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75 Cards in this Set
- Front
- Back
What are the 4 functions of the nervous system?
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1. Detect CHANGES OR STIMULI within the internal and external environment
2. Interprets all sensory impulses and determines response (INTEGRATION) 3. Initiates and controls responses to changes in order to maintain HOMEOSTASIS 4. Conceptual THOUGHT |
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What are 2 main divisions of the nervous system?
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1. CNS: Central NS
2. PNS: Peripheral NS |
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Which are the 2 components of the CNS?
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1. brain
2. spinal cord |
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What are the collective components of the PNS?
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1. cranial nerves
2. spinal nerves |
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What are the 2 divisions of the PNS?
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1. sensory (afferent) division
2. motor (efferent) division |
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What is the function of the sensory (afferent) division of the PNS?
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carry impulses from receptors to the CNS
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What are 2 divisions of the sensory (afferent) division of the PNS? Give examples for each classification.
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1. somatic: muscles, skin, and joints
2. visceral: visceral organs |
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What is the function of the motor (efferent) division of the PNS?
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carry impulses away from the CNS to the effectors (i.e., muscles or glands that are innervated)
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What are 2 divisions of the motor (efferent) division of the PNS? Give examples for each classification.
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1. Somatic: to skeletal muscles
2. Autonomic: to cardiac muscle, smooth muscle, and glands |
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What are 2 further divisions of the autonomic nervous system (a portion of the motor (efferent) division of the PNS)?
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1. sympathetic
2. parasympathetic |
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What are 2 types of nervous tissue?
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1. Neuroglia
2. Neurons |
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What are the 6 types of neuroglia?
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1. ependymal
2. astrocytes 3. oligodendrocytes 4. microglia 5. Schwann cells 6. satellite cells To remember: Eat At Our Mini Sweet Shop |
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Name the function of this neuroglia and the division of the nervous system in which it is found: ependymal
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fxn: lines cavities in the CNS-produces cerebrospinal fluid
part of: CNS |
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Name the function of this neuroglia and the division of the nervous system in which it is found: astrocytes.
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fxn: supports and binds neurons together
part of: CNS |
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Name the function of this neuroglia and the division of the nervous system in which it is found: oligodendrocytes
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fxn: forms myelin sheaths of neurons
part of: PNS |
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Name the function of this neuroglia and the division of the nervous system in which it is found: microglia
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fxn: phagocytic cells for protection
part of: CNS |
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Name the function of this neuroglia and the division of the nervous system in which it is found: Schwann cells
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fxn: forms myelin sheath of neurons
part of: PNS |
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Name the function of this neuroglia and the division of the nervous system in which it is found: satellite cells
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fxn: supports neurons
part of: PNS |
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What are the 4 types of neuroglia that are part of the CNS?
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1. ependymal
2. astrocytes 3. oligodendrocytes 4. microglia |
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What are the 2 types of neuroglia that are a part of the PNS?
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1. Schwann cells
2. satellite cells |
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What is the function of neurons?
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to generate and conduct action potentials (impulses)
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What are the 3 components of a neuron's anatomy?
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1. cell body
2. dendrites 3. axons |
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What does a neuron cell body consist of?
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contains most of the cytoplasm and organelles
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What are dendrites of a neuron?
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extensions of the cell body that carry information TO the cell body
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What are axons of a neuron?
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extensions of the cell body that carry impulses AWAY from the cell body
Axon=Away |
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What are 3 ways that neurons can be classified?
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1. functional
2. anatomical 3. propagation speed [of action potential] |
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What are 3 types of functional neurons?
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1. afferent (sensory)
2. efferent (motor) 3. association (internuncial) |
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What do afferent (sensory) neurons do?
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conduct impulses TO the CNS
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What do efferent (motor) neurons do?
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conduct impulses AWAY from the CNS
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What do association (internuncial) neurons do?
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conduct impulses WITHIN the CNS
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What are 3 anatomical types of neurons? Give examples of where they are found.
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1. unipolar- most sensory neurons
2. bipolar- retina, inner ear, olfactory membrane 3. multipolar- brain and spinal cord |
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What are 3 ways that neurons' propagation speed (action potential, ie AP) are classified?
