Nervous System


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  • Positive on the outside, negative on the inside. An AP is when this is reversed, requires ATP
  • Nervous System

    1. 2. Nerve Cell The nerve cell is the basic unit of communication in the vertebrate nervous system
    2. 3. Three Classes of neurons <ul><li>The Neural circuit consists of </li></ul><ul><ul><li>Sensory neurons </li></ul></ul><ul><ul><ul><li>receptor for stimulus </li></ul></ul></ul><ul><ul><li>Interneuron </li></ul></ul><ul><ul><ul><li>integrate signals </li></ul></ul></ul><ul><ul><li>Motor neuron </li></ul></ul><ul><ul><ul><li>transfer signal to effector (muscle) </li></ul></ul></ul>
    3. 5. Anatomy of a Neuron <ul><li>Cell body: functional portion </li></ul><ul><li>Dendrites: short extensions that receive signals </li></ul><ul><li>Axon: long extension that transmits impulses </li></ul>
    4. 6. How does a neuron hold and move info? <ul><li>A neuron at rest has a voltage difference across the plasma membrane called a resting voltage potential </li></ul><ul><li>An action potential is when this charge across the membrane is briefly switched </li></ul><ul><li>The action potential moves down the membrane at a rapid pace. </li></ul><ul><li>Ap can move faster over mylenated portions is called saltatory conduction </li></ul>
    5. 9. How does a signal move from one neuron to another? <ul><li>A synaptic cleft divides 2 neurons </li></ul><ul><li>The AP will not move across the synaptic cleft </li></ul><ul><li>Neuro transmitters are released by the signal cell to the receiver cell </li></ul><ul><li>Move by diffusion </li></ul>
    6. 10. Types of chemical synapse <ul><li>Acetylcholine: neuromuscular junctions, glands, brain and spinal cord </li></ul><ul><li>Norepinepherine: affects brain regions concerned with emotions, dreaming </li></ul>
    7. 12. Paths of information flow <ul><li>Signals between the brain and spinal cord move to the body regions by nerves </li></ul><ul><li>Sensory nerves move a signal towards the brain and spinal cord </li></ul><ul><li>Motor neurons move a signal from the brain or spinal cord to the body </li></ul>
    8. 13. Divisions of the nervous System <ul><li>Central nervous system </li></ul><ul><li>CNS </li></ul><ul><li>Is the brain and spinal cord </li></ul><ul><li>Peripheral nervous system </li></ul><ul><li>PNS </li></ul><ul><li>all nerves that carry signals to and from the CNS </li></ul>
    9. 14. Parts of the PNS <ul><li>Sensory Division carries info to the brain and spinal cord. </li></ul><ul><li>Motor Division carries info from the brain to the bodies effectors (things that do the work) </li></ul>
    10. 15. The Motor division of the PNS has 2 divisions <ul><li>Somatic nerves relay commands to and from skeletal muscle </li></ul><ul><li>Voluntary control </li></ul><ul><li>Autonomic nerves send signals to and from smooth muscles </li></ul><ul><li>Involuntary control </li></ul><ul><li>Sympathetic </li></ul><ul><li>Parasympathetic </li></ul>
    11. 16. The autonomic divisions <ul><li>Parasympathetic </li></ul><ul><li>slow down the body activity when the body is not under stress </li></ul><ul><li>Rest and digest </li></ul><ul><li>Sympathetic </li></ul><ul><li>increase overall body activity during times of stress, excitement or danger </li></ul><ul><li>fight or flight response </li></ul><ul><li>hormone epinephrine </li></ul>
    12. 17. Sympathetic and Parasympathetic <ul><li>Are Antagonistic </li></ul><ul><li>Work towards the automatic, subconscious maintenance of homeostasis. </li></ul>
