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THE NERVOUS SYSTEM

THE NERVOUS SYSTEM. Central Nervous System(CNS)- brain/spinal cord Peripheral Nervous System(PNS)-nerves through the body 31 pairs of spinal nerves 12 pairs of cranial nerves. A. Two Parts. Sensory- gathers info - receptors of PNS send signals to CNS Integrative- info is brought together

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THE NERVOUS SYSTEM

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  1. THE NERVOUS SYSTEM

  2. Central Nervous System(CNS)- brain/spinal cord • Peripheral Nervous System(PNS)-nerves through the body • 31 pairs of spinal nerves • 12 pairs of cranial nerves A. Two Parts

  3. Sensory- gathers info - receptors of PNS send signals to CNS • Integrative- info is brought together - interpreted, create sensations, create thoughts, add to memory, make decisions • Motor – response to signals (impulses) • Signals sent from CNS to muscles/glands • Homeostasis- maintain stable conditions B. 3 Basic Functions

  4. Somatic Nervous System- skeletal muscles Autonomic Nervous System- smooth muscles, glands Motor:

  5. Body with many extensions(nerve fibers) that conduct impulses • 2 types of processes • Dendrites- shorter more numerous • Receive input • Axons- single long fiber • Conducts impulse away C. Neurons-Nerve cells

  6. Support tissue of the nervous system 5 Types 1. Microglial : scattered throughout, digest debris or bacteria D. Neuroglial Cells

  7. 2.  Oligodendrocytes:  provide insulation around the axons Creates myelin sheath that insulates axons

  8. 3. Astrocytes:  connect blood vessels to neurons

  9. 4.  Ependymal Cells:  form a membrane that covers brain-like parts

  10. 5.  Schwann cells:  form the insulating sheath around the neurons within the PNS *Myelin Sheaths - necessary for insulation of neurons

  11. Cell body- contains cellular organelles Neurofibril -  fibers- support organelles Chromatophilic substance (rough ER) - transport system Myelin -insulation surrounding axons Nodes of Ranvier - gaps in the insulation Synaptic cleft- space between neurons Neuron Structure

  12. Myelinated (white matter) – myelinated axons Unmyelinated (grey matter) - unmyelinated White vs Grey Matter

  13. 1. Receive a signal. • Can be any type of stimulus (change in environment, signal from another neuron, etc). 2. Transmit a signal to another location. • Ex: finger touching something • signal to spinal cord or brain. 3. Stimulate another cell • Another neuron • transmit signal • Muscle • contraction • Gland • secretion All neurons do three things:

  14. Structural • Multipolar • Bipolar • unipolar Classification of Neurons

  15. Functional - sensory neurons - motor neurons - interneurons

  16. Nerve- bundle of nerve fibers Nerve Impulse- weak electric current - series action potential along a nerve

  17. Presynaptic neuron- brings impulse to synapse Postsynaptic neuron- neuron stimulated/inhibited by impulse Synaptic Transmission- signal Synapse

  18. Axon end- hold neurotransmitter

  19. Excitatory - increase membrane permeability, increases chance for threshold to be achieved • Inhibitory - decrease membrane permeability, decrease chance for threshold to be achieved • Synaptic Transmission • Dendrite cell body axon synapse Neurotransmitters

  20. Neuron membrane maintains resting potential Threshold stimulus is received Sodium channels open Sodium ions diffuse inward, depolarizing the membrane Potassium channels open Potassium ions diffuse outward, repolarizing membrane Resulting action potential causes a local bioelectric current that stimulates adjacent portions of membrane Wave of action potentials travel the length of the axon as a nerve impulse Steps

  21. http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__the_nerve_impulse.htmlhttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__the_nerve_impulse.html http://outreach.mcb.harvard.edu/animations/actionpotential.swf

  22. Acetylcholine - stimulates muscle contraction Monoamines - Norepinephrine & Dopamine (sense of feeling good, low levels = depression) Serotonin (sleepiness) Endorphins (reduce pain, inhibit receptors) Types of Neurotransmitters

  23. Curare Strychnine Cocaine, morphine, alcohol, ether and chloroform Mescaline and LSD Ecstasy Drugs that affect Neurotransmitters

  24. Zoloft is part of a class of drugs called selective serotonin reuptake inhibitors, or SSRIs for short. SSRIs act on a specific chemical within the brain known as serotonin. This is one of several chemicals used to send messages from one nerve cell to another. Antidepressants

  25. Neuronal pool- Groups of neurons making synaptic connections to perform a common function Impulse Processing

  26. Sensory Nerves - conduct impulses into the brain or spinal cord Motor Nerves - carry impulses to muscles of glands Mixed Nerves - contain both sensory and motor nerves Types of Nerves

  27. Nerve Pathways Sensory/Afferent Neuron Receptor- Detects stimulus Central Nervous System- processes information Motor/Efferent Neuron Muscle or Gland- reacts

  28. Reflex Arc- simple pathway, includes few neurons • Reflex- simplest response • Reflex Behavior- automatic, subconscious response to stimuli • Sneezing, heart beat, vomiting, digestion Nerve Pathways

  29. Knee-jerk reflex- stimulus knee- sensory nerve-spinal cord-motor nerve Withdrawal reflex- occurs when you touch something painful http://www.intelligencetest.com/reflex/index.htm

  30. Brain = cranial cavity spinal cord= vertebral canal Protection= Mengines- membranes located between bone and soft tissue of nervous system Central Nervous SYStem

  31. Dura mater- outermost layer, blood vessels, nerves Arachnoid mater- no blood vessels, inbetween layer Pia mater- inner layer, contains many nerves and blood vessels to nourish cells Meninges- 3 layers

  32. LAYER OF DURA MATER

  33. Cerebrospinal fluid= between arachnoid and pia maters

  34. Nerve column, passes from brain down through vertebral canal 31 segments – each with a pair of spinal nerves Spinal nerves- branch to various body parts SPINAL CORD

  35. Cervical enlargement- supplies nerves to upper limbs (neck) Lumbar enlargement- lower back, supplies nerves to lower limbs

  36. Conduct impulses, serves as center for reflexes Ascending tracts= carry sensory info to brain Descending tracts= carry motor impulses from the brain to muscles/glands Spinal reflexes- reflex arcs pass through the spinal cord Function of Spinal Cord

  37. Cerebrum – largest, sensory and motor functions, higher mental function (memory, reasoning) Cerebellum – coordinate voluntary muscles Brain stem – regulate visceral functions BRAIN

  38. Balance and Coordination

  39. 1. Cerebral hemispheres- mirror images 2. Corpus callosum- nerve fibers that connect hemispheres Structures of The Cerebrum

  40. Wrinkles and Grooves of the brain gyri- ridges on brain Sulcus- deep grooves Fissure- very deep groove 3.Convolutions of the Brain

  41. Longitudinal fissure - separate right and left sides Transverse fissure- Separates cerebrum from cerebellum 4. Fissures

  42. Lateral fissure- separates the temporal lobe from the Frontal and Parietal lobes

  43. 5. Frontal – reasoning, thinking, language 6. Parietal – touch, pain, relation of body parts (somatosensory) 7.  Temporal Lobe – hearing 8.  Occipital – vision 9. Cerebral Cortex - thin layer of gray matter that is the outermost portion of cerebrum (the part with all the wrinkles) LoBes of The Brain

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