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Lesson 6.1

Chapter 6: The Nervous System. Lesson 6.1. Overview of the Nervous System. Agenda & Key Points. organization of the nervous system two major divisions the efferent nerves-subdivisions nervous tissues Neuroglia-support and protection Neurons-transmitting information (nerve impulses).

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Lesson 6.1

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  1. Chapter 6: The Nervous System Lesson 6.1 Overview of the Nervous System

  2. Agenda & Key Points • organization of the nervous system • two major divisions • the efferent nerves-subdivisions • nervous tissues • Neuroglia-support and protection • Neurons-transmitting information (nerve impulses)

  3. Organization of the Nervous System • two major divisions • central nervous system (CNS) • peripheral nervous system (PNS) • Autonomic-(Cardiac & Smooth) • Parasympathetic-routine involuntary • Sympathetic-high alert • Somatic- (Skeletal) • sensory receptors ( special nerves- pressure, pain and temp) • afferent (sensory) nerves- From PNS to CNS • efferent (motor) nerves- From CNS to PNS

  4. Two Major Divisions

  5. The Efferent Nerves (Motor Nerves) • somatic nervous system • Voluntary • skeletal • autonomic nervous system • Involuntary • Smooth and cardiac • Sympathetic -6.4 (fight or flight) • Parasympathetic -6.4 ( rest and digest)

  6. Nervous Tissues • neuroglia • also known as glial cells • support the neurons • protect the neurons • Types: • Astrocytes- between neurons and capillaries ½ of all glials • Microglia- disposals • Ependymal cells- line, cover and protect cavities • Oligodendrocytes- produce myelin in CNS • Schwann cells- produce myelin in PNS • Satellite Cells- cushion and support

  7. Neuroglia

  8. Nervous Tissues • Neurons-transmit nerve impulses • Neuron Anatomy • Cell body-nucleus and mitochondria • Axon-sends info away from cell body • Dendrites-collect and transport stimuli • Myelin sheath-fatty insulation to increase rate on impulse transmission ( white vs gray matter) • Neurilemma-external covering of schwanncells • Nodes of ranvier-uninsulated gap between schwann cell • Synapse-gap between axon terminals and muscles or other neurons (neuromuscular junction if muscles)

  9. Neuroglia

  10. Neuron Types by Function • sensory neurons • send impulses toward CNS • motor neurons • send impulses away from CNS • interneurons • bridges between neurons

  11. Neuron Structures • bipolar • one axon and one dendrite • (eyes and nose) • unipolar • one axon • PNS • multipolar • one axon and many dendrites • CNS, Motor and interneurons

  12. Review and Assessment Match these words with 1–4 below: sympathetic nervous system, myelin, synapse, axon. 1. high alert 2. transmits impulses away from cell body 3. fatty insulating material 4. gap between neurons

  13. Chapter 6: The Nervous System Lesson 6.2 Transmission of Nerve Impulses

  14. Agenda and Key Points • Neurons are irritable too! • action potentials • change in cell membrane charge • impulse transmission • charge change travels along axon • reflexes • response to stimulus

  15. Action Potentials • Conductivity-ability to transmit nerve impulses • Polarized-difference in charge inside the cell (negative), Sodium outside, Potassium inside • Depolarized-(positive), flood of sodium ions inside • Nerveimpulse-wave of depolarization (action potential) all or none • Repolarized-return to original state • RefractoryPeriod-between impulse and repolarization (fatigue). Can’t respond

  16. Impulse Transmission • Speed of transmission: 1-119 m/s • Myelin sheath- any impulse>1m/s • Diameter of axon • Body temperature- warmer=faster • Saltatoryconduction-jump overs • Faster transmission • Nodes of Ranvier (myelin) • transmission at synapses • gap junctions • neurotransmitter • excitatory effect-acetylcholine • inhibitory effect-endorphins