    13. 19. Components of the CNS <ul><li>Spinal cord </li></ul><ul><ul><li>31 pair of spinal nerves </li></ul></ul><ul><ul><li>Grey matter </li></ul></ul><ul><ul><li>White matter </li></ul></ul><ul><ul><li>Controls some reflex actions like bladder emptying </li></ul></ul><ul><li>Brain parts </li></ul><ul><ul><li>Hindbrain </li></ul></ul><ul><ul><ul><li>medulla oblongata </li></ul></ul></ul><ul><ul><ul><li>cerebellum </li></ul></ul></ul><ul><ul><ul><li>pons </li></ul></ul></ul><ul><ul><li>Midbrain </li></ul></ul><ul><ul><li>Forebrain </li></ul></ul><ul><ul><ul><li>cerebrum </li></ul></ul></ul><ul><ul><ul><li>thalamus </li></ul></ul></ul><ul><ul><ul><li>hypothalamus </li></ul></ul></ul>
    14. 20. Other parts of the CNS <ul><li>The two cerebral hemispheres communicate through the corpus collosum </li></ul><ul><ul><li>left verbal skills </li></ul></ul><ul><ul><li>right nonverbal skills such as music math, abstract </li></ul></ul><ul><li>Brain cavities and Canals </li></ul><ul><ul><li>cerebrospinal fluid surrounds and fills in cavities in the brain </li></ul></ul><ul><ul><li>Blood Brain barrier- controls what moves into the brain. Will prevent infections. </li></ul></ul>
    15. 21. Our state of consciousness <ul><li>The CNS governs sleeping, dozing, daydreaming and full alertness </li></ul><ul><li>neurons of the reticular activating system control the changing levels of consciousness by releasing serotonin. </li></ul>
    16. 22. Limbic system <ul><li>Involved in both memory and emotion. </li></ul><ul><li>Is involved with behavior. </li></ul><ul><li>Odors pass through this system and may influence or behavior and emotions. </li></ul>
    17. 23. Memory <ul><li>Association is the linkage of information to structural and chemical changes </li></ul><ul><li>short term- few bits lasts a couple of hours </li></ul><ul><li>Long term- permanent and limitless </li></ul><ul><li>The most important info goes rapidly into long term storage </li></ul><ul><li>memory is stored in a form resistant to degradation </li></ul><ul><li>Possibly caused by changes in synapses. </li></ul>
    18. 24. Tips on studying <ul><li>Concentrate on what you study. </li></ul><ul><li>Minimize interference. </li></ul><ul><li>Study takes time. </li></ul><ul><li>Break material into smaller portions. </li></ul><ul><li>Rephrase materials in your own words. </li></ul><ul><li>Test yourself to see what you know. </li></ul>
    19. 25. Disorders of the nervous system <ul><li>Trauma </li></ul><ul><li>Infections </li></ul><ul><li>Transmission and synaptic defects. </li></ul><ul><li>Abnormal growth </li></ul>
    20. 26. Sensory Reception If a tree falls in the woods with no one to listen does it make a sound?
    21. 27. Receptors <ul><li>Are the actual structures that respond to our environment. </li></ul><ul><li>Each receptor will respond to a different signal. </li></ul><ul><li>Essentially translators, they translate an energy into one that can be perceived by the brain. </li></ul>
    22. 28. Sensory systems consist of <ul><li>Each system has 3 parts </li></ul><ul><ul><li>1) sensory receptors. </li></ul></ul><ul><ul><li>2) pathway to the brain. </li></ul></ul><ul><ul><li>3) region of the brain that recognizes this section. </li></ul></ul>
    23. 29. Types of sensory Receptors <ul><li>Chemoreceptors </li></ul><ul><li>Mechanoreceptors </li></ul><ul><li>Thermoreceptors </li></ul><ul><li>Nociceptors </li></ul><ul><li>Photoreceptors </li></ul><ul><li>olfaction and taste </li></ul><ul><li>touch, stretch, hearing, equilibrium </li></ul><ul><li>radiant energy, infared </li></ul><ul><li>pain receptors </li></ul><ul><li>light </li></ul>
    24. 30. Sensory Pathways <ul><li>If a receptor is stimulated enough it results in an action potential. </li></ul><ul><li>The action potential reaches the brain. </li></ul><ul><li>The stronger the stimulus the greater number of action potentials reach the brain. </li></ul><ul><li>Sensory adaptation is when the action potentials are reduced by a constant stimulus. </li></ul><ul><li>Certain receptors will not adapt. </li></ul>
