Term
| What is membrane potential? |
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Definition
| The electrical difference across the cell membrane |
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Term
| What is the typical value for resting membrane potential? |
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Definition
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Term
| What are the 3 major ions that are responsible for establishing the resting membrane potential? |
|
Definition
| sodium, potassium and chloride |
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Term
| What is the intracellular and extracellular concentration of sodium? |
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Definition
| intracellular = 15mEq/L Extracellular = 145 mEq/L |
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Term
| What is the intracellular and extracellular concentration of potassium? |
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Definition
| intracellular = 135mEq/L Extracellular = 5mEq/L |
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Term
| What is the intracellular and extracellular concentration of Chloride? |
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Definition
| Intracellular = 8mEq/L extracellular = 110mEq/L |
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Term
| What are the relative permeabilities of the three ions of importance? |
|
Definition
| sodium = 0.05; potassium = 1.0; Chloride = 0.45 |
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Term
| What are the two main factors that contribute to Vm? |
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Definition
| 1. magnitude of the concentration gradients of ions 2. permeabilities of the membrane to ions |
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Term
| At resting Vm, which ion has the greatest permeability to the membrane? |
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Definition
| potassium (1.0) then chloride(0.45) then sodium (0.05) |
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|
Term
| What maintains the concentration gradient needed to establish Vm? |
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Definition
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|
Term
| What causes the range in values of Vm for different excitable cells? |
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Definition
| Different cells are under different concentrations of ions and different permeabilities |
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Term
| What dictates the movement of ions into and out of the cell? |
|
Definition
| The electrochemical gradient |
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Term
| Describe how the electrochemical gradient influences the movement of sodium? |
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Definition
| electrical - positively charged sodium is attracted to negative Vm; Chemical - large concentration gradient for sodium to move into the cell |
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Term
| Describe how the electrochemical gradient influences the movement of potassium? |
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Definition
| Electrical - positively charged K+ is attracted to negative Vm; Chemical - Large concentration gradient for K+ to move OUT of the cell |
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Term
| Describe how the electrochemical gradient influences the movement of Chloride? |
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Definition
| Electrical - Negatively charged Cl- is repulsed by negative Vm; Chemical - large concentration gradient for Cl- to move into the cell |
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Term
| What would be the effect to resting Vm if you increase extracellular Na+? |
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Definition
| Causes Vm to become more positive (depolarization) |
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|
Term
| What would be the effect to resting Vm if you increase extracellular K+? |
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Definition
| Causes Vm to become more positive (depolarization) |
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Term
| What would be the effect to resting Vm if you increase extracellular Cl-? |
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Definition
| Causes Vm to become more negative (hyperpolarization) |
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Term
| What would be the effect to resting Vm if you Decrease extracellular Na+? |
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Definition
| Causes a hyperpolarization |
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|
Term
| What would be the effect to resting Vm if you Decrease extracellular K+? |
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Definition
| Causes a hyperpolarization |
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|
Term
| What would be the effect to resting Vm if you Decrease extracellular Cl-? |
|
Definition
|
|
Term
| What would be the effect to resting Vm if you increase intracellular Na+? |
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Definition
| Causes a hyperpolarization |
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|
Term
| What would be the effect to resting Vm if you increase intracellular K+? |
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Definition
| Causes a hyperpolarization |
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|
Term
| What would be the effect to resting Vm if you increase intracellular Cl-? |
|
Definition
|
|
Term
| What would be the effect to resting Vm if you decrease intracellular Na+? |
|
Definition
|
|
Term
| What would be the effect to resting Vm if you increase intracellular K+? |
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Definition
| causes a HYPERpolarization |
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|
Term
| What would be the effect to resting Vm if you increase intracellular Cl-? |
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Definition
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Term
| Changing the concentration of which ion will have the greatest effect on Vm? |
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Definition
| Potassium (K+) because it is the most permeable to the membrane |
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Term
