Chapter 4 The Brain
The Nervous System Central Nervous System (CNS) receives, processes, interprets and stores info (taste, sound, smell, color etc.) Sends information to muscles, glands and internal organs Brain Spinal Cord extension of brain, brain to center of back, protected by spinal column; bridge to lower body Spinal reflexes movements without brains help (jerk from hot surface before brain registers pain) Peripheral Nervous System (PNS) All other nerves; sensory & motor nerves Handles CNS input and output All nervous system outside brain Sensory nerves put us in touch with outside world and inside activities Motor nerves enable use to move 2 parts of the Peripheral Nervous System Somatic nervous system (skeletal nervous system) sensory receptors Autonomic nervous system regulates internal organs and glands Sympathetic nervous system increase energy - mobilizes body in tine of emotion or stress (fight or flight) Parasympathetic nervous system conserves energy; slows down; operates in relaxed states
Communication: Nervous System Neuron basic unit of nervous system; nerve cell building block of nervous system microscopic; 100 billion; 200 types (size / shape) Glial Cells supports; nurtures and insulates neurons remove debris when neurons die; enhance performance & maintenance of neural connection; modify neuronal functioning; role in learning and memory Greek for glue
3 Structures of the Neuron Dendrite branches that receive information from other neurons & transmits information toward the cell body (tree like) Cell body - keeps neuron alive; determines if it will fire fire transmit message to other neurons Axon extending fiber that conducts impulses away from cell body & transmits them to other neurons Myelin sheath fatty insulation that may surround the axon Nerve bundle of nerve fibers (axons & sometimes dendrites) in peripheral nervous sys.
Stem cell research: Pro or Con Neurogenesis production of new neurons from immature stem cells Stem Cells immature cells that renew themselves potential to develop into mature cells in encouraged environment; grow into any cell type Need cells a few days old Abortion clinics Excess from fertility clinics
How Neurons Communicate Synapse site where transmission of nerve impulse from one nerve cell to another occurs; axon terminal synaptic cleft receptor sites in membrane of receiving cells
How Neurons Communicate Action potential brief change in electrical voltage that occurs btw the inside /outside of axon when a neuron is stimulated; produces an electrical impulse Neurotransmitter chemical substance that is released by transmitting neuron at the synapse & alters the activity of a receiving neuron
Neurotransmission / Synapse 1- Nerve impulses move down axon; Positively charged ions flow faster (mylenation = faster) 2- When impulse reach button tip; must get across synaptic cleft; synaptic vesicle release neurotransmitter 3- When reaches the other side; briefly bond w/ receptor sites (lock & key) 4- Receiving membrane will change; excite increase firing (+ voltage) inhibit decrease firing (- voltage) -multiple +/- messages sent; take average; how many fire; rate of fire; synchrony; type of neuron & location
3 Types of Nervous System Chemicals 1) Neurotransmitters Serotonin sleep; appetite; sensory perception; temperature regulation; pain suppression; mood Dopamine voluntary movement, learning; memory; emotion; pleasure or reward; response to novelty Acetylcholine - muscle action; cognitive functioning; memory; emotion Norepinephrine - ^ heart rate; slow intestinal activity during stress; learning, memory; dream; wake from sleep; emotion GABA - (gamma-aminobutyric acid) major inhibitory neurotransmitter in brain Glutamate major excitatory neurotransmitter in brain; 90% of neurons
3 Types of Nervous System Chemicals 2) Endorphins endogenous opioid peptide natures opiate reduce pain; increase pleasure appetite; sex; mood; learning; memory endorphin rush: falling in love / battle field
3 Types of Nervous System Chemicals 3) Hormones produced by endocrine glands effects the functioning of other organs endocrine glands organs produce hormone & release into blood stream Melatonin secreted by pineal gland regulate daily biorhythms; promote sleep Oxytocin produced by pituitary gland enhances uterine contractions during birth; ejection of milk nursing Adrenal hormones - produced by adrenal glands emotion and stress respond to heat; cold; pain; exercise; caffeine; nicotine Cortisol - ^blood sugar; boost energy; gain weight Epinephrine adrenaline; fight or flight; memory Sex hormones development and maintenance of reproductive organs stimulates male / female characteristics androgen testosterone male characteristics at puberty estrogen female characteristics at puberty progesterone lining of uterus in prep for fertilized egg
