Test Answers on Neurochemistry Terms

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what is neuroplasticity
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the brain’s ability to reorganize itself by forming new connections between dendrites; changes in the spine/thorn morphology of the dendrites are associated with learning and memory.
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What is the function of the hypothallamus?
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Responsible for regulating basic biological needs: hunger, thirst, temperature control
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what is the function of the cerebrum?
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aka the cerebral cortex, which is the outer later of grey matter; responsible for sensing, thinking, learning, emotion, consciousness and voluntary movement.
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what is the function if the corpus callosum
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bridge of fibers passing information between the two cerebral hemispheres
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what is the function of the thalamus ?
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the relay center for the cerebral cortex/cerebrum; handles incoming and outgoing signals
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what is the function of the hippocampus?
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part of the limbic system involved in learning and memory
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what is the function of the pituitary gland?
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The pituitary gland is the master gland that regulates other endocrine glands. The pituitary gland releases oxytocin and vasopressin
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what is the function of the pons?
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The pons is involved in sleep and arousal
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what is the function of the midbrain?
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The midbrain controls Eye movement and auditory and visual reflexes
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what parts of the brain make up the brainstem
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The brainstem is made up of the pons, medulla and midbrain
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what is the function of the limbic system and what parts of the brain does it include?
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The limbic system is made up of the amygdala the thalamus, the hypothalamus and the hippocampus. The limbic system is the emotional brain which is concerned with behavior and emotional expression as well as learning and memory processes
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what is the function of the medulla
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The medulla is responsible for regulating largely unconscious functions such as breathing and circulation
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what is the function of the reticular formation
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The reticular formation is a group of fibers that carry stimulation related to sleep and arousal through the brainstem. the reticular formation serves as a filter and is inhibited by psychedelics
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what is the function of the spinal cord
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The spinal cord is responsible for transmitting information between the brain and the rest of the body. the spinal cord handles simple reflexes
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what is the function of the cerebellum
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The cerebellum is the structure that ordinates fine muscle movement and balance
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what is the amygdala
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The amygdala is the part of the limbic system involved in emotion and aggression
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what is the function of the central nervous system and what makes up the central nervous system
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The CNS is made up of the brain and spinal cord. the central nervous system functions as an integrative (spinal cord) and control (brain) center
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what is the function of the peripheral nervous system and what does it include
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The peripheral nervous system allows for communication between the central nervous system and the rest of the body. The cranial and spinal nerves make up the peripheral nervous system; the peripheral nervous system contain ganglia.
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what are the two branches of the peripheral nervous system
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The peripheral nervous system includes the autonomic nervous system and the somatic nervous system
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what is the autonomic nervous system
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The autonomic nervous system is the visceral motor system and controls involuntary nervous movements. The autonomic nervous system conducts impulses from the central nervous system to cardiac muscles smooth muscles and glands
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what is the somatic nervous system
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The somatic motor system is the voluntary motor system. It conducts impulses from the central nervous system to the skeletal muscles
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what are the two divisions of the autonomic nervous system? Is there a third?
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The autonomic nervous system is divided into the sympathetic division and the parasympathetic division however there is also an enteric division
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describe the sympathetic division
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The sympathetic division is part of the autonomic nervous system of the peripheral nervous system. The sympathetic division controls fight or flight responses and mobilizes the body system during activity
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describe the parasympathetic division
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The parasympathetic division is a division of the ANS of the PNS. The parasympathetic division controls rest and digest reflexes. It conserves energy, and promotes housekeeping functions during rest
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describe the enteric division
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the enteric division is part of the autonomic nervous system. There are two types of neurons in the enteric division. Sensory neurons are neurons that control mechanical and chemical conditions. Motor neurons control peristaltic contractions. The enteric division is part of the gut
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what are the six primary responses of the parasympathetic nervous system
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1. stimulates flow of saliva 2. lowers the heartbeat 3. constricts bronchi 4. stimulates peristalsis and secretion 5. stimulates release of bile 6. contracts bladder
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what are the seven main function of the sympathetic nervous system
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1. Dilate pupils 2. inhibits flow of saliva 3. accelerates heartbeat 4. dilates bronchi 5. inhibits peristalsis and secretion 6. conversion of glycogen to glucose 7. secretion of adrenaline and noradrenaline 8. inhibits bladder contraction
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what does the occipital lobe control
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vision
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what does the cerebellum control
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balance and coordination
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what does afferent mean
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neurons that carry signals to the central nervous system for processing. For example sensory neurons
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what did efferent mean
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neurons they carry signals from the central nervous system to the peripheral nervous system or two peripheral tissue. These neurons create a response
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what is a sensory neuron
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an afferent neuron; the connects impulses from receptors to the sensory nervous system, impulses include touch, pain, heat, etc.
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what is a motor neuron
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an efferent neuron that conducts impulses from the CNS to effector organs i.e. muscles
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what are the three main components of a neuron
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The cell body or soma, the dendrites, and the axon
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describe the cell body. what are the main functions of the cell body?
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the cell body is the control center of the neuron; it contains organelles and a phospholipid bilayer with integral proteins; the cell body makes proteins for other parts of the neuron.
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describe the phospholipid bilayer
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the phospholipid bilayer is a powerful insulator that contains many proteins, which are electronically active, such as the voltage gated ion channels.
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what are dendrites?
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dendrites receive incoming singles; they are branch like structures that protrude from the cell body and collect incoming signals from other neurons and transfer them to the soma
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what are dendritic spines?
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dendritic spines, or thorns, are small membrane protrusions of a neurons’s dendrite that receive input.
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describe the axon
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the axon transmits the outgoing electrical signal from the integration center to the end of the axon; axons can vary in length and can branch out, which are called axon “collaterals” or “branches.’
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what are the three segments of an axon?
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the axon hillock, the axon proper and the axon terminal
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what is the axon hillock?
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the axon hillock is the initial portions that comes out of the cell body – called the axon initial segment – where the action potential (aka nerve signal) is initiated
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what is the axon proper?
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the axon proper is the middle segment of the axon
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what is the axon terminal?
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the axon terminal, aka the presynaptic terminal, is the terminal where the axon meets its target; houses NT and can contain 40-50 synaptic vessicles
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what is long term potentiation?
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long term potentiation is a long lasting enhancement in signal transmission (interneuronal communication) affected by dendritic spines and an increase in interneuronal connections
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what is long term depression?
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long term depression is a reduction in the efficacy of neuronal synapses; LTD is one of several processes that serves to selectively weaken specific synapses in order to make constructive use of synaptic strengthening caused by LTP. This is necessary because, if allowed to continue increasing in strength, synapses would ultimately reach a ceiling level of efficiency, which would inhibit the encoding of new information
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what are the three types of neurons?
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sensory neurons (afferent), motor neurons (efferent), and interneurons
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describe interneurons
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interneurons are responsible for the coordination and integration of sensory input and motor output, entirely in the central nervous system, except enteric interneurons
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what is a preganglionic neuron?
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fibers from the central nervous system to the ganglion; the cell body is located in the central nervous system (brain stem or spinal cord) and the preganglionic neuron makes synaptic connections in the ganglia.
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what are the ganglia?
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ganglia are aggregates of nerve cell bodies in the peripheral nervous system
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what is the neurotransmitter at the preganglionic synapse?
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acetylcholine
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what is the neurotransmitter at the post-ganglionic synapse for parasympathetic response? sympathetic response?
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parasympathetic = acetylcholine, rest and digest sympathetic = norepinephrine and epinephrine and acetylcholine
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diagram autonomic pathways
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CNS -preganglionic neuron ->Autonomic ganglion -postganglionic neuron -> Target tissue NT are released from the preganglionic neuron (ACh) and the postganglionic neuron (ACh, NE, E)
question