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1. Type A
2. Type B 3. Type C |
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What are characteristics of Type A neurons?
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-LARGE (4-20 um) MYELINATED axons with speeds up to 140m/s
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What are characteristics of Type B neurons?
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-MEDIUM (2-4 um) MYELINATED axons with speeds of about 18m/s
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What are characteristics of Type C neurons?
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-SMALL (less than 2um) UNmyelinated axons with speeds of 1m/s
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What is a transmembrane potential (TP)?
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the ELECTRICAL POTENTIAL between the inside and outside of a cell membrane
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What causes a transmembrane potential?
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a slight excess of (+) charged ions on the OUTSIDE and a slight excess of (-) charged ions on the INSIDE of the membrane.
outside: excess + inside: excess - |
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What is the range of the transmembrane potential?
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-10mv to -100 mv
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What is the resting potential (RP)? Give definition and number.
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The transmembrane potential of an UNDISTURBED cell
ave: -70mv |
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What are the 4 general features of a resting (non-stimulated) cell?
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1. HIGH extracellular [Na+] and a LOW intracellular [NA+]
2. HIGH intracellular [K+] and LOW extracellular [K+] 3. INTRAcellular fluid has ANIONS, mostly proteins that cannot cross the membrane 4. the extracellular fluid and the interior of the cell are electrically NEUTRAL |
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What causes the high extracellular and low intracellular [Na+] of a resting cell?
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1. membrane actively transports Na+ OUT
2. membrane has a LOW permeability to Na+ 3. low permeability is the result of FEW open Na+ gates |
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What causes a high intracellular and low extracellular [K+]?
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1. membrane actively transports K+ IN
2. membrane has a HIGH permeability to K+ 3. high permeability is the result of MANY open K+ gates |
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Why are the extracellular fluid and the interior of the cell electrically neutral?
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1. on the outside, the cations (Na+) are balanced by the anions (Cl-)
2. on the inside, the cations (K+, Na+) are balanced by the anions (proteins) |
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What effect does the cell membrane's permeability to K+ have on the cell resting potential?
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K+ can constantly diffuse to the OUTSIDE of the membrane, adding positive charges to the outside and leaving the inside slightly negative (hence, a resting potential of -70mv)
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How does the sodium-potassium pump maintain the resting potential?
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The Na+-K+ pump returns the Na+ that diffuse in and the K+ that diffuse out (3 to 2), thus maintaining the resting potential
good na-k video: http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodium_potassium_pump_works.html |
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What are 2 types of membrane channels? Describe them.
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1. passive (leak): always open
2. active: can open or close |
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What are 3 types of active membrane channels? Describe them.
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1. chemically regulated
--->open or close when they bind to specific chemicals 2. voltage regulated --->open or close when the membrane potential changes 3. membrane regulated ---> open or close in response to distortions of the membrane surface |
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What are graded (local) potentials?
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changes in the TP that are unable to spread far from the site of stimulation
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How does a graded potential DEPOLARIZE the cell membrane?
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if a stimulus causes the opening of the Na+ gates, Na+ will diffuse into the cell and the TP will become LESS negative
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How does a graded potential HYPERPOLARIZE the cell membrane?
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If a stimulus causes the opening of K+ gates, K+ will diffuse OUT of the cell and the TP will become MORE negative
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The degree of depolarization or hyperpolarization will depend upon ...?
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how MANY Na+ or K+ gates are opened, which in turn depends on the STRENGTH of the stimulus
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What does the movement of Na+ or K+ generate?
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a local current
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What is repolarization? When does it occur?
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-when the sodium-potassium pump returns the TP BACK TO NORMAl
-occurs when the stimulus is removed. |
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What are action potentials (ie impulses or APs)?
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Propogated changes in the TP (or RP)
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What are the 4 stages of AP return to normal?
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1. depolarization to threshold (the TP that causes voltage-regulated Na+ gates to open, -60mv)
2. once the Na+ gates are open, Na+ diffuses into the cell and the TP depolarizes to +30mv 3. At +30mv, voltage-regulated Na+ gates close, and the voltage-regulated K+ gates open. K+ diffuses out of the cells 4. At -70 mv, voltage-regulated K+ gates close, but because they don't all close at the same time, the membrane becomes temporarily hyperpolarized (over shoot) before returning to normal *over time, the Na-K pumps return the [Na+] and [K+] to their original distributions across the membrane |
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What are 2 types of AP propogation?
