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Understanding the Nervous System: Functions, Organization, and Cells

Explore the functions, organization, and cells of the nervous system, including the central and peripheral divisions. Learn about neurons, neuroglial cells, action potential, synapses, neurotransmitters, and more.

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Understanding the Nervous System: Functions, Organization, and Cells

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  1. Nervous System

  2. Functions • Stimulate all movement • Receive sensory input • Store and integrate information • Maintain homeostasis

  3. Organization • Two main divisions: 1. Central Nervous System(CNS) a. Brain and spinal cord b. Command and sensory integration center. 2. Peripheral Nervous System(PNS) a. All nerves that communicate with spinal cord and cranial region.

  4. Nice concept map to review with! 

  5. Nervous System Cells Neurons: carries the nerve impulses, mitosis not possible after reaching maturity Neuroglial cells: supports neurons, does not carry impulses, mitosis is possible throughout lifespan

  6. Neuron cell body Neuroglial cell nucleus

  7. Neuroglial Cells • Most abundant in CNS • 5 Major Types: 1. Microglial – phagocytes, protection 2. Oligodendrocytes – forms myelin in CNS 3. Astrocytes – provide support & connection between neurons and blood supply 4. Ependymalcells – lines cavities (Ventricles) of brain & spinal cord, helps form CSF, ciliated 5. Schwanncells – forms myelin in PNS

  8. Can you find two neurons in this picture? What division of the NS is being shown here? What neuroglial cell is not shown here and why not?

  9. Neurons • Large in size • Very high metabolic rate • Amitotic (no replacing after destruction), no centrioles • Extreme longevity…over 100 yrs. possible • Cell structures: - cell body, axon, dendrites, myelin sheath, nodes of Ranvier, nucleus, axon terminals, end bulbs, synapse (If myelinated, will have Schwann cells or Oligodendrocytes attached to axon)

  10. Basic Neuron Anatomy

  11. Impulses move along a one-way path! Dendrites Cell body Axon

  12. Neurons Structural Differences 1. Bipolar – rare, found in retina of eye • Unipolar – afferent (sensory) PNS • Multipolar –majority of all neurons; most in brain are multipolar.

  13. Neuron Organization

  14. Neuron types: Sensory, Interneurons, Motor

  15. Neuron Functional Differences Integrates and coordinates info from afferent, sends out response to efferent

  16. Neuron Pathway Types **Be able to describe the difference between the pathways.

  17. Nerve Impulse Conduction

  18. Membrane is polarized (charged!) -70mv inside cell Inside more negative than outside. What keeps it neg? Large, negative proteins, chloride ions, and nucleic acids inside. Neuron at Resting Potential Leaky membrane allows Na+ and K+ ions to diffuse, so Na/K pump is always working.

  19. Moving Action Potential Action potentials are pulse-like waves of voltage. Diffusion and electrochemical attraction move ions in/out Myelinated axons increase speed of action potential. Animation Animation 2

  20. Moving Impulse Along Neuron a. Resting potential = -70mv b. Depolarization – reversal of charges 1. Na+ gates open and enters cell 2. Potential changes to = +35mv c. Repolarization – reversal of charges to restore resting pot. 1. Na+ gates shut 2. K+ gates open and leaves cell d. Hyperpolarization – 1. Too much K+ moved out than was necessary e. Refractory period – Fixing overcorrection with active transport. Cannot respond to another stimulus. 1. Na/K+ pumps move Na+ out and K+ into cell to re-establish polarity Animation Animation 2 Animation 3

  21. Synapse • Neurotransmitters: communication chemicals (50+ types known!) • Threshold – minimum amount of stimulus needed for depolarization. • Reuptake transporters recycle neurotransmitters. Animation Neuron Communication Video

  22. Neurotransmitters • Excitatory – Increases activity of postsynaptic neuron. • Inhibitory – Decreases activity of postsynaptic neuron. • More than one type of neurotransmitter can be released by a single neuron and one neuron can have synapses with several different neurons (convergence and divergence), thus, a single neuron can have receptors for many different types of neurotransmitters.

