| 6363489749 | Neurons | - Nerve cells that transfer information within the body.
- Communication→long distance electrical signals & short distance chemical signals. |  | 0 |
| 6363489750 | Cell body | - Consists if a neuron's organelles (including nucleus) | | 1 |
| 6363489751 | Dendrites | - Branchlike parts of a neuron that are specialized to receive information.
- Receive signals from other neurons. | | 2 |
| 6363489752 | Axon | - An extension of the neuron that transmits signals to other cells.
- Axon hillock →where cells signals that ravel down the axon are generated. | | 3 |
| 6363489753 | Synapse | - A junction where information is transmitted from one neuron to the next. | | 4 |
| 6363489754 | Synaptic terminal | - The part of each axon branch that forms the synapse | | 5 |
| 6363489755 | neurotransmitters | - Chemical messengers that pass information from the transmitting neuron to the receiving cell. | | 6 |
| 6363489756 | Presynaptic cell | - The transmitting neuron | | 7 |
| 6363489757 | Postsynaptic cell | - The neuron, muscle or gland cell that receives the signal. | | 8 |
| 6363489758 | glia | - Cells in the nervous system that support, nourish, and protect neurons.
- Sometimes function in replenishing certain groups of neurons and in transmitting information. | | 9 |
| 6363489759 | 3 stages of Information processing | 1. Sensory input, 2. Integration, and 3. motor output. | | 10 |
| 6363489760 | Sensory neurons | - Transmit information to processing centers in the brain or ganglia.
- Detect external stimuli (light, touch) & internal stimuli (blood pressure).
- They integrate the sensory input. |  | 11 |
| 6363489761 | Interneurons | - Neurons which form the local circuits connecting neurons in the brain.
- Majority of neurons in the brain. | | 12 |
| 6363489762 | Motor neurons | - Transmit signals to muscle cells & cause them to contract. | | 13 |
| 6363489763 | Central Nervous System | - Includes the brain and a longitudinal nerve cord. | | 14 |
| 6363489764 | Peripheral nervous system | - A division of the nervous system consisting of all nerves that are not part of the brain or spinal cord. | | 15 |
| 6363489765 | Nerves | - Bundles of neurons. | | 16 |
| 6363489766 | Membrane potential | - A measurable difference in electrical charge between the cytoplasm (negative ions) and extracellular fluid (positive ions)
- Inputs from other neurons or specific stimuli cause changes in the neuron's membrane potential that act as signals, transmitting information.
- Largely due to ion channels. | | 17 |
| 6363489767 | Resting potential | - Membrane potential for a resting neuron.
- Usually between -60 and -80 mV.
- Net flow of each ion across the membrane →K+ & Na+ currents are equal and opposite. | | 18 |
| 6363489768 | Sodium-potassium pump | - Na+ and K+ gradient are maintained.
- Uses energy from ATP hydrolysis→ 3 Na+ out and 2 K+ in (resulting voltage only a difference of a few millivolts). |  | 19 |
| 6363489769 | Ion Channels | - Pores formed by clusters of specialized proteins that span the membrane.
- Ions diffuse through channels & carry with them units of electrical charge→net movement of positive/negative charge generates a membrane potential. | | 20 |
| 6363489770 | Potassium Channel | - Have selective permeability→allow only certain ions to pass and thus convert chemical potential energy from concentration gradients of K+ and Na+ to electrical potential energy.
- Allows K+→140 mM inside and 5mM outside (favors outflow of K+ )
- Resting neuron →many open potassium channels but few sodium, K+ outflow →net negative charge. | | 21 |
| 6363489771 | Equilibrium potential | - The magnitude of the membrane voltage at equilibrium for a particular ion. |  | 22 |
| 6363489772 | Gated ion channels | - Ion channels that open or close in response to stimuli.
- Responsible for changes in the membrane potential →Alters the membranes permeability to particular ions and thus alters the membrane potential. | | 23 |
| 6363489773 | Hyperpolarization | - Increase in the magnitude of the membrane potential that makes the inside of the membrane more negative.
