Module 3 Brains Building Blocks DEVELOPMENT OF THE

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 – ___________________________________________ – there about 20, 000 -25, 000 genes that contain chemical instructions that equal about _______ pages of written instructions – genes program the development of individual parts into a complex body & brain

DEVELOPMENT OF THE BRAIN (CONT. )

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 – _________________ – 1 trillion cells divided into • _______________________

STRUCTURE OF THE BRAIN (CONT. ) • Glial cells – 3 Functions: • ________________________________________ ____________________

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

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

BRAIN VERSUS MIND • Mind-body Question – how complex mental activities such as • ______________________ • _____________ – can be explained by the • _______________________ • _____________ – ___________

PARTS OF THE NEURON • Cell Body – large egg-shaped structure that provides fuel, manufactures chemicals, and ___________________________________________ • Dendrite – branchlike extensions that arise from the cell body – ___________________________________________ – pass these signals onto the cell body

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

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

ALZHEIMER’S DISEASE AND NEURONS • Alzheimer’s disease – _______________________________________ • Researchers recently discovered an experimental vaccine that may help stop the buildup of these glue-like, killer substances and they continue to search for other interventions

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

PERIPHERAL & CENTRAL NERVOUS SYSTEM • Peripheral Nervous System – ___________________________________________ • Central Nervous System – ___________________________________________

PERIPHERAL & CENTRAL NERVOUS SYSTEM (CONT. ) • Nerves – String-like 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

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 ___________________________________________ – opposite charges _____ and like charges ______

SENDING INFORMATION: ACTION POTENTIAL SEQUENCE (CONT. )

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

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

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

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 the very end of the axon • Nerve impulse – nerve impulse is made up of ______________, with the first occurring at the beginning of the axon

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 • ___________________ – inhibitory transmitters • ___________________

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

ALCOHOL • Alcohol (ethyl alcohol) – A psychoactive drug that is classified as a __________, which means that it depresses the activity of the _____________________

WHAT DOES ALCOHOL DO? • Alcohol affects the brain by imitating a naturally occurring neurotransmitter, GABA • GABA Neurons – GABA neurons have ___________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 __________________________________

WHAT DOES ALCOHOL DO? (CONT. ) • many people drink alcohol to _________________________________ • 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

NEW TRANSMITTERS • Number of well-known neurotransmitters, such as – A_________ – G__________ – N__________ – E___________ – D___________ – S___________

NEW TRANSMITTERS (CONT. ) • New – Endorphins (1970’s) • ____________ • ______ effects of pain during great bodily stress – Anandamide (1990’s) • similar to THC (active ingredient in marijuana) – involved with » memory » Motor movements » emotions

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

REFLEX • Reflex – Unlearned, _______reaction to some stimulus – neural connections underlying a reflex are prewired by genetic instructions

REFLEX (CONT. ) • Reflex sequence – sensors • ____________________ – afferent neurons • carry information from ________________________________

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

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. ) • Parkinson’s Disease – it is caused by ______________________________________ – L-dopa is a medication that _______ 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 • Removing part of the brain – Thalamotomy (Michael J. Fox) • Brain Stimulation – ________________________________________ – ____________________