Central Nervous System Notes.docx

Central Nervous System                                          

evolution of vertebrate brain - sponges are only multicellular animals w/o nerves cnidarians - have simplest nervous systems (nerve net) no control/association flatworms - simplest animals w/ association in nervous system bigger mass of nervous tissue (beginnings of brain) >> complex control interneurons/tracts added to brain as it evolved (interneurons - complex, high-level neurons found in brain/spinal cord) hindbrain (rhombencephalon) - extension of spinal cord coordinates motor reflexes cerebellum (“little cerebrum”) - controls balance, body position pons - controls automatic functions, links cerebellum/medulla oblongata w/ other parts of brain medulla oblongata - contains respiration, circulation midbrain (mesencephalon) - consists of mostly optic lobes that receive/process visual information controls eye/ear reflex forebrain (prosencephalon) - processes most of sensory information diencephalons - thalamus, hypothalamus thalamus - relays info between spinal cord and cerebrum hypothalamus - controls emotions, pituitary gland cerebrum (telencephalon) - dominant part of mammalian brain ascending tracts - carry sensory info to brain descending tracts - carry impulses from brain to motor neurons human forebrain - divided into 2 hemispheres connected by corpus callosum each hemisphere receives info from opposite side cerebral cortex - layer of gray matter on outer surface of cerebrum contains 10% of all neurons in brain folded/wrinkled to increase surface area primary motor cortex - right in front of central sulcus (crease), controls mov’t primary somatosensory cortex - right behind central sulcus, receives info from sensory neurons of skin/muscles auditory cortex - in temporal lobe visual cortex - in occipital lobe association cortex - used for higher mental activities basal ganglia - collections of cell bodies, dentrites that produce gray matter islands receives info from ascending tracts, motor commands from cerebrum/cortex sends info to spinal cord to control mov’t damaged ganglia >> Parkinson's thalamus - main area of senses (especially pain) receives visual, auditory, somatosensory info relays info to occipital (visual), temporal (auditory), parietal (somatosensory) lobes hypothalamus - controls instinct regulates body temperature, hunger, thirst, emotion controls pituitary gland (regulates other endocrine glands) limbic system - responsible for emotional responses includes hypothalamus, hippocampus (may control memories), amygdala spinal cord - cable of neurons going from brain through backbone protected by vertebral column and meninges (membrane layers that also cover the brain) inner zone (gray matter) - consists of interneuron, motor neuron, neuroglia cell bodies

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unmyelinated cell bodies