  23. Common Neurotransmitters • Acetylcholine – Excitatory, skeletal muscle contraction • Norepinephrine – Excitatory; increase HR. • GABA – Inhibitory, reduces anxiety. • Glutamate – Excitatory, involved in learning and memory. • Endorphins – Inhibitory, natural opiates. • Serotonin – Involved in regulating attention, emotions, mood disorders • Dopamine – Contributes in voluntary movement; feel good emotions, Parkinson’s

  24. Drug Effects on Neurotransmitters • Pain killers – stop the release or block receptor sites or increase threshold. • Caffeine – lowers threshold at synapses so neurons are more easily excited. • Zoloft/Prozac/Paxil– keeps serotonin in the synapse longer; anti-depressants • Dilantin – increasing effectiveness of ion transport; treats seizures Go to Mouse Party for the affects of illegal drugs on neurotransmitters…

  25. The Brain Sections 9.11 and 9.13 * Contains approximately 100 Billion neurons * Weighs about 3 pounds

  26. Meninges: The Coverings • Three Layers: 1. Dura mater – outermost, tough, white 2. Arachnoid mater – middle, web-like, CSF in subarachnoid space 3. Pia mater – innermost, very thin on top of brain tissue Meningitis: Inflammation of the meninges and CSF; typical causes are bacteria or virus; spinal tap needed to diagnose

  27. Get your vaccination before college!

  28. Cerebrospinal Fluid - CSF • Clear and colorless • Circulates within the ventricles and sub-arachnoid space throughout CNS. • Produced by the ependymal glial cells. • Provides cushioning, optimum chemical environment, and nutrient/waste exchange. • Hydrocephalus – too much CSF, blockage usually the cause, can cause neuron damage.

  29. Hydrocephalus

  30. Major Brain Structures • Cerebrum- Divided into 4 lobes: (frontal, parietal, occipital, temporal) • Diencephalon: (thalamus, hypothalamus, epithalamus) • Brain Stem: (midbrain, pons, medulla oblongata) • Cerebellum

  31. Cerebrum • Two cerebral hemispheres • Longitudinal fissure separates hemispheres. • Surface area increased with Gyri (ridges) and Sulci (creases) or Fissures (deep grooves). • Connected by the Corpus Callosum • Function: Intelligence, memory, learning • Cerebral cortex – gray matter, outermost, all conscious thinking occurs here • Olfactory bulb – sense of smell

  32. Parieto-occipital sulcus

  33. Functions of the Cerebrum

  34. Let’s Probe the brain! – find out how scientists found out where primary motor functions are.

  35. Comparing Human, Dog and Rat Brains

  36. Diencephalon Main structures: 1. Thalamus – main relay station for sensory impulses (except smell) to the cerebral cortex. 2. Hypothalamus – regulates visceral movement (BP, GI tract, HR), body temperature, water and electrolytes, hunger, thirst, stimulate pituitary, maintains sleep and wake patterns. 3. Epithalamus – contains the Pineal gland which regulates biological clock.

  37. Brain Stem Three sections: 1. Midbrain – visual and auditory reflex centers, main motor pathway • Pons – “bridge”, relays impulses between: a. medulla/cerebrum b. cerebrum/cerebellum 3. Medulla Oblongata –regulates heart rate, blood pressure, respiration, coughing, sneezing, vomiting, swallowing

  38. Cerebellum • 2nd largest part of brain • Controls muscular coordination • Maintains posture • Allows for smooth, refined movements • Involuntary once learned

  39. Brain Disorders and Diseases

  40. Common Brain Injuries • Concussion – abrupt, but temporary loss of consciousness from a blow to the head. Symptoms: headache, confusion, memory loss, lack of concentration • Contusion – bruising of the brain due to trauma, leaking capillaries, commonly follows a concussion. Pia mater torn. Signs: Immediate loss of consciousness, loss of reflexes, decreased blood pressure, cessation of respiration. • Laceration – tear of the brain, large vessel rupture, cerebral hematoma, increased intercranial pressure.

  41. Brain Tumors

  42. Brain Aneurism Cerebral thrombosis video

  43. Strokes

  44. Injury Effects

  45. Phineas Gage Man who survived a terrible brain injury in the 1800’s. First opportunity for scientists to study the frontal lobe and limbic system connection. Limbic system is the emotional region and frontal keeps the limbic region in control. Injury re-enactment video

  46. CAN YOU READ THIS? cdnuolt blveiee taht I cluod aulaclty uesdnatnrd waht I was rdanieg. The phaonmneal pweor of the hmuan mnid, aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoatnt tihng is taht the frist and lsat ltteer be in the rghit pclae. The rset can be a taotl mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. Amzanig huh? yaeh and yuo Iawlyas tghuhot slpeling was ipmorantt!

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