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Module 3

Module 3. Brain’s Building Blocks. DEVELOPMENT OF THE BRAIN. fact that your brain does not develop into a nose is because of instructions contained in your genes Genes chains of chemicals that are arranged like rungs on a twisting ladder

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Module 3

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  1. Module 3 Brain’s Building Blocks

  2. DEVELOPMENT OF THE BRAIN • fact that your brain does not develop into a nose is because of instructions contained in your genes • Genes • chains of chemicals that are arranged like rungs on a twisting ladder • there are about 20,000-25,000 genes that contain chemical instructions that equal about 300,000 pages of written instructions • genes program the development of individual parts into a complex body & brain

  3. DEVELOPMENT OF THE BRAIN (CONT.)

  4. DEVELOPMENT OF THE BRAIN (CONT.) Six week old brain

  5. STRUCTURE OF THE BRAIN • Human brain: • is shaped like a small wrinkled melon • 1,350 grams (less than 3 pounds) • pinkish-white color • consistency of firm Jell-O • Fueled by sugar (glucose) • 1 trillion cells divided into • glial cells • neurons

  6. STRUCTURE OF THE BRAIN (CONT.) • Glial cells • 3 Functions: • guide the growth of developing neurons • wrap around neurons and form an insulation to prevent interference from other electrical signals • release chemicals that influence a neuron’s growth and function

  7. STRUCTURE OF THE BRAIN (CONT.)

  8. STRUCTURE OF THE BRAIN (CONT.) • Neuron • a brain cell with 2 specialized extensions • one extension is for receiving electrical signals • the other extension is for transmitting electrical signals

  9. STRUCTURE OF THE BRAIN (CONT.)

  10. STRUCTURE OF THE BRAIN (CONT.) • http://www.dnatube.com/video/1301/Neurons-and-Neuro-transmitters

  11. GROWTH OF NEW NEURONS • Can a brain grow new neurons? • canary brain • can grow about 20,000 neurons a day during the spring (learns new breeding song) • primate and human brain • researchers conclude that adult monkey and human brains are capable of growing relatively limited numbers of neurons throughout adulthood • Some new neurons play important role in continuing to learn and remember new things (hippocampus) • http://www.youtube.com/watch?v=FZ3401XVYww

  12. GROWTH OF NEW NEURONS (CONT.) • Repairing the Brain • advances in stem research suggest the human brain may be able to grow more neurons • repair damages: • accident • disease • Alzheimer’s

  13. BRAIN VERSUS MIND • Mind-body Question • how complex mental activities such as • feeling • thinking • learning • can be explained by the • physical • chemical • electrical activities • of the brain

  14. PARTS OF THE NEURON • Cell Body • large egg-shaped structure that provides fuel, manufactures chemicals, and maintains the entire neuron in working order • Dendrite • branchlike extensions that arise from the cell body • receive signals from other neurons, muscles, or sense organs • pass these signals onto the cell body

  15. PARTS OF THE NEURON (CONT.) • Axon • a single threadlike structure that extends from and carries signals away from the cell body to neighboring neurons, organs, or muscles • Myelin Sheath • looks like separate tubelike segments composed of fatty material that wraps around and insulates an axon • prevents interference from electrical signals generated in adjacent axons

  16. PARTS OF THE NEURON (CONT.) • End bulbs or Terminal bulbs • located at extreme ends of the axon’s branches • miniature container that stores chemicals called neurotransmitters (used to communicate with neighboring cells) • Synapse • infinitely small space (20-30 billionths of a meter) • exists between and end bulb and its adjacent body organ, heart, muscles, or cell body

  17. ALZHEIMER’S DISEASE AND NEURONS • Alzheimer’s disease • excessive buildup of gluelike substances • gradually destroy neurons • Researchers recently discovered an experimental vaccine that may help stop the buildup of these gluelike, killer substances and they continue to search for other interventions

  18. NERUONS VERSUS NERVES • Reattaching Limbs • John Thomas • lost arms in farming accident • Transplanting a Face • Isabelle • face severely disfigured by a dog • received • new nose • lips • chin

  19. PERIPHERAL & CENTRAL NERVOUS SYSTEM • Peripheral Nervous System • made up of nerves that are located throughout the body, except in the brain & spinal cord • Central Nervous System • made up of neurons located in the brain & spinal cord

  20. PERIPHERAL & CENTRAL NERVOUS SYSTEM (CONT.) • Nerves • stringlike bundles of axons and dendrites that come from the spinal cord and are held together by connective tissue • carry information from the senses, skin, muscles, and the body’s organs to and from the spinal cord • nerves in the peripheral nervous system have the ability to grow or reattach if severed or damaged

  21. SENDING INFORMATION: ACTION POTENTIAL SEQUENCE • axon membrane has chemical gates that can open to allow electrically charged particles to enter or can close to keep out these particles • ions are chemical particles that have electrical charges • opposite charges attract and like charges repel

  22. SENDING INFORMATION: ACTION POTENTIAL SEQUENCE (CONT.)

  23. SENDING INFORMATION: ACTION POTENTIAL SEQUENCE (CONT.) • Resting state • the axon has a charge • the charge results from the axon membrane separating positive ions on the outside from negative ions on the inside

