CBIO 2200 1nd Edition Lecture 20 Outline of Last Lecture I The Refractory Period II Chemical Synapses III Memory and Synaptic Plasticity IV Common Degenerative Disorders of the Brain Outline of Current Lecture I Dermatomes and Cutaneous Innervation II Diseases III Reflexes IV Spinal Cord Trauma Current Lecture I II Dermatomes and Cutaneous Innervation a Dermatome b Dermatome map i C1 vertebrae 1 Does not innervate skin 2 Only spinal nerve without dermatome 3 Not included on map Diseases a Shingles i Chickenpox causes shingles stays in body once you ve had it ii Caused by varicella zoster virus iii Virus remains for life in the posterior root ganglia iv Shingles herpes zoster 1 Stress can bring it on 2 Breakout in dermatome of spinal nerve where virus has been activated These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 3 Characterized by blisters or skin discoloration III Reflexes a Four properties i Require stimulation ii Quick iii Involuntary iv Stereotyped happen same way every time b Learned vs unlearned reflexes i Learned ex Pavlov s dog c Pathway of Reflex arc i Somatic receptors ii Afferent nerve fibers iii Integrating center involves interneurons iv Efferent nerve fibers v Effectors glands or muscles d The muscle spindle stretch receptor i Muscle spindle stretch receptors embedded in skeletal muscles ii Propioceptors monitoring body position and movement of body parts iii Intrafusal fibers muscle fibers within spindle receive information iv Extrafusal fibers do the work v Three classes of nerve fibers 1 One primary afferent nerve fiber 2 Up to eight secondary afferent fibers 3 Gamma motor neurons innervate intrafusal fibers e Somatic reflexes i Stretch myotatic reflex stretch receptor activated 1 Patellar tendon reflex reflex test they do at doctors a A monosynaptic reflex only uses one synapse afferent sensory neurons synapse directly on the afferent motor neuron b Reciprocal inhibition quads activated hamstrings inhibited allows muscles to work together instead of against each other ii Flexor withdrawal reflex 1 Quick contraction of flexor muscles resulting in the withdrarwal of a limb from a painful stimulus 2 Polysynaptic reflex arc involves multiple synapses 3 Requires cross extension reflex allows you to not fall over when lifting up foot from stepping on something iii Crossed extension reflex iv Tendon reflex 1 Tendon organs a Propioceptors in the tendon itself IV 2 Tendon reflex in response to excessive tension on the tendon 3 Keep muscles from contracting too strongly Spinal Cord Trauma a Complete transaction complete severance of cord i Immediate loss of motor control below level of injury above C4 puts person at risk of respiratory failure ii Spinal shock temporary loss of neurological activity iii Paralysis 1 Paraplegia paralysis of both lower limbs 2 Quadriplegia paralysis of all four limbs 3 Hemiplegia paralysis on one side of body 4 Paresis partial paralysis or weakness of the limbs