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Dendrite
branching extensions that detect information from neighboring neurons
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axon
extended projection from the cell body that transmits information from cell body to terminal buttons
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Terminal button
point of release for chemical signals being sent from the neuron into the synapse
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Synapse
Point of chemical communication between neurons
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Synaptic cleft
Small gap between two neurons
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Presynaptic neuron
"sender"
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Postsynaptic neuron
"receiver"
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Myelin sheath
fatty lining around axons
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How does myelin affect the speed of info transmission?
increases speed of information transmission down an axon
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Nodes of Ranvier
small gaps between sections of myelin where action potentials are transmitted
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Action potential
Neural impulse sent down an axon that results in the release of chemicals from the terminal buttons
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What are the steps of action potential?
- Resting potential
- Action potential
- 1. Sodium channels open
- 2. Potassium channels open
- 3. Sodium channels close
- 4. Potassium channels close
- 5. Hyperpolarization
- Resting potential
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What happens when neuron is hyperpolarized?
Refractory period – neuron cannot fire
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Resting Potential
- Neuron is polarized
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- Slightly more negatively charged inside the neuron than outside
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Neurotransmitters
Chemicals released from the terminal button of the presynaptic neuron to signal the postsynaptic neuron
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What is the primary excitatory neurotransmitter?
increase action of the postsynaptic neuron
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What is the primary inhibitory neurotransmitter?
decrease action of the postsynaptic neuron
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What is the 1st step for neurotransmitters to get released from a neuron?
1. Neurotransmitter production in the axon
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What is the 2nd step for neurotransmitters to get released from a neuron?
2. Once produced, neurotransmitter is stored in vesicles
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What is the 3rd step for neurotransmitters to get released from a neuron?
3. Vesicles attach to presynaptic membrane
They open and release stored neurotransmitters into the synaptic cleft
Result of action potential
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What is the 4th step for neurotransmitters to get released from a neuron?
4. Neurotransmitter binds to receptors on postsynaptic membrane
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What is the 5th step for neurotransmitters to get released from a neuron?
- 5. Unbound neurotransmitter activity is stopped by one of 3 methods
- 1.)Reuptake
- 2.)Deactivation
- 3.) Autoreception
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Reuptake
- After release from the vesicles at the terminal button
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- any neurotransmitter that does not bind to a postsynaptic receptor
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- is taken back up by the presynaptic terminal button
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Enzymatic deactivation
After release from the vesicles at the terminal button
any neurotransmitter that does not bind to a postsynaptic receptor
is broken down in the synapse by specific enzymes
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Autoreception
Released neurotransmitters bind to receptors on the presynaptic neuron
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Acetylcholine (ACh)
Motor control of muscles
Learning and memory
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what happens if there's a dysfunction in ACh?
Paralysis – botulism blocks ACh release, inhibits muscle movement
- Violent muscle contractions – black widow spider venom
- causes a flood of ACh to be released, causing too much muscle contraction
Over-release leads to ACh depletion, paralysis
Temporary amnesia – occurs if ACh release is blocked
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Dopamine (DA)
Motor control of voluntary movement
Reward and motivation
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What happens if there's a dysfunction in DA?
Movement difficulties
Parkinson’s – too little DA production
Schizophrenic-like symptoms – too much DA production
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Serotonin
aka
5-HT (5-hydroxytryptophan)
- Mood
- Hunger
- Sleep and attentiveness
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What happens if there's a dysfunction in serotonin?
Depression – an underproduction of 5-HT is related to depressive disorders
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Norepinephrine (NE)
Alertness and vigilance
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What happens if there's a dysfunction in norepinephrine?
Depressive mood – underproduction of NE can depress moods
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GABA (gamma-aminobutyric acid)
Primary inhibitory neurotransmitter
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What happens if there's a dysfunction in GABA?
Seizures – potentially linked to underproduction of GABA
Tremors – underproduction decreases muscle control
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Glutamate (Glu)
Primary excitatory neurotransmitter
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What happens if there's a dysfunction in Glu?
