Presentation on theme: "Divisions of the Human Nervous System"— Presentation transcript:
1Divisions of the Human Nervous System Central Nervous System-the brain and the spinal cordPeripheral Nervous System-the nerves outside the brain and spinal cordTwo Division of the PNSSomatic Nervous System-the nerves that convey messages from the sense organs to the CNS and from the CNS to the muscles and glandsAutonomic Nervous System-a set of neurons that control the heart, the intestines, and other organs
2Figure 4.1 The human nervous system Both the central nervous system and the peripheral nervous system have major subdivisions. The closeup of the brain shows the right hemisphere as seen from the midline.
3The Brain: the big picture… The basic components of the CNS include the:CerebrumDiencephalonCerebellumBrain stemSpinal cord
5The Brain: development… Our central nervous system has humble origins early in our development (by 3rd wk.)A plate (neural plate) of cells develop crests (neural crests) that rise and eventually meet and fuse leaving the hollow dorsal nerve cord & and ventricles of our CNS
6BI 201 Human Anatomy & Physiology The Brain: development…What happens if those crests DON’T meet and fuse?Failure of neural arch formation can result in Spina bifida. In mild cases results in a dimple or discolored spot (S.b. occulta), severe cases (S.b. cystica), meninges, CSF and nervous tissue may protrude.
7The Brain: from the outside in… The brain and spinal cord are protected by meninges3 layers: Dura mater ~ outermost, tough, continuous with periosteumArachnoid mater ~ middle layer, spiderweb appearancePia mater ~ innermost layer, not visible to naked eye
8The Brain: from the outside in… The dura mater helps keep the brain in position and the cerebral spinal fluid (CSF) helps cushion/protect the brainWhere does the fluid come from?Choroid plexuses on ventricle wallsEpendymal cells allow fluids in from capillaries
9The Brain: from the outside in… The CSF circulates throughout the ventricles, down the central canal of the spinal cord and throughout the subarachnoid space.CSF is reabsorbed back into blood primarily at the venous sinuses found within the dura mater.
10Cerebral Hemispheres (Cerebrum) Paired (left and right) superior parts of the brainInclude more than half of the brain massFigure 7.13aSlide 7.28a
11Layers of the Cerebrum Gray matter Outer layer Composed mostly of neuron cell bodiesFigure 7.13aSlide 7.33a
12Layers of the Cerebrum White matter Fiber tracts inside the gray matterExample: corpus callosum connects hemispheresFigure 7.13aSlide 7.33b
13Cerebral Hemispheres (Cerebrum) The surface is made of ridges (gyri) and grooves (sulci)Figure 7.13aSlide 7.28b
14The Lobes The Occipital Lobe-posterior end of cortex Contains primary visual cortexThe Parietal Lobe-between occipital love the central sulcusContains the primary somatosensory cortex-receiving touch sensation, muscle-stretch information and joint position informationThe Temporal Lobe-lateral portion of each hemisphere, near the templesContains targets for audition, essential for understanding spoken language, complex visual processes, emotional and motivational behaviorsThe Frontal Lobe-extends from the central sulcus to the anterior limit of the brainContains Primary Motor Cortex-fine movementsContributes to shifting attention, planning of action, delayed response tasks as examples
15Lobes of the CerebrumFissures (deep grooves) divide the cerebrum into lobesSurface lobes of the cerebrumFrontal lobeParietal lobeOccipital lobeTemporal lobeSlide 7.29a
17Specialized Areas of the Cerebrum Somatic sensory area – receives impulses from the body’s sensory receptorsPrimary motor area – sends impulses to skeletal musclesBroca’s area – involved in our ability to speakSlide 7.30
22Specialized Area of the Cerebrum Figure 7.13cSlide 7.32c
23The Brain: Cerebrum (lobes) Cerebrum divided into 4 lobes:Frontal: motor function, motivation, aggression, smell and moodParietal: reception and evaluation of sensory info.Temporal: smell, hearing, memory and abstract thoughtOccipital: visual processing
24The Brain: Cerebrum (bumps and grooves) The sulcus dividing frontal and parietal lobes is Central Sulcus.Ridges on either side are Pre & Post gyriPre CS ~ motor cortexPost CS ~ somatic sensory cortexMotorSensory
25Layers of the Cerebrum Basal nuclei – internal islands of gray matter Regulates voluntary motor activities by modifying info sent to the motor cortexProblems = ie unable to control muscles, spastic, jerkyInvolved in Huntington’s and Parkinson’s DiseaseFigure 7.13aSlide 7.33c
26Figure 4.20 Some major subdivisions of the human cerebral cortex The four lobes: occipital, parietal, temporal, and frontal.
27The Brain: Cerebrum (makin’ waves) Sum electrical activity can be read as waves with EEGbio-feedback to control brain activity
28The Brain: Cerebrum (memories) 3 types:Sensory ~ less than a secondShort-term ~ seconds to minutes (about bits)Long-term ~ minutes to life timeassociated with re-shaping neurons and formation of memory engrams (pattern of neurons and their connections)
29The Brain: Cerebrum (memories) Long term memories are divided into 2 types:Declarative memory ~ ability to recall details, names etc.Procedural memory ~ ability to repeat behaviors or actions.Example: Pavlov and conditioning
30The Brain: Cerebrum (memories in “limbo”) Deepest portion of cerebrum and brainstem associations called the Limbic systemThis is involved with mood, base emotions and interacts with hypothalamus to influence food/H2O acquisition.Major input is olfaction
31The Brain: Cerebrum (hemispheres) Not really a “dominant” sideHemispheres communicate via the corpus callosumStructurally and functionally differentRight brain -- usually RepresentationalLeft brain -- usually CategoricalAnteriorSmell R.Smell L.Shape mem.Verb. Mem.MusicalSymbolicIntuitiveLanguageSpatialPosterior