The Nervous System A network of billions of nerve cells linked together in a highly organized fashion to form the rapid control center of the body. Functions.
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Presentation on theme: "The Nervous System A network of billions of nerve cells linked together in a highly organized fashion to form the rapid control center of the body. Functions."— Presentation transcript:
1 The Nervous SystemA network of billions of nerve cells linked together in a highly organized fashion to form the rapid control center of the body.Functions include:Integrating center for homeostasis, movement, and almost all other body functions.The mysterious source of those traits that we think of as setting humans apart from animals
2 Upper motor neurones Lower motor neurones Performance of normal voluntary movement,the integrity of two sets of neurons is importantUpper motor neuronesNeurons originating in the cerebral cortex and the brain stemSynapse directly or indirectly with the anterior horn cells or with the motor neurones of the cranial nervesGrouped into pyramidal and extrapyramidal systemsLower motor neuronesMotor cranial nuclei and their axons, i.e. motor fibres of the cranial nerves (3rd, 4th, 5th, 6th, 7th, 9th, 10th, 11th and 12th)In the spinal cord they include the anterior horn motor neurones and their axons, i.e. the motor nerves to skeletal muscles
3 Basic Functions of the Nervous System SensationMonitors changes/events occurring in and outside the body. Such changes are known as stimuli and the cells that monitor them are receptors.IntegrationThe parallel processing and interpretation of sensory information to determine the appropriate responseReactionMotor output.The activation of muscles or glands (typically via the release of neurotransmitters (NTs))
4 Nervous vs. Endocrine System Similarities:They both monitor stimuli and react so as to maintain homeostasis.Differences:The NS is a rapid, fast-acting system whose effects do not always persevere.The ES acts slower (via blood-borne chemical signals called H _ _ _ _ _ _ _) and its actions are usually much longer lasting.
5 Organization of the Nervous System 2 big initial divisions:Central Nervous SystemThe brain + the spinal cordThe center of integration and controlPeripheral Nervous SystemThe nervous system outside of the brain and spinal cordConsists of:31 Spinal nervesCarry info to and from the spinal cord12 Cranial nervesCarry info to and from the brain
7 Cerebral Cortex 3 types of functional areas: Motor Control voluntary motor functionsSensory Allow for conscious recognition of stimuliAssociation Integration
8 Cortical Motor Areas Primary Motor Cortex Premotor Cortex Broca’s Area Frontal Eye Field
9 1.Primary motor cortex2.Premotor cortex4.Frontal Eye Field3.Broca’s Area
10 Primary (Somatic) Motor Cortex Located in the precentral gyrus of each cerebral hemisphere.Contains large neurons (pyramidal cells) which project to SC neurons which eventually synapse on skeletal musclesAllowing for voluntary motor control.These pathways are known as the corticospinal tracts or pyramidal tracts.
11 Primary (Somatic) Motor Cortex SomatotopyThe entire body is represented spatially in the primary motor cortex,_ i.e., in one region we have neurons controlling hand movements and in another region leg movements, etc.What does it mean to say that motor innervation is contralateral?
13 Sensory Areas Found in the parietal, occipital, and temporal lobes. Primary somatosensory cortexSomatosensory association cortexVisual areasAuditory areasOlfactory cortexGustatory cortexVestibular cortex
14 Primary Somatosensory Cortex Found in the postcentral gyrus.Neurons in this cortical area receive info from sensory neurons in the skinand from proprioceptors which monitor joint position.Contralateral input.
16 Somatosensory Association Cortex Found posterior to the primary somatosensory cortex and is neurally tied to it.Synthesizes multiple sensory inputs to create a complete comprehension of the object being felt.How would damage to this area differ from damage to the primary somatosensory cortex ?
17 Basal NucleiInfo arrives at the caudate nucleus and the putamen from sensory, motor, and association areas of the cortex.Processing and integration occurs w/i the nuclei and then info is sent from the globus pallidus to the motor cortex via the thalamus.The basal nuclei alter motor commands issued by the cerebral cortex via this feedback loop.
18 Parkinson’s DiseaseEach side of the midbrain contains a nucleus called the substantia nigra.Neurons in the substantia nigra inhibit the activity of basal nuclei by releasing dopamine.Appearance of symptoms of Parkinson’s disease: tremor, slow movement, inability to move, rigid gait, reduced facial expressionDamage to SN neuronsDecrease in dopamine secretionGradual increase in muscle toneIncreased activity of basal nuclei
19 Diencephalon Forms the central core of the forebrain 3 paired structures:ThalamusHypothalamusEpithalamusAll 3 are gray matter