BS) neurons do? | Activate neurons in MC and BS to stimulate contraction of antagonistic muscles (usually inactive because inhibited by Dopamine from Substantia Nigra (SN) located in Mesencephalon of Brainstem) |
| Function of Substantia Nigra (SN) | Secrete Dopamine the inhibits ACh secretions from the Basal Nuclei (this allows for smooth movement because when ACh is secreted, it stimulates contraction of antagonistic muscles) |
| Location of Substantia Nigra (SN) | Mesencephalon of Brainstem |
| How do antipsychotic meds cause motor problems? | They block Dopamine receptors which means there is less Dopamine coming from the Substantia Nigra which means more ACh from BN = shaky/jerky movements |
| What motor symptoms are caused by the effects of neuroleptic drugs on the Extrapyramidal System? | Dystonias, Dyskinesias, Akathesia, Oculogyric Crisis, Opisthotonus, Parkinsonism |
| Dystonias | Slow, painful, twisting movements |
| Dyskinesias | Rapid, brief, jerky movements |
| Akathisia | Restlessness |
| Oculogyric Crisis | Involuntary eye-rolling |
| Opisthotonus | Spasm with arching of back |
| Parkinsonism | Tremor, shuffling gait, etc |
| What disease involves a damaged Substantia Nigra? | Parkinson’s |
| Causes of Parkinson’s Disease | Genetics, synthetic Heroin, pesticides, boxing |
| Motor problems caused by Parkinson’s Disease | Opposing muscles fight each other; Spasticity (voluntary movements are hesitant and jerky); Tremors (while resting, opposing muscles are contracting) |
| Spasticity | Voluntary movements are hesitant and jerky |
| Tremors | While resting, opposing muscles are contracting |
| Treatments for Parkinson’s Disease | L-Dopa, Amantadine, Deprenyl, Bromocriptine |
| L-Dopa | Precursor to Dopamine that WILL cross the BBB (used to treat Parkinson’s) |
| Amantadine (Namenda) | Increases Dopamine release (used to treat Parkinson’s) |
| Deprenyl | Decreases Dopamine removal (used to treat Parkinson’s) |
| Bromocriptine | Dopamine Agonist; stimulates Dopamine receptors (used to treat Parkinson’s) |
| What disease involves damaged Basal Nuclei? | Huntington’s Disease |
| Causes of Huntington’s Disease | Mutated gene (mutated Huntingtin protein which then damages the nuclei of neurons) |
| Huntington’s Disease | Damaged Basal Nuclei; Loss of ACh and GABA Secreting neurons in BN – GABA loss causes decreased inhibition on Cortex and Brainstem which causes increased stimulation of muscles |
| Dysfunctional Basal Nuclei results in: | Loss of ACh and GABA Secreting neurons in BN; Hyperkinetic; Hypokinetic |
| Hyperkinetic | Chorea (abnormal, involuntary movement); initially mild = fidgeting, severe = flailing |
| Hypokinetic | Rigidity; progress to tremors and dystonia |
| Degeneration of frontal cerebral lobes in Huntington’s results in: | Cognitive decline (earliest symptom of Huntington’s) |
| Treatment for Huntington’s Disease | Valproic Acid (stimulates GABA release which opens Cl- channels); Clonazepam (directly opens Cl- channels) |
| Cerebral Palsy involves damage to: | Basal Nuclei, Cerebellum, and additional Brain areas |
| Cerebral Palsy involves damage to the Cerebellum which causes: | Problems with posture/balance |
| Cerebral Palsy involves damage to additional Brain areas which causes: | Problems with memory, speech, learning |
| Treatments for Cerebral Palsy | Valproic Acid, Baclofen, Diazepam, Phenobarbital |
| How does Valproic Acid treat Cerebral Palsy? | Stimulates GABA release (opens Cl- channels) |
| How does Baclofen treat Cerebral Palsy? | GABA antagonist |
| How does Diazepam and Phenobarbital treat Cerebral Palsy? | Stimulates Cl- channels |
| Cerebral Palsy is caused by compromising a pregnancy with: | Alcohol or drug exposure, Inadequate oxygen to fetus, Stressful birth |
| Amyotrophic Lateral Sclerosis (ALS) | Degeneration of motor neurons in Cortex, Brainstem, and Spinal Cord which leads to atrophy of muscles, but there is no affect on sensory neurons or intellect |
| Causes of ALS are ___% unknown and ___% genetic | 90% unknown; 10% genetic |
| Symptoms of ALS don’t usually start until after ____ years old | 45-50 |
| Symptoms of ALS | Difficulty with voluntary movements, physical weakness |
| ALS patients usually die within ___ years | 5 years |
| Theoretical Pathophysiology of ALS | Abnormal Glutamate activity leads to excess free radicals |
| Treatment of ALS | Riluzole (decreased Glutamate release and/or binding) |
Created by:
Cyndi1087
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