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Transcript of Section A Neural Communication: Neurons Neuron a nerve cellNeuron –Sensory neurons (afferent...
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Section ANeural Communication: Neurons
• Neuron a nerve cell– Sensory neurons (afferent Neurons) carry incoming
information from the sensory receptors to spinal cord or brain.
– Motor neurons (efferent neurons) carry outgoing information from the brain and spinal cord to the muscles and glands.
– Interneurons neurons in the brain and spinal cord that communicate between the sensory inputs and motor outputs. Communication between sensory and motor neurons
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Neurons
Parts of a Neuron:Dendritethe bushy, branching extensions of a neuron that receive
messages from other neurons and conduct impulses toward the cell body.
Axon messages pass to other neurons or to muscles or glands.
Myelin sheath fatty tissue encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.
Multiple sclerosis=wearing down of Myelin Sheath
Terminal branches(end button, axon terminal, synaptic knobs) -branched end of axon that contains neurotransmitters
Cell body (aka Soma)-contains nucleus and other parts needed to sustain life
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Neurons
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Neurons
– Action potential firing of a neuron, a neural impulse; a brief electrical charge that travels down an axon
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Action Potential
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Neurons• Firing of a neuron
– Depolarize=when axons allow info in and cause a domino effect with axons
– Refractory period=inactivity after neuron had fired-can’t respond to stimulation, the inside of the cell membrane is negative compared to the outside
– Excitatory neurotransmitters (chemicals released from terminal buttons that excite next neuron to fire)versus
– inhibitory (chemicals inhibit next button from firing)– Threshold a level of stimulation required to trigger a
neural impulse.
-All or none response-neurons fire completely or not at all
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How Neurons Communicate
• Synapse = Synaptic gap = synaptic cleft-the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or synaptic cleft.
• Neurotransmitters chemical messengers that cross the synaptic gaps between neurons.
• Reuptake a neurotransmitter’s absorption
Into the terminal buttons of the sending neuron.• Postsynaptic membrane/Pre-synaptic
membrane
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How Neurons Communicate
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How Neurotransmitters Influence Us
• Know ALL information in chart, p.57 Plus:
Endorphins “opiate Like” linked to pain control
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How Neurotransmitters Influence UsHow Drugs and Other Chemicals Alter
Neurotransmitters• Agonists versus antagonists
– Agonists
Mimics
neurotransmitter– Antagonists
Blocks reuptake of
neurotransmitter
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Introduction
• Nervous System is speedy and consists of all the nerve cells of the peripheral and central nervous systems.
– Central Nervous System (CNS) the brain and spinal cord.– Peripheral Nervous System (PNS) =Somatic (voluntary movement) and
Autonomic (automatic functions)• Nerves= bundled axons
that form neural “cables”
connecting the
central nervous system
with
muscles
glands and
sense organs
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The Peripheral Nervous System
Somatic Nervous System controls skeletal muscles. • Also called the skeletal nervous system.
Autonomic Nervous System controls glands/muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms.
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The Nervous System-. 59 (Know these divisions)
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The Central Nervous System
• Brain and spinal cordReflex a simple, autonomic
response to a sensory
stimulus such as the
knee-jerk response.
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A Simple Reflex
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Endocrine System-Contains Most Glands
Endocrine system the body’s “slow” chemical
communication system; a set of glands that
secrete :
Hormones into the bloodstream-longer lasting than neurotransmitters
Adrenal glands a pair sit just above the kidneys and secrete
hormones (epinephrine and norepinephrine)
that arouse body in times of stress.
-Epinephrine a.k.a norepinephrine
-Adrenaline a.k.a. noradrenaline
Fight or flight response
Pituitary gland-endocrine system’s most influential gland. Under influence of the hypothalamus, regulates growth and controls other endocrine glands
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The Brain-Part B
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Introduction• Lesion tissue destruction
is a naturally or experimentally caused destruction of brain tissue.
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Neuroimaging Techniques
CT (Computed Tomography) or CATscan (xrays from dif. Angels and combined by computer to give complete view)
PET Scan(Positron Emission Tomography) visual display metabolic activity (chemical reactions that maintain life) of brain -detects where a radioactive form of glucose goes while the brain performs a given task.
MRI (Magnetic Resonance Imaging)revealing blood flow and
brain activity
fMRI (Functional MRI)show brain function.
Electroencephalogram (EEG)measures brain waves
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Brain Functions-SEE Page 73 in Myers
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The BrainstemBrainstem is where
spinal cord swells as it enters
the skull; responsible for
automatic survival functions.
Medulla base of brainstem;
controls heartbeat and breathing.
