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Published byAngelina Jefferson Modified over 8 years ago
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Nervous System Functions Organization –CNSCNS –PNSPNS Tissue Nerve Impulse Reflexes Talking nerves
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Functions Sensory input (sensory receptors to monitor stimuli) Integrations (processing and interpreting input) Motor output (effects a response)
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Sensory Input Special organs receive information from environment and send it to brain
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Integration Making “sense” out of sensory input Electric guitar example
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Motor Output Response to stimuli The sound from the amp of the guitar example
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Organization (Structural)
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Organization (functional)functional
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Organization (functional) Afferent (sensory) division – conveys impulses to the CNS from receptors Efferent (motor) division – carries impulses from the CNS to muscles and glands –Somatic NS – voluntary control –Autonomic NS – involuntary control
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Nervous Tissue Structures –NeuronsNeurons –neuroglianeuroglia
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Neuron
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3 Forms –Efferent neurons (motor neurons)Efferent CNS to muscles/glands –Interneurons (connect efferent and afferent) –Afferent neurons (sensory neurons) Receptors to CNS
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Neuroglia Supporting cells that don’t transmit impulses –Ex. Myelin sheath, made of Schwann cells Insulates neurons and speeds up signal
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Nerve Impulse Neuron polarized (resting state where more Na+ on outside and more K+ inside Action potential created by depolarization of a neuron when Na+ swept into cell through membrane All or nothing
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Nerve Impulse K+ ions diffuse outside the membrane to restore electrical condition so that neuron is repolarized back to resting state Na+/K+ pump restores initial concentration of ions inside and outside the neuron
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Reflexes Rapid, predictable, involuntary response to stimuli Occurs on pathways called reflex arcs Impulse travels from receptor to afferent neuron to spinal cord Automatic reflexes – smooth muscle, cardiac muscle, glands Somatic reflexes – skeletal muscle
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Central Nervous System protection
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Cerebral Cortex Largest region Ridges (gyri) and grooves (sulci and fissures) 2 hemispheres seperated by corpus callosum
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Cerebral Cortex Lobes
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Frontal Centers for complex reasoning and language comprehension Motor area for speech and primary motor skills
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Parietal Centers for speech, reading, and primary sensory area
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Temporal Centers for memory, smells, language formation/comprehension and hearing
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Occipital Visual association
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Interbrain Diencephalon Thalamus = relay station for sensory impulses Hypothalamus = regulates automatic nervous responses like water balance, metabolism, thirst, temperature –Also center for emotions and “drives”
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Brain Stem Pons: breathing Midbrain: vision and hearing Medulla oblongata: heart rate, blood pressure, breathing, swallowing, vomitting Reticular formation: conciousness (importance filter) and wake/sleep cycles
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Cerebellum Coordinates skeletal muscle activity and balance Guages “intentions” vs. present body positions
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Protecting the Brain Skull Meninges = 3 connective tissue membranes surrounding the brain and spinal cord
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Protecting the Brain Cerebrospinal fluid (CSF) = constantly circulating liquid that forms a cushion –Plasma-like –Extracted during spinal taps for testing Blood Brain barrier = relatively impermeable series of capillaries in the brain
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Peripheral Nervous System Composed of thousands of nerves (bundled neurons) Cranial Nerves – stem from the brain and primarily serve neck and head (12 pair) Spinal Nerves – stem from the spinal column and serve as message carriers for the rest of the body (31 pair)
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Peripheral Nervous System Somatic – voluntary control of bodily functions –Ex. Muscular control Autonomic (Involuntary) Nervous System – regulates smooth and cardiac muscles and glands
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Autonomic Nervous System Homeostasis of the body is dependent of ANS and balance of its 2 divisions Sympathetic – fight or flight response Parasympathetic – “rest and digest” mechanism
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Nerve-Nerve Communication Axon terminal – Dendritic connection Space in between is called SYNAPSE Chemical signal that spans the gap is a NEUROTRANSMITT ER Once signal is transferred, neurotransmitters are reabsorbed.
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Synapse Action
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Depression and SSRI’s Normal bodies produce a certain amount of serotonin Chemical depression usually deals with a lack of serotonin
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Depression and SSRI’s To combat this, SSRI drugs (selective serotonin reuptake inhibitors) prevent the reabsorption of serotonin after it travels into the synapse.
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