Module 3 Brains Building Blocks INTRODUCTION Alzheimers disease
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: – Problems with memory – Forgetting and repeating things – Getting lost – Being mildly confused
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 – _____________________________________________ – Certain chemicals (_________) that occur naturally in all brains seem to multiply and are believed to cause Alzheimer’s (________________)
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 20, 000 to 25, 000 genes that contain chemical instructions equaling roughly 300, 000 pages of written instructions – Genes program the development of individual parts into a complex body and brain
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 sugar (glucose) 1 trillion cells divided into • ___________________
STRUCTURE OF THE BRAIN (CONT’D)
Neuron
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 – Gradually destroy neurons • 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 ________________________________________________ • Dendrite – Branch-like extensions that arise from the cell body • ______________________________________________ ______________________________________________
PARTS OF THE NEURON (CONT’D) • Axon – A single thread-like structure that extends/carries signals away from the cell body to neighboring neurons, organs, or muscles • Myelin sheath – Looks like separate tube-like segments composed of fatty material that wraps around and insulates an axon – ________________________________________________
PARTS OF THE NEURON (CONT’D) • End bulbs or terminal bulbs – Located at extreme ends of the axon’s branches – Miniature container that ________________________________________________ • 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
NEURONS 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, ________________________________________________ • Nerves – __________________ that come from the spinal cord and are held together by connective tissue – Carry information from the ________________________________________________ – Those in the peripheral nervous system have the ability to grow or reattach if severed or damaged
PERIPHERAL & CENTRAL NERVOUS SYSTEM (CONT’D) • Central nervous system – Made up of neurons located in the ______________________ • Multiple sclerosis – ________________________________________ ____________________
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)
SENDING INFORMATION: ACTION POTENTIAL SEQUENCE (CONT’D) • Resting state – Axon has a charge – Charge results from the axon membrane separating ________________________________________________ • 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 – ________________________________________________ – Enormous _____ of sodium ions inside the axon causes the ________to ______ its charge – Inside becomes ______ and outside becomes _________
SENDING INFORMATION: NERVE IMPULSE
SENDING INFORMATION: NERVE IMPULSE (CONT’D) • Nerve impulse – Nerve impulse is made up of six action potentials, with the first occurring at the beginning 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 same speed segment to the very end 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 (agonists) • ____________________ – Inhibitory transmitters (antagonists) • ____________________
Agonists
Antagonists
NEUROTRANSMITTERS • Neurotransmitters – Dozens of different chemicals made by ______________ and then used for ________ between neurons during the performance of ______________________ activities
NEUROTRANSMITTERS (CONT’D)
Acetylcholine (ACH) • Deals with motor movement and memory. • Too much and you will…. • Too little and you will… • Lack of ACH has been linked to Alzheimer’s disease.
Dopamine • Deals with motor movement and alertness. • Lack of dopamine has been linked to Parkinson’s disease. • Too much has been linked to schizophrenia.
Serotonin • Involved in mood control. • Lack of serotonin has been linked to clinical depression.
ALCOHOL • Alcohol (ethyl alcohol) – A __________________, which means that it ___________ the activity of the ______________________
ALCOHOL (CONT’D)
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
WHAT DOES ALCOHOL DO? (CONT’D) • 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
Neurotransmitters
NEW TRANSMITTERS • Number of well-known neurotransmitters, such as – – Norepinephrine GABA Dopamine Serotonin
NEW TRANSMITTERS (CONT’D) – 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 » 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-1990 s) • may be involved in regulating aggressive and impulsive behaviors
NEW TRANSMITTERS (CONT’D) – Orexin (hypocretin) • • • late 1990 s involved in the brain’s pleasure and reward system high levels: ______________ low levels: _______________ involved in sleep and wakefulness – ___________________
REFLEX (CONT’D) • Reflex sequence – Sensors • ________________________________________ – Afferent neurons (sensory neurons) • ________________________________________
REFLEX (CONT’D) – Interneuron • relatively short neuron whose primary task is ________________________________________ – Efferent neuron • ________________to produce __________ in various muscles and organs throughout the body
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)
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