  24. SENDING INFORMATION: ACTION POTENTIAL SEQUENCE (CONT.) • Action potential • tiny electric current that is generated when the positive sodium ions rush inside the axon • enormous increase of sodium ions inside the axon causes the inside of the axon to reverse its charge • inside becomes positive and outside becomes negative

  25. SENDING INFORMATION: ACTION POTENTIAL SEQUENCE (CONT.)

  26. The Action Potential PLAY VIDEO

  27. SENDING INFORMATION: NERVE IMPULSE • Sending information • action potential is a tiny electrical current that is generated when the positive sodium ions rush inside the axon • the enormous increase of Na ions inside the axon causes the inside to reverse its charge • the inside becomes positive & the outside becomes negative

  28. SENDING INFORMATION: NERVE IMPULSE (CONT.) • All-or-None law • if an action potential starts at the beginning of the axon, the action potential will continue at the same speed segment to segment to the very end of the axon • Nerve impulse • nerve impulse is made up of 6 action potentials, with the first occurring at the beginning of the axon

  29. SENDING INFORMATION: NERVE IMPULSE (CONT.)

  30. TRANSMITTERS • A transmitter is a chemical messenger that transmits information between nerves and body organs, such as muscles and heart • Excitatory and Inhibitory • excitatory transmitters • open chemical locks and turn on neurons • inhibitory transmitters • block chemical locks and turn off neurons

  31. NEUROTRANSMITTER • Neurotransmitters • dozens of different chemicals that are made by neurons and then used for communication between neurons during the performance of mental or physical activities

  32. ALCOHOL • Alcohol (ethyl alcohol) • A psychoactive drug that is classified as a depressant, which means that it depresses the activity of the central nervous system

  33. ALCOHOL

  34. WHAT DOES ALCOHOL DO? • Alcohol affects the brain by imitating a naturally occurring neurotransmitter, GABA • GABA Neurons • GABA neurons have chemical locks that can be opened by chemical keys in the form of the neurotransmitter GABA • GABA Keys • alcohol molecules so closely resemble those of the GABA neurotransmitter that alcohol can function like GABA keys and open GABA receptors • when GABA neurons are excited, they decrease neural activity

  35. WHAT DOES ALCOHOL DO? (CONT.) • many people drink alcohol to feel less anxious and more relaxed • appears to be a biological link between alcohol and anxiety • deficiency in a specific brain protein is associated with high anxiety and excessive alcohol use

  36. NEW TRANSMITTERS • Number of well-known neurotransmitters, such as • Acetylcholine • GABA • Norepinephrine • Epinephrine • Dopamine • Serotonin

  37. NEW TRANSMITTERS (CONT.) • New • Endorphins (1970’s) • painkiller similar to morphine • decreases effects of pain during great bodily stress • Anandamide (1990’s) • similar to THC (active ingredient in marijuana) • involved with • memory • motorcoordination • emotions

  38. NEW TRANSMITTERS (CONT.) • Anandamide may help people regulate emotions, which would help them to better deal with anxiety and stress • Nitric oxide (mid-1990’s) • may be involved in regulating aggressive and impulsive behaviors

  39. REFLEX • Reflex • unlearned, involuntary reaction to some stimulus • neural connections underlying a reflex are prewired by genetic instructions

  40. REFLEX (CONT.) • Reflex sequence • sensors • sensors trigger neurons that start the withdrawal effect • afferent neurons • carry information from the senses to the spinal cord

  41. REFLEX (CONT.) • Interneuron • relatively short neuron whose primary task is making connections between other neurons • Efferent neuron • carry information away from the spinal cord to produce responses in various muscles and organs throughout the body

  42. REFLEX (CONT.)

  43. PARKINSON’S DISEASE • Parkinson’s Disease • includes symptoms of tremors and shakes in the limbs, a slowing of voluntary movements, muscle stiffness, problems with balance and coordination and feelings of depression • as the disease progresses, patients develop a shuffling walk and may suddenly freeze in space for minutes or hours at a time • Michael J. Fox

  44. PARKINSON’S DISEASE (CONT.) • Parkinson’s Disease • it is caused by destruction of neurons that produce dopamine • L-dopa is a medication that boosts the levels of dopamine in the brain • eventually the drug causes involuntary jerky movements • after prolonged use, L-dopa’s beneficial effect may be replaced by unwanted jerky movements

  45. EXPERIMENTAL TREATMENTS • Sterotaxic procedure • fixing a patient’s head in a holder and drilling a small hole through the skull • the holder has a syringe that can be precisely guided into a predetermined location in the brain

  46. EXPERIMENTAL TREATMENTS

  47. EXPERIMENTAL TREATMENTS

  48. EXPERIMENTAL TREATMENTS • Removing part of the brain • Thalamotomy (Michael J. Fox) • Brain Stimulation • electrodes placed into thalamus • patient controls amount of stimulus • helps reduce tremors

  49. EXPERIMENTAL TREATMENTS

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