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124 Cards in this Set
- Front
- Back
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Endogenous substances
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substances from internal sources
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Exogenous substances
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substances from external sources
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Ionotropic receptors
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act quickly and directly
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Metabotropic receptors
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act slowly and indirectly, cause a cell to metabolize and then prompt another substance to open the ion channel
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5 criteria for being a neurotransmitter
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Substance is synthesized in presynaptic neurons and is stored in axon terminals
Is released when action potentials reach axon terminals Is recognized by receptors on postsynaptic membrane Causes changes in the postsynapitc cell Blocking its release interferes with the ability of the presynaptic cell to cause changes in the postynaptic cell |
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4 main types of Amine transmitters?
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Cholinergic (containing Ach)
Dopamine (DA) Serotonin (5-HT) Norepinephrine (NE/Noradernaline) |
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Cholinergic amine transmitters
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Basal forebrain
Project to structures involved in learning and memory Losss assoc. w/Alzheimer's |
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Dopamine amine transmitters
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2 Pathways
Mesostriatal and mesolimbocortical |
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Mesostriatal (DA) pathway
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originates in the substantia nigra and is important for motor control
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Mesolimbocortical pathway
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originates in the ventral tegmental area (VTA) and is importans for positive reinforcement learing (reward
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Serotonin (5-HT) amine transmitter
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found along the midline of the midbrain and brainstem in the raphe nuclei and important for many aspects such as mood, anxiety, and sleep
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Norepinephrine/Noradenaline (NE) amine transmitter
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found in the locus coeruleus and the lateral tegmental area and responsible for behaviors ranging from alertness to sexual behavior
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2 main types of amino acid transmitters and are they excitatory or inhibitory?
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Glutamate-excitatory
Gamma-aminobutyric acid - inhibitory |
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Benzodiazepines
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Valium and Ativan; mimic and are used to reduce anxiety
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What is the function of an opioid transmitter?
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Opioid peptides reduce the perception of pain
Peptide hormones inclue oxytocin and vasopressin |
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Peptides
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act a s neurotransmittes at some synapses and can also act as hormones
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4 types of neurotransmitters
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Amines
Amino Acids Peptides Gases |
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What are 2 peptide hormones and the function of each?
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Oxytocin - love hormone
Vasopressin - regulates water |
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In what 3 ways do gas neurotransmitters differ from others?
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Mainly produced in dendrites and diffuse as soon as it is produced
No receptors involved (diffuses into target cell and activates 2nd msnger) Can function as a retrograde transmitter (diffuses from the postsynaptic neuron back into the presynaptic neuron |
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Retrograde transmitter
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diffused from the postsynaptic neuron to the presynaptic neuron
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Binding affinity
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the degreee of a chemical attraction between a ligand and a recptor
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Binding efficacy
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the ability of a bound ligand to activate the receptor
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Dose response curve (DRC)
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graph of the relationship between drug doses and observed effects
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What are four ways in which drugs can be administered/ingested?
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Central injection - injected into the CNS
Peripheral injection - injected into the PNS Inhalation - smoking/nasal injection Ingestion |
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Duration of a drugs effects?
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How it's metabolized
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metabolic tolerance
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organ system becomes more effective at eliminating the drug
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Functional tollerance
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alter sensitivity to the drug by changing the number of receptors
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Agonist
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bind to receptor and mimic transmitter (opiates)
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Antagonist
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block the receptor but do not activate receptor (MAO's)
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Down regulate
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receptors down regulate in response to an agonist, they shut down receptors so there are fewer to respond to drug/transmitter
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Up regulate
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receptors up regulate in response to an antagonist, they create more receptors to compensate for the blocked receptors
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In what 3 ways can drugs interfere with transmitter production?
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Block synthesis enzymes
Axonal transport of raw materials Ability to store the transmitter |
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What is a way that drugs can interfere with transmitter release? Example?
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By blocking calcium channels
Ex. Botox |
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In what 2 ways can drugs interfere with transmitter clearance?