-Resting neuron →this results from any stimulus that increases the outflow of positive ions or inflow of negative ions. | | 24 |
| 6363489774 | Depolarization | - A reduction in the magnitude of the membrane potential.
- Often involves gated sodium channels →if they open in a resting neuron, the membrane's permeability to Na+ increases & Na+ diffuses in which causes a depolarization. | | 25 |
| 6363489775 | Graded potential | - Response to hyper polarization or depolarization that causes a shift in the membrane potential.
- large stimulus → greater change in membrane potential.
- Induce a small electrical current that leaks out of the neuron as it flows along the membrane.
- Decay with distance from their source. | | 26 |
| 6363489776 | Action potential | - A massive change in membrane voltage caused by depolarization.
- Constant magnitude & can regenerate (can spread along axons).
- All-or-none response to a stimuli.
- Rate at which they are produced conveys information about the strength of the input signal. | | 27 |
| 6363489777 | Voltage-gated ion channels | - Ion channels in neurons that open or close when the membrane potential passes a particular level.
- If depolarization opens→ flow of Na+ into the neuron results in further depolarization (result: positive feedback that triggers rapid opening of many voltage-gated sodium channels & change in membrane potential that defines an action potential). | | 28 |
| 6363489778 | Threshold | - The level of stimulation required to trigger a neural impulse.
- Many mammalian neurons →threshold is -55 mV | | 29 |
| 6363489779 | Refractory period | - The downtime when a second action potential cannot be initiated is called.
- Limits the maximum frequency at which the action potentials can be generated.
- Ensures that ensures that all singles in an anon travel in one direction ,from the cell body to the axon terminals.
- Due to the inactivation of sodium channels. | | 30 |
| 6363489780 | Axon hillock | - Site where an action potential is initiated.
- Action potential that starts here moves along the axon toward the synaptic terminals.
- Neuron's integrating center →region where the membrane potential at any instant represents the summed effect of all EPSPs and IPSPs. | | 31 |
| 6363489781 | Conduction of an action potential | 1. An action potential is generated as Na+ flows inward across the membrane at one location.
2. Depolarization of an action potential spreads to neighboring region of the membrane (reinitiating the action potential there). To the left of this region, the membrane is repolarizing as K+ flows outward.
3. Depolarization-repolarization process is repeated in the next region. Local currents of ions across the plasma membrane cause the actin potential to be propagated along the length of the axon. |  | 32 |
| 6363489782 | Evolutionary adaptations- Axon structure | - Wider axon →provides less resistance to the current associated with an action potential than does a narrow axon.
- Electrical insulation →causes the depolarization current associated with an action potential to spread farther along the axon interior, bringing more distant regions to the threshold sooner. | | 33 |
| 6363489783 | Myelin Sheath | -Electrical insulation that surrounds vertebrate axons.
- Produced by 2 types of glia: *oligodendrocytes* in the CNS & *Schwann cells* in the PNS (wrap axons in layers of membrane). | | 34 |
| 6363489784 | Nodes of Ranvier | - Gaps in the myelin sheath to which voltage-gated sodium channels are confined. | | 35 |
| 6363489785 | Saltatory conduction | - Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane.
- Action potentials are not generated at nodes of ranvier & inward occurrent produced during rising phase of action potential at a node travels to the next node, where it depolarizes the membrane & regenerates the action potential. | | 36 |
| 6363489786 | Myelination | - The process by which axons become coated with myelin, a fatty substance that speeds the transmission of nerve impulses from neuron to neuron.
- Advantage: space efficiency | | 37 |
| 6363489787 | Electrical synapses | - Contain gap junctions which allow electrical current to flow from one neuron to another.
- Synchronize the activity of neurons responsible for rapid, unvarying behaviors. | | 38 |
| 6363489788 | Chemical synapses | - Involve the release of a chemical neurotransmitter by the synaptic neuron.
- At each terminal, presynaptic neuron synthesizes the neurotransmitter and packs it into synaptic vesicles.
