Term
| Is the sensory system afferent or efferent? |
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Definition
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Term
| What two components of the CNS are efferent? |
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Definition
| Somatic motor system & autonomic motor system |
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Term
| What portion of the autonomic nervous system is responsible for 'fine tuning' when the body is at rest? |
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Definition
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Term
| What portion of the autonomic nervous system is responsible for a rapid response during critical situations? |
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Definition
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Term
| What two types of cell make up nervous tissue? |
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Definition
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Term
| What components make up a neuron, and what do they do? |
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Definition
Axon - info moves away from the cell body
Dendrite - info move towards the cell body
Cell body - integrates incoming & outgoing information |
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Term
| How are neurons classified? |
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Definition
| Based on the number of processes and also by function |
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Term
| What are the classifications of neurons in regards to number of processes, and where are they found? |
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Definition
Multipolar (mainly in CNS)
Pseudomultipolar (mainly in CNS)
Bipolar (in sensory organs) |
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Term
| What are the classifications of neurons in regards to function, and what do each do?? |
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Definition
Sensory (from PNS to CNS)
Motor (from CNS to muscles & glands)
Interneurons (relay info between neurons in CNS)
Transducers (convert stimuli to signals) |
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Term
| What are the functions of glial cells? |
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Definition
-provide structural support
-assist in myelin formation (oligodendrocytes)
-secrete glutamate to regulate excitation (astrocytes)
-phagocytosis (microglia)
-transport nutrients & waste between blood vessels & neurons |
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Term
| Is grey matter composed of fibers or cell bodies? |
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Definition
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Term
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Definition
| clusters of sensory neuron cell bodies |
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Term
| Are cell bodies of motor nerves found inside or outside the CNS? |
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Definition
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Term
| How are myelin sheaths formed? |
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Definition
| glial cells wrap around an axon, cytoplasm is lost, leaving only layers of lipids |
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Term
| What is the function of myelin sheaths? |
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Definition
| -insulation, preventing loss of electrical activity, speeds up transmission process |
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Term
| Are myelin sheaths found in grey or white matter? |
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Definition
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Term
| What are nodes of Ranvier? |
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Definition
| interruptions in the myelin sheath which allow depolarisation, speeding up transmission of AP |
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Term
| Why do all cell membranes have a resting membrane potential? |
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Definition
| there is a difference in charge across the cell membrane, particularly unequal distribution of Na+ and K+ across the membrane |
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Term
| At RMP, is the inside of the cell negative or positive relative to the outside of the cell? |
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Definition
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Term
| What is the average RMP in nerve cells? |
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Definition
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Term
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Definition
1. Selective permeability
2. Na+/K+ pump
3. Large anions trapped on inner surface of mmb |
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Term
| For every ___ Na+ going out, ___ K+ come in |
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Definition
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Term
| What causes positive charges to accumulate outside of the membrane? |
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Definition
membrane is highly permeable to K+, can diffuse passively
Na+, Ca2+ and Cl- cannot move so freely |
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Term
| Why does the Na/K ion pump require a lot of energy? |
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Definition
-pumping ions against the concentration gradient
-pumping Na+ against the electric polarity of the membrane |
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Term
| What effect do chemical/electrical/physical stimulations have on the membrane of excitable cells? |
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Definition
| -increase Na+ or Ca2+ permeability via opening of gated channels |
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Term
| What happens in depolarization? |
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Definition
-channels open
-Na+ rushes inside
-mmb potential becomes less negative, and then eventually positive |
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Term
| What happens in repolarization? |
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Definition
-K+ gated channels open
-K+ flows out, returning the mmb potential to RMP |
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Term
| What is an action potential? |
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Definition
| a wave of depolarization moving along the membrane |
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Term
| What is hyperpolarization? |
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Definition
| -K+ gated channels close more slowly, so the outflow of K+ continues even after RMP is reached |
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Term
| Describe the action of the two gates of the Na+ channel |
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Definition
| -when resting, 'activation' gate is closed, 'inactivation' gate is open -depolarization causes activation gate to open -after short delay, inactivation gate closes -repolarization causes activation gate to close, inactivation gate reopens more slowly This creates a refractory period |
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Term
| Where does the AP generation occur in myelinated axons? |
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Definition
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Term
| What is the term for the jumping of electrical current from one node to another? |
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Definition
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Term
| What is the synaptic cleft? |
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Definition
| gap between pre & post -synaptic cell membranes, where chemical synapse occurs |
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Term
| What is the synaptic gap? |
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Definition
| similar to synaptic cleft, but continuity is directly from electrical impulse (in cardiac & smooth muscle cells) |
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Term
| What are neurotransmitters? |
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Definition
| molecules which convert the electrical signal from an AP into a chemical signal which elicits a response when it binds to a receptor on the post-synaptic membrane |
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Term
| What are the 2 classifications of tneurotransmitters? |
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Definition
Small molecules
-synthesized at the nerve terminals
-derivatives of AAs
Neuropeptides
-synth. in cell body, transported to site of release |
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Term
| Describe synaptic transmission at a neuromuscular synapse |
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Definition
1. AP opens Ca2+ channels
2. Ca2+ flow in, triggers exocytosis
3. Acetylcholine diffuse into cleft, binds to receptors
4. Ion channels on post-synaptic mmb open (depolarization)
5. Degradation of acetylcholine to terminate signal transmission |
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Term
| How is termination of transmission achieved in the case of small molecules? |
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Definition
-they are picked back up at presynaptic neuron via endocytosis
-deactivate by enzymes e.g. acetylcholinesterase |
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Term
| How is termination of transmission achieved in the case of neuropeptides? |
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Definition
-can be internalized by post-synaptic membrane via endocytosis
-broken down by peptidases |
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