what are glial cells?
answer

glial cells are non neuronal cells. they are any cells that do not directly participate in synaptic interactions and electrical signaling, but have supportive functions for it and help define and maintain the signaling abilities of a neuron; they help hold our nervous system together functionally and they outnumber neurons.
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what is a synapse
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the site of interneuronal communication
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what is a neurotransmitter?
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the chemical messenger for interneuronal communication
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what is a myelinated axon?
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allows nerve impulses to transmit faster; axon is covered in a myelin sheath made up of lipids, proteins, and sphingolipids produced by cells called schwann cells
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what is a myelin sheath? what are the 3 things that make up the myelin sheath?
answer

helps speed up the signal, prevents loss of signal, aids in signal transmission, prevents ion leakage; lipids are cholesterol, sphingomyelin and cerebroside; made up of 75% lipid and 15% protein
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what are the nodes of ranvier?
answer

the tiny segments of the axon that are exposed after wrapping up of the axon by the schwann cells; we see a high concentration of voltage-gated sodium channels at the nodes of ranvier; excitable patches of the membrane; contain large amount of Nav, Kv, and Na/K-ATPases
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what is the resting cell potential? intracellular ion?
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-70mV, K
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what is white matter?
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myelinated neurons
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what is grey matter?
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nerve cell bodies and dendrites; unmeylinated axons
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what are schwann cells?
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these make up the myelin sheath for the axon, which insulate axons to form white matter; in the PNS
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what are satellite cells?
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nonmyelinating schwann cells, encapsulate neurons and form supporting capsules around them; in the PNS
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what are the two types of glia cells in the PNS?
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schwann cells and satellite cells
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what are the four types of glia in the CNS?
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oligodendrocytes; astrocytes; microglial cells; ependymal cells
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what are oligodendrocytes?
answer