Quick Quiz a) Which word in ( ) better fits each of the following definitions? 1. Basic building blocks f the nervous system (nerves, neurons) 2. Cell parts that receive nerve impulses (axons, dendrites) 3. Site of communication between neurons (synapse, myelin sheath) 4. Opiate-like substance in the brain (dopamine, endorphin) 5. Chemicals that make it possible for neurons to communicate (neurotransmitters, hormones) 6. Hormone closely associated with emotional excitement (epinephrine, estrogen)
The Brain Location of function brain areas for particular functions Brain stem top of spinal cord ; pons & medulla Pons sleeping; waking and dreaming Medulla some automatic functions; breathing and heart rate functions that are not consciously willed Hanging cut medulla stop respiration Reticular activating system: Dense network of neurons at core of brain stem Arouses cortex and screens incoming information
The Brain Thalamus relays sensory message (except smell) to the cerebral cortex Traffic officer of the brain directs to higher area olfactory bulb (smell) The cerebellum Lesser brain memory of simple skills movement and balance gross motor - walking fine motor hold pencil; thread needle Hypothalamus and pituitary gland Hypothalamus Emotions; survival (hunger; fear; thirst; sex; reproduction) Regulates the autonomic system Pituitary gland master gland Small endocrine gland at base of spine Release hormones Regulate other endocrine glands
The Brain The limbic system memory; emotional reactions and motivated behavior Amygdala arousal and regulation of emotions initial emotional response to sensory information danger or threat Hippocampus sea horse in Latin storage of new information in memory gateway to memory compare new info with what is expected (also hypothalamus)
The Brain The Cerebrum higher forms of thinking largest grain structure upper part of brain; 2 hemispheres most sensory; motor and cognitive processes Cerebral hemispheres 2 halves of cerebrum Corpus callosum bundle of nerves fibers connecting 2 cerebral hemispheres Lateralization specialization of 2 hemispheres for particular operations Cerebral cortex collection of several thin layers of cells covering cerebrum higher mental functions 1/8 thick ¾ of all cells in human brain deep crevices and wrinkles (more neurons) rat-smooth Grey matter grey tissue of brain (White matter long myelin coved axons)
Lobes of the Cortex Occipital visual cortex receive visual information blindness / recognition Parietal somatosensory cortex receive info; pressure; pain; touch Temporal auditory cortex memory; perception; emotion Frontal motor cortex 600 muscles make plans; think creatively; emotions; initiative; short term memory Left lobe - Broca s area speech
Prefrontal Cortex - personality Rats and mice only 3.5% Humans 29% Phineas Cage railroad worker inch thick 31/2 foot rod through head miracle lived; think; speak; remember Dr. Jekyll / Mr. Hyde change not Phineas mild mannered to mean & angry responsible to not work; hold jobs
Right and Left Brain Right Brain Spatial visual ability Facial recognition Read facial expressions Music Intuitive Some language Some math Left Brain Logic Symbolic Sequential tasks Understanding technical materials Rational / analytic Math
Split Brain
Split Brain: Shown composite of photo (a) asked to pick out the face seen from series of photos (b); Stated; seen face on right side of composite; Yet, pointed with their left hands to the face that had been on the left 2 hemisphere not communicate Verbal left side only saw right half Mute right side aware of left half is left dominant?
Quick Quiz 1) Keeping in mind what both sides of the brain are involved in most activities, which of the following is / are more closely associated with the left hemisphere? a) Enjoying a musical recording b) Wiggling the left big toe c) Giving a speech in class d) Balancing a checkbook e) Recognizing a long lost friend
His and Her Brains?
His and Her Brains Gender differences (intuition, abilities) are stereotypes More alike than different. Sex differences; result rather than cause of behavioral differences Nature or nurture Brain difference not explain behavior or performance Difference in brain activity but not ability to complete Listen to John Grisham; women left and right temporal; men only left.