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1. continuous propogation
2. saltatory conduction |
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Which types of neurons undergo continuous propagation?
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non-myelinated neurons
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Describe the process of continuous propagation.
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1. At the point of the stimulus, an AP occurs (assuming threshold is reached), resulting in LOCAL current flow
2. local current flow depolarizes the adjacent membrane sections to threshold, resulting in an AP in those sections while initial segments return to normal 3. local current flow now develops between these secondary segments of the membrane and the adjacent sections **The cycle repeats until the AP REACHES THE END OF THE AXON |
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Which types of neurons undergo saltatory conduction?
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myelinated neurons
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Describe the process of saltatory conduction.
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1. In areas of the membrane surrounded by myelin (INTERNODES), the myelin prevents ions from crossing the membrane, thus depolarization can NOT occur
2. depolarization CAN occur in those areas of the membrane NOT covered by the myelin sheath (nodes of Ranvier--1-2 mm apart) 3. Whan an AP occurs in the initial segment, local current flow occurs between there and the next NODE, which causes it to depolarize to threshold, and an AP is produced. This causes local current flow between it and the next node. This cycle continues until the end of the axon. |
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Define threshold stimulus.
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the SMALLEST stimulus strength required to initiate an impulse
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Define summation.
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addition of sub-threshold stimuli so that the threshold is reached
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Define accomodation.
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increase in threshold due to a CHRONIC threshold stimulus
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Define all-or-none law.
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threshold stimulus (or higher) will cause a MAXIMAL response
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What are 2 types of synapses?
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1. excitatory
2. inhibitatory |
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Describe the mechanism of the excitatory synapse.
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1. AP at the synaptic knob opens voltage-regulated Ca2+ channels
2. Ca2+ diffuses into the cell--->causes release of neurotransmitters from the synaptic vesicles via exocytosis 3. Neurotransmitters diffuse across the synaptic cleft and attach to receptors (chemical-regulated Na+ channels) on the postsynaptic membrane causing the gates to open, allowing Na+ to diffuse in 3. as a result, a graded potential, excitatory postsynaptic potential (EPSP) is generated 4. summation of individual EPSPs occurs at the axon hillock, and if threshold is reached, an AP occurs |
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Describe the mechanism of the inhibitory synapse
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1. AP at the synaptic knob opens voltage-regulated Ca2+ channels
2. Ca2+ diffuses into the cell--->causes release of neurotransmitters from the synaptic vesicles via exocytosis **3. Neurotransmitters diffuse across the synaptic cleft and attach to receptors (chemical-regulated K+ channels) on the postsynaptic membrane causing the chemically-regulated gates to open, allowing K+ to diffuse out **3. as a result, the TP becomes more postive on the outside (hyperpolarization), the new potential is called an inhibitory post synaptic potential (IPSP) 4. IPSP makes the membrane less excitable (inhibited) since it will now take a greater stimulus strength to cause depolarization to threshold |
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Define summation in terms of time and space.
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def: the addition of EPSPs or IPSPs at the axon hillock
1. temporal: stimuli occurring in rapid succession at a single synapse 2. spatial: results from stimuli acting upon several synapses simultaneously |
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List the 6 categories of transmitter substances.
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1. Acetylcholine (Ach)
2. Biogenic amine 3. Excitatory amino acids 4. Inhibitory amino acids 5. Neuropeptides 6. Dissolved gases 7. Others |
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Give examples of biogenic amines
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dopamine, norepinephrine, epinephrine, serotonin
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Give examples of excitatory amino acids
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glutamate, aspartate
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Give examples of inhibitory amino acids
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gamma aminobutryic acid (GABBA) and glycine
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Give examples of neuropeptides
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endorphins, enkelphalins
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Give examples of transmitter substances that are dissolved gases
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carbon monoxide (CO), nitric acid (NO)
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Give examples of transmitter substances that are classified as others
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ATP, hormones (ADH, insulin, secretin, oxytocin, etc.), prostaglandins
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