CNS analogy to Schwann cells; form myelin sheaths around the axons of the CNS
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what are astrocytes? what are their three main functions?
answer

starlike, highly branched cells in CNS; make up œ of the cells in the brain, 3 main functions: i) take up and release chemicals; ii) take up extracellular K+; iii) feet-like structures surround the blood brain barrier and tighten the barrier, which helps protect the brain from chemical trauma
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what are microglial cells?
answer

macrophages; immune system cells, help digest dead neurons and engulf and digest cellular debris, in CNS
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what are ependymal cells?
answer

neural stem cells; help circulate spinal fluid and produce cerebral spinal fluid (CSF)
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what is the blood brain barrier? what can pass through it?
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serves to protect the brain from chemical injury and is a highly selective barrier that separates the blood vessels from the brain’s extracellular fluid; allows for passage of gases, water and lipophilic molecules
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what is “potential”?
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a measure of how badly one area of charge is attracted to another (volts), RMP is -70 millivolts
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what is the membrane potential?
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inside charge (V) – outside charge (V)
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what is depolarization?
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an event that makes the intracellular space more positive, and decreases the membrane potential, caused by an influx of positive ions
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what is hyper polarization?
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an event that makes the intracellular space more negative, and increases the membrane potential, caused by an outflux of positive ions or an influx of chloride
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what are ion channels?
answer

transmembrane and integral proteins that allow ions to pass from one side of the lipid membrane to the other
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what are gated channels?
answer

a specific action initiates the opening or closing of the channel, and that action usually precedes the name (i.e. a voltage gated channel, whose gate is opened or closed based on the membrane potential in volts)
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what are leak channels?
answer

not gated; continuously open and allow ions to leak across the membrane; ions flow with the concentration gradient and you find these types of channels all over the neuron
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what is the action potential?
answer

rapid electrical signals that travel undiminished in amplitude (strength) from the cell body to axon terminal; a depolarizing stimulus causes the membrane potential to rise to -55 mV, the threshold potential, and Nav open, causing an influx of Na ions; the cell depolarizes due to the influx of Na, and eventually Nav closes, while Kv opens and K moves out of the cell; the outflux of K causes a repolarization of the membrane, and Kv channels are slow to close, causing hyperpolarization, until the leak channels and Na/K-ATPase cause the return to RMP
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what are ion gated channels?
answer

opening and closing is affected by the intracellular concentrations of ions
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what are ligand gated ion channels?
answer

bind chemicals (i.e. ligands, NT or structural analogs) to extracellular receptors, causing opening or closing of channels
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what are voltage gated sodium channels? what potential causes them to open? close?
answer

voltage gated sodium channels; open at the threshold potential of -55 mV and close at the action potential of +30 mV; cause Na ions to rush into the cell
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what are voltage gated potassium channels? what potential causes them to open? close?
answer

voltage gated potassium channels; open at the action potential of +30 mV, allow K ions to rush out of the cell, would close at RMP, but are initially slow to close, so they will stay open until about -80 mV, but the leaky K channels and Na/K-ATPase will bring the cell back to RMP and the Kv will close
question

what is saltatory conduction?
answer

the propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials without needing to increase the diameter of an axon; the action potential is said to “jump” from node to node through the myelinated axon, but really it is diffusion of the sodium ions
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what is inactivation
answer

something comes in and physically blocks the pore
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what is deactivation?
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has to do with voltage and the channel requires reactivation, usually deactivation occurs when the voltage sensor has been reset during repolarization
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what is chemical transmission?
answer

the major means by which neurons communicate with one another
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what is signal transduction?
answer

a mechanism or phenomenon that converts a mechanical or chemical stimulus into a particular cellular response, i.e. the activation of an enzyme, the expression of a protein, or depolarization or hyper polarization; facilitated by receptors
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what is a receptor?
answer

transmembrane protein that accepts signal (extracellularly) and communicates it to the inside of the cell
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what is a ligand?
answer

the chemical or molecule that binds to the extracellular side of a receptor, i.e. a neurotransmitter in ionotropic receptors or a g-protein in metabotropic receptors
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what are ionotropic receptors?
answer

i.e. ligand gated ion channel receptors, which bind agonists, resulting in the opening of Na, K and Cl ion channels, resulting in depolarization or hyperpolarization
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what are metabotropic receptors?
answer

i.e. g-protein coupled receptors, coupled to a g-protein, so these receptors act on a g-protein when the g-protein agonist binds; cellular response is dictated by the g-protein the receptor is coupled to
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what are agonists?
answer

ligands that, upon binding, cause the desired cellular response
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what are direct agonists?
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bind to desired receptor and/or elicit a response
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what are indirect agonists
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does not bind directly to a receptor but still results in the desired response, or release of NT (i.e. it may block reuptake of a NT or prevent the breakdown of a NT)
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what are inverse agonists?
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bind to receptor but elicits the opposite cellular response
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what are antagonists
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ligands that bind to receptor but do not cause a change in basal level activity of the cell; counteract the affect of the agonists
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what are competitive antagonists
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compete with an agonist for the same receptor
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what are noncompetitive antagonists
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bind to allosteric site and weaken the agonists binding affinity
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what is synaptotagmin?
answer

a calcium sensing protein located on the SV
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what is synaptobrevin? it’s alternative?
answer

synaptobrevin is a vesicle associated membrane protein, alternative is VAMP
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what is syntaxin?
answer

a tSNARE protein on presynaptic membrane
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what is SNAP-25
answer

a tSNARE protein on presynaptic membrane

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