- Action potential at a synaptic terminal →depolarizes plasma membrane, allowing Ca2+ to diffuse in thru channels and synaptic vesicle fuse with the terminal membrane releasing a neurotransmitter which diffuses across *Synaptic cleft* | | 39 |
| 6363489789 | Ligand-gated ion channel | - Type of membrane receptor that has a region that can act as a "gate" when the receptor changes shape.
- Inotropic receptor
- Clustered in the membrane of the postynaptic cell, opposite the synaptic terminal. | | 40 |
| 6363489790 | Excitatory postsynaptic potential | - Membrane potential that occurs because of the influx of Na+ through chemically gated channels in the receptive region of a neuron.
- Brings the membrane potential towards threshold. | | 41 |
| 6363489791 | Inhibitory postsynaptic potential | - A postsynaptic potential that hyperpolarizes the neuronal membrane, making a cell less likely to fire an action potential.
- Moves the membrane farther from threshold. | | 42 |
| 6363489792 | Temporal summation | - Two ESPSPS occur at a single synapse in such rapid succession that the postsynaptic neuron's membrane potential has not returned to the resting potential before the arrival of the second EPSPS.
- EPSPS add together | | 43 |
| 6363489793 | Spatial summation | - EPSPs produced nearly simultaneously by different synapses on the same postsynaptic neuron can add together and create this. | | 44 |
| 6363489794 | Modulate Signaling at Synapses | - Neurotransmitter binds to a metabotropic receptor which activates a signal transduction pathway in the postsynaptic cell involving a second messenger.
- SEcond messengers modulate the responsiveness of postsynaptic neurons to inputs in diverse ways.
- Signal transduction pathways play a role in modulating synaptic transmission. | | 45 |
| 6363489795 | Acetylcholine | - A common neurotransmitter in both invertebrates and vertebrates.
- Vital for nervous system functions that include muscle stimulation, memory formation and learning.
- A metabotropic acetylcholine receptor is found alt locations that include the vertebrate CNS and heart.
- Toxins disrupt neurotransmission by acetylcholine →sarin inhibits acetylcholinesterase and causes a buildup of acetylcholine to levels that trigger paralysis & death. | | 46 |
| 6363489796 | Neuromuscular junction | - The site where a motor neuron forms a synapse with a skeletal muscle cell.
- Acetylcholine released by motor neurons binds this receptor, ion channel opens producing an EPSP.
- Excitatory activity is terminated by acetylcholinesterase. | | 47 |
| 6363489797 | Glutamate | - Amino acid that acts as a neurotransmitter.
- In invertebrates →neurotransmitter at neuromuscular junction. | | 48 |
| 6363489798 | gamma-aminobutyric acid | - Amino acid that is a neurotransmitter at most inhibitory synapses in the brain.
- Binding of GABA to receptors in postsynaptic cells →increases membrane permeability to Cl-→IPSP.
- Valium reduces anxiety through binding to a site on a GABA receptor. | | 49 |
| 6363489799 | Biogenic amines | - Neurotransmittes that are synthesized from amino acids and include norepinephrine (made of tyrosine).
- Role in many nervous system disorders and treatments. | | 50 |
| 6363489800 | Dopamine | - Biogenic amine made from tyrosine.
- Parkinson's is associated with a lack of dopamine in the brain. | | 51 |
| 6363489801 | Serotonin | - Biogenic amine made from tryptophan.
- Prozac enhances the effect of serotonin by inhibiting its repute after release. | | 52 |
| 6363489802 | Neuropeptides | - Relatively short chains of amino acids.
- Many serve as neurotransmitters that operate via metabotropic receptors. | | 53 |
| 6363489803 | Endorphins | - Neuropeptides that function as natural analgesics, decreasing pain perception.
- Produced during times of stress.
- Reduce urine output, decrease respiration and produce euphoria. | | 54 |
| 6363489804 | Gases | - Some vertebrate neurons release dissolved gases that act as local regulators.
- Human males →certain neurons release NO into the erectile tissue of the penis during sexual arousal. | | 55 |