Pons: controls facial expressions;
helps coordinate Movement
Thalamus sensory control center for
All senses but SMELL
Reticular formation nerve network in
brainstem through thalamus:
role in controlling arousal and focusing;
if does not function, we fall into deep
coma
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The Cerebellum
• Cerebellum–“Little brain”processes sensory
input and coordinating
balance and voluntary
movement will help
from Pons
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The Limbic System
Limbic System-• doughnut-shaped neural system -including the Hippocampus: processesmemoriesAmygdala: aggression andemotions(2 -lima bean sized) Hypothalamus: emotions and drives (hunger, thirst,sex, body temp), reward center; helps governs endocrine
system via the pituitary gland
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Introduction
• Cerebrum–Cerebral cortexHas about 20 billion nerve cellsand 300 billion synaptic connections: interconnected neural cells covering cerebral hemispheres; the body’s ultimate control and information-processing center.
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Functions of the CortexAssociation Areas
• Association areas areas of the cerebral cortex that are not involved in primary motor or sensory functions; are involved in higher mental functions such as learning,
remembering, thinking, and speaking. AA found in all 4 lobes
-Frontal lobes (judgment, planning, process new Memories-damage may remove Inhibitions
• Phineas Gage (AP-look him up)– Parietal lobes (math and spatial reasoning-Einstein’s were large and unusually shaped)– Temporal lobes (recognize faces)
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Structure of the Cortex• Glial cells (“glue cells”) cells in the nervous system that support,
nourish, and protect neurons.• Lobes:1. Frontal lobes portion of cerebral cortex lying behind the forehead; involved in speaking, muscle movements (motor cortex in rear of Frontal lobe), Making plans and judgments2. Parietal lobes top of the head and toward the rear; receives sensory input for touch and body position (via sensory cortex in front of parietal lobe)3. Occipital lobes at the back of the head; includes areas that receive
info. from visual fields4. Temporal lobes above the ears; includes the auditory(hearing)
areas, each receiving info. primarily from opposite ear.
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Language
• Aphasia impairment of language, usually caused by left hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding).
-Broca’s area (producing speaking)– Wernicke’s area (understanding speech) – Angular Gyrus-seeing/reading words
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The Brain’s Plasticity
• Brain Damage– Plasticitythe brain’s ability to
change, especially during
childhood, by reorganizing after
damage or by building new
pathways based on experience.
– Neurogenesis
the formation of new neurons/brain cells.
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Splitting the Brain– Corpus-callosum band of neural
fibers connecting the two brain
hemispheres and carrying messages
between them.– Split brain isolates the brain’s two
hemispheres by cutting the fibers of
the corpus callosum connecting them.Gazzaniga (key figure)-divided
brains of cats/monkeys
without serious effects
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Right-Left Brain Differences
• Hemispheric SpecializationL controls R and visa versa
–Perceptual, spatial tasks-right hemisphere
–Language-L–Sense of self-R–Read Emotions- R; motor skills R
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Cognitive Neuroscience
• Cognitive neuroscience study of the brain activity linked with cognition (including perception, thinking, memory and language)
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Section C- Genes: Our Codes for Life
• Chromosome=threadlike structures made of DNA molecules that contain the genes.
• DNA=contains genetic information that takes up chromosomes.Genes=biochemical units of heredity
Recessive =(both parents need gene) verses Dominant Trait =(one parent needs gene)Genome=shared genetic profile Makes us human and not chimps(or) Genetic make-up of an organism
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Genotype is simply the information within a gene, or the genetic makeup of a specific organism.
Examples of genotype:• The gene responsible for eye color• The gene responsible for hair color• The gene responsible for height• The gene responsible for how your voice sounds• The gene responsible for certain diseases• The gene responsible for certain behaviors• The gene responsible for the size of a bird’s beak• The gene responsible for the length of a fox’s tail• The gene responsible for the color of stripes on a cat• The gene responsible for the spots on a dog’s back• The gene responsible for a person’s shoe size
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Whereas genotype is the set of genes responsible for a particular trait, phenotype is the physical
expression of that trait.
Examples of phenotype:• Eye color• Hair color• Height• The sound of your voice• Certain types of disease• Certain behaviors• The size of a bird’s beak• The length of a fox’s tail• The color of the stripes on a cat• The size and shape of the spots on a dog’s back• An individual’s shoe size
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TwinsIdentical (monozygotic)Versus Fraternal
(dizygotic)Twins
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Dad determines a child’s sexmother gives us X (female) chromosomedad gives either another X or a Y (male
chromosome)XX=girl; XY=boySex chromosomes are the 23rd pair (46
chromosomes total-23 from mom and 23 from dad) of chromosomes
Up until 7 weeks after conception, you are anatomically (genital) neutral
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Mutation
= the random error in gene replication that leads to a change.
Example=color blindness
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Genome
= the complete instructions for making an organism, consisting of all the genetic material in that organism’s chromosomes.
Genetic make-up of an organism
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Identical Twins
= twins who develop from a single fertilized egg that splits in two, creating two genetically identical organisms.
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Fraternal Twins
= twins who develop from separate fertilized eggs. They are genetically no closer than brothers and sisters, but they share a fetal environment.
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Heritability
= the proportion of variation among individuals that we can attribute to genes. The heritability of a trait may vary, depending on the range of populations and environments studied.