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Can block reuptake of transmitter
Can block enzymes, allowing the transmitter to accumulate |
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What is the difference between depressants and stimulants?
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Stimulants; increase exitatory input/decrease inhibitory activity
Depressants; increase inhibitory input/decrease excitatory activity |
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What are 2 types of antidepressants and how do they work?
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Monoamine oxidase MAO inhibitors, prevent the breakdown of monoamines in the synapses
Tricyclic antidepressants, prevent the reuptake of serotonin and norepinephrine |
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Selective Serotonin Reuptake Inhibitors
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SSRI's like Prozac or act specifically at serotonergic synapses
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Examples of opiates
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Morphine and Heroine
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How do opiates affect receptors?
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Metabotropic receptors that increase dopamine release....relaxation, decreased sensitivity to pain, less attention to problems
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What part of the brain are opiates typically found?
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periaqueductal gray
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What 2 mechanisms does alcohol work through?
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Glutamate (excitatory) antagonist
GABA receptor agonist (inhibit brain areas that usually inhibit risky behavior) |
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Fetal alcohol syndrome
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duh...
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Effects of FAS on the brain?
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stunted brain growth and no corpus callosum
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Effects of binge drinking on the adult brain?
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May cause brain damage and reduces the rate of neurogenesis
Effects are reversible with time and abstinence |
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Ligand
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A substance that binds to a receptor
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What is the active ingredient in marijuana, how does it affect behavior, and how does it interact with cannabinoid receptors?
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The main ingredient is delta-9-tetrahydrocannabinol (THC)
Effects include relaxation, mood alteration Sometimes stimulation, hallucination, and paranoia THC is an agonist for cannabinoid receptors located on presynaptic neuron |
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How does nicotine affect behavior, what type of neurotransmitter does it mimic, and where are the receptors located?
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Increases heart rate, blood pressure, digestive action, and alertness
An agonist of nicotinic ACh receptors in the ventral tegmental area enhances some cognitive function but also stimulates rewarding/addicting effects |
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What is an autoreceptor?
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Autoreceptors: monitor amount of release and give feedback
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How does caffeine affect adenosine autoreceptors, and what neurotransmitter is increased when caffeine binds to the autoreceptors?
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antagonist of presynaptic adenosine autoreceptors; Caffeine increases dopamine release
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How does cocaine affect behavior, and how does it affect synaptic transmission?
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Increases endurance, reduces hunger, increases pleasurable feelings
Blocks reuptake of amine transmitters Transmitter accumulates in synapses, boosting their effects |
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What are synthetic stimulants and how do they affect behavior?
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Amphetamines and Methamphetamines
Increase vigor and stamina, promote wakefulness and feelings of euphoria |
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In what 2 ways do synthetic stimulants increase the amount of transmitter in the synapse?
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In the axon terminals, cause a larger-than-normal release of transmitter
Then interferes with the breakdown of the transmitter |
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How do hallucinogens affect behavior, and what neurotransmitter do they increase?
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Alter sensory perception and LSD (acid) strongly activates serotonin receptors in the visual cortex
LSD also produces mood changes and feelings of creativity |
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What are the long-term effects of Ecstasy use?
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Visual cortical serotonin levels and...
Long-term use damages serotonin-producing neurons and produces long-lasting side effects Mood and memory |
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How do dissociative drugs work, and how do they affect behavior?
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Phencyclidine (PCP) and ketamine (Special K)
Produce feelings of depersonalization and detachment from reality Glutamate receptor antagonists Regular use produces symptoms of psychosis and degenerative brain changes |
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What is the difference between dependence and substance abuse?
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Dependence: the desire to self-administer a drug of abuse
criteria include patterns of: consumption craving time and energy impact on one’s life Substance abuse: a pattern of use that does not fully meet the criteria for dependence |
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What is the moral model of drug abuse, and what is evidence against it?