    25. 31. Somatic sensations <ul><li>Touch & Pressure </li></ul><ul><li>Temperature </li></ul><ul><li>Pain </li></ul><ul><li>Muscle sense </li></ul><ul><li>Mechanoreceptors that respond to changes or constant pressure </li></ul><ul><li>Increase in temperature causes and increase in AP </li></ul><ul><li>Respond to intense stimulus on other receptors, cannot be ignored </li></ul><ul><li>Mechanoreceptors give measurement as to the location of all the muscles and bones in a given moment. </li></ul>
    26. 32. Limb position, length and tension <ul><li>How do we know where we are at? </li></ul>
    27. 33. Referred pain
    28. 34. Taste and Smell <ul><li>Gustation : Taste </li></ul><ul><li>Receptors located on tongue, roof of mouth, throat and palate </li></ul><ul><li>Four tastes </li></ul><ul><ul><li>sweet </li></ul></ul><ul><ul><li>sour </li></ul></ul><ul><ul><li>bitter </li></ul></ul><ul><ul><li>salty </li></ul></ul><ul><li>Olfaction : smell </li></ul><ul><li>detect chemicals </li></ul><ul><li>olfactory bulbs in brain interpret smell </li></ul><ul><li>smell is often combined with emotion </li></ul>
    29. 35. Taste <ul><li>Taste Bud 25 cells </li></ul><ul><li>Taste hairs project into mouth </li></ul><ul><li>Hairs contain receptors </li></ul><ul><li>Categories </li></ul><ul><ul><li>Sweet </li></ul></ul><ul><ul><li>Sour </li></ul></ul><ul><ul><li>Salty </li></ul></ul><ul><ul><li>bitter </li></ul></ul>
    30. 36. Hearing <ul><li>Acoustical receptors detect vibrations </li></ul><ul><li>The ear </li></ul><ul><li>In the organ of corti loudness is determined by The total number of cells that are stimulated </li></ul><ul><li>Pitch depends on frequency of vibration </li></ul>
    31. 38. Balance <ul><li>Vestibular apparatus </li></ul><ul><li>Closed system of fluid filled sacs </li></ul><ul><li>Contain otoliths that detect changes in orientation as well as acceleration </li></ul><ul><li>Overstimulation of the hair cells of the vestibular apparatus results in motion sickness </li></ul>
    32. 39. Vestibular apparatus
    33. 41. The Eye
    34. 42. Structure of the eye <ul><li>Outer sclera (white) (is all the way around) </li></ul><ul><li>Cornea (clear) </li></ul><ul><li>Pupil (opening to the back) </li></ul><ul><li>Lens (transparent) </li></ul><ul><li>Retina (back side has photoreceptors and support material) </li></ul><ul><li>Fovea has highest concentration of photoreceptors. </li></ul>
    35. 43. Regulating light amount <ul><li>The iris adjusts to amount of light entering the eye. </li></ul><ul><li>The lens goes through accommodation to adjust lens curvature (as we age the lens cannot buldge enough to focus on a close object) </li></ul>
    36. 44. Light must reach the sensors by going through neurons. <ul><li>Outermost layer is pigmented to absorb light not absorbed by the sensors </li></ul><ul><li>Photoreceptors are in middle layer </li></ul><ul><li>Translucent neurons and ganglions are on top of the photoreceptors. </li></ul>
    37. 45. Production of Action Potentials by Rods and Cones <ul><li>Within these cells flattened disks contain photopigment </li></ul><ul><li>When this protein absorbs light it changes conformation, if enough are activated they cause an action potential. </li></ul><ul><li>Rods contain rhodopsin and are most sensitive to dim light </li></ul><ul><li>Cones contain different pigments </li></ul>
    38. 46. Rods and Cones <ul><li>Bright light tends to use more cones, 300x more sensitive </li></ul><ul><li>Dim light uses Rods and Rhodopsin, it is broken apart by light and must be remade (hence the 5-10 minute wait to see in darker areas) </li></ul>
