Colliculus colliculus of the mesencephalon rather of

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Unformatted text preview: ansmits typical Functionally, it transmits typical spinothalamic iimpulses (touch) spinothalamic mpulses (touch) iinto tthe tectum, where it drives ectum nto he ttectum, where it drives reflexes, aiming the head (gaze) reflexes, aiming the head (gaze) att the location of sensory input a the location of sensory input on the body surface (a bee on the body surface (a bee stings, you rapidly look at the stings, you rapidly look at the bee!). bee!). Reflex Actions Reflex An automatic response to a specific stimulus stimulus Reflex Arcs Reflex Most don’t involve conscious thought Most don’t involve conscious thought Some involve lower brain Some involve lower brain Some are carried out by the spinal cord Some are carried out by the spinal cord without any brain involvement without any brain involvement Types of Reflexes Types Monosynaptic Reflexes Monosynaptic Chain of only 2 neurons involved Chain Example: Patellar reflex (stretch reflex) Example: Patellar reflex (stretch reflex) Patellar – Quadriceps tendon stretched muscle – Quadriceps tendon stretched muscle spindles send impulse (muscle stretching) spindles send impulse (muscle stretching) spinal cord motor neuron spinal cord motor neuron quadriceps muscle contracts quadriceps muscle contracts Stretch Reflex Stretch Types of Reflex Types Polysynaptic Reflexes Polysynaptic Require 3 or more sets of neurons Require Example: Withdrawal reflex (crossed Example: (crossed extensor reflex) extensor – Pain receptors spinal cord Pain association neuron integration motor neurons (to muscles for contraction) flexors contract extensors extend for balance extensors Crossed Extensor Reflex Crossed Referred Pain Referred Perceived by the brain as pain from an extremity or body region rather than visceral pain than Diseases and Disorders Diseases Ataxia Ataxia Staggering gait, slurred speech, overshooting of target when touching things things May result from damage to cerebellum May Cerebrovascular Accidents (Strokes) Cerebrovascular Caused by lack of blood to the brain Caused Possible blockage of a cerebral artery or rupture of an aneurysm rupture Diseases and disorders Diseases Transient Ischemic Attacks (TIA’s) Transient Temporary blood deprivation lasting from 5 to 50 min. 50 Temporary numbness, paralysis, or impaired speech speech Usually warning of an impending, more serious of Usually stroke stroke Alzheimer’s Disease Alzheimer Progressive degeneration of brain function Progressive Deficit of Ach Deficit Memory loss, shortened attention span, disorientation, possible language loss disorientation, Diseases and disorders Diseases Parkinson’s Disease Parkinson Degeneration of dopamine releasing neurons neurons Basal ganglia become deprived of dopamine dopamine Persistent tremors, forward bent posture when walking and shuffling gait when Diseases and Disorders Diseases Huntington’s Disease Huntington Hereditary Hereditary Massive degeneration of the basal ganglia and eventually the cerebral cortex and Causes spastic, abrupt, jerky movements Causes Mental deterioration and death result Mental...
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