Migraines – potentially linked to overproduction of Glu
Seizures – potentially linked to overproduction of Glu
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What parts does the brain stem have?
What are the brain stem's basic functions?
Includes the medulla, pons & midbrain
- Important for regulating basic functions
- Heart rate
- Respiration
- Vomiting
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What does the cerebellum do?
Coordinated movement & balance
Contains lobes similar to the cortex
Each control different functions related to motor behavior
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What are the 6 subcortical structures in brain?
- Hypothalamus
- Thalamus
- Hippocampus
- Amygdala
- Basal ganglia
- Nucleus accumbens
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subcortical structure: hypothalamus
Major regulatory structure
- Motivated behaviors
- Thirst
- hunger
- Aggression
- Sexual behavior
Endocrine system control
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subcortical structure: thalamus
Relay center for sensory information
Except olfaction!
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subcortical structure: hippocampus
Memory formation
May be subject to plasticity (the brain's natural ability to change)
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subcortical structure: amygdala
Emotional association learning
Fear response
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subcortical structure: basal ganglia
Planned movement production
DA production here controls fluid movement
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subcortical structure: nucleus accumbens
Reward
Motivating behavior
DA neurons here are activated during pleasurable experiences
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Cerebral Cortex
Outermost layer of the brain
Responsible for sensory integration, thought production complex behavior
4 lobes
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What is the function of the frontal lobe cortex?
Higher-order processing & planning
Movement
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What is the function of the the parietal lobe?
Conceptualizing spatial layouts
Touch sensation
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What is the function of the temporal lobe?
Memory
Auditory information processing
Specialized visual processing area
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What is the function of the occipital lobe?
Visual information processing
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When would your sympathetic nervous system be activated?
Activation prepares the body for some required action
Non-vital systems deactivated
Fight-or-flight response
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When would your Parasympathetic nervous system be activated?
Activation returns the body to a resting state
Maintains homeostasis
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Nervous System
Neurotransmitters
Released from terminal buttons
Travel short distances
Act very quickly
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Endocrine System
Hormones
Released from endocrine glands
Travel throughout the body
Slow-acting
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In endocrine system, how does hormone behave?
its chemicals released into the bloodstream from endocrine glands that act on a target tissue
Hormones bind to receptors on the target tissue and influence its actions
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In endocrine system, what does the hypothalamus do?
Produces hormones in response to a wide range of stimuli
- Feeding
- stress
- social behavior
- sexual behavior
- physical growth
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In endocrine system, what does the Pituitary do? and what does it have?
Release point for hormones from CNS to periphery
- oxytoxin- uterine contractions
- mother&infants bond
- romantic relationship
- Vasopressin – water balance
- social bonds
- chronic stress regulation
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In endocrine system, what does the thyroid do?
Thyroid hormones
Metabolism rates
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In endocrine system, what does the adrenal do?
Glucocorticoids (hormone)
increase blood sugar level
speed up break down of proteins
have anti-inflammatory effects
epinephrine & norepinephrine
fight or flight response
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In endocrine system, what does the pancreas do?
insulin
regulates glucose levels
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In endocrine system, what does the gonads do?
- androgens (testes)
- estrogens (ovaries)
Development of reproductive organs (prenatal)
Secondary sex characteristics
Adult sexual behavior
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genotype
the genetic make-up of an organism
determined at fertilization
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phenotype
observable characteristics
due to genotype and the environment
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What is a dominant gene?
Gene is expressed if it is present
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What is a recessive gene?
Gene is expressed only if it is present with another recessive gene
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How did the work by Wiesel and Hubel w/ artificial loss of vision contribute to our understanding of critical periods in development?
- Critical period
- Plasticity occurs only inside a defined developmental period.
- Experiences outside this period do not result in plasticity.
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Polygenic characteristics
A trait is determined by multiple genes, as well as by environmental influences
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Apoptosis
intentional cell death
may be pruning of unused neural networks to make brain work efficiently
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