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The moral model: blames the abuser for a lack of moral character or a lack of self-control
Programs such as “just say no” not effective |
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What is the disease model of drug abuse and is there existing evidence that supports this model?
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The disease model: says the abuser requires medical treatment
An abnormal condition in abusers has not been identified |
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What is the physical dependence model of drug abuse?
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The physical dependence model: abusers use drugs to avoid withdrawal symptoms like dysphoria, strong negative feelings that can only be relieved by the drug
Cocaine doesn’t have severe withdrawal symptoms, still highly addictive |
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What is the positive reward model of drug abuse, what brain pathway is involved, and what other activities activate this pathway?
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The positive reward model: says drug use is a behavior controlled by positive rewards, with no disease
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What region may contain a second reward pathway and why?
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Another reward pathway may involve the insula, a brain region within the frontal cortex
People with damage to this area have been able to stop smoking effortlessly |
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Three cell layers of an embryo
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Endoderm, Mesoderm, Ectoderm
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What cell layer develops into the nervous system in an embryo?
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Ectoderm
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What is the first stage of neural development, and what are stem cells?
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Proliferation
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What is neurogenesis?
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Neurogenesis is the production of new neurons
Stem cells (unspecialized) lining the ventricles divide Cells leave the ventricular zone and become either neurons or glial cells |
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What happens during cell migration?
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During cell migration, neurons and glial cells move away from the ventricles to their eventual locations
Some don’t reach their destinations until adulthood Occurs in a variety of directions throughout the brain When cells reach their destinations they express particular genes, to make the proteins they need |
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What happens during differentiation?
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Differentiation refers to the forming of parts of a neuron that give it a distinctive shape
Acquire appearance and functions of neurons characteristic of that region Can occur either during migration or once it has reached its target Axon growth occurs first, followed by the development of the dendrites |
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What is myelination, and when does it occur?
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Myelination refers to process by which glia produce the fatty sheath that covers the axons of some neurons
First occurs in the spinal cord and then in the hindbrain, midbrain and forebrain Occurs gradually for decades |
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What is synaptogenesis?
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Synaptogenesis: the formation of the synapses between neurons
Occurs throughout life as neurons are constantly forming new connections and discarding old ones Slows significantly later in the lifetime |
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What is apoptosis, when, and why does it occur?
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Apoptosis (cell death) is an important part of brain development
½ of motor neurons in spinal cord die before birth Cells undergo this process as part of complex interactions with other cells |
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When does synapse rearrangement occur, and when does thinning start?
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synapse rearrangement:
After the period of cell death, neurons grow longer and more elaborate dendrites, each with many new synapses Some original synapses are lost In human cortex there is a net loss of synapses from late childhood through adolescence The thinning process continues through maturation, reaching the prefrontal cortex last |
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What is phenylketonuria (PKU), and how does it relate to the interaction of genes with environment?
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Phenylketonuria (PKU) is a disorder of protein metabolism
Absence of an enzyme that metabolizes phenylalanine If not corrected by diet, high levels of phenylalanine will cause intellectual disability The interaction of genes and environment is important intellectual disability occurs only in the presence of phenylalanine |
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What is epigenetics, and how does maternal care relate to the interaction of genes with environment?
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Epigenetics is the study of factors that change gene expression, without changing the gene sequences
Maternal care is an important epigenetic factor Genetically identical male mice raised by mothers of a different strain show differences in behavior |
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How does axon re-growth differ between the CNS and PNS?
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good question
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If an axon is severed, what is a potential problem with re-growth?
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If axon is cut instead of crushed, may not connect to proper muscle due to scar tissue
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What is collateral sprouting?
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Collateral sprouts: new branches formed by other non-damaged axons that attach to vacant synapses
Cells release chemicals that induce nearby axons to form collateral sprouts |
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When a body part is amputated, what happens to the region of cortex that used to represent the body part?
