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Module 3 Brain’s Building Blocks INTRODUCTION • Alzheimer’s disease – 10% of cases start after age 50 – 90% of cases start after age 65 • Symptoms: – _____________________________ – _____________________________ – _____________________________ – _____________________________ INTRODUCTION (CONT’D) • Alzheimer’s disease – – – – – – Period of 5 to 10 years, symptoms worsen Result is profound memory loss Lack of recognition of family and friends Deterioration in personality Emotional outbursts Widespread damage to the brain (hippocampus, involved in memory) • no cure; always fatal INTRODUCTION (CONT’D) • Alzheimer’s disease • Diagnosis and causes – Researchers are close to identifying cause – Genetic – Neurological – Possible environmental factors – Certain chemicals (____________) that occur naturally in all brains seem to multiply and are believed to cause Alzheimer’s (chemicals act like glue and destroy brain cells) DEVELOPMENT OF THE BRAIN • Fact that your brain doesn’t develop into a nose is because of instructions contained in your genes • Genes – Chains of chemicals arranged like rungs on a twisting ladder – You have about _______________genes that contain chemical instructions equaling roughly ________ pages of written instructions – Genes program the development of individual parts into a complex body and brain DEVELOPMENT OF THE BRAIN (CONT’D) DEVELOPMENT OF THE BRAIN (CONT’D) STRUCTURE OF THE BRAIN • Human brain – – – – – – Shaped like a small, wrinkled melon 1,350 grams (less than three pounds) Pinkish-white color Consistency of firm Jell-O Fueled by ______________________________ 1 trillion cells divided into • ____________________ • ____________________ STRUCTURE OF THE BRAIN (CONT’D) • Glial cells – ________________________________ – __________________________________ – __________________________________________ __________________________________________ ______________ STRUCTURE OF THE BRAIN (CONT’D) STRUCTURE OF THE BRAIN (CONT’D) • Neuron – Brain cell with two specialized extensions – One extension is for ____________ electrical signals – The other extension is for ______________ electrical signals STRUCTURE OF THE BRAIN (CONT’D) 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) GROWTH OF NEW NEURONS (CONT’D) • Repairing the brain – Advances in stem research suggest the human brain may be able to grow more neurons – Repair damages due to • accident • disease • Alzheimer’s 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 ALZHEIMER’S DISEASE AND NEURONS • Alzheimer’s disease – Excessive buildup of glue-like substances – _______________________________________ • Researchers can study a person’s mental activities by taking brain scans of the neural activities going on inside the living brain ALZHEIMER’S DISEASE AND NEURONS PARTS OF THE NEURON • Cell body – Large egg-shaped structure that provides ______, _______________, and maintains the entire neuron in working order • Dendrite – __________________that arise from the cell body • ____________ signals from other ___________, ____________, or _________________ • ____________ these signals onto the cell body PARTS OF THE NEURON (CONT’D) • Axon – A _________________that extends/carries signals away from the cell body to neighboring neurons, organs, or muscles • Myelin sheath – Looks like ____________________ composed of fatty material that wraps around and insulates an axon – Prevents ______________ from ________________generated in adjacent axons PARTS OF THE NEURON (CONT’D) • End bulbs or terminal bulbs – Located at _______________of the axon’s branches – Miniature container that stores chemicals called ______________________(used to communicate with neighboring cells) • Synapse – Infinitely small space (20-30 billionths of a meter) – Exists between an end bulb and its adjacent body organ, heart, muscles, or cell body 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 NERUONS VERSUS NERVES PERIPHERAL & CENTRAL NERVOUS SYSTEM • Peripheral nervous system – Made up of nerves located throughout the body, _________________ in the brain and spinal cord • Nerves – String-like bundles of axons and dendrites that come from the ______________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 – Those in the ________________have the ability to _______________ _____________________ PERIPHERAL & CENTRAL NERVOUS SYSTEM (CONT’D) • Central nervous system – Made up of neurons located in the ______________________________ • Multiple sclerosis – Disease that attacks the ________________________that wrap around and insulate cells in ___________________________________ SENDING INFORMATION: ACTION POTENTIAL SEQUENCE – Stimulus (tack or nail) – Skin has sensors that pick up mechanical pressure and transform it into electrical signals – Signals are sent by the neuron’s axon to various areas in the spinal cord and brain – Brain interprets electrical signals as “pain” • 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 SENDING INFORMATION: ACTION POTENTIAL SEQUENCE (CONT’D) • Resting state – Axon has a charge – Charge results from the __________________positive ions on the outside from negative ions on the inside • Sodium pump – Transport process that picks up any sodium ions that enter the axon’s chemical gates and returns them back outside – Results in keeping axon charged by keeping sodium ions outside the axon membrane SENDING INFORMATION: ACTION POTENTIAL SEQUENCE (CONT’D) • Action potential – Tiny electric current generated when _____________ sodium ions rush inside the axon – Enormous increase of sodium ions inside the axon causes the inside of the axon to _____________ its charge – Inside becomes ____________ and outside becomes ________________ SENDING INFORMATION: NERVE IMPULSE (CONT’D) • Nerve impulse – Nerve impulse is made up of ____________ action potentials, with the ___________ occurring at the _________________ of the axon • All-or-none law – If an action potential starts at the beginning of the axon, the action potential will continue at the _________________ segment to segment to the very end of the axon SENDING INFORMATION: NERVE IMPULSE (CONT’D) TRANSMITTERS • A _____________ is a chemical messenger that transmits information between nerves and body organs, such as muscles and heart • Excitatory and inhibitory – Excitatory transmitters • _______________________________________ – Inhibitory transmitters • _______________________________________ NEUROTRANSMITTERS • Neurotransmitters – Dozens of different chemicals made by neurons and then used for communication between neurons during the performance of mental or physical activities NEUROTRANSMITTERS (CONT’D) ALCOHOL • Alcohol (ethyl alcohol) – A psychoactive drug classified as a __________________, which means that it depresses the activity of the central nervous system WHAT DOES ALCOHOL DO? • Alcohol affects the brain by imitating a naturally occurring neurotransmitter, ____________ • 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 ___________, they _____________ neural activity WHAT DOES ALCOHOL DO? (CONT’D) • Many people drink alcohol to feel ______________ and more ________________ • Appears to be a _____________ link between ______________ and __________________ • Deficiency in a specific brain protein is associated with high anxiety and excessive alcohol use NEW TRANSMITTERS • Number of well-known neurotransmitters, such as – – – – Norepinephrine GABA Dopamine Serotonin NEW TRANSMITTERS (CONT’D) – Endorphins (1970s) • painkiller similar to morphine • decreases effects of pain during great bodily stress – Anandamide (1990s) • similar to THC (active ingredient in marijuana) – involved with » memory » motor coordination » emotions NEW TRANSMITTERS (CONT’D) • Anandamide may help people regulate emotions, which would help them to better deal with anxiety and stress – Nitric oxide (mid-1990s) • may be involved in regulating aggressive and impulsive behaviors NEW TRANSMITTERS (CONT’D) – Orexin (hypocretin) • late 1990s • involved in the brain’s ____________ and _______________ • high levels: __________________ • low levels: _____________________ • involved in sleep and wakefulness – ______________________________ REFLEX • Reflex – _____________, ____________ reaction to some ________________ – Neural connections underlying a reflex are prewired by genetic instructions REFLEX (CONT’D) • Reflex sequence – Sensors • sensors trigger neurons that start the withdrawal effect – Afferent neurons (sensory neurons) • ________________________________________ ________________________________________ REFLEX (CONT’D) – Interneuron • relatively short neuron whose primary task is making connections between other neurons – Efferent neuron • ________________________________________ ________________________________________ ________________________________________ REFLEX (CONT’D) 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 PARKINSON’S DISEASE (CONT’D) • Parkinson’s disease – 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 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 EXPERIMENTAL TREATMENTS (CONT’D) EXPERIMENTAL TREATMENTS (CONT’D) EXPERIMENTAL TREATMENTS (CONT’D) • Removing part of the brain – Thalamotomy (Michael J. Fox) • Brain stimulation – Electrodes placed into thalamus – Patient controls amount of stimulus – Helps reduce tremors EXPERIMENTAL TREATMENTS (CONT’D)