Brain’s Building Blocks Module 3 Brain’s Building Blocks

INTRODUCTION Alzheimer’s disease 10% of cases start after age 50 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) Glial cells _______________________________________ ______________________________________________________________________________________________________________________________

STRUCTURE OF THE BRAIN (CONT’D)

STRUCTURE OF THE BRAIN (CONT’D) Neuron ________________________________________ ________________________________________________________________________________________________________________________________________________________________________

Neuron Preview Question 1: What are neurons, and how do they transmit information?

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 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) 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) ______________________________________________________________________________________________________________________________ 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 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 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 (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 pleasure and reward system high levels: ____________________________ low levels: ______________________________ involved in sleep and wakefulness _____________________________________

REFLEX Reflex ______________________________________________________________________________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________

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) 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)