What makes up the CNS
cerebral cortex, cerebellum, brainstem, spinal cord
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| Term | Definition |
|---|---|
| What makes up the CNS | cerebral cortex, cerebellum, brainstem, spinal cord |
| Afferent neurons | info from periphery to spinal cord via dorsal roots |
| Efferent neurons | info from spinal to periphery via ventral roots |
| Types of glia & functions | Oligodendrocytes: make myelin in CNS, make Schwann cells in PNS Astrocytes: buffer K+, maintain BBB Microglia: immunity |
| Types of neurons | Bipolar, Psuedo-unipolar (aff/eff neuron), multipolar |
| What is the resting membrane potential? | -70 mv |
| Pumps vs ion channels? | Pumps: active transport Ion channels: passive or gated (ligand/voltage) |
| T/F: 3Na/2K pump requires ATP | True |
| T/F: Na wants to go inside cell | True, but 3 Na come out and 2 K come in due to conc gradient = net negative charge inside cell (which is why Na wants to come in) |
| Leak channels | - Passive flow in or out - always open - selective |
| Equilibrium potential for K | -90 mv (Eq movement = no net movement) |
| Equilibrium potential for Na | +55 mv |
| Which ion is more permeant? Na or K | K+ - the more permeant = the greater ability to force Em to its Eq potential |
| What causes depolarization | stimulus to get resting membrane to -50 mv |
| How does a neuron depolarize | - a stimulus causes voltage-gate ion channels to open and makes Na flow inside cell = less negative membrane potential |
| What is the absolute refractory period | 1. Na channels open 2. K channels open, Na is inactivating - cannot fire another AP |
| What is the relative refractory period | 1. K channels are still open, Na channels in resting state - need a strong stimulus to fire an AP |
| What causes hyperpolarization | K is going through leak channels AND OPEN voltage gated channels at the end of AP |
| Electrotonic conduction | spread of current inside axon - AP at one point, current spreads to adjacent membrane then depolarizes the next one w/ AP |
| T/F: there is myelin of the cell body and dendrites | False |
| T/F: Many Schwann cells ensheath many axons in the PNS | False, they ensheath 1 axon in the PNS |
| T/F: One Oligodendrocyte ensheath many axons in the CNS | True |
| Saltatory Conduction | AP doesn't depolarize every cell, it goes from node to node |
| Group 1 fiber type | - thickest diameter - fastest conduction |
| T/F: electrical synapses are bidirectional | True |
| Directly gate synapses | - binds - receptor channels open - ions pass through - fast, short lasting effects - receptor/effector are same molecule |
| Indirectly gated synapses | - binds - 2nd messenger system: ATP to cAMP - ions flow - slow, long effects - receptor/effector are different molecule |
| What does cAMP do? | activates protein kinases to phosphorylate = open or close channel / change permeability |
| T/F: inhibition is only possible with electrical synapses | False, inhibition is only possible with CHEMICAL synapses |
| EPSP | Na pass through |
| IPSP | Cl- or K+ pass through |
| Excitatory presynaptic neuron | glutamate binds and opens Na channels - creates EPSP - doesnt reach threshold |
| Inhibitory presynaptic neurons | GABA/glycine binds and opens Cl- channels - hyperpolarizes - creates IPSP |
| T/F: synaptic potentials decay as they travel away from synapse | True, it can only travel short distances |
| Temporal summation | PSP's from presynaptic neuron overlap and add together |
| Spatial summation | PSP's in diff regions of postsynaptic neurons are added together |
| Smooth muscle | - found in walls of hollow organs - regulates blood flow, moves food, expels urine, regulated air flow - involuntary |
| Cardiac muscle | - striated walls of heart - propels blood through heart circulatory system - involuntary |
| Skeletal muscle | - muscle attached to skeleton - voluntary control |
| Endomysium | electrically isolates muscle fibers from one another |
| Ionotropic receptors | form ion channels after ligand-binding ACh binds to nicotinic receptors |