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Nervous System

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  1. Nervous System Chapter 10 & 11

  2. Do Now • Think of at least 2 ways in which the Integumentary system is directly related to the Nervous system, and describe them in your notebook • Watch this video and tell me if you know what the problem is. What are his symptoms? •

  3. The Nervous System : communication A.  Neurons = masses of nerve cells that transmit information 1. Cell Body - contains the nucleus and two extensions 2. Dendrites – shorter, more numerous, receive information 3. Axons – single, long “fiber” which conducts impulse away from the cell body, sends information

  4. Nervous System Central Nervous System (CNS): brain and spinal cord. Peripheral Nervous System (PNS): nerves of the body                    -- Includes 31 pairs of spinal nerves                    -- And  12 pairs of cranial nerves

  5. Basic Divisions of the Nervous System Figure 12.2

  6. Sensory -  gathers info • Integrative - information is brought together • Motor - responds to signals, homeostasis THREE BASIC FUNCTIONS OF THE NERVOUS SYSTEM

  7. Motor Functions Somatic Nervous System  - skeletal (voluntary) Autonomic Nervous System -  smooth muscles, glands (involuntary)

  8. Neuroglial Cells  (p 208)  - support cells for the neurons 1.  Microglial Cells: scattered throughout, digest debris or bacteria Microglial cells respond to immunological alarms

  9. Neuroglial Cells  (p 208) 2.  Oligodendrocytes:   provide insulation around the axons

  10. Neuroglial Cells  (p 208) 3. Astrocytes:  connect blood vessels to neurons I connect to blood vessels

  11. Neuroglial Cells  (p 208) 4.  Ependymal Cells:  form a membrane that covers brain-like parts

  12. 5.  Schwann cells:  form the insulating myelin sheath around the neurons Practice with neuroglia coloring!

  13. Supporting Cells - NEUROGLIA

  14. Supporting Cells- NEUROGLIA

  15. Neurons

  16. Axon - long section, transmits impulses Dendrite - small extensions from the cell body; receive information Neurofibrils - fibers within the axon

  17. Chromatophilic substance (rough ER) - transport system • Myelin -insulation surrounding axons • Nodes of Ranvier - gaps in the insulation

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

  19. Label

  20. Interesting Facts about the Neuron The nerve fibers of newborns are unmyelinated - this causes their responses to stimuli to be course and sometimes involve the whole body.  Try surprising a baby! Longevity – can live and function for a lifetime Do not divide – fetal neurons lose their ability to undergo mitosis; neural stem cells are an exception High metabolic rate – require abundant oxygen and glucose

  21. Functional: Sensory, Motor, Interneurons Structural: (A) Bipolar(B) Unipolar(C) Multipolar Types of Neurons

  22. Cell Membrane Potential

  23. At rest, the inside of a neuron's membrane has a negative charge. As the figure shows, a Na+ / K+ pump in the cell membrane pumps sodium out of the cell and potassium into it. However,  more potassium ions leak out of the cell. As a result, the inside of the membrane builds up a net negative charge relative to the outside. Nerve Impulses Animations of Nerve Impulses

  24. Synapse - junction between two communicating neurons Nerve pathway - nerve impulse travels from neuron to neuron Synaptic Transmission Dendrite ->cell body -> along axon -> synapse (gap) To complete the signal, a NEUROTRANSMITTER is released at the gap to signal the next neuron The Synapse

  25. Structure of a Synapses

  26. Excitatory - increase membrane permeability, increases chance for threshold to be achieved Inhibitory - decrease membrane permeability, decrease chance for threshold to be achieved Neurotransmitters

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

  28. Curare • Strychnine • Cocaine, morphine, alcohol, ether and chloroform • Mescaline and LSD • Ecstasy Drugs that Affect Synapses and Neurotransmitters

  29. Dangers of Ecstasy (MDMA) The neurotransmitter serotonin is vital in regulating many of our basic functions. Serotonin is, among other things, the feel good neurotransmitter and helps to regulate body temp. Our brain cells are constantly trying to bring some amount of serotonin back into the cells and out of the synapse using serotonin reuptake transporters.  Ecstasy essentially takes these upkeep transporters and reverses their roles. This causes a massive flood of serotonin from the brain cells into the synapse.  The most common cause of Ecstasy-related death is overheating (hyperthermia). MDMA interferes with the body's ability to regulate its own body temperature and to see other warning signs allowing the body to overheat without discomfort especially when dancing for hours in hot clubs.

  30. LSD; lysergic acid diethylamide Actions/Effects: LSD alters the action of the neurotransmitters serotonin, norepinephrine, and dopamine, triggering extreme changes in brain function. Physical effects include increased body temperature, heart rate, and blood pressure. Psychological effects include perceptual and thought distortions, hallucinations, delusions, and rapid mood swings. Cocaine blocks reuptake of dopamine

  31. 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

  32. Neuronal pool - groups of neurons that make hundreds of synaptic connections and work together to perform a common function These "pools" help us remember sequential tasks, like tying a shoe or riding a bike. 9.8 Impulse Processing

  33. 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 9.9 Types of Nerves

  34. Neurons Classified by Function: Sensory vs. Motor Neurons Figure 12.11

  35. Reflex arc - only includes a few neurons • Reflex Behavior - automatic, subconscious responses • Knee-jerk reflex - maintains uprightedness • Withdrawal reflex - avoidance of painful stimuli 9.10 Nerve Pathways

  36. 9.11  The Meninges Dura mater - outermost layer Arachnoid mater  -  no blood vessels, in between layer (resembles a spider web) Pia mater -inner membrane, contains nerves and blood vessels to nourish cells

  37. The Meninges CSF -  cerebrospinal fluid               See video of a Spinal Tap Figure 13.25a

  38. Dura mater is being peeled away in this photo.

  39. Subdural Hematoma

  40. passes down the vertebral canal, has 31 segments  (each with a pair of spinal nerves) Spinal Cord Cervical enlargement = supplies nerves to upper limbs (neck)Lumbar enlargement = supplies nerves to the lower limbs (lower back) FUNCTION: conducting nerve impulses, serves as a center for spinal reflexes

  41. ASCENDING  - impulses travel to the brain (sensory)DESCENDING - impulses travel to the muscles (motor)

  42. Spinal reflexes - reflex arcs pass through the spinal cord

  43. Hello and thank you for calling The State Mental Hospital. Please select from the following options menu: • If you are obsessive-compulsive, press 1 repeatedly. If you are co-dependent, please ask someone to press 2 for you. If you have multiple personalities, press 3, 4, 5 and 6. If you are paranoid, we know who you are and what you want, stay on the line so we can trace your call. If you are delusional, press 7 and your call will be forwarded to the Mother Ship. If you are schizophrenic, listen carefully and a little voice will tell You which number to press. If you are manic-depressive, hang up. It doesn't matter which number you press, nothing! will make you happy anyway. If you are dyslexic, press 9-6-9-6. If you are bipolar, please leave a message after the beep or before the beep or after the beep.   • But Please wait for the beep. If you have short-term memory loss, press 9. If you have short-term memory loss, press 9. If you have short-term memory loss, press 9. If you have low self-esteem, please hang up. Our operators are too busy to talk with you. If you are menopausal, put the gun down, hang up, turn on the fan, lie down and cry. You won't be crazy forever. MENTAL HOSPITAL PHONE MENU