    39. 47. Signaling to visual perception <ul><li>Photoreceptors are in the retina </li></ul><ul><li>When rods or cones are stimulated they send a signal to the brains visual cortex. </li></ul><ul><li>In the brain the final interpretation makes sense of sight </li></ul>
    40. 48. Problems with the Eyes <ul><li>Retinal detachment: retina separates form choroid </li></ul><ul><li>Cataracts: lens becomes opaque </li></ul><ul><li>Color blindness: Inability to distinguish colors, is a genetic disease, lacks specific types of cones </li></ul>
    41. 50. The Endocrine system The oldest method of control is using a signal molecule that moves from one part of the body to the other
    42. 51. The Endocrine System Regulates <ul><li>Salt and water balance </li></ul><ul><li>Blood pressure </li></ul><ul><li>Stress responses </li></ul><ul><li>Digestion </li></ul><ul><li>Cellular metabolism </li></ul><ul><li>Production of RBC’s </li></ul><ul><li>Growth and development </li></ul>
    43. 52. Location of Endocrine Glands
    44. 53. Hormones and other signal molecules <ul><li>Hormones : molecules secreted by glands into the blood that move to a nonadjacent target </li></ul><ul><li>Neurotransmitters : act on a directly adjacent cell </li></ul><ul><li>Local signaling molecule : act quickly and degrade quickly </li></ul><ul><li>Pheromones : secreted by glands and target cells in other organisms </li></ul>
    45. 54. Signaling Mechanisms <ul><li>Requirements </li></ul><ul><ul><li>Cells that secrete the signal molecule are either within a gland or nervous tissue </li></ul></ul><ul><ul><li>The signal molecule </li></ul></ul><ul><ul><ul><li>Steroid hormone (fat soluble will move through the plasma membrane) </li></ul></ul></ul><ul><ul><ul><li>Non steroid hormone (peptides and other molecules must bind to a receptor on the cell) </li></ul></ul></ul><ul><ul><li>Target cell </li></ul></ul>
    46. 55. Target cell activities <ul><li>Different hormones activate different cellular response mechanisms </li></ul><ul><li>No all cells have receptors for all hormones: </li></ul>Three possible hormones A cell with a single receptor on it Does not bind, No reaction Good fit rx occurs
    47. 56. Characteristics of the Endocrine system <ul><li>Each hormone acts only on certain cells </li></ul><ul><li>Cells respond only when they have receptors </li></ul><ul><li>Is slower than nervous system control </li></ul><ul><li>Endocrine and nervous system to interact with one another. </li></ul>
    48. 57. Interaction of Endocrine System and Nervous System
    49. 59. Negative Control using Hormones
    50. 60. The pancrease an endocrine and an exocrine gland <ul><li>Glucagon: raises blood sugars, release of stores and AA metabolism </li></ul><ul><li>Insulin: lowers blood sugars opposes glucagon </li></ul><ul><li>Somatostatin: inhibits secretion of the above enzymes </li></ul>
    51. 61. Bracketing using hormones
    52. 62. Regulation of Blood Calcium concentration <ul><li>Increase Calcium </li></ul><ul><ul><li>Parathyroid Hormone: removes calcium and phosphate from bone, increase absorption, retention of calcium in kidneys </li></ul></ul><ul><li>Decrease of Calcium </li></ul><ul><ul><li>Calcitonin </li></ul></ul>
    53. 65. Oxytocin and nursing, a cascade of events <ul><li>At the end of pregnancy, Estrogen rise. </li></ul><ul><li>Uterus produces more oxytocin receptors </li></ul><ul><li>Fetus produces oxytocin, starts a cycle of material production of oxytocin </li></ul><ul><li>Oxytocin is a part of the neuroendocrine reflexes and will help in the smooth muscle contractions which cause the release of milk. </li></ul>
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