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The cortex reorganizes itself after the amputation of a body part
Original axons degenerate leaving vacant synapses into which others axons sprout Becomes responsive to other parts of the body |
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What is a “phantom limb”?
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Phantom limb refers to the continuation of sensation of an amputated body part when other parts of the body are stimulated
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What are receptor cells?
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sense some stimuli but not others
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What is the concept of labeled lines?
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the brain recognizes distinct senses because action potentials travel along separate nerve tracts
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What is sensory transduction?
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Sensory transduction: the conversion of energy from a stimulus into a change in membrane potential in a receptor cell
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What are pacinian corpuscles, and how do they produce generator potentials?
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Pacinian corpuscle: skin receptor that responds to vibration and pressure
A non-neural cell that surrounds a free nerve ending A stimulus to the corpuscle opens sodium (Na+) channels in the neuron it surrounds produces a generator potential |
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Aside from pacinian corpuscles, what are 4 other types of touch receptors, and what do they sense?
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Ruffini corpuscles: detect stretching of the skin
Free nerve endings: detect pain, heat, and cold Useful for perceiving the form of objects we touch: Meissner’s corpuscles: respond to changes in stimuli Merkel’s discs: respond to edges and isolated points |
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What is a receptive field, what is it used for, and how is it arranged?
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The region in which a stimulus will alter a sensory neuron’s firing rate
Arranged like a donut, excitatory center and inhibitory outer |
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What is adaptation, and do phasic and tonic receptors show adaptation?
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Adaptation: progressive loss of receptor sensitivity as stimulation is maintained
Phasic receptors: display adaptation and decrease frequency of action potentials Tonic receptors: show slow or no decline in action potential frequency |
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What is the dorsal column system, and how does it work?
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The dorsal column system delivers touch information from the periphery to the brain
Incoming sensory information travels via the spinal nerves Receptors send axons via the spinal cord to synapse onto neurons in the brainstem Axons from those neurons cross the midline, and go to the thalamus From the thalamus, information is relayed to the cortex |
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What is a dermatome?
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Inputs are organized into dermatomes, strips of skin each innervated by a particular spinal nerve
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Where is primary somatosensory cortex and how is it organized?
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Primary somatosensory cortex:
in the postcentral gyrus receives touch information from the opposite side of the body cells are arranged as a map of the body: a sensory homunculus |
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What are 3 benefits of pain?
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Pain helps us to:
withdraw from its source engage in recuperative actions to signal others |
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What are nociceptors and how are they activated?
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Nociceptors: receptors on free nerve endings that respond to painful stimuli
Substances from injured tissue stimulate these receptors |
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What are two types of pain receptors, what type of information do they convey, and what kind of fibers are each one found on?
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transient receptor potential vanilloid type1 (TRPV1):
transient receptor potential 2 (TRP2) |
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Transient receptor potential vanilloid type 1
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transient receptor potential vanilloid type1 (TRPV1):
detects painful heat activated by capsaicin (the “hot” in chili peppers) on thin, unmyelinated C fibers that conduct slowly, producing lasting pain |
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Transient receptor potential 2
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transient receptor potential 2 (TRP2):
Detects even higher temperatures Does not respond to capsaicin Is found on A delta (Aδ) fibers—large myelinated axons that register pain quickly |
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How are pain signals conveyed to the brain?
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The spinothalamic system transmits the sensations of pain and temperature to the brain
Nerve fibers send axons into the dorsal horns of the spinal cord They synapse on neurons that project across the midline Then ascend through brainstem to the thalamus Pain information is integrated in the cingulate cortex |
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What part of the cortex are pain signals integrated in?
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cingulate cortex
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What is analgesia, what are 4 ways commonly used to achieve analgesia, and how does each one work?
