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Module 03
- 1. Module 3Module 3 Brain’sBuilding BlocksBrain’s Building Blocks
- 2. DEVELOPMENT OF THEBRAIN • 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 THEBRAIN (CONT.)
- 4. DEVELOPMENT OF THEBRAIN (CONT.)
- 5. STRUCTURE OF THEBRAIN • 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 THEBRAIN (CONT.)
- 7. STRUCTURE OF THEBRAIN (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
- 8. STRUCTURE OF THEBRAIN (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. GROWTH OF NEWNEURONS • 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)
- 10. GROWTH OF NEWNEURONS (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
- 11. PARTS OF THENEURON
- 12. PARTS OF THENEURON • Cell Body – large egg-shaped structure that provides fuel, manufactures chemicals, and maintains the entire neuron in working order
- 13. PARTS OF THENEURON • 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
- 14. PARTS OF THENEURON • Axon – a single threadlike structure that extends from and carries signals away from the cell body to neighboring neurons, organs, or muscles
- 15. PARTS OF THENEURON • 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 THENEURON • 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)
- 17. PARTS OF THENEURON • Synapse – infinitely small space (20-30 billionths of a meter) – exists between and end bulb and its adjacent body organ (e.g. heart), muscles (e.g. head), or cell body
- 18. ALZHEIMER’S DISEASE ANDNEURONS • 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
- 19. ALZHEIMER’S DISEASE ANDNEURONS
- 20. PERIPHERAL & CENTRALNERVOUS SYSTEM • Peripheral Nervous System (PNS) – made up of nerves that are located throughout the body, except in the brain & spinal cord • Central Nervous System (CNS) – made up of neurons located in the brain & spinal cord
- 21. PERIPHERAL & CENTRALNERVOUS 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
- 22. SENDING INFORMATION: ACTION POTENTIALSEQUENCE – 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
- 23. SENDING INFORMATION: ACTION POTENTIALSEQUENCE (CONT.)
- 24. SENDING INFORMATION: ACTION POTENTIALSEQUENCE (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
- 25. SENDING INFORMATION: ACTION POTENTIALSEQUENCE (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
- 26. SENDING INFORMATION: ACTION POTENTIALSEQUENCE (CONT.)
- 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. TRANSMITTERS • A transmitteris 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
- 30. NEUROTRANSMITTER • Neurotransmitters – dozensof different chemicals that are made by neurons and then used for communication between neurons during the performance of mental or physical activities
- 31. ALCOHOL • Alcohol (ethylalcohol) – A psychoactive drug that is classified as a depressant, which means that it depresses the activity of the central nervous system
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- 33. WHAT DOES ALCOHOLDO? • 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
- 34. WHAT DOES ALCOHOLDO? (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
- 35. NEW TRANSMITTERS • Numberof well-known neurotransmitters, such as – Acetylcholine – GABA – Norepinephrine – Epinephrine – Dopamine – Serotonin
- 36. 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
- 37. 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
- 38. REFLEX • Reflex – unlearned,involuntary reaction to some stimulus – neural connections underlying a reflex are prewired by genetic instructions
- 39. REFLEX (CONT.) • Reflexsequence – sensors • sensors trigger neurons that start the withdrawal effect – afferent neurons • carry information from the senses to the spinal cord
- 40. 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
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- 42. PARKINSON’S DISEASE • Parkinson’sDisease – 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
- 43. 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
- 44. EXPERIMENTAL TREATMENTS • Sterotaxicprocedure – 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
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- 47. EXPERIMENTAL TREATMENTS • Removingpart of the brain – Thalamotomy (Michael J. Fox) • Brain Stimulation – electrodes placed into thalamus – patient controls amount of stimulus – helps reduce tremors
- 48.