Exam 2 Chapter 5 Learning objectives 05 22 2013 Describe the basic components of the CNS and PNS and sketch out the flow of information Compare and contrast white and grey matter What is the function of the 4 cortex lobes thalamus hypothalamus and brainstem What is a spinal cord tract and which ones are involved with motor control and somatosensory processing Draw and label a cross section of the spinal cord What is a reflex arc Draw label and describe the patellar tendon reflex and ipsilateral withdrawal reflex Flow of information Afferent CNS Efferent Afferent division receives input from sensory stimuli and visceral o Takes this information from PNS to CNS Information then reaches CNS brain and spinal cord where Efferent division output from CNS to PNS periphery nervous stimuli processing occurs system o Splits into somatic and autonomic nervous system Somatic nervous system o Motor neurons o Skeletal muscle Autonomic nervous system splits into o Sympathetic nervous system Smooth muscle Cardiac muscle Exocrine glands Endocrine glands o Parasympathetic nervous system Smooth muscle Cardiac muscle Exocrine glands Endocrine glands o Enteric nervous system Digestive organs only Besides the requisite blood vessels and connective tissue the central nervous system is composed of neurons nerve cells o There are about 20 BILLION in the brain alone that convey process and store information o Different neurons release different neurotransmitters o Typically have lost the ability to divide so they cannot be regenerated if injured Central Nervous system gray matter vs white matter Gray matter mostly cell bodies of neuroglia cells and neurons o Synaptic terminals unmyelinated CNS interneurons o Regions dorsal horn lateral horn ventral horn o Central canal at center contains cerebrospinal fluid White matter mostly myelinated axons nerve fibers of neurons o Regions various named ascending tracts and descending Cerebral cortex Thalamus Hypothalamus and Brainstem tracts The four lobes o Frontal lobe Voluntary motor activity Speech Integrative thinking o Parietal lobe Somatosensory information processing and perception Spatial perception Facilitates cross talk and integrative processing among other 3 lobes o Temporal lobe o Occipital lobe Auditory information processing and perception Visual information processing and perception Cerebellum maintain balance posture enhance muscle tone coordinate planning of skilled voluntary muscle activity Amount of motor control is proportional to the amount of grey matter in the primary motor cortex of the frontal lobe Amount of sensory perception is proportional to the amount of grey matter in the primary somatosensory cortex of the parietal lobe Thalamus o Very deep brain structure o Bilateral left side right side o Forms lateral walls of 3rd ventricle o Functions Crude awareness of sensation Synaptic relay station for all sensory input en route to cerebral cortex Some degree of consciousness A role in motor control by virtue of connections to frontal lobe basal nuclei cerebellum Hypothalamus o Inferior anterior to thalamus superior to pituitary gland o Receives inputs from thalamus and brainstem o Functions Controls Body temperature Thirst drive Urine output Food intake Anterior pituitary gland hormone secretion Uterine contractions Milk ejection Releases posterior pituitary hormones DIRECTLY INTO BLOOD Ex Hypothalamus releases the posterior pituitary gland hormone oxytocin which goes to the uterus cervix and causes contraction dilation Participates in regulation of Sleep wake cycles Emotions Instinctual and learned behavioral patterns Is a coordination center for the autonomic nervous system which controls smooth muscle cells cardiac muscle cells and gland cells all over the Brainstem functions body o Location of CONTROL AND REGULATION CENTERS for CARDIOVASCULAR respiratory and digestive body systems o Regulates muscle function with cerebellum involved with equilibrium and posture o Involved with arousal and activation of cerebral cortex o Role in regulating sleep wake cycles The spinal cord Spinal cord o Continuation of brainstem from base of skull in vertebral column ending a few inches below your rib cage o Your spinal cord is about the diameter of your thumb o Divided into 5 unequal segments CTLSC Cervical Thoracic Lumbar Sacral like sacred Coccygyeal o 31 pairs of spinal nerves attach to spinal cord Recall that a nerve is not a neuron There are 31 pairs of spinal nerves There are 12 pairs of cranial nerves Grey matter and white matter Dorsal horn cell bodies of interneurons on which afferent neurons terminate Posterior Lateral horn cell bodies of automatic efferent nerve fibers Ventral horn cell bodies of somatic efferent neurons o Go to skeletal m o Anterior Tract bundle of CNS interneurons that share common origin and destination Ascending tracts carry nerve impulses through the spinal cord and project to many brain centers Ex Ventral spinocerebellar tract o Muscle stretch velocity Dorsal column tract Touch pressure vibration Lateral spinothalamic tract Pain temperature brain stem to gray matter in the spinal cord Ex Lateral corticospinal tract o Voluntary control of skeletal muscle o Ventral corticopsinal tract Voluntary control of skeletal muscle Descending tracts carry nerve impulses from higher brain centers or the Dorsal columns Conscious muscle sense concerned with awareness of body position crossed touch pressure vibration Ventral spinocerebellar Crossed unconscious muscle tense Ventral corticospinal cord voluntary control of muscles Lateral spinothalamic Lateral corticospinal Crossed pain and temperature Crossed voluntary control of skeletal muscles Uncrossed down spinal cord crosses at level of termination in spinal Amyotriphic laternal sclerosis hardening of neurons in lateral columns of spinal cord progressive fatal degeneration of motor neurons in the cerebral cortex and lateral corticospinal tracts eventual loss of motor control Spinal reflexes A reflex any response that occurs automatically WITHOUT constant input or regulation by the cerebral cortex although the cerebral cortex may perceive the reflex after the fact the reflex sensation integration and motor output i e input processing output is ENTIRELY handled at specific levels in the spinal cord a REFLEX ARC is the specific neuroanatomical pathway required to bring about a reflex response spinal reflexes e g tendon reflexes are common diagnostic procedures used by clinicians to