| What is an action potential? |
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Definition
| This is an electrical impulse. It is local, very large and very rapid change in Vm. Occurs solely in excitable cells and is caused by the rapid movement of Na+ into the cell and K+ out. |
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Term
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Definition
| Point at which sufficient depolarization of Vm occurs to elicit an action potential (tremendous increase in the permeability of Na+ and K+) |
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Term
| What is the all or none response of an action potential mean? |
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Definition
| If threshold is met; an action potential will always be elicited. If threshold is not met; action potentials will not necessarily be met |
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Term
| Describe what happens during an action potential? |
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Definition
| An excitable cell is stimulated, depolarized and threshold is met. Voltage gated sodium chanels will open and dramatically increase the permeability of Na causing a large rapid increase in Vm. This change in Vm will cause sodium chanels to inactivate (stoping sodium coming in) and also open K+ channels causing a repolarization. Because K+ channels remain open for a period of time, you get an after hyperpolarization and then the cell returns to Vm |
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Term
| What is a refractory period? |
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Definition
| Period of time when a cell fails to respond to a stimulus of threshold intensity |
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Term
| What is the absolute refractory period? |
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Definition
| No action potentials can be elicited during this time; this is due to the fact that sodium channels are inactivated (occurs during the depolarization/repolarization phase) |
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Term
| What is the relative refractory period? |
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Definition
| Possible to elicit an action potential during this period of time. It occurs during the afterhyperpolarization phase. However, a greater stimulus is needed during this time. |
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Term
| What determines the velocity that an action potential is conducted down an axon? |
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Definition
| Fiber diameter (larger fibers are faster) and mylenation (more myelinated is faster) |
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Term
| What is continuous conduction? |
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Definition
| occurs with unmyelinated axons, action potential in one region stimulates an action potential in an adjacent region. Conduction velocity = 2 meters/sec. Unidirectional action potential is ensured by absolute refractory period |
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Term
| What dictates the frequency of action potentials? |
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Definition
| How intense the stimulation is. For example, mild pain will cause low frequency; severe pain will cause very high frequency |
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Term
| What is a synapse and what are the 2 types? |
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Definition
| Junction between two cells that allows communication between those two cells. Two types are 1. electrical and 2. chemical |
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Term
| What is an electrical synapse? |
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Definition
| communication between two cells via gap junctions. These gap junctions are formed by connexins (a 6 subunit pore forming protein) |
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Term
| What is a Chemical synapse? |
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Definition
| Communication between two cells via release of chemicals. There is a pre-synaptic membrane (membrane at the synapse where AP are transmitted from), post-synaptic (membrane at the synapse where AP are transmitted to) and synaptic cleft (small gap between presynaptic and postsynaptic membranes) |
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Term
| What is a neurotransmitter? |
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Definition
| Chemicals that transmit signals from presynaptic to postsynaptic membranes. Most commonly released from synaptic vessicles at synaptic knobs. |
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Term
| How is neurotransmitter released? |
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Definition
| Action potential travels down the synaptic knob of presynaptic membrane. Causes voltage-gated calcium channels to open which increases intracellular calcium and signals for the release of neurotransmitter from synaptic vessicles. Neurotransmitter is released into synaptic cleft and binds to receptors on the post-synaptic membrane. Ions channels open in postsynaptic membrane and transmission continues. |
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Term
| What happens to neurotransmitter after it has been released while it is in the synaptic cleft (what is its fate)? |
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Definition
| it is either taken back up by the presynaptic membrane or astrocytes or it is degrades |
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Term
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Definition
| a depolarizing current that could cause the cell to reach threshold but not always |
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|
Term
|
Definition
| A hyperpolarizing current |
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Term
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Definition
| Integration of EPSP's and IPSP's; determines if there will be a change in Vm to get an action potential |
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Term
| What is temporal summation? |
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Definition
| When multiple postsynaptic potentials from the SAME SYNAPSE converge at about the same time |
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Term