  17. Reflexes • somatic • stimulate skeletal muscles, voluntary • autonomic • stimulate involuntary muscles, cardiac/smooth

  18. Chapter 6: The Nervous System Lesson 6.3 Functional Anatomy of the Central Nervous System

  19. Agenda and Key points • Brain (2.25-3.25 lb, 100 billion neurons) • Cerebrum • 2 hemispheres • diencephalon • brain stem • cerebellum • meninges • blood-brain barrier

  20. Cerebrum • cerebral cortex- outer surface=gray matter, inner= white matter • Convolutions= wrinkles • Gyrus- raises • Sulcus- grooves • Fissure- deep grooves • lobes • Frontal- • broca’s area (L) • primary motor cortex- coordination • parietal • primary somatic sensory cortex-sensory info • Occipital • vision • Temporal • Speech, hearing, vision, memory and emotion

  21. Cerebrum

  22. Diencephalon • Thalamus • Relay station • Sleep and awake • Hypothalamus • Pearl sized • Metabolism, heart rate, bp, pain and pleasure • epithalamus • Pineal gland and sleep hormones

  23. Brain Stem • Midbrain – most superior part of brain stem • Sensory and motor impulses • Vision, hearing, motor, temperature, sleep cycle • Pons- middle of brain stem • Breathing regulation • medulla oblongata- most inferior • Heart rate, blood pressure, breathing • Reflexes for cough, sneeze and vomiting • As long as the brain stem is functional, the body will live (with hydration and nutrition)

  24. The Brain • Cerebellum • Below occipital lobe • Balance and coordination, body position • blood-brain barrier • Lots of blood flow (20-25% at any given time) • Capillaries are impermeable to many substances • Water, glucose and amino acids can pass • So can alcohol, nicotine and anesthetics • Meninges- protective membranes • duramater • Tough, double layered. Inner layer extends to spinal cord • arachnoid mater • Web-like • Underneath is CSF • pia mater • Delicate. Attaches directly to brain

  25. Meninges

  26. Spinal Cord

  27. Chapter 6: The Nervous System Lesson 6.4 Functional Anatomy of the Peripheral Nervous System

  28. Functional Anatomy of the Peripheral Nervous System • nerve structure • cranial nerves • spinal nerves and nerve plexuses • autonomic nervous system

  29. Nerve Structure • endoneurium • covers axons • perineurium • bundles fascicles • epineurium • wraps nerves

  30. Cranial Nerves

  31. Spinal Nerves and Nerve Plexuses • 31 pairs • dorsal root • ventral root • dorsal ramus • ventral ramus • plexuses

  32. Autonomic Nervous System • preganglionic and postganglionic neurons • sympathetic nerves • fight-or-flight action • parasympathetic nerves • resting or digesting action

  33. Review and Assessment Match these words with 1–4 below: efferent, ganglion, optic, perineurium. 1. wraps fascicles 2. motor 3. a cranial nerve 4. enlarged junction

  34. Chapter 6: The Nervous System Lesson 6.5 Injuries and Disorders of the Nervous System

  35. Injuries to the Brain and Spinal Cord • traumatic brain injury • cerebral palsy • spinal cord injury

  36. Traumatic Brain Injury • violent impact to head • mild • moderate • severe

  37. Cerebral Palsy • damage to brain • before birth • during birth • during infancy • motor function impairment

  38. Spinal Cord Injuries • C1–C3: usually fatal • C1–C4: quadriplegia • C5–C7: paralysis of lower extremities • T1–L5: paraplegia Corepics/Shutterstock.com

  39. Common Diseases and Disorders of the CNS • meningitis • multiple sclerosis • epilepsy • Parkinson’s disease • dementia and Alzheimer’s disease

  40. Review and Assessment Match these words with 1–4 below: quadriplegia, multiple sclerosis, dementia, cerebral palsy. 1. inflammation destroys myelin sheath 2. loss of memory and thinking 3. loss of function below the neck 4. may begin before birth

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