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The loss of pain sensation
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First strategy to achieve analgesia
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Opiate drugs bind to specific receptors in the brain to reduce pain
Epidural injections place opiates directly into the spinal cord |
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2nd method to achieve analgesia
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Transcutaneous electrical nerve stimulation (TENS): stimulating nerves around the source of the pain
Triggers release of endogenous opioids Naloxone, an opioid antagonist, can block the analgesic effect of TENS |
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3rd method to achieve analgesia
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3. Treating with a placebo can induce a placebo effect: a relief of pain, even though the treatment is an inert substance
Placebos sometimes activate brain’s endogenous opioid system |
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4th method to achieve analgesia
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Acupuncture relieves pain by activating endogenous opioid system
Naloxone blocks the analgesic effect of acupuncture |
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How does emotional pain resemble physical pain?
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Emotional pain resembles physical pain in many regards:
Increased activity in the cingulate cortex when someone feels left out of an activity People taking acetaminophen (Tylenol) report less incidences of hurt feelings and social pain Also show less activity in the cingulate cortex |
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What are tendons?
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Tendons connect muscle to bone
Muscles are connected in a reciprocal fashion When one muscle group contracts, it stretches the other group: they are antagonists |
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How are muscle groups antagonistic? Give an example.
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When one muscle group contracts, it stretches the other group: they are antagonists
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What is skeletal muscle known as and why?
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Skeletal muscles are made of striate muscle:
Overlapping layers of proteins myosin and actin give a striped appearance Contraction of the muscle increases the overlap of actin and myosin filaments |
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What is the neuromuscular junction, and which transmitter is released here?
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Neuromuscular junction: where the motor neuron terminal and the muscle fiber meet
Acetylcholine (ACh) is released |
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What is proprioception?
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the collection of information about body movements and position (feedback)
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What are two types of proprioceptors, what kind of information do they respond to, and where are they found?
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Muscle spindle
Golgi tendon organs |
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Muscle spindle
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Muscle spindle: responds to stretch
If a muscle is stretched, the muscle spindle also stretches and triggers action potentials in sensory nerves The spinal cord and brain are informed about the extent and rate of stretch, and the load |
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Golgi tendon organs
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Golgi tendon organs: muscle tension
Golgi tendon organs monitor the force of muscle contractions They also detect overloads on muscles and cause a reflexive relaxing of the muscle, preventing damage Located in tendons |
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What system controls movement via commands from the brain?
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CNS
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Where is the primary motor cortex, and how is it organized?
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across midbrain
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Can representations in primary motor cortex change?
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yes, with training. like musicians
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What two regions comprise nonprimary motor cortex, and what kind of movements are they involved in?
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Supplementary motor area (SMA): important for initiation of movement sequences, especially when preplanned
Premotor cortex: activated when motor sequences are guided by external events |
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Supplementary motor area (SMA)
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Important for initiation of movement sequences
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Premotor cortex
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activated when motor sequences are guided by external events
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Where are mirror neurons found and what is their purpose?
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A subregion of premotor cortex contains mirror neurons
The same neurons fire before making a movement as when observing another making that movement May be useful for analyzing the behavior of others |
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All have to do with movement PPA
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Plegia: paralysis
Paresis: weakness of voluntary movements Apraxia: the inability to carry out movements, even though no paralysis or weakness is present |
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Plegia
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paralysis
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Paresis
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weakness of voluntary movements
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Apraxia
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inability to carry out movements though no disability present (can't dunk)
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What are extrapyramidal systems? Give two examples.
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Extrapyramidal systems regulate and fine-tune motor commands
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Basal Ganglia extrapyramidal system
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basal ganglia modulate movement
Receive inputs from the substantia nigra and subthalamic nucleus Help control the amplitude and direction of movement |
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Cerebellum extrapyramidal system
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cerebellum receives inputs from sensory sources and other brain motor systems:
Fine-tunes skilled movements |
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What are the effects when extrapyramidal systems are damaged?
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Cerebellum: abnormal gait and posture and ataxia (loss of coordination) of the legs
Parkinson’s disease shows progressive loss of dopaminergic cells in the substantia nigra with slowed movement Huntington’s disease caused by basal ganglia damage, but shows excessive movement |