| What is Spatial summation? |
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Definition
| When multiple postsynaptic potentials from DIFFERENT SYNAPSES converge at about the same time |
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Term
| What is synaptic plasticity? |
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Definition
| ability of some component of a synapse to change (either 1. change in neurotransmitter release 2. change in receptor sensitivity 3. change in the number of receptors) |
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Term
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Definition
| Very short term retention of sensory input. Information that is scanned, evaluated and acted upon. Lasts less than a second and is electrical in nature |
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Term
| What is a short-term memory? |
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Definition
| Last seconds to minutes and most likely is electrical in nature |
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Term
| What is a long-term memory? |
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Definition
| Lasts hours and as long as a lifetime. Synaptic in nature (i.e. synaptic plasticity). Results in long term potentiation that enhances the neurotransmitter release, enhances receptor sensitivity and increases the number of receptors |
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Term
| What are the 2 types of long term memory and describe each? |
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Definition
| 1. declarative/explicit - retention of events, people, places, facts etc... stored in various parts of the cerebrum. 2. Procedural/implicit - development of skills. stored in cerebrum and cerebellum. conditioned reflexes (pavlovs dogs). |
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Term
| Where are acetlycholine receptors located? |
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Definition
| Throughout the CNS and PNS |
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Term
| Are Acetylcholine receptors excitatory or inhibitory? |
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Definition
| Both; it is dictated by the postsynaptic membrane |
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Term
| What disease is associated wtih the loss of cholinergic (acetylcholine) receptors? How is it treated? |
|
Definition
| Alzheimers - this can be tre |
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Term
| What are the 3 types of monoamine neurotransmitters? |
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Definition
| 1. dopamine 2. norepinephrine 3. serotonin/5-HT |
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Term
| Is dopamine excitatory or inhibitory? |
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Definition
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Term
| Where is dopamine primarily used? |
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Definition
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|
Term
| What 4 things is dopamine used for? |
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Definition
| Movement, attention, motivation and pleasure |
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Term
| What is the result of high levels of dopamine being released? |
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Definition
| linked to tourette's, schizophrenia and psychosis. One would treat with a dopamine receptor antagonist (phenothiazines) |
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Term
| What is the result of low levels of dopamine being released and how would you treat for thes things? |
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Definition
| Linked to depression (treat with reuptake inhibitors like wellbutrin). Linked to addictive behavior (like smoking) and you would treat with a reuptake inhibitor like zyban. Also linked to attention deficit disorder and you would treat with a reuptake inhibitor like ritalin. |
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Term
| What happens if dopamin producing cells die and how is this treated? |
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Definition
| Results in parkinson's disease and is traditionally treated with levodopa (l-dopa) which is a precursor to dopamine |
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Term
| Is Norepinephrine excitatory or inhibitory? |
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Definition
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Term
| What is norepinephrine important for in the body? |
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Definition
| affects mood and attention |
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Term
| What happens if you have low levels of norepinephrine and how would you treat this? |
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Definition
| low levels linked to attention deficit disorder and you would treat with a norepinephrine reuptake inhibitor like ritalin. Also linked to depression and you would treat with a norepinephrine reuptake inhibitor like wellbutrin. |
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Term
| What is the effect of serotonin/5-HT? |
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Definition
| this is the "feel good" neurotransmitter |
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|
Term
| Where is serotonin/5-HT found; where is it used? |
|
Definition
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Term
| What is serotonin/5-HT important for? |
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Definition
| Regulating temperature, sleep, mood and appetite |
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Term
| What are low levels of serotonin/5-HT linked to and how is it treated? |
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Definition
| linked to depression and treated with a selective serotonin reuptake inhibitor (SSRI). Also may be linked to sudden infant death syndrome. |
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Term
| What is the effect of the drug ecstasy (or E) on serotonin/5-HT? |
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Definition
| Causes massive serotonin/5-HT secretion and inhibits serotonin reuptake. Long term use can stop natural serotonin production |
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Term
| What are the 3 types of amino acid neurotransmitters? |
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Definition
| 1. glutamate 2. GABA and 3. Glycine |
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Term
| Where is glutamate found/used in the body? |
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Definition
|
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Term
| Is glutamate excitatory or inhibitory? |
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Definition
| it is the major excitatory hormone of the CNS |
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Term
| What is glutamate important for in the body? |
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Definition
| Thought to be involved in learning and memory |
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Term
| What is the effect of high levels of glutamate in the body? |
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Definition
| Thought to be involved in seizures and neural degeneration. Treated with drugs that block glutamate receptors |
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|
Term
| What recreational drug blocks glutamate receptors and what is the effect? |
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Definition
| PCP/angel dust will block glutamate receptors and cause hallucinations |
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|
Term
| Where is GABA found/used in the body? |
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Definition
|
|
Term
| Is it excitatory or inhibitory? |
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Definition
| Major inhibitory neurotransmitter of the CNS |
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|
Term
| Drugs that increase GABA are used to treat what? |
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Definition
| Epileptic activity (GABAergic drugs) |
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Term
| The death of GABA-producing cells results in what disease and how would you treat this? |
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Definition
| Huntingtons's disease would be treated with GABAergic drugs |
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Term
| Where is Glycine used/found in the body? |
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Definition
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|
Term
| Is it an inhibitory or excitatory neurotransmitter? |
|
Definition
| Inhibitory neurotransmitter of the CNS |
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|
Term
| What are the 3 types of neuropeptide neurotransmitters? |
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Definition
| 1. endorphins 2. enkephalins and 3. substance P |
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Term
| Where are the neuropeptide neurotransmitters found/used in the body? |
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Definition
| Throughout the CNS and PNS |
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|
Term
| Are the endorphins and enkephalins excitatory or inhibitory? |
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Definition
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|
Term
|
Definition
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|
Term
| What two major drugs act on endorphins and enkephalins receptors in the body? |
|
Definition
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|
Term
|
Definition
| Used to treat opiod overdoses in the body by countering depression of the CNS |
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Term
| Is substance P excitatory or inhibitory? |
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Definition
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|
Term
| What physiological processes does substance P regulate in the body? |
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Definition
| pain, anxiety, nausea and breathing |
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|
Term
| What is the effect of inhibiting substance P in the body? |
|
Definition
| prevents nausea and reduces pain |
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|
Term
| What are the two types of gaseous neurotransmitters? |
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Definition
| Nitric oxide and carbon MONOxide (CO not CO2) |
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|
Term
| Can gaseous neurotransmitters be stored? |
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Definition
| No, they are produced as they are needed |
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|
Term
| Where is nitric oxide found/used in the body? |
|
Definition
| Throughout the CNS and PNS |
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|
Term
| Is nitric oxide excitatory or inhibitory? |
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Definition
|
|
Term
| What processes is nitric oxide involved in? |
|
Definition
| Memory specifically, but also plays a role in erection, blood vessel tone, and neurotransmitter release to name a few |
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|
Term
| Where is Carbon MONOxide found/used in the body? |
|
Definition
| Throughout the CNS and PNS |
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|
Term
| Is Carbon MONOxide neurotransmitter excitatory or inhibitory? |
|
Definition
|
|
Term
| What is the function of Carbon MONOxide neurotransmitter? |
|
Definition
| similar in function to nitric oxide... It is also thought to be a co-neurotransmitter with nitric oxide. |
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|
Term
| Which Neurotransmitters are used only in the CNS? |
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Definition
| The amino acid neurotransmitters (glutamate, GABA and glycine), Dopamine and serotonin/5-HT. All other neurotramsmitters are used throughout the CNS and the PNS. |
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|
Term
| Which neurotransmitters are only excitatory or inhibitory? |
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Definition
| Excitatory - glutamate, substance P; Inhibitory - GABA, Glycine and teh endorphins and enkephalins. All others can be excitatory or inhibitory depending on the circumstances or the post-synaptic membrane. |
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|
Term
| Which neurotransmitter is released at the neuromuscular junction? |
|
Definition
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